Courtenay Orin, Quinnell Rupert J, Garcez Lourdes M, Shaw Jeffrey J, Dye Christopher
Ecology and Epidemiology Group, Department of Biological Sciences, University of Warwick, Coventry, United Kingdom.
J Infect Dis. 2002 Nov 1;186(9):1314-20. doi: 10.1086/344312. Epub 2002 Oct 11.
The elimination of seropositive dogs in Brazil has been used to control zoonotic visceral leishmaniasis but with little success. To elucidate the reasons for this, the infectiousness of 50 sentinel dogs exposed to natural Leishmania chagasi infection was assessed through time by xenodiagnosis with the sandfly vector, Lutzomyia longipalpis. Eighteen (43%) of 42 infected dogs became infectious after a median of 333 days in the field (105 days after seroconversion). Seven highly infectious dogs (17%) accounted for >80% of sandfly infections. There were positive correlations between infectiousness and anti-Leishmania immunoglobulin G, parasite detection by polymerase chain reaction, and clinical disease (logistic regression, r2=0.08-0.18). The sensitivity of enzyme-linked immunosorbent assay to detect currently infectious dogs was high (96%) but lower in the latent period (<63%), and specificity was low (24%). Mathematical modeling suggests that culling programs fail because of high incidence of infection and infectiousness, the insensitivity of the diagnostic test to detect infectious dogs, and time delays between diagnosis and culling.
在巴西，扑杀血清反应呈阳性的犬类被用于控制人兽共患内脏利什曼病，但成效甚微。为阐明其中原因，通过用白蛉媒介长须罗蛉进行叮咬诊断，对50只暴露于自然感染恰加斯利什曼原虫的哨兵犬的传染性进行了长期评估。42只受感染犬中有18只（43%）在野外平均333天（血清转化后105天）后具有传染性。7只高传染性犬（17%）导致了超过80%的白蛉感染。传染性与抗利什曼原虫免疫球蛋白G、通过聚合酶链反应检测寄生虫以及临床疾病之间存在正相关（逻辑回归，r2 = 0.08 - 0.18）。酶联免疫吸附测定检测当前具有传染性犬类的灵敏度较高（96%），但在潜伏期较低（<63%），且特异性较低（24%）。数学模型表明，扑杀计划失败的原因在于感染和传染性的高发生率、诊断测试检测具有传染性犬类的不敏感性以及诊断和扑杀之间的时间延迟。
