Detection of Trypanosoma brucei rhodesiense in animals from sleeping sickness foci in East Africa using the serum resistance associated (SRA) gene

Njiru, Z. K.; Ndung’u, Kariuki; Matete, G.; Ndung'u, J. M.; Gibson, Wendy

doi:10.1016/j.actatropica.2004.01.001

Cited by 27 publications

(20 citation statements)

References 16 publications

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“…Furthermore, in the Chiawa area where the majority of the tsetse flies were captured, the trypanosome infection rate of female G. pallidipes was 2.6 times higher than in the male flies. Similar difference has been reported previously [23]. This is likely because female flies have longer life span and feeding frequency than males.…”

Section: Discussionsupporting

confidence: 77%

Virological and Serological Studies of Porcine Respiratory Coronavirus Infection on a Japanese Farm

et al. 2008

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ABSTRACT. The prevalence of trypanosome infections in tsetse flies, Glossina pallidipes, collected from Chiawa and Chakwenga in Zambia with endemic trypanosomosis was assessed by polymerase chain reaction (PCR). Out of the 550 G. pallidipes, 58 (10.5%) flies were found to harbor trypanosome DNA. Infection rates of tsetse with Trypanosoma vivax universal, Trypanosoma congolense savannah, T. congolense forest and T. congolense kilifi were 4.2% (23/550), 4.7% (26/550), 1.1% (6/550) and 1.6% (9/550), respectively. To determine the mammalian hosts of T. congolense and T. vivax infections from the tsetse flies, mammalian mitochondrion DNA of blood meal in these flies were analyzed by PCR and subsequent gene sequence analysis of the amplicons. Sequence analysis showed the presence of cytochrome b gene (cyt b) of 7 different mammalian species such as human, elephant, buffalo, goat, warthog, greater kudu and cattle. Goats which were main livestock in these areas were further examined to know the extent of its contribution in spreading the infection. We examined the prevalence of trypanosome infections in the domestic goat population in 6 settlements in Chiawa alone. Of the 86 goats sampled, 4 (4.6%), 5 (5.8%), 4 (4.6%) and 4 (4.6%) were positive for T. vivax universal, T. congolense savannah, forest and kilifi, respectively. These findings showed that the host-source of trypanosome infections in vector fly give a vital information about spread of infection. The result of this study will certainly contribute in elucidating more the epidemiology of trypanosomosis.

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Section: Discussionsupporting

confidence: 77%

Virological and Serological Studies of Porcine Respiratory Coronavirus Infection on a Japanese Farm

et al. 2008

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“…The SRA gene has been PCR-amplified exclusively from human-infective trypanosome stocks [40] and transfection of Tbb with the SRA gene is sufficient to confer resistance to human serum [39]. Therefore, in eastern Africa, the SRA gene has emerged as a useful marker for identifying human-infective trypanosomes in their animal reservoir [33], [40], [41]. Given the potential for recombination between Tbr and Tbb [35], the SRA gene could potentially occur on all genetic backgrounds (i.e.…”

Section: Introductionmentioning

confidence: 99%

Phylogeography and Taxonomy of Trypanosoma brucei

et al. 2011

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BackgroundCharacterizing the evolutionary relationships and population structure of parasites can provide important insights into the epidemiology of human disease.Methodology/Principal FindingsWe examined 142 isolates of Trypanosoma brucei from all over sub-Saharan Africa using three distinct classes of genetic markers (kinetoplast CO1 sequence, nuclear SRA gene sequence, eight nuclear microsatellites) to clarify the evolutionary history of Trypanosoma brucei rhodesiense (Tbr) and T. b. gambiense (Tbg), the causative agents of human African trypanosomosis (sleeping sickness) in sub-Saharan Africa, and to examine the relationship between Tbr and the non-human infective parasite T. b. brucei (Tbb) in eastern and southern Africa. A Bayesian phylogeny and haplotype network based on CO1 sequences confirmed the taxonomic distinctness of Tbg group 1. Limited diversity combined with a wide geographical distribution suggested that this parasite has recently and rapidly colonized hosts across its current range. The more virulent Tbg group 2 exhibited diverse origins and was more closely allied with Tbb based on COI sequence and microsatellite genotypes. Four of five COI haplotypes obtained from Tbr were shared with isolates of Tbb, suggesting a close relationship between these taxa. Bayesian clustering of microsatellite genotypes confirmed this relationship and indicated that Tbr and Tbb isolates were often more closely related to each other than they were to other members of the same subspecies. Among isolates of Tbr for which data were available, we detected just two variants of the SRA gene responsible for human infectivity. These variants exhibited distinct geographical ranges, except in Tanzania, where both types co-occurred. Here, isolates possessing distinct SRA types were associated with identical COI haplotypes, but divergent microsatellite signatures.Conclusions/SignificanceOur data provide strong evidence that Tbr is only a phenotypic variant of Tbb; while relevant from a medical perspective, Tbr is not a reproductively isolated taxon. The wide distribution of the SRA gene across diverse trypanosome genetic backgrounds suggests that a large amount of genetic diversity is potentially available with which human-infective trypanosomes may respond to selective forces such as those exerted by drugs.

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“…This very small proportion, which may indicate that humans are an unimportant and perhaps accidental source of food for this subspecies in Busia, is probably responsible for the generally low incidence of HAT, despite the presence of human-infective strains of trypanosome (Njiru et al, 2004). It is also evidence indicating that domestic livestock is important as reservoir hosts in Busia (N'gayo et al, 2005).…”

Section: Discussionmentioning

confidence: 91%

Hosts ofGlossina fuscipes fuscipesandG. pallidipesin areas of western Kenya with endemic sleeping sickness, as determined using an egg-yolk (IgY) ELISA

Wamwiri

Nkwengulila

Clausen

2007

Annals of Tropical Medicine & Parasitology

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Bloodmeal sources of Glossina fuscipes fuscipes and G. pallidipes, from the western Kenyan foci of human African trypanosomiasis (HAT) on Mageta Island and in Busia district, were identified using an ELISA based on chicken egg-yolk (IgY) antibodies. After absorption with cross-reacting antigens, the antibodies, which were produced against representatives of eight families of vertebrate host, were capable of differentiating serum from the different families. With the ELISA, it was possible to identify the family of host for 100% of laboratory-fed flies tested up to 48 h post-bloodmeal but only for 12% of such flies tested 96 h post-feed. Subsequently, attempts were made to identify the family of host that was the source of the (most recent) bloodmeal for each of 223 wild-caught flies, and these attempts were successful for 142 (63.7%) of the samples. Among the flies with identified bloodmeals, most (81.9%) of the G. f. fuscipes caught on Mageta Island had last fed on reptiles whereas most of the G. f. fuscipes (70.4%) and G. pallidipes (57.1%) caught in Busia had last fed on bovids. Bloodmeals of human origin accounted for <2% of the bloodmeals identified, perhaps indicating that, in the presence of alternative hosts, humans are not attractive hosts for tsetse in the study areas. This finding may account for the low reported incidence of HAT, despite the presence of circulating human-infective trypanosomes. In Busia at least, the use of animals, especially cattle, covered in insecticide would probably be an effective method of controlling the tsetse vectors of the trypanosomes that cause human and 'animal' trypanosomiases.

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Detection of Trypanosoma brucei rhodesiense in animals from sleeping sickness foci in East Africa using the serum resistance associated (SRA) gene

Cited by 27 publications

References 16 publications

Virological and Serological Studies of Porcine Respiratory Coronavirus Infection on a Japanese Farm

Virological and Serological Studies of Porcine Respiratory Coronavirus Infection on a Japanese Farm

Phylogeography and Taxonomy of Trypanosoma brucei

Hosts ofGlossina fuscipes fuscipesandG. pallidipesin areas of western Kenya with endemic sleeping sickness, as determined using an egg-yolk (IgY) ELISA

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