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[dynamics of chagas infection transmission in chile: model and simulation].triatoma infestans is the principal vector for chagas disease in chile. although there is enough epidemiological information about human infection, the effect of vector and host (animals and man) populations interrelations over chagas disease prevalence has not been studied. this work studies a determinist mathematical model for the dynamics of chagas disease transmission by triatoma infestans, relating entomological population parameters with infection propagation. the effect of invasion of sus ...19921343375
effect of azadirachtin on the development of trypanosoma cruzi in different species of triatomine insect vectors: long-term and comparative studies.studies were carried out on the effects of azadirachtin on the course of trypanosoma cruzi infection in the gut of different triatomine vector species. in rhodinus prolixus the development of t. cruzi clone dm28c decreased in a dose-dependent manner, and the ed50 of this inhibitory effect was 0.25 microgram azadirachtin/ml bloodmeal. using this insect, we conducted a long-term experiment which showed that azadirachtin (1.0 microgram/ml bloodmeal) completely blocks the development of t. cruzi eve ...19921401990
infectivity to the vector triatoma infestans of dogs infected with trypanosoma cruzi in north-west argentina.the influence of reinfections on the infectivity to triatoma infestans of dogs seropositive to trypanosoma cruzi was investigated in amamá, north-west argentina, before (1984) and after (1986-1987) elimination of domestic bugs with residual insecticides in 1985. infectivity was quantified by the percentage of infected bugs in each xenodiagnosis of a seropositive dog, i.e. the infective force (if). exposure to reinfection was represented by the domiciliary density of infected bugs and by an index ...19921417201
population dynamics and control of triatoma infestans.analysis of field populations of triatoma infestans (hemiptera: reduviidae), after a 3-year study, shows that population growth rate is affected by both density-dependent and density-independent mortality. although an equilibrium exists, apparently as a consequence of a density dependent-mechanism, population density fluctuates throughout the year because of the effect of monthly mean minimum temperature as a density-independent source of mortality. simulation studies based on moran curves shows ...19921421494
the effect of plastering in a house persistently infested with triatoma infestans (klug) 1934.the replastering of a house in mambai-goias, brazil, as a measure to wall-in triatoma infestans, is briefly described. unfortunately, because the houseowner would not cooperate the roof tiles were not improved and eventually t. infestans reappeared at this site. a brief discussion follows of some aspects of house improvement in the vigilance phase of a chagas disease control programme. t. infestans appeared in the house described 51 and 258 days after the replastering.19921460702
autogeny in three species of triatominae: rhodnius prolixus, triatoma rubrovaria, and triatoma infestans (hemiptera: reduviidae).autogeny, the capacity of a female to lay eggs without having ingested any blood meal in the adult stage, was studied in three species of triatominae: triatoma infestans, triatoma rubrovaria, and rhodnius prolixus. when nymphs of t. rubrovaria and r. prolixus were fed chicken blood, autogeny occurred frequently, even with only one meal. in t. infestans autogeny was frequent as well, but demanded at least two nymphal blood meals. total number of autogenic eggs was positively correlated with the b ...19921495041
acute chagas' disease (trypanosomiasis americana) in acquired immunodeficiency syndrome: report of two cases.two heterosexual men, aged 31 and 40 years, with the acquired immunodeficiency syndrome and presenting with the acute form of chagas' disease are reported. the first patient, a carrier of hemophilia a, was treated for 20 years with chilean and brazilian cryoprecipitates. this patient acquired both diseases through this medium. the second patient, an inhabitant of northern chile (fourth region), was allegedly bitten by triatoma infestans and was an intravenous drug addict. the hemophilic patient ...19921544668
sylvatic american trypanosomiasis in argentina. trypanosoma cruzi infection in mammals from the chaco forest in santiago del estero.trypanosoma cruzi infection in sylvatic mammals of the quebracho woods of the eastern part of santiago del estero province, argentina, was studied from october 1984 to december 1987. 301 mammals of 20 different species were caught. t. cruzi, characterized biologically and biochemically, was isolated by xenodiagnosis from 23 of 72 (32%) didelphis albiventris opposums, 2/36 (5.5%) conepatus chinga skunks, and one ferret (galictis cuja). 53 opossum refuges were located and triatomine bugs were foun ...19921566301
control of the transmission of chagas' disease in mambai, goias, brazil (1980-1988).the results of entomologic surveillance conducted after chagas' disease control in mambai, goias, brazil are reported for the years 1985-1988, including a summary of results from 1980 to 1988. a progressive decrease in the incidence of triatoma infestans in houses reached zero in 1988. the threat of secondary vector colonization and the continued need for vigilance are discussed.19921575291
dispersive flight by triatoma infestans under natural climatic conditions in argentina.male and female t. infestans were released on two consecutive nights in the salinas of cordoba province, argentina, when air temperatures during the flying period averaged 28.5 degrees c. 136 males (43% of the total released) and 170 females (57%) flew on the first night, and 6 males (18%) and 7 females (27%) on the second. of these, we recovered 23 males and 14 females within 100 m, and a further female within 200 m, all from the first night's release. the remainder appear to have flown more th ...19921600228
determinants of the domiciliary density of triatoma infestans, vector of chagas disease.in two heavily infested rural villages of santiago del estero, argentina, where no indoor-spraying with residual insecticides had ever been carried out by official control services, we studied the influence of roof and wall structure, domestic use of insecticide, family size and the number of domestic dogs, on the domiciliary density of triatoma infestans (klug). bug density was significantly associated with (1) the interaction between insecticide use and type of roof, (2) the structure of indoo ...19921600232
vectorial transmission of trypanosoma cruzi: an experimental field study with susceptible and immunized hosts.the dynamics of vectorial transmission of trypanosoma cruzi and the level of host (guinea pigs) protection after immunization with attenuated parasites (tcc strain) was studied under natural climatic conditions in an endemic region of northern argentina. the experimental design included two guinea pig corrals isolated by mosquito netting. one (controls) had 17 healthy and susceptible adult guinea pigs. the other had 19 guinea pigs immunized with attenuated t. cruzi tcc strain. each corral was co ...19921636879
attachment of blastocrithidia triatomae (trypanosomatidae) by flagellum and cell body in the midgut of the reduviid bug triatoma infestans.the pathology and attachment of blastocrithidia triatomae in two regions of the midgut of the reduviid bug triatoma infestans (the stomach and the small intestine) were investigated by electron microscopy. in both regions the extracellular-membrane layers and the apical microvilli were often reduced, and some cells of the intestinal wall were vacuolated. in the stomach two types of attachment occurred: flagella with intraflagellar swellings lay over and between the apices of the microvilli of th ...199223195236
feeding behavior of different species of chagas' disease vectors stimulated with blood sources at different temperatures.1. the feeding behavior of six triatomid species toward latex condoms filled with blood at 26 +/- 1 and 36 +/- 1 degrees c was observed for 4 h. 2. the species studied were triatoma infestans, triatoma brasiliensis, triatoma vitticeps, triatoma pseudomaculata, rhodnius prolixus and panstrongylus megistus, and 34 to 348 insects were studied in each group (average, 190). all the life stages of each species were used. 3. although most insects (80%, average for 6 species) preferred the warmer blood, ...19921304939
the role of temperature and nutritional status in flight initiation by triatoma infestans.flight initiation in triatoma infestans is associated with low nutritional status and increases with rising temperature; it appears to be largely independent of bug age and sex. a predictive model for the probability of flight initiation was constructed based on weight:length ratios of the bugs and maximum ambient temperature, both of which can be ascertained in the field. the model accurately predicted the proportion of bugs initiating flight in > 85% of the groups used in our study. the predic ...19921359758
influence of the nutritional state of triatoma infestans over the insecticidal activity of ddt.1. the influence of nutritional state over topical insecticidal activity of ddt in nymph ii of triatoma infestans was analyzed. 2. ddt ld50 for starved nymph ii was more than 150 micrograms/insect, while for nymph ii fed to repletion on artificial feeder, was 0.79(0.50-3.13) micrograms/insect and a similar result was obtained for nymph ii fed on pigeons (1.09(0.36-7.55) micrograms/insect). 3. a very slow penetration rate of 14c-ddt was obtained in non fed insects (4.4% penetrated 46 hr after tre ...19921354138
eradication of triatoma infestans: a new regional programme for southern latin america. 19921417170
[population effects of fluctuation in fecundity and mortality in triatoma infestans: simulation using leslie matrices].the population effects of known fluctuations in fecundity and mortality of t. infestans was studied through simulation using leslie matrices. the effect of mortality and fecundity cycles was a stepped cycling through the growing phase, with no significant population decreases. density dependent regulation stabilizes changes during the steady phase. the main effect is on population composition with the establishment of a regular annual cycle in the proportion of different age groups. cycles with ...19919723073
[biology of triatoma infestans populations: fluctuations of fecundity and mortality].fecundity and mortality in population of insects is relevant to the epidemiology of insect transmitted diseases. these variables were studied for t. infestans during 5 years under constant conditions of temperature, relative humidity, light periods and individual density. mean fecundity was 0.96 +/- 0.69 eggs/female-week, range 0 to 4. minima were observed in april and maxima in october and november. mean mortality of intermediate forms was 0.058 +/- 0.031/individual-week, range 0.009 to 0.135, ...19911845105
pathological effects of blastocrithidia triatomae (trypanosomatidae) on the reduviid bug triatoma infestans after infection by membrane feeding and long-term starvation.developmental time and mortality in larvae of the reduviid bug triatoma infestans were studied in uninfected groups and in those infected with blastocrithidia triatomnae by in vitro feeding with 10(4) cyst stages/cm(3) blood. bugs were subsequently subjected to two different starvation periods. in bugs fed at weekly intervals infection with b. triatomae was associated with developmental retardation, increasing in the final instars, and with increased mortality in the third and preadult instar. c ...19911909355
development of blastocrithidia triatomae (trypanosomatidae) in triatoma infestans after vitamin b-supplementation of the blood-diet of the bug.investigations of the interrelationships of the trypanosomatid blastocrithidia triatomae and the reduviid bug triatoma infestans indicated an interference of b. triatomae with bug symbionts or with their vitamin supply. for an initial study of this possibility, b. triatomae-infected bugs were fed two or three times at monthly intervals on defibrinated sheep blood with or without b-group vitamin supplementation (folic acid, nicotinic acid, pantothenic acid, pyridoxine, riboflavin, and thiamin). t ...199123194605
rapid isolation of metacyclic trypomastigotes of trypanosoma cruzi from feces and urine of the vector.metacyclic trypomastigotes of trypanosoma cruzi from infected triatoma infestans were isolated and purified by an improved procedure. by using feces and urine of bugs the duration and the number of steps for purification were greatly reduced, thereby minimizing any possible effects on the flagellates. after deae-sephacel column chromatography, a buffer supplemented with bovine serum albumin protected against the slight surface alterations of the trypomastigotes otherwise observed. about 10(7) me ...19911686144
recovery of triatoma infestans populations after insecticide application: an experimental field study.the capacity of populations of triatoma infestans (klug) (hemiptera: reduviidae) to survive and recover was assessed after application of insecticide (gamma-hch at a rate of 0.5 g a.i./m2) at different seasons. t. infestans populations were maintained in experimental chicken houses under natural climatic conditions in a region of argentina endemic for chagas disease transmitted by these bugs. based on previous studies of t. infestans populations in these habitats, each experimental group was set ...19911722730
[experimental antitriatomic program in santiago].the rural migration to urban centers occurred since the 40s in many latin american countries, including santiago the capital city of chile, originated a growing belt of premises built with light poor material (the rests of previous rural habitations, mud, pieces of timber, plastic and cardboard for walls, and cane stalks and artificial clinkstones for roofs) giving raise to many types of slums. this situation facilitated the passive transport of the different instars, including eggs, of triatomi ...19911726919
lethality of triatomines (hemiptera: reduviidae), vectors of chagas' disease, feeding on blood baits containing synthetic insecticides, under laboratory conditions.a laboratory study was conducted to test the toxicity of synthetic insecticides added to defibrinated sheep blood kept at room temperature and offered as food to the following triatomine species: triatoma infestans, panstrongylus megistus, triatoma vitticeps, triatoma pseudomaculata, triatoma brasiliensis and rhodnius prolixus. the insecticides used, at a concentration of 1 g/l, were: hch, ddt, malathion and trichlorfon, and the lethalithy observed at the end of a 7-day period varied according t ...19911726952
the biting rate of triatoma infestans in argentina.1. the daily proportion of fed individuals in a population of the reduviid bug triatoma infestans (klug), maintained under natural climatic conditions in experimental chicken houses in central argentina, was estimated from the proportion of bugs retaining colourless urine in the rectum. 2. from the estimates of feeding frequency throughout a 1 year period, it was shown that temperature has a dominant effect on biting rate, but density-dependent effects became apparent during the warmest months. ...19911768924
vector population responses to control interventions.in 1981, kenyan authorities attempted eradication of tsetse (glossina pallidipes) from the lambwe valley, by sequential aerial spraying of endosulfan. fly populations were reduced by over 99.9% in the main habitats, but recovered to their original levels within one year. in 1986, an argentine research team attempted local elimination of domestic triatominae (triatoma infestans) in an area of santiago del estero. house infestation rates were reduced to an apparent zero, but recovered to pre-contr ...19911793271
chagas disease in north-west argentina: infected dogs as a risk factor for the domestic transmission of trypanosoma cruzi.the association between household seroreactivity to trypanosoma cruzi in dogs and children and t. cruzi infection rates in domestic triatoma infestans was investigated in 1988-1989 in the rural community of amamá, north-west argentina, where house spraying with residual pyrethroids was carried out in 1985. three years after spraying, a greater reduction of the average t. cruzi prevalence rate in dogs (from 83% to 40%) than in children (from 48% to 30%) was accompanied by a substantial decrease i ...19911801342
density-dependent timing of defaecation by triatoma infestans.defaecation timing of the triatominae vectors of trypanosoma cruzi directly affects the transmission probability of chagas disease to mammal hosts. experimental studies with fifth instar nymphs of triatoma infestans showed that defaecation time was negatively affected by blood meal size and positively affected by starvation period and bug initial weight. since blood meal size and starvation period are both density-dependent, low density domestic populations of t. infestans would represent a high ...19911801360
the status of transmission of trypanosoma cruzi in an endemic area of argentina prior to control attempts, 1985.a field survey of transmission of trypanosoma cruzi was carried out in an area which had never been sprayed with insecticide. a population census, mapping and house classification, examination of insects in houses, and a human serological survey were performed. the entomological examination showed that 97% of the houses (433/445) were infested by triatoma infestans and that 31% of the bugs examined were infected with t. cruzi. the level of infection, as well as the number of insects captured, ha ...19911809241
the importance of the opossum (didelphis albiventris) as a reservoir for trypanosoma cruzi in bambuí, minas gerais state.in a survey realized on the sylvatic and peridomestic environments at bambuí county, minas gerais state, 44 (37.9%) out of 116 opossums (didelphis albiventris) captured were found to be naturally infected with trypanosoma cruzi. one hundred and forty three parasite samples were obtained from 43 infected opossums using simultaneously hemoculture, xenodiagnosis (triatoma infestans, panstrongylus megistus and rhodnius neglectus) and examination of anal glands contents. the parasite samples were cha ...19911842405
the distribution of agglutinins and lytic activity against trypanosoma rangeli and erythrocytes in rhodnius prolixus and triatoma infestans tissue extracts and haemolymph.haemolymph, heads, salivary glands, crops, midguts, hindguts, and malpighian tubules from rhodnius prolixus and triatoma infestans were extracted in phosphate or tris buffer saline with calcium, and tested for agglutination and lytic activities by microtitration against both vertebrate erythrocytes and cultured epimastigote forms of trypanosoma rangeli. haemagglutination activity against rabbit erythrocytes was found in the crop, midgut and hindgut extracts of t. infestans but only in the haemol ...19911842412
are dead triatoma infestans a competent vector of trypanosoma cruzi?after triatoma infestans death, trypanosoma cruzi survived several days, maintaining the ability to infect a vertebrate host. dead bugs from an endemic area collected during an official spraying campaign showed mobile rectal trypanosomes up to 14 days after vector death. two days after vector death 2,760 trypomastigotes were found alive in its rectal material. however, the number of mobile trypomastigotes decreased significantly from the 5th day after death. laboratory proofs with third and fift ...19911842421
evaluation of the xenodiagnosis of chronic chagas patients infected ten years or over in an area where transmission has been interrupted--iguatama and pains, west minas gerais state, brazil.to evaluate the results of xenodiagnosis in chronic chagas patients infected for ten years or over in an area where transmission has been stemmed as well as the performance of these tests applied one or more times to determine the presence of the parasite in serum-positive patients for trypanosoma cruzi infection, 570 xenodiagnosis were performed in 246 patients by exposing each patient to 40 triatoma infestans nymphs of 3rd/4th stage once, twice or three times, at 30 days intervals. the 570 xen ...19911842429
[survival and occurrence of molting in triatoma infestans klug (hemiptera, reduviidae) after temperature shock].survival and molting occurrence were studied in specimens of triatoma infestans over 30 days after temperature shocks. hyperthermal and hypothermal shocks could be found to affect both survival and molting incidence as a function of temperature and period of the development phase and sex of the specimens. considering the various test conditions, the shock at 0 degree c for 12 h was found to elicit the most deleterious effect, whereas shocks at 40 degrees c and 0 degree c even for 1 h are interpr ...19911843235
[overview of the epidemiology of chagas' disease in chile].chile is a long and narrow country located in the south western coast of south america. chagas' disease exists in the seven first (18 degrees 30'-34 degrees 36' south lat.) of the total of thirteen administrative regions of the country. in the 1982-1990 period a series of studies considering different epidemiological aspects of this parasitic zoonosis has been carried out with the following results: 5,601 rural of periurban dwellings were surveyed for the presence of triatoma infestans (the most ...19911843858
[presence of triatoma infestans in relation to various cultural patterns in a rural population of the province of san juan, argentina].this paper reports results from a punctual epidemiological survey performed in san juan, at bermejo, a rural village located 100 km east from the provincial capital, in december 1987. the village had been rebuilt after almost complete destruction by an earthquake, in 1977. according to a census performed by local primary health care agents, there were 82 households, where 72 (88%) of them were inhabited, with a total human population of 198 people. forty-eight from those inhabited dwellings (67% ...19911843863
[yielding of xenodiagnosis, according to the number of boxes used in 1,181 persons with chronic chagasic infection diagnosed with indirect hemagglutination reaction].a study for evaluation of the yielding of xenodiagnosis (xd) in 1,181 persons with a previous positive indirect hemagglutination test (ihat) for trypanosoma cruzi infection was carried out. the infection of these people was detected during epidemiological surveys performed in rural-periurban and urban sections of the endemo-enzootic area of chagas' disease in chile, which involves the first seven, out of the thirteen political-administrative regions of the country. the sex distribution was 75.0% ...19911844135
[chagas disease in the chilean altiplane. epidemiological, parasitological, and clinical aspects].chagas' disease is endemo-enzootic in periurban and rural sections of the first seven (18 degrees 30'-34 degrees 36' south lat.), out of the thirteen political-administrative regions of chile. permanent inhabited localities situated at different altitudes over the sea level (osl) are classified in: coastal settlement (0-1,499 m osl), intermediate settlement (1,500-3,000 m osl) and altiplano settlement (> 3,000 m osl). a total of 1,558 dwellings and their occupants from regions i and ii were surv ...19911844136
[household chagasic endemia detected as a consequence of a case of congenital infection].during a study on prevalence of parasitic and viral serological markers in pregnant adolescents, a 17-year-old primipara from polpaico, village near santiago, gave birth to a normal male newborn in a santiago hospital. as both of them presented positive an indirect hemagglutination test (ihat) for chagas' disease and the corresponding xenodiagnosis (xd), the infection in the infant was considered to be acquired through the placental route. according to recent epidemiological surveys polpaico is ...19911844139
antibodies from chagas patients serum bind to the gut epithelial cell surface of triatoma infestans.serum of chagasic patients with a high title of specific antibodies against t. cruzi antigens, binds epitopes in the midgut and hindgut of the insect vector triatoma infestans free of parasites. these antigens were recognized at ultrastructural level by immunocytochemistry with serum of chagasic patients as first antibody and protein "a"-gold as marker. controls with normal human serum were negative. the positive reaction occurs principally in the apical epithelial portion (microvilli and peritr ...19911844359
[attempts to culturing triatominae in the laboratory using "in vitro" feeding].in order to simplify breeding of triatominae in the laboratory, for performing xenodiagnosis and other biologic studies, we tried to feed the insects "in vitro" with citrated or defibrinated blood from commercially abated chicken. two types of efficacy observations were carried out with triatoma infestans: a) analysis of the chaining of successive nymphal stages, viability of satisfactory matching, fertile oviposition and adequate reproduction; b) assessment of viability and infectivity of trypa ...19911844539
[behavior of trypanosoma cruzi strains after passage in different triatominae species].to study the influence of the intermediate host stage on the course of mouse infection, trypanosoma cruzi belonging to the peruvian (type i), 12 sf (type ii) and colombian (type iii) strains were passaged through either rhodnius prolixus, panstrongylus megistus or triatoma infestans. t. cruzi metacyclic forms (dose 10(4)) from the different strains were obtained from each bug and inoculated into 8-10 gm mice. comparison was made in mice inoculated with blood forms. parasitaemia curves were plott ...19911845005
circadian rhythm of egg hatching in triatoma infestans (hemiptera: reduviidae).the timing of hatching of triatoma infestans (klug) eggs was analyzed by means of time-lapse photography. under a photoperiod of 12:12 (l:d) and constant darkness, maximum eclosion occurred at the end of the subjective night. under constant light, the rhythmicity disappeared. hatching rhythm seems to be maintained by a circadian endogenous oscillator. by hatching close to dawn, when relative humidity is high, insects may avoid excessive water loss.19911941946
the prophenoloxidase system and in vitro interaction of trypanosoma rangeli with rhodnius prolixus and triatoma infestans haemolymph.the presence of the prophenoloxidase (propo) system in the haemolymph of rhodnius prolixus and triatoma infestans and the role played by trypanosoma rangeli in the in vitro activation of propo were tested. both r. prolixus and t. infestans whole blood preparations showed a very active propo system. the propo cascade of the two insect species were differentially activated by microbial-derived extracts: laminarin was a better activator of t. infestans haemolymph than of r. prolixus blood, and lipo ...19911956701
seasonal changes in infectivity of domestic populations of triatoma infestans.this paper examines the infection rate of trypanosoma cruzi in triatoma infestans, the main vector of chagas disease in argentina and neighbouring countries. the study was carried out in 1986-1987 on 5 houses (ranchos) in the endemic area of central argentina. domestic t. infestans populations were sampled in each season with a constant capture effort (2.5 man-hours/house) using a chemical irritant. the rectal content of the bugs was examined for the presence of t. cruzi. the vector population d ...19902124395
probability of transmission of chagas disease by triatoma infestans (hemiptera: reduviidae) in an endemic area of santiago del estero, argentina.the daily probability (p) of transmission of trypanosoma cruzi to a noninfected human host by an infected triatoma infestans bug was estimated using field data from a 2-year longitudinal study carried out in a rural settlement of 20 households in amamá, santiago del estero, argentina. the following information was used for this purpose: the bug density and the proportion of infected bugs; the bug biting rate and the distribution of bites between humans and animals; the age-specific seropositivit ...19902127382
development and interactions of trypanosoma rangeli in and with the reduviid bug rhodnius prolixus.two strains of trypanosoma rangeli and three strains of rhodnius prolixus were used in various combinations to transmit the trypanosomes via the reduviid bug. a persisting infection in the midgut lumen posterior to the stomach resulted in all 2,500 bugs being third and fourth instars. infectious, metacyclic forms developed exclusively in the salivary glands; forms excreted with bug feces were noninfectious to mice. the midgut epithelium was the main barrier to transmission of the parasite. in on ...19902186407
the effect of blastocrithidia triatomae (trypanosomatidae) on the reduviid bug triatoma infestans: influence of group size.developmental time and mortality in uninfected larvae of the reduviid bug triatoma infestans and in those infected by feeding a mixture of blood and cysts of the homoxenous trypanosomatid blastocrithidia triatomae were compared. larvae were maintained isolated in 77-cm3 (area 9.6 cm2) beakers or in groups of 20, 30, 40, and 50 bugs per 1-liter beaker (area 722 cm2). in uninfected groups, only a minor proportion of isolated bugs showed delayed development, but in groups infected with b. triatomae ...19902125629
the effect of blastocrithidia triatomae (trypanosomatidae) on the midgut of the reduviid bug triatoma infestans.the pathogenic flagellate blastocrithidia triatomae disrupts the digestion of triatoma infestans; the midgut ultrastructure of bugs infected with the flagellate and of uninfected bugs is compared. third or fourth instar larvae were dissected either unfed or 1 week after feeding. in all uninfected bugs extracellular membrane layers (e.m.l.) covered the apical microvillar border of the epithelial cells. some midgut regions of bugs infected with b. triatomae appeared normal but often adjacent cells ...19902107501
membrane feeding for infection of the reduviid bug triatoma infestans with blastocrithidia triatomae (trypanosomatidae) and pathogenic effects of the flagellate.to investigate the pathogenic effects of the trypanosome blastocrithidia triatomae on triatoma infestans, a method for direct infection by in vitro feeding was developed. after isolation of b. triatomae cysts from infected dead bugs, a suspension of cysts was disinfected with desogen and chloramin t, then mixed with sterile blood, spread on a sterile, parallel-grooved glass plate or a hammered aluminium plate and covered with a thin, sterile silicone membrane. the blood and plate were warmed to ...19902110672
developmental time and mortality of the reduviid bug triatoma infestans with differential exposure to coprophagic infections with blastocrithidia triatomae (trypanosomatidae).developmental time and survival in larvae of the reduviid bug triatoma infestans were studied in uninfected groups and in those exposed to a coprophagic infection with blastocrithidia triatomae. addition to young uninfected larvae of (a) different numbers of infected bugs, (b) infected and uninfected bugs, and (c) fresh or dry infectious feces were compared. retardation of development was evident in groups given infected larvae or fresh feces. mortality rates were correlated with infection rates ...19902105356
does trypanosoma cruzi stress its vectors?trypanosoma cruzi seems to compete with its vector, triatoma infestans, for nutrients. when starved the resistance of infected triatoma is reduced but it is rarely affected i f it is given an adequate food supply. infected individuals also might be more sensitive than uninfected bugs to other environmental stress factors. günter schaub believes that the theory, that t. cruzi does not affect its vectors, should be re-examined.198915463208
myocardial involvement in cavia porcellus naturally infected with trypanosoma cruzi.this paper describes the myocardial involvement analyzed by histopathological examination in rural cavia porcellus during natural t. cruzi infection. four cavia porcellus of both sexes were bred in a house free of triatoma infestans. in contrast, four animals were born and lived in a rural yard colonized by t. infestans. autopsies were performed at 6-9 months of age, in animals weighing 550 to 750 grams. the naturally infected cavia porcellus presented moderate and severe lymphocyte and plasmocy ...19892487739
cannibalism and coprophagy are modes of transmission of blastocrithidia triatomae (trypanosomatidae) between triatomines.transovarial transmission was not detectable among blastocrithidia triatomae-infected triatoma infestans. rather, b. triatomae was transmitted directly between triatomines by cannibalism and coprophagy. cannibalism conditions that excluded coprophagy always resulted in an infection of dipetalogaster maxima. the efficiency of transmission was not influenced by the blood source--mice or chickens--fed to the infected donor bugs although chicken blood lyses the epimastigotes of the stomach populatio ...19892498511
cultivation of blastocrithidia triatomae (trypanosomatidae) on a cell line of its host triatoma infestans (reduviidae).blastocrithidia triatomae parasitizes vectors of chagas' disease and is very difficult to cultivate in conventional media. however, co-cultivation with a cell line of its host triatoma infestans (ti-32; in schneider's drosophila medium supplemented with 20% foetal calf serum and 10% tryptose phosphate broth) led to vigorous growth at 24 or 28 degrees c without an adaptation phase. more than 60 primary cultures were initiated successfully without any failures. subcultures could be started immedia ...19892505214
parasite/host-interrelationships of the trypanosomatids trypanosoma cruzi and blastocrithidia triatomae and the reduviid bug triatoma infestans: influence of starvation of the bug.we have investigated the effects of trypanosoma cruzi and blastocrithidia triatomae on the life span of starved second/third (l2/3), third/fourth (l3/4), and fourth/fifth instars (l4/5) of triatoma infestans, which had been infected in the first instar and fed last in the second, third or fourth instar respectively. the intestines and sometimes also the flagellate populations of dead bugs were examined. in uninfected l2/3 a higher relative humidity prolonged the life span. with a maximal surviva ...19892513786
[isolation of trypanosoma cruzi samples by xenodiagnosis and hemoculture from patients with chronic chagas' disease].fifty nine chronic chagasic patients were simultaneously submitted to xenodiagnosis and hemoculture for trypanosoma cruzi samples isolations. the xenodiagnosis was done with 40 panstrongylus megistus, triatoma infestans and dipetalogaster maximus nymphs, performing 120 triatomines. groups of 10 insects per specie were dissecated and the intestinal content pooled and examined, after previous trituration and homogenization. the microscopically negative material was seed into lit medium and examine ...19892517566
population dynamics of triatoma infestans under natural climatic conditions in the argentine chaco.using experimental chicken houses at a site in central argentina where the bug triatoma infestans (klug) is endemic, nine populations of this vector of chagas disease were monitored during a 34-month period. bug populations with four chickens as hosts were consistently larger than those with two chickens as hosts. age structure of the bug population followed a similar pattern irrespective of the initial age structure. egg to adult mortality was consistently around 98.5% and there was no consiste ...19892519662
[seroprevalence of antibodies against trypanosoma cruzi in 13 departments of uruguay].in 1985 a study was undertaken of the prevalence of trypanosoma cruzi antibodies in 13 departments of uruguay where transmission of the parasite by the vector triatoma infestans persists. a total of 5,924 serum samples were selected using a probabilistic method--3,840 from individuals over the age of 12 (sample i) and 2,084 from subjects who were 12 years old (sample ii). the population was classified according to place of residence (capital city, non-capital city, suburban area, and rural area) ...19892529870
binding of lectin-gold conjugates by two trypanosoma cruzi strains in ampullae and rectum of triatoma infestans.the ampullae and recta of triatoma infestans infected with trypanosoma cruzi were incubated with lectin-gold conjugates of wheat germ agglutinin (wga) and soy bean agglutinin (sba) and investigated by electron microscopy. t. cruzi colonized the whole lumen of the ampullae. the rectal pads with their intensive intracellular membrane system and thin cuticle were often covered by a compact layer of flagellates, whereas the remaining rectal sac- recognizable by a thick layered cuticle - was colonize ...19892575865
trypanosoma cruzi: quantitative studies of development of two strains in small intestine and rectum of the vector triatoma infestans.this paper describes the development stages and numbers of flagellates of two strains of trypanosoma cruzi living in the small intestine and rectum of the insect, triatoma infestans, during the first 12 weeks postinfection (pi). mainly epimastigotes and occasionally amastigotes and final trypomastigotes developed in the small intestine but after starvation periods of 3 or 4 weeks higher percentages of spheromastigotes including their transitional forms to/from epimastigotes were found. in the re ...19892649388
critical electrolyte concentration of heterochromatin and euchromatin in cells of starved animals.the critical electrolyte concentration (cec) of chromatin, considered to be the salt concentration at which the phenomenon of metachromasy is completely abolished, when using toluidine blue as the cationic dye and mg2+ ions as inorganic cations, was determined for the euchromatin and chromocentral heterochromatin of cells from starved animals. the objective was to determine variations in cec induced by the starvation stress, which could be related to structural alterations and/or to the composit ...19892699727
purification and properties of the very high density lipoprotein from the hemolymph of adult triatoma infestans.the very high density lipoprotein (vhdl) of triatoma infestans hemolymph from adult males has been isolated and purified by two-step density gradient ultracentrifugation. it appears to be homogeneous as judged by native polyacrylamide gel electrophoresis. the content of vhdl in hemolymph was estimated to be 8 mg protein/ml. the purified protein has a molecular weight (mr) of 450,000, is composed of six subunits of mr approximately equal to 77,000, and possesses a high content of aromatic amino a ...19892677201
fatty acid biosynthesis in the integument tissue of triatoma infestans.1. the biosynthesis of lipids and their distribution in several tissues were investigated by injection of 1-14c acetate in females and 5th instar nymphs of the hematophagous hemiptera t. infestans. 2. biosynthesis of palmitic, palmitoleic, stearic, oleic and very long chain fatty acids up to 26 carbons and hydrocarbons, was shown. they were found in haemolymph, fat body, integument, epicuticle and oocytes with special distribution. 3. epicuticular hydrocarbon labelling was shown to precede that ...19892680250
darwin's illness.darwin's chronic ill health began after 1838. by his own account he had been exposed to triatoma infestans, a vector of chagas' disease, and his symptoms were compatible with chagas' disease. the case for rejecting a diagnosis of chagas' disease is reviewed; however, the weight of evidence favors this diagnosis, as originally suggested by saul adler.19892496051
critical electrolyte concentration of the heterochromatin and euchromatin of triatoma infestans.the binding of toluidine blue molecules under mg2+ competitive staining conditions was investigated in chromocentres and the euchromatin of single- and multi-chromocentred nuclei of triatoma infestans malpighian tubule cells. it was demonstrated that the chromocentre of single-chromocentred nuclei exhibited the largest critical electrolyte concentration (cec) value (0.4 m), followed by the chromocentres of multi-chromocentred nuclei (0.3 m) and the euchromatin (0.2 m). the differences in cec val ...19892480868
studies on the trehalase from the hemolymph of triatoma infestans. 19883071834
lipid thermotropic transitions in triatoma infestans lipophorin.the structure and lipid thermotropic transitions of highly purified lipophorin of triatoma infestans were examined by several techniques: steady-state fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (dph), cis-parinaric acid (cis-pna) and trans-parinaric acid (trans-pna), light scattering fluorescence energy transfer between the lipophorin tryptophan residues and the bound chromophores, dph, trans-parinaric acid cis-parinaric acid, gel electrophoresis, and gel filtration. fluorescence ...19883284956
junctional specializations in the seminiferous epithelium of an insect (triatoma infestans): a freeze fracture and lanthanum tracer study.intercellular junctions in the seminiferous epithelium of the testis of triatoma infestans were examined by conventional electron microscopy, tannic acid fixation, electron-opaque tracers, and freeze-fracture techniques. distinctive aspects of the intercellular junctions are described in different regions of the testis follicles. in the basal region, close to the basal lamina, smooth septate junctions intermingled with gap junctions were observed between sustentacular cells. in the parabasal reg ...19883070831
direct transmission of trypanosoma cruzi between vectors of chagas' disease.trypanosoma cruzi was transmitted directly between triatomines by cannibalism or coprophagy. different conditions involving cannibalism that excluded coprophagy were studied in dipetalogaster maximus. infections occurred if an uninfected donor bug sucked infectious blood and if this blood was taken up from the stomach by a cannibalistic bug. if the donor was infected and sucked uninfected blood afterwards, the source of the uninfected blood determined the transmission rate: if the uninfected blo ...19882896441
dispersal flight by triatoma infestans in an arid area of argentina. 19882980200
developmental time and mortality of larvae of triatoma infestans infected with trypanosoma cruzi.triatoma infestans were infected with trypanosoma cruzi (zymodeme 1) at the first feed after eclosion from the egg; interstadial development times and mortality rates were then recorded until the imaginal moult and compared with those of uninfected controls. no retardation of development occurred in infected bugs and their mean total mortality rate (9%) was only slightly higher than that (6%) of uninfected controls (due solely to 4 additional deaths). this is the first demonstration, under optim ...19883051552
inhibition of xanthine dehydrogenase from triatoma infestans by some purine analogues.xanthine dehydrogenase (ec 1.2.1.37) activity was determined in the fat body of the chagas' disease vector triatoma infestans using a system in which phenazine methosulphate was associated with p-iodonitrotetrazolium violet as electron acceptors for the oxidation of the substrate xanthine. under the standard conditions used, xanthine was the substrate of choice. the apparent michaelis-menten constant (km) for xanthine was found to be 0.217 +/- 0.020 mm (mean +/- standard deviation of four indepe ...19883052441
characterization of triatoma virus, a picorna-like virus isolated from the triatomine bug triatoma infestans.some properties of triatoma virus (trv), a picorna-like virus recently isolated from triatoma infestans, have been studied. electron microscopic observations of purified viral preparations showed the presence of non-enveloped viral particles 30 nm in diameter. the sedimentation coefficient of virus particles was about 165s and the buoyant density in cscl was 1.39 g/ml. the viral genome was composed of one single-stranded rna molecule with an mr of 3 x 10(6). three major polypeptides with mr valu ...19883053988
development of isolated and group-reared first instars of triatoma infestans infected with trypanosoma cruzi. 19883057492
cardiac morbidity due to chagas' disease in a rural community in bolivia.the prevalence of cardiac morbidity due to chagas' disease was assessed in a rural community in central bolivia. sixty-nine of 104 persons (66%) were seropositive to trypanosoma cruzi by two serological methods. two of 35 (6%) seronegative individuals presented with modest ecg alterations (left anterior hemiblock), but 21 of 69 (30%) seropositives showed modest and severe abnormalities (6 complete right bundle branch block, 2 polyfocal or frequent extrasystoles, 9 ischaemic st alterations). a hi ...19883063552
metacyclogenesis of trypanosoma cruzi in the vector triatoma infestans. 19883075693
suitability of in-vitro xenodiagnosis: development of trypanosoma cruzi in triatoma infestans depending on larval stage of bugs and number of trypomastigotes taken during in-vitro blood meal.a study on artificial xenodiagnosis was carried out for the identification of t. cruzi, the causative organism of the american trypanosomiasis (chagas disease) using the natural vector t. infestans. it was investigated whether one single t. cruzi (strain b) is sufficient for successful infection of t. infestans. since the infection took place by artificial feeding, the average amount of blood taken by larval stages i-v in one meal was determined. on the basis of these results the feeding solutio ...19883134769
influence of blastocrithidia triatomae (trypanosomatidae) on the reduviid bug triatoma infestans: alterations in the malpighian tubules.to investigate the cellular basis of our recent observation that the trypanosome blastocrithidia triatomae disturbs excretion in triatoma infestans, we compared the morphology and ultrastructure of malpighian tubules in infected and noninfected bugs. tubules of bugs infected 3-4 months before dissection did not show any morphological alterations in either the upper or lower regions. in fifth instars with a long lasting infection (9-10 months) and a correspondingly retarded larval development, th ...19883148931
trypanosoma cruzi: origin of metacyclic trypomastigotes in the urine of the vector triatoma infestans.population density and percentage of the different stages of an established infection of trypanosoma cruzi were determined for two parts of the excretory system and for the rectum of fifth instars of triatoma infestans unfed and 4 hr after feeding. these data were also evaluated for feces and urine of the fed bugs. in the first unfed group only small populations of the flagellate occurred in the malpighian tubules and ampullae and not in all bugs. the three rectal populations (rectal lumen and a ...19883280333
the influence of blastocrithidia triatomae (trypanosomatidae) on the reduviid bug triatoma infestans: in vivo and in vitro diuresis and production of diuretic hormone.the homoxenous flagellate blastocrithidia triatomae disturbs excretion in triatoma infestans. during the first 4 and 24 h after feeding, infected 5th instars excreted approximately a 2.5-fold smaller volume of urine. consequently, about double the normal volume of haemolymph could be obtained from these infected bugs 24 h after feeding. surprisingly, the in vitro secretion rates of malpighian tubules from uninfected and infected bugs were nearly identical. in addition, the storage and release of ...19883129692
developmental time and mortality in larvae of the reduviid bugs triatoma infestans and rhodnius prolixus after coprophagic infection with blastocrithidia triatomae (trypanosomatidae). 19883127477
control of chagas disease in brazil.chagas disease (south american trypanosomiasis) is a chronic but often fatal disease endemic throughout much of latin america. serological surveys suggest around 24 million people seropositive for the causative agent, trypanosoma cruzi (fig. 1), with over 65 million living in the endemic areas and at risk to infection. in brazil, over 25 million people are considered at risk, and control of the disease constitutes one of brazil's public health priorities. treatment or vaccination against t. cruz ...198715462880
colonization of the rectum of triatoma infestans by trypanosoma cruzi studied by scanning electron microscopy: influence of blood uptake by the bug.the colonization of the different regions of the rectum of triatoma infestans by trypanosoma cruzi was studied in unfed larvae, during and after feeding of the bug by scanning electron microscopy. the rectal pads always possessed the highest population densities, but in some bugs the main rectal sac and the region around the anus were also covered by a "carpet" of flagellates. such high densities were never observed at the midgut/rectal junction. a slight decrease in this region might be caused ...19873309941
polyploidization of the btc-32 cell line from triatoma infestans (hemiptera, reduviidae).the cytophotometric evaluation of the feulgen-dna content of the btc-32 cells at passage 160 after 6 days of growth demonstrated that polyploidy is relatively frequent in this cell line. 4c values were assumed to pertain to diploid nuclei at the s or g2 phases but also to polyploid nuclei at the g1 phase. polyploidy in 4c nuclei is assumed to be attained by endomitosis. however, there are morphological indications that polyploidization in cells with an 8c-128c feulgen-dna content could result fr ...19873333490
[home ecology of trypanosomiasis americana: feeding profile of triatoma infestans in a rural area of the santiago del estero province, argentina]. 19873333976
isozyme evidence of lack of speciation between wild and domestic triatoma infestans (heteroptera: reduviidae) in bolivia. 19873546693
small nonoccluded viruses from triatomine bug triatoma infestans (hemiptera: reduviidae). 19873549911
epidemiology of chagas' disease in northern chile: isozyme profiles of trypanosoma cruzi from domestic and sylvatic transmission cycles and their association with cardiopathy.trypanosoma cruzi was isolated from 98 patients, 59 triatoma infestans, 51 triatoma spinolai, and 1 octodon degus from northern chile. with few exceptions, stocks originating from domestic hosts were classified, based on their isozyme profile, as principal zymodeme (z)2, while sylvatic stocks from t. spinolai and the rodent o. degus showed z1 profiles. these results indicate the existence of separate domestic and sylvatic transmission cycles. clinical data and t. cruzi isozyme profiles from 107 ...19873116867
differences in binding of lectin-gold conjugates by trypanosoma cruzi and blastocrithidia triatomae (trypanosomatidae) in the intestine of triatoma infestans (reduviidae).two species of trypanosomatid flagellates, trypanosoma cruzi and blastocrithidia triatomae which develop in the intestine of triatoma infestans, were incubated with lectin-gold conjugates to demonstrate sugar components of the cell surface with the electron microscope. t. cruzi, strain "chile 5" (zymodeme 1), bound sba-gold, revealing n-acetyl-galactosamine and/or galactose residues. wga-bsa-gold, specific for n-acetylglucosamine, did not bind to the surface of this flagellate. on the other hand ...19873125542
dynamics of transmission of trypanosoma cruzi in a rural area of argentina: ii. household infection patterns among children and dogs relative to the density of infected triatoma infestans. 19873126846
trypanosoma cruzi: differentiation to metacyclic trypomastigotes in the presence of adp-ribosyltransferase inhibitors.the participation of adp-ribosyltransferase in trypanosoma cruzi differentiation to the metacyclic stage was evaluated by analyzing morphogenesis blockage by specific enzyme inhibitors: benzamide, 3-aminobenzamide, theophylline, and nicotinamide. in vitro assays showed a statistically significant reduction in the number of metacyclic forms only when any one of the four inhibitors was added during the period of interaction between epimastigote and triatoma infestans intestinal homogenate or when ...19872960557
trypanosoma cruzi isolates from argentina and chile grouped with the aid of dna probes.fifty-two isolates and several clones from trypanosoma cruzi, the agent of chagas' disease, were analyzed using cloned minicircles or total kinetoplast dna as probes. isolates were obtained from triatomines, guinea pigs and infected humans in the central and northern regions of argentina and the north of chile. 35% of all the randomly selected isolates could be identified with one cloned minicircle probe. this widely distributed t. cruzi group was detected on both sides of the andes mountain ran ...19872823134
recombination nodules, synaptonemal complexes and heterochromatin in the hemipteran triatoma infestans. 19873332298
the occurrence of arachidonic acid in triatoma infestans.1. gas-liquid chromatography and mass spectrometry were used to verify the presence of arachidonic acid (20:4 omega 6) in adult male and female organs of the blood-suckling bug triatoma infestans. fat body, gonad and head lipids were analyzed. 2. male gonads contained the highest percentage of phospholipids and the highest percentage of arachidonic acid. 3. phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine and sphingomyelin were isolated from gonads and head ...19873117486
activity of the insect growth regulator fenoxycarb (ro-13-5223) on triatoma infestans (hemiptera).1. fenoxycarb (ro-13-5223) exhibits a strong juvenile hormone type of activity against triatoma infestans. 2. topical treatment of last-stadium nymph with the juvenoid caused the formation of superlarvae, adult-larvae intermediates and adultoids. the ed50 was 0.02 microgram/insect. 3. taking into account abnormalities in oceli, head, thorax, legs, wings, abdomen, conexivo and external genitalia, a scoring system to evaluate the retention of juvenile characters after moulting was developed. 4. in ...19872888581
a permeability barrier in the testis of an insect triatoma: a freeze-fracture and lanthanum tracer study.in vertebrates, the testicular permeability barrier has been the subject of numerous studies. some recent observations also indicate the existence of such a barrier in some invertebrates, e.g. insects and worms. with the aim of determining whether the morphological features of the blood-testis barrier generally found in vertebrates can be extended to other animals, we studied the testis of the insect triatoma infestans using electron-dense tracers and freeze-fracture techniques. this organ is di ...198618620169
[biochemistry of the evolutive cycle of triatoma infestans. ix. composition of cuticular hydrocarbons compared to other triatominae].the hydrocarbon composition of epicuticular lipids of different species of triatomini were determined and compared by gas-liquid chromatography. t. infestans, t. delpontei, t. rubrovaria, t. sordida, t. guasayana and t. vitticeps from infestans subgroup and t. pallidipennis from rubrofasciata, were studied. all these species had in common the same kind of hydrocarbons. the major components were n c29; n c31; 12+14+15+18 methyl c38; 15, 19+14, 18 dimethyl c39; 12+14+17+19 methyl c36 and 4 methyl ...19862945401
vitellin and vitellogenin characterization of triatoma infestans and related species.the vitellogenin-vitellin (vg-vn) of triatoma infestans is a glycolipoprotein with a mol. wt. of 220,000; is a high density lipoprotein (1.18-1.21 g/ml) with low electrophoretic mobility at ph 8.2. there are many common proteins present in females, males, nymphs and eggs, but none is a glycolipoprotein. the major band of protein revealed a mol. wt. of 43,000, it is an anodic protein which appears in all the fractions of saline gradient. males and females have a glycolipoprotein with electrophore ...19863111174
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