Incidence of Symptomatic and Asymptomatic Leishmania donovani Infections in High-Endemic Foci in India and Nepal: A Prospective Study

Abstract

Incidence of Leishmania donovani infection and Visceral Leishmaniasis (VL) was assessed in a prospective study in Indian and Nepalese high-endemic villages. DAT-seroconversion was used as marker of incident infection in 3 yearly surveys. The study population was followed up to month 30 to identify incident clinical cases. In a cohort of 9034 DAT-negative individuals with neither active signs nor history of VL at baseline, 42 VL cases and 375 asymptomatic seroconversions were recorded in the first year, giving an infection∶disease ratio of 8.9 to 1. In the 18 months' follow-up, 7 extra cases of VL were observed in the seroconverters group (N = 375), against 14 VL cases among the individuals who had not seroconverted in the first year (N = 8570) (RR = 11.5(4.5<RR<28.3)). Incident asymptomatic L. donovani infection in VL high-endemic foci in India and Nepal is nine times more frequent than incident VL disease. About 1 in 50 of these new but latent infections led to VL within the next 18 months.

The Burden of Visceral Leishmaniasis in India: Challenges in Using Remote Sensing and GIS to Understand and Control

“…In this connection it is important to note that infection rates in human that act as reservoirs for VL transmission (e.g., post-kala-azar dermal leishmaniasis, P�DL) are signi�cantly higher, as observed in the four main states (e.g., Bihar, Jharkhand, West Bengal, and Uttar Pradesh) of India [6]. Previous study has shown the conspicuous increase of visceral leishmaniasis cases in India, especially in Bihar [45,46]. One of the factors for increasing trend of the disease could be due to the increase in reporting of kala-azar cases at public health centers (PHCs) due to massive kala-azar awareness programme undertaken by health agencies and Government of India.…”

“…However, there is a great need to rigorously implement control interventions in those areas where the disease continues to be endemic, as documented by the latest available data of VL on a national scale [45,46,51,52]. In fact, north Bihar (India) that covers 31 districts along the Ganges River is characterized by high population densities, suitable climate, and large areas that are favourable for proliferation of P. argentipes breeding.…”

A Correlative Study of Splenic Parasite Score and Peripheral Blood Parasite Load Estimation by Quantitative PCR in Visceral Leishmaniasis

“…The sensitivity of amastigote detection in splenic smear is 96% to 98% (11,12); however, splenic aspiration is associated with the risk of lifethreatening hemorrhage. Additionally, serological tests cannot discriminate between subclinical, current, and past infections (13,14). Various DNA-based molecular methods (PCR) have been used for the diagnosis of VL using blood, buccal swabs, or urine samples; however, their inability to discriminate between symptomatic or asymptomatic VL is a major drawback (7,15,16).…”

Infection with Leishmania (Leishmania) infantum of 0 to 18-Month-Old Children Living in a Visceral Leishmaniasis-Endemic Area in Brazil

“…30 Furthermore, in India and Nepal, Ostyn and others (2011) showed that the probability of progression to disease was higher among individuals with seroconversion of direct agglutination test, but the disease also occurred in previously seronegative individuals. 31 It should be noted that the two children of this study developed the disease about 3 to 6 months after a negative result in the three tests. The fact that these children were exposed in an endemic area suggests that they contracted the disease during the period between assessments.…”