Hostname: page-component-586b7cd67f-dlnhk Total loading time: 0 Render date: 2024-11-22T23:39:11.043Z Has data issue: false hasContentIssue false
  • English
  • Français

Epidemiology of trypanosome infections of the tsetse fly Glossina pallidipes in the Zambezi Valley

Published online by Cambridge University Press:  06 April 2009

M. E. J. Woolhouse ,
J. W. Hargrove  and
J. J. McNamara
M. E. J. Woolhouse
Affiliation:
Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS
J. W. Hargrove
Affiliation:
ODA Insect Pest Management Initiative, c/o Tsetse and Trypanosomiasis Control Branch, Box 8283, Causeway, Zimbabwe
J. J. McNamara
Affiliation:
Tsetse Research Laboratory, Department of Veterinary Medicine, University of Bristol, Langford, Bristol BS18 7DU
Get access Rights & Permissions [Opens in a new window]

Summary

The epidemiology of trypanosome infections of Glossina pallidipes was studied at a riverine site in the Zambezi Valley, Zimbabwe for a period of 13 months. Over 9000 flies were captured using a single trap. These flies were dissected, screened for trypanosome infection, sexed, and aged using both wing fray and (for females) ovarian category indices. Midgut infections were identified to species using recently developed DNA probes. The overall prevalence of mature infections was 5·5%, comprising 3·1% Trypanosoma vivax-type and 2·4% T. congolense-type (which included very low prevalences of T. brucei, T. simiae and another Nannomonas species). The prevalence of infection increased with age. For T. vivax-type infections in flies aged by ovarian category this relationship could be described by a simple ‘catalytic’ model assuming a constant per capita rate of infection. For T. congolense-type infections this model tended to over-estimate prevalence in older age classes, implying that the rate of infection decreases with age, and/or that infected flies have higher mortality rates, and/or that a significant fraction of the population is resistant to infection. Prevalences of infection also varied between months. This variation was more marked for T. vivax-type infections and was negatively correlated with both temperature and rainfall. The shape of the age-prevalence relationship, however, did not vary significantly between months. These observations are not fully explained by variation in the age-structure of the tsetse population and are consistent with temporal variation in the rate of infection (rather than in the trypanosome developmental period or in effects of infection on fly mortality). Possible causes of this variation are discussed.

Keywords

age–prevalenceDNA probeseasonalityTrypanosoma spp.tsetse flyZimbabwe
Type
Research Article
Information
Parasitology , Volume 106 , Issue 5 , June 1993 , pp. 479 - 485
Copyright
Copyright © Cambridge University Press 1993

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

Baker, R. D., Maudlin, I., Milligan, P. J. M., Molyneux, D. H. & Welburn, S. C. (1990). The possible role of Rickettsia-like organisms in trypanosomiasis epidemiology. Parasitology 100, 209–17.Google Scholar
Davies, H. (1977). Tsetse Flies in Nigeria, 3rd Edn.Ibadan: Oxford University Press.Google Scholar
Ford, J. & Leggate, B. M. (1961). The geographical and climatic distribution of trypanosome infection rates in G. morsitans group of tsetse-flies. Transactions of the Royal Society of Tropical Medicine and Hygiene 55, 383–97.Google Scholar
Gashumba, J. K. (1990). Speciation and subspeciation in Nannomonas trypanosomes and their epidemiological significance. Insect Science and its Application 11, 265–9.Google Scholar
Gibson, W. C., Dukes, P. & Gashumba, J. K. (1988). Species–specific DNA probes for the identification of African trypanosomes in tsetse flies. Parasitology 97, 63–73.CrossRefGoogle ScholarPubMed
Glasgow, J. P. (1961). The feeding habits of Glossina swynnertoni Austen. Journal of Animal Ecology 30, 77–85.CrossRefGoogle Scholar
Hargrove, J. W. (1981). Discrepancies between estimates of tsetse fly populations using mark-recapture and removal trapping techniques. Journal of Applied Ecology 18, 737–48.Google Scholar
Hargrove, J. W. (1990). Age-dependent changes in the probabilities of survival and capture of the tsetse, Glossina morsitans morsitans Westwood. Insect Science and its Application 11, 323–30.Google Scholar
Hargrove, J. W. & Langley, P. (1990). Sterilizing tsetse in the field: a successful field trial. Bulletin of Entomological Research 80, 397–403.CrossRefGoogle Scholar
Jackson, C. H. N. (1946). An artificially isolated generation of tsetse flies (Diptera). Bulletin of Entomological Research 37, 291–9.CrossRefGoogle ScholarPubMed
Jordan, A. M. (1976). Tsetse flies as vectors of trypanosomes. Veterinary Parasitology 2, 143–52.CrossRefGoogle Scholar
McNamara, J. J. (1990). Subgeneric variation in Nannomonas: the characterization of isolates from The Gambia. Ph.D. thesis, University of Bristol.Google Scholar
McNamara, J. J., Dukes, P., Snow, W. F. & Gibson, W. C. (1989). Use of DNA probes to identify Trypanosoma congolense and T. simiae in tsetse flies from The Gambia. Acta Tropica 46, 55–61.Google Scholar
Maudlin, I. (1991). Transmission of African trypanosomiasis: interactions among tsetse immune system, symbionts, and parasites. Advances in Disease Vector Research 7, 117–48.Google Scholar
Mohamed-Ahmed, M. M., Ahmed, A. I. & Ishag, A. (1989). Trypanosome infection rate of Glossina morsitans submorsitans in Bahl el Arab, South Darfur Province, Sudan. Tropical Animal Health and Productivity 21, 239–44.Google Scholar
Moloo, S. K. & Shaw, M. K. (1989). Rickettsial infections of midgut cells are not associated with susceptibility of Glossina morsitans centralis to Trypanosoma congolense infection. Acta Tropica 46, 223–7.Google Scholar
Molyneux, D. H. & Ashford, R. W. (1983). The Biology of Trypanosoma and Leishmania, Parasites of Man and Domestic Animals. London: Taylor & Francis.Google Scholar
Nesbitt Tarimo, S. T., Njau, B. C. & Otieno, L. H. (1991). Epizootiology of trypanosomiasis in Lambwe Valley, Kenya, East Africa. Insect Science and its Application 12, 379–84.Google Scholar
Nitcheman, S. (1988). Comparison des longévités des glossines (Glossina morsitans morsitans Westwood, 1850) infectées par les trypanosomes (Trypanosoma nannomonas congolense Broden 1904) et des glossines saines. Annales de Parasitologie Humaine et Comparée 63, 163–4.CrossRefGoogle Scholar
Rogers, D. J. (1988). A general model for the African trypanosomiasis. Parasitology 97, 193–212.Google Scholar
Ryan, L. (1984). The effect of trypanosome infection on a natural population of Glossina longipalpis Wiedemann (Diptera: Glossinidae) in Ivory Coast. Acta Tropica 41, 355–9.Google Scholar
Ryan, L., Kupper, W., Goff, S. L., Molyneux, D. H. & Clair, M. (1982). differences in rates of acquisition of trypanosome infections between Glossina species in the field. Annales de la Société Beige de Médecine Tropicale 62, 291–300.Google ScholarPubMed
Saunders, D. S. (1962). Age determination for female tsetse flies and the age composition of samples of Glossina pallidipes aust., G. palpalis fuscipes Newst. and G. brevipalpis Newst. Bulletin of Entomological Research 53, 579–95.Google Scholar
Woolhouse, M. E. J. (1989). On the interpretation of age–prevalence curves for schistosome infections of host snails. Parasitology 99, 47–56.Google Scholar