A prospective study of the effects of sustained vector surveillance following community-wide insecticide application on Trypanosoma cruzi infection of dogs and cats in rural northwestern Argentina

CARDINAL MV; CASTAÑERA MB; LAURICELLA MA; CECERE MC; CEBALLOS LA; VAZQUEZ-PROKOPEC GM; KITRON U; GURTLER RE

AMERICAN JOURNAL OF TROPICAL MEDICINE AND HYGIENE

Año: 2006 vol. 75 p. 753 - 761

0002-9637

Domestic dogs were used as natural sentinels to assess prospectively the long-term impact of selective,community-based spraying with pyrethroid insecticides after community-wide spraying on transmission of Trypanosomacruzi in rural villages under surveillance between 1992 and 2002. In 2000 and 2002 light infestations by Triatoma infestanswere recorded, and 523 dogs and cats were examined serologically or by xenodiagnosis. The prevalence of T. cruziinfection in dogs decreased from 65% at baseline to 8.9% and 4.7% at 7.5 and 10 years after sustained vector surveillance,respectively. The average annual force of infection dropped 260-fold from 72.7 per 100 dog-years at baseline to<0.3% in 2002, as determined prospectively and retrospectively from the age-prevalence curve of native dogs bornduring surveillance. Multiple logistic regression analysis showed that prevalent cases in dogs in 2000 and 2002 wereassociated positively and significantly with the peak number of T. infestans caught in domestic areas at the dog’scompound during its lifetime. The sustained decline in T. cruzi infections in dogs and cats is the result of selective,community-based insecticide spraying that kept the abundance of infected T. infestans at marginal levels, fast hostpopulation turnover, and low immigration rates from areas with active transmission.