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two different vibratory signals in rhodnius prolixus (hemiptera: reduviidae).in this study the substrate-borne stridulatory vibrations produced by rhodnius prolixus females were recorded and analysed in two different behavioural contexts. in the context of sexual communication females spontaneously stridulated to reject copulatory attempts performed by males. these male-deterring stridulations were fully effective: out of 61 attempts, no copulation occurred. these stridulations consisted of short series of repetitive syllables, each one composed by a single chirp. in the ...200011114389
[comparative study of sensitivity and mortality of triatoma infestan nymphs iii and iv used in the xenodiagnosis of chronic chagasic patients].triatoma infestans nymphs have shown a good sensitivity for detecting trypanosoma cruzi in the blood stream of infected hosts when are used in the xenodiagnosis (xd). this method, with its natural limitations, using seven nymphs iii of t. infestans, has been routinely utilized with a satisfactory yield. with the aim of an eventual improving of the yield of xd (with 7 nymphs), two series of 54 xd boxes each, containing a total of 378 nymphs iii and 378 nymphs iv respectively, were applied--one of ...200011757411
[comparison of trypanosoma cruzi infection in less than 10 years old children from the v región, chile, 1982-1995].evaluation of desinsectation programs carried out in the two health services from the v region, was undertaken by comparing serologic prevalences of t. cruzi infection age groups exposed to the risk of infection in rural areas during the antivectorial campaign activities (1982 vs 1995). thus, were studied 2,193 blood samples from children under 10 years of age, proceeding from six chagasic endemic provinces in which antitriatomic domiciliary insecticide sprayings had been performed. indirect hem ...200011757414
influence of the blood meal source on the development of triatoma infestans, triatoma brasiliensis, triatoma sordida, and triatoma pseudomaculata (heteroptera, reduviidae).the objective of this study was to determine the influence of the blood meal source on the life cycle and reproductive development of female triatoma infestans (klug, 1834), triatoma brasiliensis neiva, 1911, triatoma sordida (stal, 1859), and triatoma pseudomaculata corrga & espfinola, 1964. in all triatomine species studied the life cycle was shorter for the groups fed on mice than for those fed on pigeons, the range of differences being between 1.5 times (t pseudomaculata and t. infestans) an ...200015535580
insecticide resistance in brazilian triatoma infestans and venezuelan rhodnius prolixus.resistance levels to insecticides used in control of chagas disease vectors were assessed in two species of bugs (hemiptera: reduviidae): triatoma infestans (klug) from brazil and rhodnius prolixus stål from venezuela. the resistance ratios, compared to susceptible laboratory strains, were determined by topical application bioassays. the t. infestans pa strain exhibited resistance ratios of 7x to deltamethrin, 3.6x to beta-cyfluthrin and 3.3x to cypermethrin, but was susceptible to beta-cypermet ...200010759312
[seroprevalence of triatoma infestans chagas disease after vector control measures].the study is part of a project intended to retrieve information about the serology of the american trypanosomiasis in the state of são paulo, brazil, during the period when there was a state effort to control the vector. data from the municipality of taquarituba, administrative region of sorocaba, which was then important in the epidemiology of chagas disease in that region, were analyzed. despite the government efforts started in the 1950s, domiciliary triatomines were still being captured in t ...200010769355
comparison of feeding behaviour of triatoma infestans, triatoma brasiliensis and triatoma pseudomaculata in different hosts by electronic monitoring of the cibarial pump.feeding behaviour of triatoma infestans, t. brasiliensis and t. pseudomaculata on pigeons and mice was compared by electronic monitoring of the cibarial pump. the methodology developed permits the study detailed of triatomine feeding behaviour using an artificial feeder as well as on live hosts. t. infestans was the species that fed most rapidly on the two hosts tested (28.03+/-1.6 mg/min for pigeon and 21.33+/-1.7 mg/min for mouse), followed by t. brasiliensis (17.09+/-1.4 mg/min and 13.1+/-1.5 ...200010817838
horizontal transmission of triatoma virus through the fecal-oral route in triatoma infestans (hemiptera: triatomidae).feces from triatoma infestans (klug) infected with trv showed a large number of well-preserved viral particles when examined by electron microscopy. no viral particles were observed in suspensions of feces uninfected insects. fecal suspensions inoculated parenterally into uninfected triatomines killed the insects within 36 h, showing that infective trv is present in the feces of infected insects. it also is demonstrated that t. infestans becomes infected with trv while feeding on contaminated ch ...200010730499
absence of both circadian rhythm and trypanosoma cruzi periodicity with xenodiagnosis in chronic chagasic individuals.xenodiagnoses were performed every 3 hours using 10 triatoma infestans 3rd instar for 24 to 72 hours, in 18 chronic chagasics with positive serology and/or xenodiagnosis. there was no statistically significant difference in the positivity of assays performed during the day (9:00 to 18:00 h) compared to those performed at night (21:00 to 6:00 h), (chi 2 = 0.1526 p = 0.696). xenodiagnosis was performed in ten of the patients for 13 successive days but there was no periodicity detected in the posit ...200011064578
effects of triatoma virus (trv) on the fecundity and moulting of triatoma infestans (hemiptera: reduviidae).triatoma virus (trv) is a picorna-like virus affecting triatoma infestans (klug, 1834), the most important transmitter of trypanosoma cruzi in south america. the subjects of the present, laboratory study were the longevity and oviposition of female tri. infestans, from stocks with and without viral infection, and the survivorship and developmental time of their progeny through to second-instar nymphs. on average, adult females from an infected stock lived only a third as long as those from the u ...200011064765
[current situation with chagas disease vector control in the americas].this article identifies and describes various epidemiological aspects in the natural transmission of chagas disease in the americas. it also examines the relative importance of the principal vector species in the disease's transmission and the control levels that are feasible in each instance. estimations of the population at risk, number of infected cases, and number of chronic cases are presented. prospects for control are discussed on the basis of past results to predict the expected results ...200011119318
interaction of visual and olfactory cues in the aggregation behaviour of the haematophagous bug triatoma infestans.we analysed how the assembling behaviour of triatoma infestans is modulated by the convergence of chemical cues released by their faeces and the spectral quality of the light associated with refuges. second-instar larvae were confronted with refuges associated with a visual stimulus (either blue, green or red lights having the same intensity, or darkness) and a chemical cue (presence or absence of faeces). in this context, faeces constitute a major attractant for bugs. in the absence of faeces, ...200011138797
[biological potential of triatoma brasiliensis].biological and physiological parameters of triatoma brasiliensis, triatoma infestans, and triatoma pseudomaculata were studied and compared. t. brasiliensis, reared on mice, showed a faster evolutionary cycle from first stage to adult and higher fecundity, when compared to the other species. t. infestans showed the fastest blood intake in both hosts tested, followed by t. brasiliensis and t. pseudomaculata. clotting tests using salivary gland extracts of t. brasiliensis presented intermediary va ...200011119327
effects of organic acids on lipid synthesis and ecdysis in triatoma infestans eggs.medium chain fatty acids are known inhibitors of the activity of lipogenic enzymes at the transcriptional level. mature triatoma infestans eggs incorporate [14c]-acetate into phospholipid (pl), triacylglycerol (tg), and free fatty acid (ffa) fractions. in the presence of sodium octanoate (so) or sodium phenylethylpropionate (phep), lipid synthesis is inhibited in a dose-dependent manner. when eggs are incubated in vivo with [14c]-acetate, the usual fatty acid products are largely palmitic and ol ...200010904863
meiosis in holocentric chromosomes: orientation and segregation of an autosome and sex chromosomes in triatoma infestans (heteroptera).the meiotic behaviour of the x chromosome and one autosomal pair of the heteropteran triatoma infestans was analysed by means of c-banding plus dapi staining. at first metaphase, the x univalent is oriented with its long axis parallel to the equatorial plate, which suggests a holocentric interaction with the spindle fibres. after this initial orientation, kinetic activity is restricted to one of both chromatid ends. the election of the active chromatid end is random and it is independent of the ...200010730585
[comparative yield of two methods of rearing triatoma infestans (author's transl)]. 20004596481
artificial feeding of the blood-sucking bug triatoma infestans klug, 1834. i. feeding characteristics and the inducement of abnormal metamorphosis. 20005843246
fatty acid delta9-desaturation in the triatoma infestans fat body: response to food and trehalose administrations.the effects of food intake and carbohydrate administration on fatty acid delta9-desaturation were investigated in isolated microsomes from triatoma infestans fat body. fifth instar nymphs, which were solely blood-fed just after the molt and then fasted, were used as controls and for determination of optimal assay conditions. both [1-14c]palmitic and [1-14c]stearic acids in a medium containing atp, coa, mgcl2, nadh, naf, and o2 were tested. for the control group, optimal conditions were a ph of 6 ...199910606043
purification and properties of a small lipid-binding protein from the hemolymph of triatoma infestans.a small lipid-binding protein (slbp) was purified from the hemolymph of the blood-sucking bug triatoma infestans. its isolation involved size exclusion-high performance liquid chromatography (hplc) followed by anion exchange chromatography-hplc. the molecular weight of the protein, as determined by gel permeation chromatography, was 20 kda. sodium dodecyl sulphate-polyacrylamide gel electrophoresis (sds-page) resolved the protein into a single polypeptide with m(r) approximately equal to 16 kda. ...199910327599
the southern cone initiative against chagas disease.chagas disease (also known as american trypanosomiasis) is now ranked as the most serious parasitic disease of the americas, with an economic impact far outranking the combined effects of other parasitic diseases such as malaria, schistosomiasis and leishmaniasis. although the chronic infection remains virtually incurable, transmission can be halted by eliminating the domestic insect vectors and screening blood donors to avoid transfusional transmission. in line with this strategy, governments o ...199910050271
susceptibility and resistance to insecticides of chagas disease vectors.chemical control of chagas disease vectors appears to be the best practical way to reduce the incidence of the disease. ddt was initially tested in the 1950s for the campaigns of control of chagas disease vectors. its low level of effectiveness against triatomine caused the failure of these control actions. hch was then introduced in the southern cone and dieldrin in the north of latinoamerica. starting in the late 1960s anticholinesterasic organophosphorus and carbamate compounds were introduce ...199910668241
differences of susceptibility of five triatomine species to pyrethroid insecticides - implications for chagas disease vector control.as pyrethroids are presently the favored group of insecticides to control triatomines, we performed a series of bioassays to determine the intrinsic activity of some of the main compounds used in the control campaigns, against five of the main species of triatomines to be controlled. comparing the insecticides it can be seen that lambdacyhalothrin is more effective than the other three pyrethroids, both considering the ld50 and 99 for all the three species with comparable results. on triatoma in ...199910677770
sporulation of beauveria bassiana on cadavers of triatoma infestans after infection at different temperatures and doses of inoculum. 199910066403
monitoring house reinfestation by vectors of chagas disease: a comparative trial of detection methods during a four-year follow-up.domestic reinfestations by triatomine bugs were monitored after application of deltamethrin and apparent elimination of triatoma infestans in amama and other nearby rural villages, north-west argentina, from 1992 to 1996. the five methods used were sensor boxes, sheets of pink typing-paper, timed manual catches by a skilled three-person team aided by a flushing-out agent, collections by house-dwellers, and knockdown using insecticide fumigant canisters. in bedrooms, house-dwellers collected t. i ...199910206120
trypanosoma cruzi infection in triatoma infestans and other triatomines: long-term effects of a control program in rural northwestern argentina.the prevalence of trypanosoma cruzi infection in triatoma infestans, triatoma guasayana, and triatoma sordida was evaluated in amamá and other neighboring rural villages in northwestern argentina for five years after massive spraying with deltamethrin in 1992 and selective sprays thereafter. local residents and expert staff collected triatomines in domiciliary and peridomestic sites. during 1993-1997, the prevalence of t. cruzi was 2.4% in 664 t. infestans, 0.7% in 268 t. guasayana, and 0.2% in ...199910446505
a new tactic for triatoma infestans control: fabrics impregnated with beta-cypermethrin.triatoma infestans is the most important vector of chagas' disease in argentina. experiences from argentine national campaigns have shown indoor spraying to control triatomine bugs is both expensive and difficult. an alternative control method may be the use of pyrethroid-impregnated fabrics (pifs), which could be both a practical and cheap complement to conventional control measures. in this study, a formulation of emulsifiable concentrate of beta-cypermethrin [alpha-cyano-3-phenoxybenzyl-3-(2, ...199910446509
immunocytochemical reaction of sera from chagasic patients against trypanosoma cruzi, intestine of triatoma infestans and normal human heart.chagas disease has been considered by some authors as an autoimmune pathology and denied by others. in this paper we present by means of immunocytochemical reactions with sera of chagasic patients, evidence in favor of the presence of similar antigens in the parasite, vector and non chagasic human heart. the immunocytochemical technique used permits the localization by electron microscopy of the antigens in the peritrophic membrane of the parasite and basement membranes of the vector's midgut an ...199910451560
chagas disease in an area of recent occupation in cochabamba, bolivia.a descriptive, entomological and seroepidemiological study on chagas disease was conducted in a place of recent occupation on the outskirts of cochabamba, bolivia: avaroa/primer de mayo (population:3,000), where the socio-economic level is low and no control measures have been made available.199910456995
comparison of some behavioral and physiological feeding parameters of triatoma infestans klug, 1834 and mepraia spinolai porter, 1934, vectors of chagas disease in chile.there are two vectors of chagas disease in chile: triatoma infestans and mepraia spinolai. we studied the feeding behavior of these species, looking for differences which could possibly explain the low impact of the latter species on chagas disease. both species used thermal cues to locate their feeding source and consumed a similar volume of blood which was inversely related to the body weight before the meal and directly related to the time between meals. the average time between bites were 6. ...199910464419
effects of non-susceptible hosts on the infection with trypanosoma cruzi of the vector triatoma infestans: an experimental model.we tested experimentally the effects of the presence of non-susceptible hosts on the infection with trypanosoma cruzi of the vector triatoma infestans. the experiment consisted in two treatments: with chickens, including two chickens (non-susceptible hosts) and two infected guinea pigs (susceptible hosts), and without chickens, including only two infected guinea pigs. the hosts were held unrestrained in individual metal cages inside a closed tulle chamber. a total of 200 uninfected t. infestans ...199910348993
feeding frequency and nutritional status of peridomestic populations of triatoma infestans from argentina.we studied the nutritional characteristics of peridomestic populations of triatoma infestans from 25 habitats in an endemic area of chagas disease in argentina. the aim was to determine the feeding frequency, fresh weight of adults and older nymphs, and the gonotrophic status of females, in order to compare them with previous studies of domestic populations in the same region. the average infection rate of the bugs and blood meal origins were also determined in order to calculate the maximum ris ...199910546845
small-scale field trial of a sensing device for detecting peridomestic populations of triatoma infestans (hemiptera: reduviidae) in northwestern argentina.two prototypes of sensing devices for detecting peridomestic populations of triatoma infestans klug were tested in paired trials with bamboo canes in amamá and nearby rural villages under triatomine surveillance. in infested peridomestic structures housing domestic animals, 1-2 pairs of numbered devices were placed per test site, left for 3-9 nights, and inspected for evidence of infestation. prototype a was a black plastic cylinder 19 cm high and 10 cm diameter, with a screw cap on the top, 2 o ...199910593096
[control campaigns against triatoma infestans in a rural community of northwestern argentina].control campaigns against triatoma infestans, the principal vector of trypanosoma cruzi, have relied on the application of residual insecticides and have regarded the system as homogeneous. reinfestation generally starts in peri-domestic residual foci or in preexisting foci that escaped spraying for diverse reasons. from these foci t. infestans adults actively invade other sites, or they are transported passively within objects or goods from infested communities. in the absence of additional spr ...199910668242
temperature and relative humidity affect the selection of shelters by triatoma infestans, vector of chagas disease.the preference of triatoma infestans for shelters at different temperatures or relative humidities (rh) was tested in laboratory assays. the insects preferred refuges at a temperature of 34 degrees c rather than 26 degrees c, and chose to stay in refuges with an rh of 20% rather than 80%. temperature and rh records made inside and outside experimental chicken-houses under natural climatic conditions showed that such habitats tend to maintain an inner climate favourable to t. infestans. typical r ...199910232780
[contribution to knowledge of reservoirs of trypanosoma cruzi (chagas, 1909) in corrientes province, argentina].in order to identify trypanosoma cruzi reservoirs in transmission areas, 60 mammals in capital and san luis del palmar departments, corrientes, argentina were studied. primates, rodents, carnivores, marsupials and edentates were investigated, 40 of them living in captivity and 20 caught with traps in a rural area. the mammals were examined by xenodiagnosis and third or fourth instars nymphs of triatoma infestans starved for 2 weeks were used. the feces were microscopically observed (400x) for tr ...199910380566
the effect of azadirachtin on blastocrithidia triatomae and trypanosoma cruzi in triatoma infestans (insecta, hemiptera).the effect of azadirachtin on blastocrithidia triatomae and trypanosoma cruzi, which colonise the intestinal tract of the blood-sucking bug triatoma infestans, was investigated. in established infections of controls without azadirachtin treatment, the small intestine of fifth-instar t. infestans contained up to 7 x l0(6) b. triatomae and the rectum 3 x 10(6). in comparison to this homoxenous flagellate, the population densities of t. cruzi in the respective regions were 99.3 and 76% lower. treat ...199910333323
[longitudinal study, by xenodiagnosis, of parasitemia in patients with chronic trypanosoma cruzi infection].a 2-5 years follow-up of parasitemia, by the use of xenodiagnosis (xd) was carried out in nine patients with chronic t. cruzi infection who proceeded from chagasic endemic areas of chile. the patients (mean age 55 years) were hospitalized in the chronic section of a psychiatry institution sited in a permanent triatomines free urban area. clinical examination, x-rays images (cardiovascular, esophagus and colon) and electrocardiogram resulted normal in all the patients. basic study unit of parasit ...199910488588
action of the saliva of triatoma infestans (heteroptera: reduviidae) on sodium channels.saliva of triatoma infestans (klug) produced a progressive reduction in the amplitude of the compound action potential recorded from rat sciatic nerve. the saliva also inhibited the na+ current on gh3 cells. the data demonstrate that the saliva of t. infestans has an inhibitory effect on na+ channels. we conclude that this effect may decrease the generation and conduction of nerve action potential, thereby decreasing the sensitivity of the region in which the insect probes, in a manner similar t ...199910593094
[epidemiological status of chagas disease in the endemic area from region ii of antofagasta].during 1997 a seroepidemiological study on chagas' disease was carried out in 18 localities of three provinces (tocopilla, el loa and antofagasta) of region ii (20 degrees 56'-26 degrees south lat.; 70 degrees 38'-67 degrees west long.), in order to assess the impact of the control program against triatoma infestans launched in 1988, based on insecticide spraying of dwellings. by means of elisa and an indirect hemagglutination test for chagas' disease blood samples from 1,034 children under 10 y ...199910488587
[control of the transmission of trypanosoma cruzi in argentina 1999].approximately 2 million people in argentina are infected with trypanosoma cruzi, the etiologic agent of chagas disease, thereby constituting the major tropical disease in the country. as in other six southern cone countries, triatoma infestans is the only or major vector of t. cruzi among human and domestic animals. in argentina, a vertically structured national chagas control program was established in 1962. such a program pursued the elimination of domestic and peri-domestic populations of t. ...199910668249
[elimination of vectorial transmission of chagas disease in brazil].the control of vectorial transmission of chagas disease in brazil has been systematized and structured into a national program since 1975 when regulations were set up on the basis of entomological and sero-epidemiological studies which permitted the delimitation of areas at risk of vectorial transmission in the whole country as well as the orientation of the chemical control of domiciliary vector populations. the authors present the original data collected throughout the years comparing them wit ...199910668250
elimination of vector-borne transmission of chagas disease.the control of the vector-borne transmission of chagas disease in brazil was organized as a national program in 1975, when two large entomological and sero-epidemiological surveys were conducted in the country in order to identify areas at highest risk of transmission and to guide interventions regarding the chemical treatment of domestic vectors of the disease. the authors present the baseline data gathered through these studies and compare them with more recent data. the evaluation performed s ...199910677766
mitochondrial dna variation of triatoma infestans populations and its implication on the specific status of t. melanosoma.dna sequence comparison of 412 base-pairs fragments of the mitochondrial cytochrome b gene was used to infer the genetic structure of nine geographical triatoma infestans populations and their phylogenetic relationship with t. melanosoma and t. brasiliensis. t. infestans and t. melanosoma were compared by morphometry, allozyme and cytogenetic analyses, as well as subjected to reciprocal crosses, in order to clarify the taxonomic status of the latter. no differences were found to distinguish the ...199910677723
compared vectorial transmissibility of pure and mixed clonal genotypes of trypanosoma cruzi in triatoma infestans.a total of 15 mixtures involving 9 different stocks attributed to the 19/20, 32 and 39 major clonal genotypes of trypanosoma cruzi were used to infect third-instar nymphs of triatoma infestans via an artificial feeding device. three biological parameters were considered: (1) the percentage of infected insects (%ii), (2) the number of flagellates per insect (nfi), and (3) the percentage of trypomastigotes per insect (%dif). genetic characterization by both multilocus enzyme electrophoresis (mlee) ...19989610630
hydrophobic attachment of trypanosoma cruzi to the rectal cuticle of triatoma infestans and its influence on metacyclogenesis - a review.trypanosoma cruzi colonizes mainly the rectum of the vector, especially the rectal glands. we investigated the basic architecture of the rectal cuticle of triatoma infestans and the mode of attachment of t. cruzi in the small intestine and the rectum. in addition, we determined the capacity of culture-derived epimastigotes to attach to artificial substrates and the influence of attachment on metacyclogenesis. after incubation of the rectum with wheat germ lectin (wga) coupled to gold particles, ...199810622629
assessing the impact of disease vectors on animal populations.many studies have attempted to assess the relative effects of different vectors of a disease on animal populations. to this end, three measures have been proposed: vectorial efficiency, vectorial capacity and recently vectorial effectiveness (or vectorial impact). in this study we relate these measures to derive some of their properties emphasising in the vectorial impact for its importance in both, population performance of parasites and the proportion of the prevalence of one parasite due to a ...199810423827
[study of the factors determining an unexpected occurrecne of chagas cardiomyopathy in sucre, bolivia].the purpose of this case-control study carried out between february 1, 1994 and december 22, 1994 at the "instituto de gastroenterologia boliviano-japonés" in sucre, bolivia was to determine risk factors for chronic chagas cardiomyopathy in adult patients with positive serological tests for trypanosoma cruzi. a total of 196 subjects were included. inclusion criteria were positive serological tests for trypanosoma cruzi, residence in the city of sucre, bolivia for at least 3 months, and age over ...19989791592
triatoma infestans can be captured under natural climatic conditions using yeast-baited traps.the effectiveness of a trap for triatomines baited with yeast cultures has been previously demonstrated in laboratory assays. we report results from assays testing yeast-traps for triatoma infestans performed under natural climatic conditions. all assays were conducted at experimental chicken-coops colonised by bugs, situated at an endemic area for chagas disease in argentina. two different models of traps were tested, for use either on the floor, or attached to walls. the results obtained clear ...19989777714
smallness of the panmictic unit of triatoma infestans (hemiptera: reduviidae).the population genetic structure of triatoma infestans (klug), the principal vector of the causative agent of chagas disease in bolivia, was investigated by enzyme electrophoresis at 15 loci, of which 3 were polymorphic. a total of 1,286 adults and nymphs was collected from 19 localities of the cochabamba (high endemicity) and la paz (low endemicity) departments. previous results were confirmed, including a low level of polymorphism (0.20), low genetic distance between geographic areas, and a po ...19989835679
beauveria bassiana (hyphomycetes) as a possible agent for biological control of chagas disease vectors.beauveria bassiana (balsamo) vuillemin (isolate cg306) was tested on 3rd instars of 9 triatoma spp., 4 rhodnius spp., 2 panstrongylus spp. and dipetalogaster maxima (uhler) at 25 degrees c and 50% rh. quantitative sporulation of the fungus on cadavers was studied at 25 degrees c and 97% rh. mortality, estimates of survival time, and conidial production on cadavers differed significantly among the genera and species tested. panstrongylus herreri wygodzinsky, dipetalogaster maxima, triatoma pictur ...19989835689
household prevalence of seropositivity for trypanosoma cruzi in three rural villages in northwest argentina: environmental, demographic, and entomologic associations.environmental, demographic, and entomologic variables were analyzed by logistic multiple regression analysis for their association with the likelihood of being seropositive for trypanosoma cruzi in three highly infested rural villages of northwest argentina. the prevalence of seropositivity for t. cruzi, as determined by the composite results of three serologic tests, was 34% among 338 persons in 1992. the strongest positive predictors of the adjusted odds of being infected were the household nu ...19989840591
trypanosoma cruzi genotypes associated with domestic triatoma sordida in bolivia.triatoma sordida is the second species of triatominae considered of epidemiological significance in bolivia. associated with triatoma infestans in various regions, it is as yet the only triatomine species established in human dwellings in localities of velasco province, department of santa cruz. this domestication is considered as primary. flagellate parasites were detected in 16.2% of domiciliary t. sordida and the kdna-pcr confirmed the presence of trypanosoma cruzi. frequencies of t. cruzi cl ...19989879736
[triatoma infestans: importance, control and elimination of the species in the state of são paulo, brazil].considerations about the control of the vectors of chagas' disease are made in the state of sao paulo, mainly those activities that led to the elimination of t. infestans. first of all, the authors discuss different aspects of the biology of t. infestans mainly those that permitted it to adapt itself in rural areas of the state in the first middle of the century. secondary factors that helped the control such as rural exodus are also analysed. the article shows that since 1965 the control became ...19989477701
[first evidence of trypanosoma rangeli in the southeast of brazil, an endemic region for chagas' disease].this short communication informs the discovery of trypanosoma rangeli for the first time at triângulo mineiro region, south-east of brazil, a highly endemic area of chagas' disease and also the natural infection of didelphis albiventris with the same trypanosome. both the findings were demonstrated through blood smears, xenodiagnosis, microhematocrit technics and pcr. the last one was realized in faeces and hemolymph of triatoma infestans utilizing as controls strains of t. rangeli from colombia ...19989477704
influence of humans and domestic animals on the household prevalence of trypanosoma cruzi in triatoma infestans populations in northwest argentina.in three rural villages of northwest argentina, the overall proportion of domiciliary triatoma infestans infected with trypanosoma cruzi was 49% among 1,316 bugs individually examined for infection in march and october 1992). most of the variation among individual households in the proportion of infected triatomines was explained by variations among houses in the proportion of bugs that fed on dogs or cats, the prevalence of infected dogs or cats, and the proportion of bugs that fed on humans, a ...19989660458
[the control of the transmission by transfusion of chagas' disease in the southern cone initiative].the southern cone initiative against chagas' disease, was launched in 1991. the aim was to interrupt the transmission of chagas disease by elimination of domestic populations of the major vector, triatoma infestans, and by improved screening of blood donors. as a result of these activities, a marked reduction in the risk of transfusional transmission can now be seen throughout the programme area. in addition to specific legislation concerning the quality of transfused blood, a series of national ...19989662965
trypanosoma cruzi in the rectum of the bug triatoma infestans: effects of blood ingestion by the starved vector.to follow the developmental effects of feeding of the insect host after long starvation periods, the population density and composition of an established infection of trypanosoma cruzi in the rectum of triatoma infestans were determined 60 days after the last feeding (daf) and then at different intervals after feeding. the original population decreased and then increased up to the 10th daf. in starved bugs, about 30% were spheromastigotes (including intermediate forms), 20% epimastigotes, and 50 ...19989684647
hydrophobic attachment of trypanosoma cruzi to a superficial layer of the rectal cuticle in the bug triatoma infestans.in the vector triatoma infestans the human pathogenic flagellate trypanosoma cruzi colonizes mainly the rectum. the rectal cuticle and associated trypanosomes were examined by electron microscopy. the cuticle of the rectum consisted of a superficial wax layer, which was not retained by conventional preparation, an outer and inner epicuticle, and a procuticle. epimastigotes of t. cruzi attached to the superficial layer with a specialized area of the flagellum. the composition of the cuticle was a ...19989694367
modes of association of trypanosoma cruzi with the intestinal tract of the vector triatoma infestans.the interface between trypanosoma cruzi and two regions of the intestinal tract of reduviid bugs, the small intestine and the rectum, was investigated by electron microscopy. the mode of association of the trypanosomes with the midgut surface differs fundamentally from that in the rectum, the preferred site of colonisation by t. cruzi. the parasites caused no detrimental changes in the extracellular membrane layers, microvilli or epithelial cells. parasites resided mainly at the border of the gu ...19989698259
activity pattern in relation to refuge exploitation and feeding in triatoma infestans (hemiptera: reduviidae).the pattern of locomotion activity was studied in triatoma infestans, in relation to the use of an artificial refuge offered to the bugs in an experimental arena. in assays performed with insects that had a post-ecdysis starvation period of 1 week, the activity was low and mainly related to refuge leaving or entering. insects that had gone through a longer period of starvation (6 weeks) exhibited a high locomotory activity throughout the night. specific temporal windows were detected for refuge ...19989698262
the effect of azadirachtin on fresh isolates of trypanosoma cruzi in different species of triatomines.the effect of azadirachtin was investigated using three different fresh isolates of trypanosoma cruzi and five different triatomine species which were infected as third-instar larvae. the two t. cruzi strains which originated from sylvatic triatoma vitticeps showed a high prevalence after the molt to the fifth instar in panstrongylus megistus and rhodnius neglectus and a low prevalence in triatoma infestans and rhodnius robustus. the third t. cruzi strain originating from a patient in piaui show ...19989569093
different behavior of two trypanosoma cruzi major clones: transmission and circulation in young bolivian patients.specificity of two widespread trypanosoma cruzi clonal genotypes or "clonets" (20 and 39) was first analyzed by hybridization with a large set of t. cruzi stocks characterized by multigenic study relying on both mlee and rapd. then, these clonets were detected in the blood of chagasic children from a bolivian endemic area by a combination of polymerase chain reaction and clonet-specific dna hybridization. the distribution of these clonets in patients was significantly different from that observe ...19989676706
trypanosoma cruzi: compared vectorial transmissibility of three major clonal genotypes by triatoma infestans.twenty trypanosoma cruzi stocks attributed to the 19/20, 32, and 39 major clones (tibayrenc et al. 1986) were used to infect experimentally third instar larvae of triatoma infestans. three variables were considered: (i) percentage of infected insects; (ii) number of flagellates per insect (nfi); and (iii) percentage of metacyclic trypomastigotes per insect. differences between the genotypes under study for all parameters considered were detected. these differences were statistically significant ...19989709026
population structure of andean triatoma infestans: allozyme frequencies and their epidemiological relevance.triatoma infestans (hemiptera: reduviidae) from 22 andean localities in bolivia (n = 968) and peru (n = 37) were analysed by multi-locus enzyme electrophoresis. among 12 gene-enzyme systems analysed, gpd, 6gpd and pgm were polymorphic, acon, g6pd, gpi, 1dh, lap, mdh, me, pep-a and pep-b were monomorphic. allozyme frequencies were analysed in relation to geographical and climatic factors, and the presence or absence of trypanosoma cruzi infection. at one locality (vallegrande, bolivia), the frequ ...19989513935
development of trypanosoma cruzi after starvation and feeding of the vector - a review.trypanosoma cruzi develops in the intestinal tract of reduviid bugs and may be affected by changes in the nutritional state of the vector. in regularly fed triatoma infestans the population of t. cruzi in the rectum consists mainly of equal amounts of epi- and trypomastigotes. starvation of the bug reduces the total number of flagellates and the number and percentage of trypomastigotes. the number and the percentage of drop-like forms and of resulting spheromastigotes, however, increases up to 3 ...199810622631
random amplification of polymorphic dna as a tool for taxonomic studies of triatomine bugs (hemiptera: reduviidae).eleven of 27 decameric primers were found to be suitable for random amplification of polymorphic dna (rapd) from triatomine bugs on the basis that they produced discrete profiles and distinguished among panstrongylus megistus (burmeister), rhodnius prolixus stål, and triatoma infestans (klug). the legs, or single leg segments, of individual bugs were used as the source of dna so that the taxonomic value of the bug was conserved. within the scope of the specimens studied, rapd profiles allowed as ...19989542343
the development of trypanosoma cruzi (trypanosomatidae) in the reduviid bug triatoma infestans (insecta): influence of starvation.fifth instars of triatoma infestans with established trypanosoma cruzi infections were dissected after different periods of starvation to determine the population density and the percentage of different developmental stages of t. cruzi in the small intestine and rectum of the bugs. after a short starvation period of 20 days, the population density in the small intestine was 20% (about 60,000) of the rectal population. the population in the small intestine was strongly reduced after an additional ...19989495034
selection of beauveria bassiana and metarhizium anisopliae isolates to control triatoma infestans.twenty three isolates of beauveria bassiana and 13 isolates of metarhizium anisopliae were tested on third instar nymphs of triatoma infestans, a serious vector of chagas disease. pathogenicity tests at saturated humidity showed that this insect is very susceptible to fungal infection. at lower relative humidity (50%), conditions expected in the vector microhabitat, virulence was significantly different among isolates. cumulative mortality 15 days after treatment varied from 17.5 to 97.5%, and e ...19989921313
evaluation of dogs as sentinels of the transmission of trypanosoma cruzi in a rural area of north-western argentina.dogs, the main domestic reservoirs of trypanosoma cruzi in the argentine chaco, may be useful as sentinels of vector-mediated transmission of trypanosoma cruzi in control programmes if canine infections acquired by all other routes could be excluded. in the present study, in the province of santiago del estero, argentina, the dog populations in the neighbouring villages of amamá, trinidad, mercedes, villa matilde and pampa pozo were studied immediately before spraying of residual insecticides (i ...19989924546
biological characterization of trypanosoma cruzi stocks from chilean insect vectors.fifty-seven trypanosoma cruzi stocks isolated from triatoma infestans and triatoma spinolai of the five different geographic endemic areas of chile were studied by schizodeme and molecular karyotype analysis. four different genotypes are found in the sylvatic t. spinolai vector and five in the t. infestans domiciliary vector. of these genotypes, two common genotypes overlap on both transmission cycles exclusively in the extreme northern endemic areas of chile. metacyclic trypomastigotes obtained ...19989676709
effect of fasting on the composition of the fat body lipid of dipetalogaster maximus, triatoma infestans and panstrongylus megistus (hemiptera: reduviidae).modifications in content and lipid composition induced by fasting were examined in fat bodies from adults of triatominae, dipetalogaster maximus, triatoma infestans and panstrongylus megistus. with fasting, total lipid stores dropped approximately 50% for t. infestans and more than 70% for p. megistus. total lipids analyzed by thin layer chromatography and fractionated by column chromatography on unisil showed triacylglycerols as the main component in the three species, although p. megistus show ...19989810719
[determination of hiv protein 24 in feces of triatoma infestans fed with blood from aids patients].to verify any possibility of the elimination of p24 in feces of triatoma infestans, p24 being an antigen and one of the markers of hiv infection. the purpose of the study was the evaluation of any risk of contamination by laboratory staff who work with activities related to this particular insect, and also investigate any mechanism that might thus lead to the dissemination of hiv.199810030063
identification and characterization of a sialidase released by the salivary gland of the hematophagous insect triatoma infestans.sialidases (ec 3.2.1.18) are commonly found in viruses, bacteria, fungi, protozoa, and vertebrates, but not in invertebrates. we have previously reported the presence of a new sialidase activity in the gut of exclusively hematophagous insects of the triatoma genus, which transmit chagas' disease (amino, r., acosta, a., morita, o. m., chioccola, v. l. p., and schenkman, s. (1995) glycobiology 5, 625-631). here we show that this sialidase is present in the salivary gland of triatoma infestans, and ...19989733752
factors limiting the domestic density of triatoma infestans in north-west argentina: a longitudinal study.reported are the environmental and demographic risk factors associated with the domestic infestation and density of triatoma infestans in three heavily infested rural villages in santiago del estero province, argentina. in a one-factor unadjusted analysis, the number of t. infestans captured per person-hour was associated significantly and negatively with the use of domestic insecticides by householders, type of thatch used in the roofs and the age of the house; and positively with the following ...19989803588
attachment of trypanosoma cruzi epimastigotes to hydrophobic substrates and use of this property to separate stages and promote metacyclogenesis.in vivo, epimastigotes of trypanosoma cruzi colonize a lipidic superficial layer of the rectal cuticle of the vector triatoma infestans. in vitro, epimastigotes of four cultured strains and one strain from reduviids use a terminal area of the flagellum to attach to a variety of artificial hydrophobic substances, such as hydrocarbons and a range of synthetic plastics. trypomastigotes did not attach to these substrates. hydrophilic molecules, such as neutral or negatively charged polysaccharides, ...19989783457
uruguay declared free of chagas disease transmission.according to 1997 entomological and sero-epidemiological data, the transmission of chagas disease has been interrupted in uruguay; this has been certified by an independent commission appointed by the pan american health organization/world health organization (paho/who). transmission of chagas disease, which is endemic in uruguay, is via the vector triatoma infestans or through transfusion with infected blood. in 1983, t. infestans lived in dwellings in 80% of uruguay; in 1996, in all department ...199812321803
comparative kinetics of bloodmeal intake by triatoma infestans and rhodnius prolixus, the two principal vectors of chagas disease.chagas disease vector insects triatoma infestans and rhodnius prolixus (fifteen stage iii nymphs per 4 litre cage) were allowed to feed on anaesthetized mice for 1 h (control group), or on active non-anaesthetized mice (nam) for 2, 4 or 8 h exposure. the bloodmeal size (weight increase) for both species was proportional to the duration of contact with nam, due to ingestion of multiple small bloodmeals, up to 142% of control weight for t. infestans with 8 h exposure to nam. the mean weight increa ...19989513943
feeding is not necessary for triggering plasticization of the abdominal cuticle in haematophagous bugs.a simple device was used to quantify changes in the mechanical properties of the cuticle of rhodnius prolixus and triatoma infestans that take place when these insects feed, i.e., plasticization. different stimuli were presented for 1min to test for their ability to trigger plasticization. these were: a blood meal, a ringer solution meal, contact with a warm surface and thermal stimulation without such contact. our results supplant any previous hypotheses that have supposed that the presence of ...199812770155
the effects of aposymbiosis and of an infection with blastocrithidia triatomae (trypanosomatidae) on the tracheal system of the reduviid bugs rhodnius prolixus and triatoma infestans.we have investigated the effects of the absence of symbionts and of infection with a trypanosome on the tracheal supply to different organs in larvae of the blood-sucking bugs, rhodnius prolixus and triatoma infestans. in bugs grown without symbionts there were extensive reductions in the tracheal supply to all the internal organs examined. these bugs also excreted less fluid after blood meals, perhaps because of a reduction in the oxygen supply to the malpighian tubules. inclusion of vitamin b ...199812769885
peroxidase activity in malpighian tubules of triatoma infestans klug.benzidine and diamino benzidine (dab) oxidation, typically performed by peroxidases, was demonstrated by light and electron microscopy in peroxisomes, mitochondria and membranous structures which occurred in close contact with urate crystals in malpighian tubules of nymphs and adults of triatoma infestans. peroxisomes were predominantly identified in cells of the distal region of the tubules, which is engaged in excretory mechanisms. dab oxidation in mitochondria, even in the absence of hydrogen ...19989734344
the role of the ocelli in the phototactic behaviour of the haematophagous bug triatoma infestans.in addition to compound eyes, most adult insects posses two or three simple eyes, the ocelli. the function of these photoreceptors remains elusive in most cases. triatomine bugs posses two well-developed ocelli, located in a latero-dorsal position, behind the compound eyes. we tested the role of the ocelli in the phototactic behaviour of triatoma infestans, by measuring the time spent by adult males in the dark half of an experimental arena, which had the other half illuminated. the occlusion of ...199812770315
meiotic behaviour of holocentric chromosomes: orientation and segregation of autosomes in triatoma infestans (heteroptera).the meiotic behaviour of the holocentric chromosomes of the heteropteran species triatoma infestans has been analysed by means of orcein staining and c-banding on squashed spermatocytes. we have focused our analysis on chromosome 3, which shows a large distal heterochromatic band at one of the ends of both homologues. at metaphase i, and independently of the chiasma position, two alternative orientations have been observed: either the heterochromatic or the euchromatic ends of both homologues ar ...19979088643
biochemistry of the evolution of triatoma infestans. xii. biosynthesis and secretion of a very high density lipoprotein.biosynthetic processes related to the production of an insect hexamerin, very high density lipoprotein (vhdl), have been examined in the fat body of fifth-instar nymph and adult triatoma infestans. fat bodies were incubated in vitro with [3h]leucine and the incubation media were precipitated using a specific antiserum. the sds-polyacrylamide gel electrophoresis followed by blotting on nitrocellulose showed that both larval and adult fat body secreted the vhdl subunit. moreover, the radiolabel re ...19979339237
two hemocyte populations in triatoma infestans: ultrastructural and lectin-binding characterization.two distinct hemocyte populations are determined in the hemolymph of the triatomine bug triatoma infestans klug, oenocytoids and plasmatocytes, and their independent origin from separate stem cells is shown. both hemocyte populations differ considerably in their morphology, ultrastructure and lectin-binding properties. while oenocytoids are quite uniform with easily definable cells which do not to bind any assayed lectin, the plasmatocytes are a very polymorphic population possessing several mor ...19979188175
chagas disease vector control in central america.as the southern cone initiative proceeds steadily towards eradication of triatoma infestans, there is increasing interest in applying similar approaches to control chagas disease vectors in mexico, central america and countries of the andean pact. here, chris schofield and jean-pierre dujardin discuss the technical feasibility of such an approach.199715275100
acid phosphatase activity in malpighian tubules of triatoma infestans klug.acid phosphatase activity was detected in the malpighian tubules of the blood-sucking hemipteran, triatoma infestans. the enzyme activity was especially prominent in the cytoplasmic globules which were assumed to be laminated 'concretions', which occur in the distal cells of the organ. it was also verified in the nuclei and in some cytoplasmic granules (lysosomes) of the proximal cells. the data indicated that lysosomes were involved with the nature or origin of the laminated concretions, but it ...19979682470
infection of triatoma guasayana, triatoma sordida and triatoma infestans by trypanosoma cruzi from a naturally infected opossum. 19979332580
incoordination, paralysis and recovery after pyrethroid treatment on nymphs iii of triatoma infestans (hemiptera: reduviidae).symptoms of poisoning for deltamethrin and cis-permethrin on nymphs iii of triatoma infestans were described. the time required for incoordination and paralysis were determined. deltamethrin was equal or more rapid in the onset of the first effect (accordingly to dose), and cis-permethrin in the onset of the second one. there were no significant differences between incoordination doses 50% (incd50s) at different times for the two pyrethroids. they showed equivalent incoordination power, but the ...19979332614
genetic variability and microdistribution of triatoma infestans genotypes and trypanosoma cruzi clones in arequipa region (peru).the genetic variability of triatoma infestans and trypanosoma cruzi populations was studied by isoenzyme analysis in two distinct areas of arequipa province (peru); one, santa rita de siguas, being an endemic area for chagas' disease, the second, arequipa, recently infected. analysis of t. infestans genetic variability indicates, (i) temporal stability of genotypes found in santa rita de siguas, (ii) high genetic differences between arequipa and santa rita de siguas populations suggesting minor ...19979332609
metric differences between silvatic and domestic triatoma infestans (heteroptera: reduviidae) in bolivia.one hundred and fifty-seven specimens of bolivian triatoma infestans (klug 1834), including 44 from the silvatic focus at cochabamba (bolivia), were compared using morphometric characters of the head capsule. from these specimens, 10 silvatic and 28 domestic adults were also compared using additional morphometric characters of the membranous part of the hemelytra. nonparametric univariate comparisons between specimens from silvatic and domestic ecotopes indicated the importance of the postocular ...19979379460
human infection with trypanosoma cruzi in nasca, peru: a seroepidemiological survey.we estimated the proportion of seropositivity for infection with trypanosoma cruzi (chagas' disease) in a sample of the rural population of the province of nasca, department of ica, southwestern peru. although triatoma infestans, the only vector species identified in the department of ica, is often found in domestic environments, data of the extent of human infection with t. cruzi are scant. this study comprised 446 houses, known to be infested with triatomines, distributed in 19 rural localitie ...19979394524
[course of serologic positivity to chagas disease in a rural community in brazil].in order to assess the evolution of seropositivity for chagas' disease in the rural community of cássia dos coqueiros, in são paulo state, we compared two cross-sectional studies performed at that site in 1971-1972 and in 1989-1991. in the first survey the complement fixation test was used to determine seropositivity for the disease. in this study, the total prevalence of chagas' disease was found to be 16.6%, with values ranging from 2.9 to 61.9% (in the 10-19 and 50-59 year age groups, respect ...19979445769
detection of sylvatic dark morphs of triatoma infestans in the bolivian chaco. 19979566222
spatial distribution of triatoma guasayana (hemiptera:reduviidae) in hardwood forest biotopes in santiago del estero, argentina.in the study area triatoma guasayana wygodzinsky & abalos is the only wild triatomine found sympatric with triatoma infestans (klug) in peridomestic premises. the trypanosoma cruzi chagas wild cycle is centered around the same biotopes occupied by t. guasayana, which are also visited mainly by opossums with annual prevalences of 29-50%. twelve hectares were sampled for 4 consecutive years during all seasons. during that time, 420 t. guasayana individuals were collected in 11.3% of 1,188 biotopes ...19979103752
trypanosoma cruzi: effect of immunization on the risk of vector-delivered infection in guinea pigs.the protective effect of experimental immunization was studied in guinea pigs exposed to vectorial infection by trypanosoma cruzi. immunized animals received an inoculum of live-attenuated t. cruzi epimastigotes into a granuloma previously induced by freund's complete adjuvant in the hind footpad. seven days later, a delayed-type hypersensitivity reaction was triggered by reinjection of the parasites in the front footpad. the animals were then placed in triatoma infestans-colonized corrals and e ...19979406779
effects of chickens on the prevalence of infestation and population density of triatoma infestans in rural houses of north-west argentina.effects of the presence of chickens on population density of the bug triatoma infestans, principal vector of chagas disease, were investigated by standardized sampling (indoors and peridomestically) from sixty-eight houses of three rural communities in north-west argentina, during march 1992. the domiciliary density of t. infestans increased linearly with the percentage of bugs that fed on chickens, as identified by agar double-diffusion tests. bug density was significantly higher in houses wher ...19979430119
molecular karyotype and schizodeme analyses of trypanosoma cruzi stocks from chilean triatomines.forty-one trypanosoma cruzi stocks isolated from the chilean vectors triatoma infestans and triatoma spinolai were characterized by pulse-field gel electrophoresis and southern blotting with the cruzipain gene, and by schizodeme analysis of kinetoplast dna with ecori and msp i. seven parasite groups were found by molecular karyotype which correlate with schizodeme and multilocus enzyme electrophoresis, supporting the concept of clonal propagation for trypanosoma cruzi. a predominant t. cruzi sto ...19979280894
chagas disease vector control in tupiza, southern bolivia.heavy domestic and peridomestic infestations of triatoma infestans were controlled in two villages in southern bolivia by the application of deltamethrin sc25 (2.5% suspension concentrate) at a target dose of 25 mg a.i./m2. actual applied dose was monitored by hplc analysis of filter papers placed at various heights on the house walls, and was shown to range from 0 to 59.6 about a mean of 28.5 mg a.i./m2. wall bioassays showed high mortality of t. infestans during the first month after the appli ...19979302405
the use of morphometrics in entomological surveillance of sylvatic foci of triatoma infestans in bolivia.jamach'uma (cochabamba, bolivia) is a small village surrounded by sylvatic foci of triatoma infestans. houses in the village were also infested with t infestans, and were sprayed in december 1992 as part of a chagas disease vector control trial. ten months later the houses were found to be again infested with a few fifth instar nymphs of t. infestans. these nymphs were compared by seven head measurements with 36 fifth instar nymphs collected from houses in jamach'uma before treatment, and with t ...19979210965
entomopathogenous fungi degrade epicuticular hydrocarbons of triatoma infestans.studies were undertaken to analyze the ability of entomopathogenous fungi to degrade insect hydrocarbons. strains of beauveria bassiana and metarhizium anisopliae pathogenic to the blood-sucking bug triatoma infestans were grown on hydrocarbon and non-hydrocarbon insect lipid extracts and on synthetic hydrocarbon-enriched media as the sole carbon source. entomopathogenous fungi were shown to utilize hydrocarbons as the only carbon source for their growth. insect-derived hydrocarbons served more ...19979244399
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