41
views
0
recommends
+1 Recommend
0 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: found
      Is Open Access

      Characterisation of the Wildlife Reservoir Community for Human and Animal Trypanosomiasis in the Luangwa Valley, Zambia

      research-article

      Read this article at

      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          Background

          Animal and human trypanosomiasis are constraints to both animal and human health in Sub-Saharan Africa, but there is little recent evidence as to how these parasites circulate in wild hosts in natural ecosystems. The Luangwa Valley in Zambia supports high densities of tsetse flies ( Glossina species) and is recognised as an historical sleeping sickness focus. The objective of this study was to characterise the nature of the reservoir community for trypanosomiasis in the absence of influence from domesticated hosts.

          Methodology/Principal Findings

          A cross-sectional survey of trypanosome prevalence in wildlife hosts was conducted in the Luangwa Valley from 2005 to 2007. Samples were collected from 418 animals and were examined for the presence of Trypanosoma brucei s.l., T. b. rhodesiense, Trypanosoma congolense and Trypanosoma vivax using molecular diagnostic techniques. The overall prevalence of infection in all species was 13.9% (95% confidence interval [CI]: 10.71–17.57%). Infection was significantly more likely to be detected in waterbuck ( Kobus ellipsiprymnus) (Odds ratio [OR] = 10.5, 95% CI: 2.36–46.71), lion ( Panthera leo) (OR = 5.3, 95% CI: 1.40–19.69), greater kudu ( Tragelaphus strepsiceros) (OR = 4.7, 95% CI: 1.41–15.41) and bushbuck ( Tragelaphus scriptus) (OR = 4.5, 95% CI: 1.51–13.56). Bushbucks are important hosts for T. brucei s.l. while the Bovidae appear the most important for T. congolense. The epidemiology of T. vivax was less clear, but parasites were detected most frequently in waterbuck. Human infective T. b. rhodesiense were identified for the first time in African buffalo ( Syncerus caffer) and T. brucei s.l. in leopard ( Panthera pardus). Variation in infection rates was demonstrated at species level rather than at family or sub-family level. A number of significant risk factors interact to influence infection rates in wildlife including taxonomy, habitat and blood meal preference.

          Conclusion and Significance

          Trypanosoma parasites circulate within a wide and diverse host community in this bio-diverse ecosystem. Consistent land use patterns over the last century have resulted in epidemiological stability, but this may be threatened by the recent influx of people and domesticated livestock into the mid-Luangwa Valley.

          Author Summary

          Animal and human trypanosomiasis are constraints to both animal and human health in Sub-Saharan Africa, but there is little recent evidence as to how these parasites circulate in natural hosts in natural ecosystems. A cross-sectional survey of trypanosome prevalence in 418 wildlife hosts was conducted in the Luangwa Valley, Zambia, from 2005 to 2007. The overall prevalence in all species was 13.9%. Infection was significantly more likely to be detected in waterbuck, lion, greater kudu and bushbuck, with a clear pattern apparent of the most important hosts for each trypanosome species. Human infective Trypanosoma brucei rhodesiense parasites were identified for the first time in African buffalo and T. brucei s.l. in leopard. Variation in infection is demonstrated at species level rather than at family or sub-family level. A number of significant risk factors are shown to interact to influence infection rates in wildlife including taxonomy, habitat and blood meal preference. Trypanosoma parasites circulate within a wide and diverse host community in this bio-diverse ecosystem. Consistent land use patterns over the last century have resulted in epidemiological stability, but this may be threatened by the recent influx of people and domesticated livestock into the mid-Luangwa Valley.

          Related collections

          Most cited references 52

          • Record: found
          • Abstract: not found
          • Article: not found

          Diseases shared between wildlife and livestock: a European perspective

            Bookmark
            • Record: found
            • Abstract: found
            • Article: not found

            Detection of Trypanosoma congolense and Trypanosoma brucei subspecies by DNA amplification using the polymerase chain reaction.

            The nuclear DNA of Trypanosoma congolense contains a family of highly conserved 369 base pair (bp) repeats. The sequences of three cloned copies of these repeats were determined. An unrelated family of 177 bp repeats has previously been shown to occur in the nuclear DNA of Trypanosoma brucei brucei (Sloof et al. 1983a). Oligonucleotides were synthesized which prime the specific amplification of each of these repetitive DNAs by the polymerase chain reaction (PCR). Amplification of 10% of the DNA in a single parasite of T. congolense or T. brucei spp. produced sufficient amplified product to be visible as a band in an agarose gel stained with ethidium bromide. This level of detection, which does not depend on the use of radioactivity, is about 100 times more sensitive than previous detection methods based on radioactive DNA probes. The oligonucleotides did not prime the amplification of DNA sequences in other trypanosome species nor in Leishmania, mouse or human DNAs. Amplification of DNA from the blood of animals infected with T. congolense and/or T. brucei spp. permitted the identification of parasite levels far below that detectable by microscopic inspection. Since PCR amplification can be conducted on a large number of samples simultaneously, it is ideally suited for large-scale studies on the prevalence of African trypanosomes in both mammalian blood and insect vectors.
              Bookmark
              • Record: found
              • Abstract: found
              • Article: not found

              Identification of human-infective trypanosomes in animal reservoir of sleeping sickness in Uganda by means of serum-resistance-associated (SRA) gene.

              The expansion of sleeping sickness caused by Trypanosoma brucei rhodesiense beyond its traditional focus in southeast Uganda has been linked with large-scale livestock restocking. To assess the risk presented to the human population by domestic livestock, human-infective T b rhodesiense must be distinguished from non-human-infective T brucei brucei, since both parasites can be present in cattle. We investigated the use of a simple genetic marker to characterise parasites collected from cattle in villages within the new sleeping sickness focus in Soroti District, Uganda. 70 T brucei sl samples of known human infectivity status collected from human beings and cattle in Tororo District, Uganda, from 1989 to 1991 were screened for the presence of the human-serum-resistance-associated (SRA) gene by conventional PCR. In 2000-01, blood samples from 200 randomly selected cattle in six villages and two markets in Soroti District were screened for T brucei sl parasites by PCR; positive samples were screened for the presence of the SRA gene. The SRA gene was present in all 29 samples from patients with sleeping sickness in Tororo District. Of the 41 samples collected from cattle at the same time, the SRA gene was present in the eight samples that tested resistant to human serum in vitro, whereas it was absent from all 33 isolates that were sensitive to human serum in vitro. Of the 200 cattle sampled in Soroti District, we estimated that up to 18% (95% CI 12-23) were infected with T b rhodesiense. Detection of the SRA gene could provide the basis for a simple diagnostic test to enable targeted control of T b rhodesiense in the domestic livestock reservoir, thereby reducing the public-health burden of sleeping sickness in east Africa.
                Bookmark

                Author and article information

                Contributors
                Role: Editor
                Journal
                PLoS Negl Trop Dis
                plos
                plosntds
                PLoS Neglected Tropical Diseases
                Public Library of Science (San Francisco, USA )
                1935-2727
                1935-2735
                June 2011
                21 June 2011
                : 5
                : 6
                Affiliations
                [1 ]Centre for Infectious Diseases, Division of Pathway Medicine, College of Medicine and Veterinary Medicine, The University of Edinburgh, Edinburgh, United Kingdom
                [2 ]Tsetse Control Section, Chilanga, Zambia
                [3 ]Centre for Infectious Diseases, Institute of Immunology and Infection Research, Ashworth Laboratories, The University of Edinburgh, Edinburgh, United Kingdom
                [4 ]Animals, Conservation and Education Department, The Royal Zoological Society of Scotland, Edinburgh Zoo, Edinburgh, United Kingdom
                Foundation for Innovative New Diagnostics (FIND), Switzerland
                Author notes

                Conceived and designed the experiments: NEA SCW MCE EMF RT KP. Performed the experiments: NEA JM KP. Analyzed the data: NEA SCW EMF. Contributed reagents/materials/analysis tools: KP. Wrote the paper: NA SCW EMF.

                Article
                PNTD-D-11-00080
                10.1371/journal.pntd.0001211
                3119639
                21713019
                Anderson et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
                Page count
                Pages: 16
                Categories
                Research Article
                Biology
                Medicine
                Veterinary Science

                Infectious disease & Microbiology

                Comments

                Comment on this article