Human African Trypanosomiasis transmission, Kinshasa, Democratic Republic of Congo.To investigate the epidemiology of human African trypanosomiasis African trypanosomiasis n. Either of two types of an often fatal, endemic infectious disease of humans and animals in tropical Africa: Gambian trypanosomiasis or Rhodesian trypanosomiasis. (sleeping sickness sleeping sickness: see encephalitis; trypanosomiasis. sleeping sickness Protozoal disease transmitted by the bite of the tsetse fly. Two forms, caused by different species of the genus Trypanosoma, occur in separate regions in Africa. ) in Kinshasa, Democratic Republic of Congo, 2 entomologic en·to·mol·o·gy n. The scientific study of insects. en  to·mo·log surveys were conducted in 2005. Trypanosoma brucei gambiense Trypanosoma bru·ce·i gam·bi·en·sen. A protozoan that is the causative agent of Gambian trypanosomiasis. and human-blood meals were found in tsetse fly tsetse fly (tsĕt`sē), name for any of several bloodsucking African flies of the genus Glossina, and in the same family as the housefly. midguts, which suggested active disease transmission. Vector control Vector control is any method to limit or eradicate the vectors of vector born diseases, for which the pathogen (e.g. virusor parasite) is transmitted by a vector which can be mammals, birds or arthropods, especially insects, and more specifically mosquitoes. should be used to improve human African trypanosomiasis control efforts. ********** Human African trypanosomiasis (HAT) (sleeping sickness) is a parasitic disease A parasitic disease is an infectious disease caused or transmitted by a parasite. Many parasites do not cause disease per se. Parasitic diseases can affect practically all living organisms, from plants to man. The study of parasitic diseases is called by parasitology. caused by a protozoan protozoan (prō'təzō`ən), informal term for the unicellular heterotrophs of the kingdom Protista. Protozoans comprise a large, diverse assortment of microscopic or near-microscopic organisms that live as single cells or in simple parasite belonging to the genus Trypanosoma. Approximately 60 million persons are exposed to the disease, and 500,000 are currently infected (1). HAT has been described as a disease affecting rural areas (2). During the recent increase in HAT in historic foci, emergence of foci with new epidemiologic features in urban areas was reported (3,4). Investigations of these new features showed that development of contiguous relationships between urban areas and surrounding HAT-endemic villages can create conditions favorable for HAT in urban areas (3-5). Few studies have suggested urban transmission of HAT despite potential epidemiologic consequences of such transmission (4). In Kinshasa, Democratic Republic of Congo, the epidemiologic situation for HAT is complex. In 1903, Dutton-Todd reported a HAT prevalence of 2.4% in apparently healthy inhabitants
The game is based loosely on the concepts from SameGame. of Leopoldville (6). In 1960, the Kinshasa focus was considered extinct, and no tsetse flies were found in the city. Until 1995, an average of 50 new cases of HAT were reported annually. However, >200 new cases have been reported annually since 1996 (e.g., 443 of 6,205 persons examined in 1998 and 912 of 42,746 persons examined in 1999) (7). Ebeja et al. reported that 39% of new cases were urban residents; 60% of them in the first stage of the disease (3). To understand the epidemiology of HAT in this context, several investigations have been undertaken (3,5,8). On the basis of epidemiologic data, some investigators (3,5) have suggested that urban or periurban transmission of HAT occurs in Kinshasa. However, in a case-control study case-control study, n an investigation employing an epidemiologic approach in which previously existing incidents of a medical condition are used in lieu of gathering new information from a randomized population. , Robays et al. concluded that HAT in urban residents of Kinshasa was linked to disease transmission in Bandundu and rural Kinshasa (8). To investigate the epidemiology of HAT transmission in Kinshasa, we identified and evaluated contact between humans and flies. The prevalence of Trypanosoma brucei gambiense in tsetse fly midguts was determined to identify circulation of this trypanosome trypanosome (trĭp`ənəsōm'), microscopic, one-celled protozoan of the genus Trypanosoma, typically living as an active parasite in the bloodstream of a vertebrate; hundreds of species are known. between humans and tsetse flies. The Study Two entomologic surveys were conducted in 2005 (during the rainy season in February and March and the dry season in June and July) at 8 sites (Ndjili Cecomaf, Ndjili Brasserie bras·se·rie n. A restaurant serving alcoholic beverages, especially beer, as well as food. [French, from brasser, to malt, brew, from Old French bracier, from Vulgar Latin , Kimwenza, Mambre, Funa, Buma, Kimbanseke, and Kinkole) in Kinshasa. These sites were selected on the basis of HAT prevalence and entomologic data previously reported (3). Rural, periurban, and urban areas (Figure) were defined according to according to prep. 1. As stated or indicated by; on the authority of: according to historians. 2. In keeping with: according to instructions. 3. recent mapping of Kinshasa (5). [FIGURE OMITTED] During each survey, tsetse flies were collected in pyramidal traps (9), and sex and species were identified. Midguts and blood meals were collected on filter paper, dried, and stored in microtubes. DNA DNA: see nucleic acid. DNA or deoxyribonucleic acid One of two types of nucleic acid (the other is RNA); a complex organic compound found in all living cells and many viruses. It is the chemical substance of genes. was extracted from midguts or blood meals with 1 mL of 5% Chelex (10). Microtubes were incubated for 1 h at 56[degrees]C, 30 min at 100[degrees]C, and centrifuged for 10 min at 14,000 rpm. The supernatant supernatant /su·per·na·tant/ (-na´tant) the liquid lying above a layer of precipitated insoluble material. supernatant the liquid lying above a layer of precipitated insoluble material. was collected and used as DNA template for PCR PCR polymerase chain reaction. PCR abbr. polymerase chain reaction Polymerase chain reaction (PCR) . Blood meals were analyzed according to a method previously described (11). Trypanosomes were identified by PCR with specific primers for T. brucei s.1. (12). and T. b. gambiense (13). Because no tsetse flies were found in Buma and Kinkole during the rainy season, these 2 sites were excluded from the second survey (Figure). Entomologic data were analyzed for 610 traps from which data were obtained during the 2 surveys. A total of 897 flies of both sexes were caught; Glossina fuscipes quanzensis was the only tsetse fly species found (Table). Fresh midguts containing blood meals or trypanosomes were obtained from 570 living flies. In rural and periurban areas, 54 (9.5%, 95% confidence interval confidence interval, n a statistical device used to determine the range within which an acceptable datum would fall. Confidence intervals are usually expressed in percentages, typically 95% or 99%. [CI] 3.7%-15.2%) teneral flies (young flies that have never taken a blood meal) were identified. Of 570 flies dissected, 117 (20.97%) had sampled blood meals and 110 were successfully identified (Table): 78 meals (67.7%, 95% CI 57.5%-75.9%) were taken from humans and 32 (27.3%, 95% CI 19%-36%) from pigs. PCR identified T. brucei s.1. in midguts of 54 (9.5%, 95% CI 7.5%- 11.5%) flies; of these, 54 flies, T. b. gambiense was found in 13. The prevalence of T. b. gambiense in tsetse tsetse /tset·se/ (tset´se) an African fly of the genus Glossina, which transmits trypanosomiasis. tsetse an African fly of the genus glossina, which transmits trypanosomiasis. midguts was 2.3% (95% CI 1.2%-3.3%). One tsetse fly with a blood meal from a pig was positive for T. b. gambiense. Conclusions This study confirmed, as reported in previous studies, the presence of G.f. quanzensis in Kinshasa (5). The most favorable biotopes for tsetse flies are located along the Ndjili, Lukaya, and Boye Boye may refer to:
Identification of tsetse flies infected with T. b. gambiense confirms contact between flies and patients. The infection rate (2.3%) in our study is comparable to the rates of 1.4% reported in Uganda and 1.9% in Brazzaville, Republic of Congo (15). However, T. b. gambiense midgut midgut /mid·gut/ (mid´gut) the region of the embryonic digestive tube into which the yolk sac opens and which gives rise to most of the intestines; ahead of it is the foregut and caudal to it is the hindgut. infection is not proof of mature infection, although it shows direct circulation of T. b. gambiense between humans and tsetse flies. Infection occurs frequently, as reflected by the feeding preference of G.f. quanzensis for humans. This finding shows that urbanization can increase transmission risk by creating conditions that may increase contact between humans and flies, as probably occurred in Kinshasa where we identified a high percentage of human-blood meals (67.7%) and tsetse flies infected with T. b. gambiense. Our results provide evidence for local transmission of HAT in Kinshasa because we detected T. b. gambiense midgut infections, human-blood meals, and most urban resident patients in the first stage of the disease. Identification of T. b. gambiense infections in flies from different sites indicates transmission in rural and periurban areas. Some patients identified in Kinshasa could have been infected during their movement through areas outside the city for subsistence activities and economic purposes. Local transmission has likely contributed to the increase in HAT in the past decade. The sites of Ndjili Brasserie, Kimwenza, Kimbanseke, and Mambre showed higher risk for HAT transmission. We suggest that vector control be integrated into improved HAT control efforts in urban areas. In Kinshasa, focused vector control activities around pigsties and places with water-related activities can reduce fly density, contact between humans and flies, and disease transmission. Contact between tsetse flies and pigs should encourage investigations of the animal reservoir of HAT in Kinshasa. This recommendation is strengthened by the finding of T. b. gambiense in a blood meal taken from 1 pig. Acknowledgments We thank T. Baldet for critically reading the manuscript. This work was supported by Institut de Recherche re·cher·ché adj. 1. Uncommon; rare. 2. Exquisite; choice. 3. Overrefined; forced. 4. Pretentious; overblown. pour le Developpement (Unite de Recherche 177) and Service de Cooperation et d'Action Culturelle de Kinshasa. Dr Simo is senior researcher at the Medical Research Center of the Institute of Medical Research and Study of Medicinal Plants medicinal plants, plants used as natural medicines. This practice has existed since prehistoric times. There are three ways in which plants have been found useful in medicine. of the Ministry of Scientific and Innovation Research of Cameroon. His research interests include the genetic and molecular epidemiology molecular epidemiology Molecular medicine An evolving field that combines the tools of standard epidemiology–case studies, questionnaires and monitoring of exposure to external factors with the tools of molecular biology–eg, restriction endonucleases, and diagnosis of sleeping sickness. References (1.) Control and surveillance of African trypanosomiasis. Report of a WHO Expert Committee. World Health Organ Tech Rep Ser. 1998;881:1-114. (2.) Laveissiere C, Sane B, Meda HA. Measurement of risk in endemic areas of human African trypanosomiasis in Cote d'Ivoire. Trans R Soc Trop Med Hyg. 1994;88:645-8. (3.) Ebeja AK, Lutumba P, Molisho D, Kegels G. Miaka mia Belinge C, Boelaert M. Sleeping sickness in the region of the town of Kinshasa: a retrospective analysis during the surveillance period 1996-2000. Trop Med Int Health. 2003;8:949-55. (4.) Courtin F, Dupont S, Zeze DG, Jamonneau V, Sand B, Coulibaly B, et al. Human African trypanosomiasis: urban transmission in the focus of Bonon (Cote d'Ivoire). Trop Med Int Health. 2005;10:340-6. (5.) de Deken R, Sumbu J, Mpiana S, Mansinsa P, Wat'senga F, Lutumba P, et al. Trypanosomiasis trypanosomiasis (trəpăn'əsōmī`əsis), infectious disease caused by a protozoan organism, the trypanosome, which exists as a parasite in the blood of a number of vertebrate hosts. in Kinshasa: distribution of the vector, Glossina fuscipes quanzensis, and risk of transmission in the periurban area. Med Vet Entomol. 2005;19:353-9. (6.) Fournet F, Traore S, Cadot E, Hervouet JP. Impact of development of agricultural land on the transmission of sleeping sickness in Daloa, Cote d'Ivoire. Ann Trop Med Parasitol. 2000;94:113-21. (7.) Louis FJ, Mia Bilengue CN, Simarro PR Meso VK, Lucas R Jannin J. Trypanosomose Humaine Africaine en milieu urbain: une problematique emergente? Bull Soc Pathol Exot. 2003:96:205-8. (8.) Robays J, Ebeja AK, Lutumba P, Miaka Mia Belinge C, Kande Betu Ku Mesu V, de Deken R, et al. Human African trypanosomiasis amongst urban residents in Kinshasa: a case-control study. Trop Med Int Health. 2004;9:869-75. (9.) Gouteux JR Lancien J. The pyramidal trap for collecting and controlling tsetse flies (Diptera: Glossinidae). Comparative trials and description of new collecting techniques. Trop Med Parasitol. 1986:37:61-6. (10.) Walsh PS, Metzger DA, Higuchi R. Chelex 100 as a medium for simple extraction of DNA for PCR-based typing from forensic material. Biotechniques. 1991;10:506-13. (11.) Njiokou F, Simo G, Mbida Mbida JA, Truc P, Cuny (5, Herder S. A study of host preference in tsetse fly using a modified heteroduplex PCR based method. Acta Trop. 2004;91:117-20. (12.) Moser DR, Cook GA, Ochs DE, Bailey CP, McKane MR, Donelson JE. Detection of Trypanosoma congolense and Trypanosoma brucei subspecies subspecies, also called race, a genetically distinct geographical subunit of a species. See also classification. by DNA amplification DNA amplification Molecular diagnostics Any method used to ↑ the copy number of a sequence of DNA. See Cycling probe technology, Gap LCR–gap ligase chain reaction, Gene amplification, NASBA–nucleic acid sequence-based amplification, PCR, using polymerase chain reaction polymerase chain reaction (pŏl`ĭmərās') (PCR), laboratory process in which a particular DNA segment from a mixture of DNA chains is rapidly replicated, producing a large, readily analyzed sample of a piece of DNA; the process is . Parasitology Parasitology The scientific study of parasites and of parasitism. Parasitism is a subdivision of symbiosis and is defined as an intimate association between an organism (parasite) and another, larger species of organism (host) upon which the parasite is . 1989:99:57-66. (13.) Herder S, Simo G, Nkinin S, Njiokou F. Identification of trypanosomes in wild animals WILD ANIMALS. Animals in a state of nature; animals ferae naturae. Vide Animals; Ferae naturae. from southern Cameroon using the polymerase chain reaction (PCR). Parasite. 2002;9:345-9. (14.) Fournet F, Traore S, Hervouet JP. Effects of urbanization on the transmission of human African trypanosomiasis in a sub-urban relict RELICT. A widow; as A B, relict of C D. forest area of Daloa, Cote d'Ivoire. Trans R Soc Trop Med Hyg. 1999:93:130-2. (15.) Rogers A, Kenyabjui EN, Wiggwah AK. A high infection rate of Trypanosoma brucei subgroup in Glossina fuscipes. Parasitology. 1972:65:143-6. Gustave Simo, * ([dagger]) Philemon Mansinsa Diabakana, ([double dagger]) Victor Kande Betu Ku Mesu, ([double dagger]) Emile Zola Manzambi, ([section]) Gaelle Ollivier, ([paragraph]) Tazoacha Asonganyi, ([dagger]) Gerard Cuny, # and Pascal Grebaut # * Institute of Medical Research and Study of Medicinal Plants, Yaounde, Cameroon; ([dagger]) University of Yaounde I, Yaounde Cameroon; ([double dagger]) Programme National de Lutte contre la Trypanosomiase Humaine Africaine, Kinshasa, Democratic Republic of Congo; ([section]) Institut National de Recherches Biomedicales, Kinshasa, Democratic Republic of Congo; ([paragraph]) Service de Cooperation et d'Action Culturelle de Kinshasa, Kinshasa, Democratic Republic of Congo; and # Institut de Recherche pour le Developpement, Montpellier, France Address for correspondence: Gustave Simo, Medical Research Center, Institute of Medical Research and Study of Medicinal Plants, Ministry of Scientific Research and Innovation. PO Box 6163, Yaounde, Cameroon; email: gustavsca@yahoo.fr The opinion expressed by authors contributing to this journal do not necessarily reflect the opinions of the Centers for Disease Control and Prevention Centers for Disease Control and Prevention (CDC), agency of the U.S. Public Health Service since 1973, with headquarters in Atlanta; it was established in 1946 as the Communicable Disease Center. or the institutions with which the authors are affiliated.
Table. Entomologic results for tsetse flies collected during the dry
and rainy seasons, Kinshasha, Democratic Republic of Congo, 2005 *
No. No.
No. dissected teneral
Survey site No. traps flies ADT flies flies
Ndjili Brasserie 112 423 0.94 244 25
Mambre 108 220 0.51 144 13
Kimwenza 104 139 0.33 93 6
Kimbanseke 118 57 0.12 49 6
Ndjili Cecomaf 58 35 0.15 22 3
Funa 110 23 0.05 18 1
Total 610 897 0.37 570 54
No. human- No. pig- No.
blood blood Trypanosoma
Survey site meals meals brucei s. l. No. TBG
Ndjili Brasserie 26 18 26 9
Mambre 25 8 12 1
Kimwenza 12 3 8 2
Kimbanseke 9 2 6 1
Ndjili Cecomaf 4 1 -- --
Funa 2 -- 2 --
Total 78 32 54 13
* ADT, apparent density per trap; teneral flies, young flies that
have never taken a blood meal; TBG, T. brucei gambfense group 1.
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