Ashford D A, David J R, Freire M, David R, Sherlock I, Eulálio M C, Sampaio D P, Badaro R
Department of Tropical Public Health, Harvard School of Public Health, Boston, Massachusetts 02115, USA.
Am J Trop Med Hyg. 1998 Jul;59(1):53-7. doi: 10.4269/ajtmh.1998.59.53.
To assess the effect of removing leishmania-infected dogs on the incidence of visceral leishmaniasis, a controlled intervention study was performed in northeast Brazil. The attempted elimination of seropositive dogs resulted in an initial significant decrease in the annual incidence of seroconversion among dogs from 36% to 6% over the first two years. In the following two years, the incidence increased to 11% and 14%, respectively. In a control area in which dogs were surveyed but seropositive dogs were not removed, the cumulative incidence did not vary significantly from year to year, ranging from 16% to 27%. In the intervention area, the prevalence of dog seropositivity decreased from 36% before the intervention to 10% and remained stable. These findings suggest that attempting to remove seropositive dogs is insufficient as a measure for eradicating visceral leishmaniasis in dogs. However, the force of transmission of infection among dogs can be reduced by such programs. Also, when the number of human cases before and after the start of the intervention was calculated, a significant decrease in incidence of disease in the intervention area was observed among children less than 15 years of age (P < 0.01). The results of this intervention study suggest that the elimination of the majority of seropositive dogs may affect the cumulative incidence of seroconversion in dogs temporarily and may also diminish the incidence of human cases of visceral leishmaniasis.
为评估清除感染利什曼原虫的犬只对内脏利什曼病发病率的影响，在巴西东北部开展了一项对照干预研究。在前两年中，试图清除血清学阳性犬只的做法使犬只血清转换的年发病率从36% 显著降至6%。在接下来的两年中，发病率分别升至11% 和14%。在一个对犬只进行调查但未清除血清学阳性犬只的对照地区，累积发病率逐年变化不显著，范围在16% 至27% 之间。在干预地区，犬只血清学阳性率从干预前的36% 降至10% 并保持稳定。这些发现表明，试图清除血清学阳性犬只作为根除犬内脏利什曼病的一项措施是不够的。然而，此类计划可降低犬只间感染的传播力度。此外，计算干预开始前后的人类病例数时，在15岁以下儿童中观察到干预地区疾病发病率显著下降（P < 0.01）。这项干预研究的结果表明，清除大多数血清学阳性犬只可能会暂时影响犬只血清转换的累积发病率，也可能降低人类内脏利什曼病病例的发病率。
