Distribution of Sand Flies (Diptera: Psychodidae) at Different Altitudes in an Endemic Region of American Cutaneous Leishmaniasis in the State of Espírito Santo, Brazil

Vol. 96(8): 1061-1067, November 2001

Adelson Luiz Ferreira⁺, Paulo Augusto Sessa, José Benedito Malta Varejão, Aloísio Falqueto

Unidade de Medicina Tropical, Departamento de Patologia, Centro Biomédico, UFES, Av. Marechal Campos 1468, 29040-090 Vitória, ES, Brasil

The involvement of different sand fly species in the transmission of American cutaneous leishmaniasis (ACL) at different altitudes was evaluated in the municipality of Afonso Cláudio in the State of Espírito Santo, Brazil, from November 1995 to February 1997. CDC light traps and Shannon traps baited with human volunteers were hung simultaneously at three altitudes of a river valley: (a) 650-750 m in an area of active ACL transmission; (b) 750-850 m in a transitional area; and (c) 850-950 m in an area where no ACL transmission occurred. A total of 13,363 specimens belonging to 28 species was collected. The five most abundant man-biting species were Lutzomyia intermedia, which constituted 24.3% of the total, Lu. migonei (22.3%), Lu. whitmani (15.4%), Lu. fischeri (14.9%) and Lu. monticola (5.8%). Analysis of the distribution of these species at the three altitudes provided evidence that Lu. fischeri and Lu. monticola were not involved in ACL transmission, whereas Lu. migonei and Lu. whitmani might act as secondary vectors of Leishmania (Viannia) braziliensis and Lu. intermedia was probably the principal vector of the parasite. These results reinforce those published in the existing literature, which indicate that Lu. intermedia is the main vector of Le. (V.) braziliensis in Southeast Brazil, while Lu. migonei and Lu. whitmani are of secondary importance.

Key words: altitude - sand flies - cutaneous leishmaniasis - Espírito Santo - Brazil

The distribution of American cutaneous leishmaniasis (ACL) is influenced by little-known geographical and climatic factors that determine the distribution of different sand fly vectors, parasites and reservoirs. Tropical climatic conditions and altitudes of up to 800 m above sea level (asl) favor transmission of Leishmania (Viannia) braziliensis (Mogollón et al. 1977, Bonfante-Garrido 1983, Añez et al. 1988), including in Brazil (Forattini et al. 1972, Aguiar et al. 1987, Azevedo & Rangel 1991, Passos et al. 1993, Hermeto et al. 1994, Domingos et al. 1998, Gomes & Neves 1998, Rangel et al. 1999).

In same areas of Northeast and Southeast Brazil that were first colonized by Europeans, the disease is transmitted predominantly in the domestic environment, affecting people of both sexes and of all age groups (Mayrink et al. 1979, Barros et al. 1985, Queiroz et al. 1991, Lainson et al. 1994). Dogs and horses appear to be the domestic reservoirs of Le. (V.) braziliensis, the main etiological agent of ACL in these areas (Falqueto et al. 1986, Aguilar et al. 1989). Among the species of sand flies that have probably adapted to habitats modified by human activities, Lutzomyia intermedia, Lu. whitmani and Lu. migonei, are proven or probable vectors of Leishmania (Rangel et al. 1984, Hoch et al. 1986, Azevedo et al. 1990a, b, Marzochi 1992, Sessa et al. 1994, Marzochi & Marzochi 1997).

The municipality of Afonso Cláudio in the State of Espírito Santo, Brazil, is an important endemic area of ACL. Sessa et al. (1994) noted that in Liberdade, a village in this municipality, most transmission of the disease was in the peridomicile of houses situated between 600-750 m asl and none occurred above 850 m. Falqueto (1995) collected five man-biting species of sand flies in the village, i.e., Lu. intermedia, Lu. whitmani, Lu. migonei, Lu. fischeri and Lu. monticola. Although this author considered that most transmission of Le. braziliensis occurred in the peridomiciliary environment, with dogs acting as reservoirs of the parasite, he suggested that a residual sylvatic cycle might also occur, with the armadillo (Euphractus sexcinctus) and the paca (Agouti paca) acting as secondary reservoirs of the parasite.

Given that man and his domestic animals, as well as wild mammals are present at all altitudes in this area, the absence of ACL above a certain altitude may be attributed to changes in the sand fly fauna. This hypothesis was tested during the present study by systematic sampling of phle-botomines at different altitudes, with the aim at incriminating possible vector species.

MATERIALS AND METHODS

RESULTS

DISCUSSION

ACKNOWLEDGMENTS

To Dr José Luiz Helmer for the revision of the statistical analysis. To Dr Bruce Alexander for English revision.

REFERENCES

Figure | Table I | Table II | Table III

⁺Corresponding author. Fax: +55-27-335.7287. E-mail: adelsonluiz@escelsanet.com.br

Received 28 December 2000

Accepted 24 July 2001