Vectors

Abstract

Chagas disease is the most important parasitic disease in Latin America, as in Mexico, where 1.5-2% of blood donations are contaminated with antiTrypanosoma cruzi antibody. Through environmental and population based stratification, we estimate that 91 million inhabitants are at risk (78% through residence), 1,768,376 individuals are infected, and mortality may oscillate between 25,500 and 63,000 individuals/yr (830 of these are under 5 yrs old). The disease incidence is estimated at 69,000 cases/yr and approximately 530,500 individuals are currently in chronic phase. More than 96% of the transmission occurs via the vector, and niche modeling with GARP estimates that 67% of the transmission occurs via one of the 6 primary phyllosoma complex species.The economic loss due to incapacity is estimated at US$ 3,160,000,000/yr, while diagnostic and treatment costs currently could attain US$ 126,000,000/ yr. In the absence of a vector control program, disease burden could duplicate in 25 yrs, while chronic case treatment will augment by a factor of 45 over the same period. VE2 -MORPHOMETRIC ANALYSIS OF MEXICAN AND GUATEMALAN POPULATIONS OF TRIATOMA DIMIDIATA.Ramsey J.M., Lehmann P., Monroy C., Bargues M.D., Ordoñez R.Center for Infectious Disease Research, National Institute for Public Health, Cuernavaca, Morelos, Mexico Current estimates suggest that 2% of the Mexican population is seropositive for Trypanosoma cruzi, and the incidence of Chagas disease may supercede 69,000 cases/yr, with mortality equally 5-6% (25,000 cases) of the country´s total burden. Among the 18 vector species found in the country, Triatoma dimidiata plays a critical role in transmission principally in Gulf coast and all states south of the Istmus of Tehuantepec. Current molecular studies using ITS-2 rDNA and mitochondrial DNA markers, suggest that the populations found in the Yucatan peninsula may be an ancestral stock, from which other Mexican, Mesomerican, and Colombian/Venezuelan populations derived. Given profound genetic differences between yucatecan and all other populations, phenotypic differences might be expected using head and wing morphometric and symmetry discriminate analysis. 187 specimens of T. dimidiata collected from the states of Yucatán, Veracruz, and San Luis Potosí (SLP), were compared to a population from the Petén, Guatemala, and T. phyllosoma from Oaxaca as outgroup (:33 specimens per species). 12 head and 14 wing characters were measured separately for male and female samples, and measurements analyzed using multigroup principal component and discriminate analyses, sexual dimorphism and wing asymmetry. Guillaumin profiles indicated no size difference between SLP and Veracruz populations, while Peten specimens were smaller, and those from the Yucatan the smallest. None of the populations were separated completely using principal component analysis, although there was a clear tendency for separation. No shape differences were observed between SLP and Veracruz populations although they were clearly separated from both the Yu...