TEGUMENTARY LEISHMANIASIS IN ARGENTINA: THE TRANSMISSION SHIFT

SALOMON OD; SOSA ESTANI, SERGIO; GABRIELA QUINTANA, MARÍA; WENCESLAO ORELLANO, PABLO; MARCELO SCAVUZZO,; MARIO LAMFRI,

Palermo, Italia

Congreso; 3 World Congress on Leishmaniosis; 2005

WorldLeish

Tegumentary leishmaniasis in Argentina: The TRANSMISSION shift   O.D. Salomon, S. Sosa Estani, M.G. Quintana1, P. Orellano, M. Scavuzzo, M Lamfri2 Ministry of Health, Buenos Aires, Argentina. 1 UNT, Tucumán. 2CONAE, Córdoba, Argentina   Tegumentary leishmaniasis (TL) transmission pattern in Argentina thorough a century is analysed to understand current epidemiological trends. Both historical and the own field data from the 9 endemic provinces (1990-2004) were examined. The median of cases reported in the 1955-1964, 1975-1984, and 1995-2004 decades were 45, 90, and 343 respectively; the highest cases/year record were 66, 328, 1240, and cumulative incidence were 1.21, 2.45, and 5.65 (0/000 inhabitants of endemic provinces). The rise in reporting was due both to improvements in the Health System, but also to an actual increase in the frequency and intensity of TL outbreaks. The sex ratio (male/female) recorded in 1930 and 1990-2004 was 4.2 and 0.9-2.1, while the proportion of cases with £ 15 yo was 6.8% and 12.4-39.1% respectively. The phlebotomine abundance turned from the 1920-1950 collections of scarce individuals to peridomestic large captures (up to 3000 sandflies/trap/night). The relative abundance of Lutzomyia neivai (Lu. intermedia s.l.) was very low in the former reports, while it was higher than 94% in almost all the studies since 1990. Therefore, an epidemiological shift took place in the TL transmission in Argentina during the XXth century from a sylvatic cycle to a peridomestic one, increasing the incidence and the outbreak probability. Biologic, climatic and anthropic intermingled factors might have contributed to this phenomenon: 1) The appearance of large populations of a capable vector of Leishmania braziliensis in peridomestic surroundings. 2) The decadal-scale rainfall since 1956 has been higher in the endemic area than any time in the last 200 years. 3) The rural to urban migration and the ‘ruralization’ of periurban borders with transitional vegetation. 4) The landscape and behavioral changes associated with the economic scenarios since 1970: extensive deforestation, dam projects, land use, and the increase of subsintence activities as fishing or fire-wood and garbage collection.