Visceral Leishmaniasis-HIV Coinfection as a Predictor of Increased Leishmania Transmission at the Village Level in Bihar, India.

Kristien Cloots,Marleen Boelaert,Pia Marino,Sakib Burza,Naresh Gill,Epco Hasker

doi:10.3389/fcimb.2021.604117

Abstract

BackgroundVisceral leishmaniasis (VL) is on the verge of being eliminated as a public health problem in the Indian subcontinent. Although Post-kala-azar dermal leishmaniasis (PKDL) is recognized as an important reservoir of transmission, we hypothesized that VL patients co-infected with Human Immunodeficiency Virus (HIV) may also be important reservoirs of sustained leishmania transmission. We therefore investigated to what extent cases of PKDL or VL-HIV are associated with VL incidence at the village level in Bihar, India.MethodsVL, VL-HIV, and PKDL case data from six districts within the highly VL-endemic state of Bihar, India were collected through the Kala-Azar Management Information System for the years 2014–2019. Multivariate analysis was done using negative binomial regression controlling for year as a fixed effect and block (subdistrict) as a random effect.FindingsPresence of VL-HIV+ and PKDL cases were both associated with a more than twofold increase in VL incidence at village level, with Incidence Rate Ratios (IRR) of 2.16 (95% CI 1.81–2.58) and 2.37 (95% CI 2.01–2.81) for VL-HIV+ and PKDL cases respectively. A sensitivity analysis showed the strength of the association to be similar in each of the six included subdistricts.ConclusionsThese findings indicate the importance of VL-HIV+ patients as infectious reservoirs for Leishmania, and suggest that they represent a threat equivalent to PKDL patients towards the VL elimination initiative on the Indian subcontinent, therefore warranting a similar focus.

Highlights

Visceral Leishmaniasis (VL) - called kala-azar (KA) - is a potentially fatal parasitic disease. in the Indian subcontinent, the vast majority of cases is caused by Leishmania donovani, L. tropica has been isolated from VL cases in this region (Khanra et al, 2012; Thakur et al, 2018)
A total of 7,497 cases were included in the analysis; 6,515 cases of VL, 397 cases of VL-Human Immunodeficiency Virus (HIV), and 585 cases of Post-kala-azar dermal leishmaniasis (PKDL). 5.7% (397/ 6,909) of all VL cases were co-infected with HIV at the time of diagnosis. 37.8% (2,247/5,938) of the included villages reported ≥ 1 case of VL during the study period; while 5.4% (322/5,938) and 7.3% (434/5,938) of the villages reported ≥ 1 VL-HIV+ case and ≥ 1 PKDL case respectively
Exact distribution of VL, VL-HIV+, and PKDL cases per year and per district is graphically represented in Figure 2; underlying numbers are available in S1 Table and S2 Table

Summary

Introduction

Visceral Leishmaniasis (VL) - called kala-azar (KA) - is a potentially fatal parasitic disease. in the Indian subcontinent, the vast majority of cases is caused by Leishmania donovani, L. tropica has been isolated from VL cases in this region (Khanra et al, 2012; Thakur et al, 2018). Following the near elimination of VL from the Indian subcontinent in the 1970s, PKDL was suspected to have been the interepidemic reservoir responsible for triggering a new VL outbreak years after the last VL case had been reported in West Bengal (Addy and Nandy, 1992). As such PKDL is considered a largely hidden but persistent reservoir of infection, and remains a major threat to the sustainability of the elimination initiative. We investigated to what extent cases of PKDL or VL-HIV are associated with VL incidence at the village level in Bihar, India

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Conclusion