Estudo da capacidade vetorial de Migonemya migonei (França) e de Pintomya fischeri (Pinto) (Diptera: Psychodidae) para Leishmania (Leishmania) infantum chagasi Cunha &Chagas / Study of the vectorial capacity of Migonemyia migonei (França) and of Pintomyia fischeri (Pinto) (Diptera: Psychodidae) as regards Leishmania (Leishmania) infantum chagasi Cunha &Chagas

Fredy Galvis Ovallos

Introduction - Visceral leishmaniasis has been affecting canine and human populations in various urban centers in São Paulo state and the area of its distribution has been growing steadily. Since its introduction into the state, the infection has been identified in canine and feline populations of Greater São Paulo. Differently from other areas, where the transmission of visceral leishmaniasis occurs in a consolidated urban environment, in Greater São Paulo it takes place in a transitional urban-rural environment, where in the residual forests the anthropophilic sandflies Pintomyia fischeri and Migonemyia migonei are found. Vectorial capacity is defined as the daily rate of the potentially infectious bites that a vector population will inflict on one single type of host while feeding on it (REISEN, 1989). Objective To compare the vectorial capacity of Pintomyia fischeri and Migonemyia migonei from a focus of visceral canine leishmaniasis of Greater São Paulo to that of Lu. longipalpis from Campo Grande, an endemic area of the Mato Grosso do Sul state, in terms of the transmission of Leishmania (L.) infantum chagasi, the agent of American visceral leishmaniasis. Methods The infective survival time of each phlebotomine species was calculated by means of vertical estimation (life table) of first generation females bred in the laboratory. The other parameters included: the attractiveness of the domestic dog to phlebotomines (field data) and; under laboratory conditions: the experimental infection of phlebotomines by L. (L.) i. chagasi after being fed on infected dogs; the extrinsic incubation period of the parasite and the duration of the gonotrophic cycle. Results As regards the studied parameters were respectively observed for Lu. longipalpis, Pi. fischeri and Mg. migonei: the density of females/dog/day 3.5, 5.5 and 0.04; the proportion of females that fed on the dog 0.71, 0.64 and 0.70; the extrinsic incubation period (days) 7, 4 and 7 (estimated); the median gonotrophic cycle (days) 5, 6 and 7, and the infective survival period(days) 4.13, 0.74 and 2.14. The vectorial capacity of the Lutzomyia longipalpis population was calculated as 2.02 new infections per day of the exposure of an infected dog. For Pintomyia fischeri this value was 0.108 and for Migonemyia migonei, 0.0024. Conclusions. The vectorial capacity of Lu. longipalpis in relation to Leishmania infantum chagasi was 18.7 times that of Pi. fischeri and that of this latter species was 45 times that of Mg. migonei. Thus, in the focus of visceral canine leishmaniasis in the Embu/Cotia region, if the vectorial competence of the two species be demonstrated, Pi. fischeri might be active in the transmission of this leishmania by virtue of its greater density and higher experimental infection rate, whereas the participation of Mg. migonei seems unlikely

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