Background Sleeping sickness is spread over 36 Sub-Saharan African countries. In West and Central Africa, the disease is caused by Trypanosoma brucei gambiense, which produces a chronic clinical manifestation. The Luba focus (Bioko Island, Equatorial Guinea) has not reported autochthonous sleeping sickness cases since 1995, but given the complexity of the epidemiological cycle, the elimination of the parasite in the environment is difficult to categorically ensure. Methodology/Principal Findings The aim of this work is to assess, by a molecular approach (Polymerase Chain Reaction, PCR), the possible permanence of T. b. gambiense in the vector (Glossina spp.) and domestic fauna in order to improve our understanding of the epidemiological situation of the disease in an isolated focus considered to be under control. The results obtained show the absence of the parasite in peridomestic livestock but its presence, although at very low rate, in the vector. On the other hand, interesting entomological data highlight that an elevated concentration of tsetse flies was observed in two out of the ten villages considered to be in the focus. Conclusions These findings demonstrate that even in conditions of apparent control, a complete parasite clearance is difficult to achieve. Further investigations must be focused on animal reservoirs which could allow the parasites to persist without leading to human cases. In Luba, where domestic livestock are scarcer than other foci in mainland Equatorial Guinea, the epidemiological significance of wild fauna should be assessed to establish their role in the maintenance of the infection.
References
[1]
Hoare CA (1972) The trypanosomes of mammals. Oxford: Blackwell Scientific Publications. 749 p.
[2]
Gibson W (2007) Resolution of the species problem in African trypanosomes. Int J Parasitol 37: 829–38. doi: 10.1016/j.ijpara.2007.03.002
[3]
WHO (2006) Human African Trypanosomiasis (sleeping sickness): epidemiological update. Weekly Epidemiological Record 69–80.
[4]
Lutumba P, Robays J, Miaka mia BC, Mesu VK, Molisho D, et al. (2005) Trypanosomiasis control, Democratic Republic of Congo, 1993–2003. Emerg Infect Dis 11: 1382–8. doi: 10.3201/eid1109.041020
[5]
Simarro PP, Franco JR, Ndongo P, Nguema E, Louis FJ, et al. (2006) The elimination of Trypanosoma brucei gambiense sleeping sickness in the focus of Luba, Bioko Island, Equatorial Guinea. Trop Med Int Health 11: 636–46. doi: 10.1111/j.1365-3156.2006.01624.x
[6]
WHO (1998) Control and Surveillance of African Trypanosomiasis. WHO Technical Report Series No. 881, Geneva.
[7]
Pittaluga G (1910) [Report of the Mission of the Instituto Nacional de Higiene Alfonso XIII sent to Spanish territories in the Gulf of Guinea to study Sleeping Sickness]. Imprenta artística J. Bass y Cía, Madrid.
[8]
Courtin F, Jamonneau V, Duvallet G, Garcia A, Coulibaly B, et al. (2008) Sleeping sickness in West Africa (1906–2006): changes in spatial repartition and lessons from the past. Trop Med Int Health 13: 334–44. doi: 10.1111/j.1365-3156.2008.02007.x
[9]
Laveissiere C, Courret D, Staak C, Hervouet JP (1985) Glossina palpalis palpalis et ses h？tes en secteur forestier de C？te d'Ivoire. Relation avec l'épidémiologie de la tripanosomiase humaine. Cah ORSTOM, Sér Ent Med Parasitol 23: 297–303.
[10]
Simo G, Mbida Mbida JA, Herder S, Njitchouang GR, Njiokou F (2005) Feeding preferences of Tsetse flies from human african trypanosomosis foci of southern Cameroon. 28th Meeting ISCTRC Addis Ababa, Ethiopia.
[11]
Simo G, Cuny G, Demonchy R, Herder S (2008) Trypanosoma brucei gambiense: Study of population genetic structure of Central African stocks using amplified fragment length polymorphism (AFLP). Exp Parasitol 118: 172–80. doi: 10.1016/j.exppara.2007.07.010
[12]
Truc P, Ravel S, Jamonneau V, N'Guessan P, Cuny G (2002) Genetic variability within Trypanosoma brucei gambiense: evidence for the circulation of different genotypes in human African trypanosomiasis patients in Cote d'Ivoire. Trans R Soc Trop Med Hyg 96: 52–5. doi: 10.1016/S0035-9203(02)90237-3
[13]
Koffi M, Solano P, Denizot M, Courtin D, Garcia A, et al. (2006) Aparasitemic serological suspects in Trypanosoma brucei gambiense human African trypanosomiasis: a potential human reservoir of parasites? Acta Trop 98: 183–8. doi: 10.1016/j.actatropica.2006.04.001
[14]
Louis FJ, Kohagne TL, Ebo'O EV, Simarro PP (2008) [Organizing an active screening campaign for human african trypanosomiasis due to Trypanosoma brucei gambiense]. Med Trop (Mars ) 68: 11–6.
[15]
Herder S, Simo G, Nkinin S, Njiokou F (2002) Identification of trypanosomes in wild animals from southern Cameroon using the polymerase chain reaction (PCR). Parasite 9: 345–9.
[16]
Njiokou F, Laveissiere C, Simo G, Nkinin S, Grebaut P, et al. (2006) Wild fauna as a probable animal reservoir for Trypanosoma brucei gambiense in Cameroon. Infect Genet Evol 6: 147–53. doi: 10.1016/j.meegid.2005.04.003
[17]
Njiokou F, Simo G, Nkinin SW, Laveissiere C, Herder S (2004) Infection rate of Trypanosoma brucei s.l., T. vivax, T. congolense “forest type”, and T. simiae in small wild vertebrates in south Cameroon. Acta Trop 92: 139–46. doi: 10.1016/j.actatropica.2004.04.011
[18]
Njiokou F, Sima FO, Njitchouang GR, Nimpaye H, Cuny G, et al. (2005) Importance of domestic animal reservoir of Trypanosoma brucei gambiense in Cameroon. 28th Meeting ISCTRC Addis Ababa, Ethiopia.
[19]
Simo G, Asonganyi T, Nkinin SW, Njiokou F, Herder S (2006) High prevalence of Trypanosoma brucei gambiense group 1 in pigs from the Fontem sleeping sickness focus in Cameroon. Vet Parasitol 139: 57–66. doi: 10.1016/j.vetpar.2006.02.026
[20]
Guedegbe B, Verhulst A, Van MN, Pandey VS, Doko A (1992) [Serological evidence of the existence of a wild reservoir of Trypanosoma brucei gambiense in the Pendjari biosphere reservation in the Republic of Benin]. Ann Soc Belg Med Trop 72: 113–20.
[21]
Jamonneau V, Ravel S, Koffi M, Kaba D, Zeze DG, et al. (2004) Mixed infections of trypanosomes in tsetse and pigs and their epidemiological significance in a sleeping sickness focus of Cote d'Ivoire. Parasitology 129: 693–702. doi: 10.1017/S0031182004005876
[22]
Makumyaviri A, Mehlitz D, Kageruka P, Kazyumba GL, Molisho D (1989) [Animal reservoir hosts of Trypanosoma brucei gambiense in Zaire: trypanosome infections in two foci in Bas-Zaire]. Trop Med Parasitol 40: 258–62.
[23]
Mehlitz D (1986) Le reservoir Animal de la Maladie du Sommeil à Trypanosoma brucei gambiense. Etudes et Synthèses de L′I E M V T.
[24]
Noireau F, Paindavoine P, Lemesre JL, Toudic A, Pays E, et al. (1989) The epidemiological importance of the animal reservoir of Trypanosoma brucei gambiense in the Congo. 2. Characterization of the Trypanosoma brucei complex. Trop Med Parasitol 40: 9–11.
[25]
Alvar J, Mas-Coma S, Carrasco M (1996) Modern history and physical geography of Equatorial Guinea. Res Rev Parasitol 2–3: 77–83.
[26]
Simarro PP, Mas J, Lancien J, Ona SF, Mateo MJ, et al. (1990) [Epidemiology of human trypanosomiasis in the Luba focus, in Equatorial Guinea]. Rev Sanid Hig Publica (Madr ) 64: 517–34.
[27]
Simarro PP, Sima FO, Mir M, Mateo MJ, Roche J (1991) [Control of human African trypanosomiasis in Luba in equatorial Guinea:evaluation of three methods]. Bull World Health Organ 69: 451–7.
[28]
Cordon-Obras C, Berzosa P, Ndong-Mabale N, Bobuakasi L, Buatiche JN, et al. (2009) Trypanosoma brucei gambiense in domestic livestock of Kogo and Mbini foci (Equatorial Guinea). Trop Med Int Health 14: 535–41. doi: 10.1111/j.1365-3156.2009.02271.x
[29]
Gouteux JP, Lancien J (1986) [The pyramidal trap for collecting and controlling tsetse flies (Diptera: Glossinidae). Comparative trials and description of new collecting technics]. Trop Med Parasitol 37: 61–6.
[30]
Cano J, Descalzo MA, Ndong-Mabale N, Ndongo-Asumu P, Bobuakasi L, et al. (2007) Spatial and temporal variability of the Glossina palpalis palpalis population in the Mbini focus (Equatorial Guinea). Int J Health Geogr 6: doi: 10.1186/1476-072x-6-36
[31]
Cano J, Descalzo MA, Ndong-Mabale N, Ndong-Asumu P, Bobuakasi L, et al. (2007) Predicted distribution and movement of Glossina palpalis palpalis (Diptera: Glossinidae) in the wet and dry seasons in the Kogo trypanosomiasis focus (Equatorial Guinea). J Vector Ecol 32: 218–25. doi: 10.3376/1081-1710(2007)32[218:PDAMOG]2.0.CO;2
[32]
Sane B, Laveissiere C, Meda HA (2000) [Diversity of feeding behavior of Glossina palpalis palpalis in the forest belt of the Ivory Coast: relation to the prevalence of human African trypanosomiasis]. Trop Med Int Health 5: 73–8. doi: 10.1046/j.1365-3156.2000.00488.x
[33]
Spath J (2000) Feeding patterns of three sympatric tsetse species (Glossina spp.) (Diptera: Glossinidae) in the preforest zone of Cote d'Ivoire. Acta Trop 75: 109–18. doi: 10.1016/S0001-706X(99)00096-0
[34]
Kuzoe FAS, Schofield CJ (2004) Strategic review of traps and targets for tsetse and African Trypanosomiasis control. Report of Special Programme for Research and Training in Tropical Disease (TDR) TDR/IDE/TRY/05.1.
[35]
Brunhes J, Cuisance D, Geoffroy B, Hervy JP, Lebbe J (1998) Les glossines ou mouches tsé-tsé. Logiciel d'identification. Glossine Expert. Manuel illustré d'utilisation. VI, ORSTOM, Paris: Université Paris.
[36]
Jackson CN (1946) An artificially isolated generation of tsetse flies (Diptera). Bull Entomol Res 37: 291. doi: 10.1017/s0007485300022203
[37]
Laveissiere C, Penchenier L (2000) Manuel de lutte contre la maladie du sommeil en Afrique centrale & occidentale. Ed OCEAC (IRD) Vol 5 Lutte Antivectorielle, Yaoundé, Cameroun.
[38]
Walsh PS, Metzger DA, Higuchi R (1991) Chelex 100 as a medium for simple extraction of DNA for PCR-based typing from forensic material. Biotechniques 10: 506–13.
[39]
Ravel S, Mariani C, Grebaut P, Jamonneau V, Cuisance D, et al. (2004) Inhibition of the DNA amplification of trypanosomes present in tsetse flies midguts: implications for the identification of trypanosome species in wild tsetse flies. Parasite 11: 107–9.
[40]
Moser DR, Cook GA, Ochs DE, Bailey CP, McKane MR, et al. (1989) Detection of Trypanosoma congolense and Trypanosoma brucei subspecies by DNA amplification using the polymerase chain reaction. Parasitology 99 Pt 1: 57–66. doi: 10.1017/S0031182000061023
[41]
Radwanska M, Claes F, Magez S, Magnus E, Perez-Morga D, et al. (2002) Novel primer sequences for polymerase chain reaction-based detection of Trypanosoma brucei gambiense. Am J Trop Med Hyg 67: 289–95.
[42]
Morrison LJ, Tait A, McCormack G, Sweeney L, Black A, et al. (2008) Trypanosoma brucei gambiense Type 1 populations from human patients are clonal and display geographical genetic differentiation. Infect Genet Evol 8: 847–54. doi: 10.1016/j.meegid.2008.08.005
[43]
Hao Z, Kasumba I, Aksoy S (2003) Proventriculus (cardia) plays a crucial role in immunity in tsetse fly (Diptera: Glossinidiae). Insect Biochem Mol Biol 33: 1155–64. doi: 10.1016/j.ibmb.2003.07.001
[44]
Ferreira F, Cano J, Furtado A, Ndong-Mabale N, Ndong-Asumu P, et al. (2008) An alternative approach to detect Trypanosoma in Glossina (Diptera, Glossinidae) without disection. J Infect Developing Countries 1: 63–7. doi: 10.3855/jidc.324
[45]
Jordan AM (1974) Recent developments in the ecology and methods of control of tsetse flies (Glossina spp.) (Diptera, Glossinidae). Bull Entomol Res 361–99. doi: 10.1017/s0007485300040876
[46]
Dagnogo M, Traore G, Souleymane F (2004) Determination of sleeping sickness transmission risk areas from trypanosome infection rates of tsetse flies in Daloa, C？te. d'Ivoire. Int J Trop Insect Sci 170–6. doi: 10.1079/ijt200413
[47]
Clausen PH, Adeyemi I, Bauer B, Breloeer M, Salchow F, et al. (1998) Host preferences of tsetse (Diptera: Glossinidae) based on bloodmeal identifications. Med Vet Entomol 12: 169–80. doi: 10.1046/j.1365-2915.1998.00097.x
[48]
Simo G, Njiokou F, Mbida Mbida JA, Njitchouang GR, Herder S, et al. (2008) Tsetse fly host preference from sleeping sickness foci in Cameroon: epidemiological implications. Infect Genet Evol 8: 34–9. doi: 10.1016/j.meegid.2007.09.005
[49]
Berberof M, Perez-Morga D, Pays E (2001) A receptor-like flagellar pocket glycoprotein specific to Trypanosoma brucei gambiense. Mol Biochem Parasitol 113: 127–38. doi: 10.1016/S0166-6851(01)00208-0
[50]
Gibson W (2009) Species-specific probes for the identification of the African tsetse-transmitted trypanosomes. Parasitology 1–7. doi: 10.1017/s0031182009006179
[51]
Rogers D (1979) Tsetse population dynamics and distribution: a new analytical approach. J Anim Ecol 48: 825–49. doi: 10.2307/4197
[52]
Hargrove J (1988) Tsetse: the limits to population growth. Med Vet Entomol 2: 203–17. doi: 10.1111/j.1365-2915.1988.tb00184.x
[53]
Vreysen MJ, Saleh KM, Ali MY, Abdulla AM, Zhu ZR, et al. (2000) Glossina austeni (Diptera: Glossinidae) eradicated on the island of Unguja, Zanzibar, using the sterile insect technique. J Econ Entomol 93: 123–35. doi: 10.1603/0022-0493-93.1.123
[54]
Da Costa B (1916) Sleeping sickness, a record of four years war against it in Principe, Portuguese West Africa. London: Ballière, Tindall and Cox editors. 300 p.
[55]
De Raadt P (1999) The history of sleeping sickness. In: Gilles HM, editor. Protozoal diseases. London: Arnold.
