Prevalence and disease spectrum in a new focus of visceral leishmaniasis in Kenya

Abstract

A cross-sectional community study was conducted in the village of Kivaa in Machakos District, Kenya, to determine the prevalence and disease spectrum of visceral leishmaniasis. The disease was first diagnosed in 1978. Demographic data was collected from 50 households comprising 374 individuals. Clinical examination, laboratory investigations and leishmanin skin tests were performed. The results showed that in spite of the presence of a susceptible population, visceral leishmaniasis occurred with a low prevalence in Kivaa as evidenced by the small number of individuals with active disease (0.30%), a low leishmanin positivity rate (7.2%) and the presence of leishmanial antibodies in only 3.7% of the population. The infection affected individuals in homesteads with or without nearby termite hills. Leishmanial antibodies and leishmanin positivity were found among asymptomatic household contacts of patients as well as in isolated individuals in non-infected homesteads. These findings suggest the existence of a spectrum of disease ranging from asymptomatic to self-healing to severe clinical illness. Furthermore, there was significant clustering of leishmanin reactors in the households of patients. The aetiology of this striking focality of visceral leishmaniasis remains obscure. Possible explanations are discussed.

Anti-leishmanial IgE antibodies: a marker of active disease in visceral leishmaniasis.

“…However, these antibodies have been observed to cross-react with antigens of other infectious agents, particularly Trypanosoma cruzi, 37 and are found in individuals with subclinical L. chagasi infection, [8][9][10] and persist after successful therapy for VL. 5,18 In the present study, the sensitivity and specificity for the anti-leishmanial IgE detection assay in diagnosing VL were 100%.…”

“…4 High titers of antibody are found in the course of L. chagasi infection and antibody detection is an important diagnostic tool in identifying cases of VL [5][6][7] and individuals with subclinical L. chagasi infection. [8][9][10] Only a few studies have investigated the immunoglobulin isotype responses elicited during the course of VL. In such cases, production of IgM, IgA, and the IgG subclasses have been documented during disease and an IgG1 isotype response appears to predominate.…”

Epidemia de leishmaniose visceral no Estado do Piauí, Brasil, 1980-1986

“…Este mesmo raciocínio pode justificar porque a epidemia não foi importante nos municípios endêmicos situados no sopé ocidental do Ibiapaba, onde seria reduzido o número de suscetíveis. No Piauí, o número de infecções assintomáticas ou oligossintomáticas foi, provavelmente, muito maior que a proporção de 18,5 infectados para cada doente, verificada no Estado da Bahia 14 ou que as proporções encontradas na Europa 45 ou na África 38 . Enquanto os dados desses trabalhos eram frutos do exame cuidadoso de pacientes para estudos, os casos do Estado do Piauí, apesar dos critérios diagnósticos satisfatórios, foram notificados por uma precária rede de serviços de saúde, onde nem sempre os médicos estavam familiarizados ou atentos ao quadro clínico da protozoose.…”

Serological diagnosis of leishmaniasis: on detecting infection as well as disease

“…The former are certainly uninfected; the latter are individuals who have been found parasitologically or clinically negative, usually after a single examination. Some examples of this approach applied to both canine and human visceral leishmaniasis, among the very many which have been published, are in the references [3][4][5][6][7][8][9][10][11][12][13][14]. It has often been concluded, particularly when using nonendemic controls, that it is possible to choose a cut-off point (threshold titre) giving sensitivity and specificity close to 100%.…”