| nigerian blood-fed blackflies (diptera. simuliidae) caught in flight: relative activity and host preferences. | using a vehicle-mounted net, over 1000 blood-fed blackflies were collected in flight, showing that they had a much higher level of activity during this stage than was previously expected, particularly in simulium squamosum. activity was greatest in blood-fed females with stage iv eggs, presumably because they were starting to search for oviposition sites. s. squamosum, s. adersi and s. vorax showed a moderate level of activity in flies with stage ii and iii eggs, although these are normally cons ... | 1987 | 3602837 |
| the distribution of the simulium damnosum complex in sierra leone and its relation to onchocerciasis. | because of the paucity of literature concerning onchocerciasis and its vectors in sierra leone, new information of the geographical distribution of the simulium damnosum complex is presented in the context of a comprehensive review of what is known generally about s. damnosum s.l. in sierra leone, and how the data relate to the transmission of onchocerciasis. neither biting adults nor breeding sites have been found on the coastal plain and freetown peninsula, and these area seem to be free from ... | 1985 | 4096566 |
| experimental studies on the transmission of onchocerca volvulus by its vector in the sanaga valley (cameroon): simulium squamosum b. intake of microfilariae and their migration to the haemocoel of the vector. | as large-scale ivermectin distribution is becoming the mainstay of onchocerciasis control in africa, the issue of its impact on local transmission is increasing in importance. the vector competence of simulium squamosum b in the severe focus of the sanaga valley, cameroon, was therefore investigated, by feeding 1320 flies on 14 carriers of onchocerca volvulus microfilariae (mff). the results enabled the relationships between skin microfilarial load, microfilarial intake by the flies, the proport ... | 2003 | 12831524 |
| seasonal variation in onchocerciasis transmission by simulium squamosum at perennial breeding sites in togo. | analyses of data collected routinely by the world health organization onchocerciasis control programme in west africa showed that the transmission of onchocerciasis by simulium squamosum at amou-oblo, in togo, was maximal in the dry season. mean monthly transmission potentials ranged from 10.4 in august to 519.6 in february. infectivity in terms of numbers of l3 larvae in the head per 1000 parous flies was highest in march. additional, more detailed, studies involving the staining of flies from ... | 1992 | 1566312 |
| an episode of resistance to permethrin in larvae of simulium squamosum (diptera: simuliidae) from cameroon, after 3 1/2 years of control. | because of the biting nuisance from females of simulium squamosum, a 30 km section of the sanaga river (cameroon) was treated since 1987 with permethrin for the control of larval populations. in 1990, resistance to permethrin occurred in a small proportion of the larvae, with a resulting 2-4x increase of the lc95 for dead larvae (moribund larvae considered as live). in 1991, after a 6-month interruption of the treatments, susceptibility to permethrin returned to the initial level, and was simila ... | 1992 | 1431861 |
| light trap collections of ovipositing simulium squamosum in ghana. | at a site near boti waterfalls in southern ghana a total of 14 644 female and two male simulium squamosum were caught in four nights in monks wood light traps. the highest catch, of 6520 females, was obtained in a single night with an ultraviolet light tube that had a one-second flash rate. about 12% of the females caught were gravid and dissections of non-gravids showed that they had oviposited very recently. the traps were clearly catching females before or soon after oviposition. the same tra ... | 1979 | 534449 |
| wing tuft colours in the progeny of single individuals of simulium squamosum (enderlein) | | 1981 | 7268843 |
| [simple device for rearing simulium squamosum in the laboratory]. | | 1987 | 3426313 |
| molecular systematics of simulium squamosum, the vector in the kinsuka onchocerciasis focus (kinshasa, democratic republic of congo). | | 2007 | 17362602 |
| cardiocladius oliffi (diptera: chironomidae) as a potential biological control agent against simulium squamosum (diptera: simuliidae). | the control of onchocerciasis in the african region is currently based mainly on the mass drug administration of ivermectin. whilst this has been found to limit morbidity, it does not stop transmission. in the absence of a macrofilaricide, there is a need for an integrated approach for disease management, which includes vector control. vector control using chemical insecticides is expensive to apply, and therefore the use of other measures such as biological control agents is needed. immature st ... | 2009 | 19393069 |
| natural interspecific hybridisation of simulium sanctipauli s.l. with simulium squamosum and simulium yahense (diptera: simuliidae). | natural hybridisation between simulium sanctipauli (sensu quillevéré et al. 1981) and simulium squamosum/yahense occurs at a rate of around 0.001. a single larva has been found which is unambiguously a backcross between s. sanctipauli s.l. and a s. sanctipauli s.l. x squamosum/yahense hybrid. this discovery indicates the possibility of genetic introgression between these species. examination of the polytene chromosomes of this backcross progeny and subsequent re-examination of the type specimens ... | 1984 | 6710602 |
| assessment of rdna igs as a molecular marker in the simulium damnosum complex. | for five cytospecies of the simulium damnosum theobald complex of blackflies (diptera: simuliidae) from west africa, both ends of the intergenic spacer region (igs) of the rdna have been sequenced with the aim of developing specific molecular markers. no specific differences in these two regions were detected between simulium sanctipauli v. & d., simulium sirbanum v. & d., simulium soubrense v. & d., simulium squamosum enderlein and simulium yahense v. & d., except in the number of a subrepeats ... | 2002 | 12510892 |
| the genomic architecture of novel simulium damnosum wolbachia prophage sequence elements and implications for onchocerciasis epidemiology. | research interest in wolbachia is growing as new discoveries and technical advancements reveal the public health importance of both naturally occurring and artificial infections. improved understanding of the wolbachia bacteriophages (wos) wocaub2 and wocaub3 [belonging to a sub-group of four wos encoding serine recombinases group 1 (sr1wos)], has enhanced the prospect of novel tools for the genetic manipulation of wolbachia. the basic biology of sr1wos, including host range and mode of genomic ... | 2017 | 28611731 |
| construction and characterisation of a bac library made from field specimens of the onchocerciasis vector simulium squamosum (diptera: simuliidae). | a bacterial artificial chromosome (bac) library was made from wild-caught simulium squamosum, which is an important vector of human onchocerciasis. the library is composed of 12,288 bacs, with an average insert size of 128 kb, and is expected to contain ~1.54 gb of cloned dna. random bac-end sequencing generated over 95 kb of dna sequence data from which putative s. squamosum gene sequences and novel repetitive dna families were identified, including dna transposons, retrotransposons and simple ... | 2010 | 20603211 |
| phylogenetically distinct wolbachia gene and pseudogene sequences obtained from the african onchocerciasis vector simulium squamosum. | wolbachia are intracellular bacteria mostly found in a diverse range of arthropods and filarial nematodes. they have been classified into seven distinct 'supergroups' and other lineages on the basis of molecular phylogenetics. the arthropod-infecting wolbachia are usually regarded as reproductive parasites because they manipulate their host species' sexing system to enhance their own spread, and this has led to their investigation as potential agents of genetic control in medical entomology. we ... | 2010 | 20005876 |
| [african programme for onchocerdasis control (apoc): onchocerca simulium squamosum in two regions in the republic of cameroon]. | in 1998, the african programme for onchocerciasis control (apoc) decided to launch a long-term impact assessment of its operations. this paper reports the baseline entomological data collected throughout a whole year in two sites of cameroon (kahn and bolo). the simulium populations of the two study sites were characterized by parous rates of 7.2% and 33.5% respectively and infectivity by o. volvulus of 31 and 190 infective larvae per 1000 parous flies respectively the annual transmission potent ... | 2006 | 17111978 |
| a new cytotype of simulium squamosum from south-west cameroon. | a new cytotype of simulium squamosum enderlein (diptera: simuliidae) (here named s. squamosum'd') is described from around mount cameroon in south-west cameroon on the basis of sex-chromosome differences on the short arm of chromosome i. two polymorphic inversions, is-to (a new inversion) and is-2, are partially y linked. these inversions usually occur together, although is-to has a higher frequency and is more strongly y linked than is-2. this sex-chromosome system has not been previously descr ... | 2004 | 15347398 |
| impact of four years of large-scale ivermectin treatment with low therapeutic coverage on the transmission of onchocerca volvulus in the mbam valley focus, central cameroon. | the extent to which ivermectin treatments have an impact on onchocerciasis transmission is a matter of some concern. we investigated this issue in the mbam valley, a hyperendemic focus located in a forest-savannah mosaic area of cameroon. parasitological examinations of 5-9-year-old children, who had never received any antifilarial drug, were conducted before the first distribution of ivermectin in 1991-1993 and again in 2002, after four annual rounds of mass treatments. after matching for gende ... | 2004 | 15251400 |
| a molecular marker for the identification of simulium squamosum (diptera: simuliidae). | all except one of the important groups of west african vectors of onchocerca volvulus that lie within the simulium damnosum complex can be distinguished from each other using morphological characteristics. the exception is s. squamosum, which overlaps with other species, and this results in significant levels of misidentification. variation in the untranscribed h3-h4 histone intergenic spacer region of flies of the s. damnosum complex has now been investigated. although a caa/cag microsatellite ... | 2004 | 15035730 |
| sex chromosome variation and cytotaxonomy of the onchocerciasis vector simulium squamosum in cameroon and nigeria. | on the basis of sex chromosome variation, three cytotypes of simulium squamosum (enderlein) (diptera: simuliidae) are described from cameroon and nigeria. simulium squamosum a is the typical form as originally described by vajime & dunbar (1975) with chromosome i as the sex chromosome. it occurs throughout most of cameroon and south-east nigeria. a second cytotype, s. squamosum b, is described from the river sanaga (cameroon). it also has chromosome i as the sex chromosome, but the nature of the ... | 2001 | 11434559 |
| [systemic action of ivermectin on culex quinquefasciatus and simulium squamosum]. | the mortality of culex quinquefasciatus mosquitoes having fed ten days earlier on a chicken treated by 2,000 micrograms/kg of ivermectin (about ten times the therapeutic dosage) is about 25% higher than the mortality recorded on mosquitoes having fed on a non treated chicken. this systemic effect occurs only if the blood meal takes place between 7 and 31 hours after the administration of the drug. however, no systemic effect is recorded either with the c. quinquefasciatus mosquito or with the si ... | 1999 | 10214528 |
| a study of onchocerciasis with severe skin and eye lesions in a hyperendemic zone in the forest of southwestern cameroon: clinical, parasitologic, and entomologic findings. | prior to the initiation of an onchocerciasis control program based on the mass administration of ivermectin in the rain forest of southwestern cameroon, a preliminary baseline study of the area was conducted. the results of this study showed that onchocerciasis was hyperendemic in the area. skin symptoms and signs were observed including pruritus (67.4% of the population examined), onchocerca nodules (51.6%), skin depigmentation (18.5%), and hanging groins (5.7%). except for pruritus, the preval ... | 1993 | 8427383 |
| [onchocerciasis control program in west africa: socioeconomic development and risk of recrudescence of transmission. 2. experimental study of the transmission of onchocerca volvulus strains from southwestern sierra leone by simulium yahense and simulium squamosum]. | the movements of human populations towards the mining wealth of the northern parts of sierra leone are favorable to a high contact rate between onchocerciasis patients coming from the south-western area of this country and the vector species simulium yahense and simulium squamosum which assume the essential of onchocerciasis transmission in the above-mentioned mining area. in fact, the onchocerca volvulus strains concerned by this contact seem to be more pathogenic than those locally transmitted ... | 1994 | 7944649 |
| sibling species distributions of the simulium damnosum complex in the west african onchocerciasis control programme area during the decade 1984-93, following intensive larviciding since 1974. | during the decade from 1984 to 1993, nine species of the simulium damnosum complex of blackflies (diptera: simuliidae) were identified from the area covered by the onchocerciasis control programme. these were s. damnosum s.s., s. dieguerense, s. konkourense, s. leonense, s. sanctipauli, s. sirbanum, s. soubrense, s. squamosum, and s. yahense. some of these species were found to consist of two chromosomal variant populations. these were s. konkourense 'konkouré' and 'menankaya' forms, s. sanctipa ... | 1998 | 9824818 |