Seroprevalence of Kala-Azar Among Humans and Dogs in Yemen

Abstract

HA Al-Shamahy, Seroprevalence of Kala-Azar Among Humans and Dogs in Yemen. 1998; 18(1): 66-68 Kala-azar (visceral leishmaniasis) is a major cause of fever in the world, and is estimated to affect 100 million people worldwide.1 Kala-azar was first reported from the northern part of Yemen over 90 years ago. 2 Sporadic cases of the disease, however, are now widely reported from all over the country, including the governorates of Sana'a, Taiz, Ibb, Al-Hodeidah, Hajjah, Damar, Sa'adah, Al-Mahweet, Mareb, and Al-Jawf. Nearly 4047 cases, mostly in young children, have been reported during the last decade.3 The scarce information of the disease epidemiology in Yemen showed that the causative organisms were Leishmania donovani complex and L. infantum complex, and vectors were Phlebotomus orientalis and P. arbicus for L. infantum and L. donovani. [4][5][6] In addition, a few other infantile cases were reported from the northern part of Yemen.7,8 Michie 9 described four adult cases from the southern part of Yemen.Canine leishmaniasis was discovered by Nicole and Comte in 1908, 10 and since then reports of infected dogs have come from almost all human visceral leishmaniasis foci in the Mediterranean area.11-13 Dogs are an efficient reservoir host because parasitized fixed macrophages are so abundant in the dermal layer that parasites are readily taken up by feeding sandflies.14,15 Canine leishmaniasis was reported by Rioux et al. from human visceral leishmaniasis focus in the Taiz area of Yemen.The objectives of this study were to determine the seroprevalence of kala-azar among children in selected localities in Yemen, and to identify the natural reservoir of human kala-azar in these areas, focusing particularly on dogs, with a view to determining infection rates among them and their role in the transmission of the disease to humans. Materials and MethodsThe study was conducted in December 1993 in three selected villages where cases of kala-azar had been reported during the year, and also in the city of Sana'a. The study population consisted of volunteer schoolchildren in Beni-Mansur (Al-Haymah, Sana'a province), Huth (Sana'a province) and in Sana'a city. Based on an expected kala-azar prevalence of 10% and the worst acceptable value of 4%, not less than 270 randomly selected subjects were needed out of a total estimated 100,000 children, at a confidence level of 99.9%.A systematic random sampling of every fifth child was done. A sample of 285 subjects were selected, comprising 68 subjects from Beni-Mansur, 85 from Huth, 75 from Sharis and 57 from Sana'a city.All study participants completed an epidemiological questionnaire and gave informed consent to participate in the study. Basic demographic data, including age, sex, address, and altitude of the house, were obtained, as well as potential risks factors for kala-azar. Serological AssayA 5 mL aliquot of venous blood was allowed to clot and the serum was separated and stored at -20°C until serological analyses were performed. All the sera were tested for kala-azar using ...

Prevalence of kala-azar infection in Pokot county, Amudat district, Northeastern Uganda

“…The prevalence of kala-azar was high in Loroo, followed by Karita and Amudat sub-counties, respectively even after stratifying by age group and sex. Although the sample size for this study was relatively small and the study not designed for risk factors assessment, the higher prevalence in Loroo and Karita sub-counties may be related to the fact that there is usually clustering of DAT positivity around active cases [13][14][15]. There were three clinical cases in Loroo and Karita compared to one in Amudat.…”

“…The ratio of symptomatic kala-azar infection to asymptomatic infection of 1:6 implies that for every symptomatic kala-azar case there are six asymptomatic kalaazar infection cases in the community. The asymptomatic cases are usually a source (reservoirs) of kala-azar infection, and thus they continue to spread the infection in the community [13][14][15][16].…”

“…Higher prevalence of kala-azar infection amongst household members with previous household case of kala-azar could be explained by the usual clustering of DAT positivity around active kala-azar cases [13,19,20].…”

First Molecular Characterization of Leishmania Species Causing Visceral Leishmaniasis among Children in Yemen

“…This in turn, limits the possibility of developing an effective VL control strategy. A high seroprevalence rate (34.7%; 99/285) of antibodies to Leishmania species was reported among schoolchildren from areas endemic with infantile VL in Sana’a and Hajjah governorates [ 12 ]. In addition, natural infection of feral dogs from the study areas with Leishmania species (50%; 8/16) was also documented for the first time [ 12 ].…”

“…A high seroprevalence rate (34.7%; 99/285) of antibodies to Leishmania species was reported among schoolchildren from areas endemic with infantile VL in Sana’a and Hajjah governorates [ 12 ]. In addition, natural infection of feral dogs from the study areas with Leishmania species (50%; 8/16) was also documented for the first time [ 12 ]. Haidar et al [ 13 ] reported that the clinical presentation of VL among children in Hajjah governorate, north of Yemen, is similar to that of the Mediterranean type.…”