Long-term trends of visceral leishmaniasis incidence and mortality in India 1990-2019: an application of joinpoint and age-period-cohort analysis.

Leishmaniasis, a vector-borne disease, remains one of the most significant parasitic disease with potential outbreak and high mortality. Despite improvements in living standards and health infrastructure, there has been a territorial expansion in the incidence and lethality of the disease. However, evidence regarding its control, prevention, and eradication remains limited. Given an understanding of the present status of the disease, this study assesses the trends and patterns in the incidence and mortality of this endemic in India from 1990 to 2019. This study obtained Visceral Leishmaniasis (VL) incidence and mortality data (1990-2019) from the Global Burden of Disease (GBD) study 2019, provided by the Institute for Health Metrics and Evaluation (IHME). To capture the overall changes and sex-specific changes in ASIRs and ASMRs of VL, joinpoint regression analysis was employed for all ages by using joinpoint regression programme version 4.5.0.1. Age-period-cohort analysis is used to estimate the net age, period, and cohort effects on the incidence and mortality of VL from observed age-specific incidence and mortality rates. The APC model was implemented using Stata 16.0, and its fit was assessed using Akaike's Information Criterion (AIC) and Bayesian Information Criterion (BIC). Findings indicate a significant decline in the age-specific incidence and mortality rates for both sex. The highest annual percentage decline in VL incidence and mortality was observed during 2011-2016 for both males and females. (Table 1). Results from the age effect show that the risk of VL incidence and mortality among both genders decreased sharply with advancing age. Period effect indicated a sharp decline in incidence and mortality risk from the period 1990-94 to 2000-04. The cohorts effect showed that compared to earlier birth cohort (1900-04),, the relative risk (RR) of VL incidence increased by 1.5 in male and 1.7 times in females in more recent birth cohort (2015-19), whereas mortality risk decreased by 48% among females. Findings highlight a notable reduction in VL incidence and mortality in the country. The age pattern in the incidence and mortality rates indicates the need for age-specific attention while performing preventive measures and comprehensive strategies. Moreover, strengthening large-scale screening, vector control measures, and public health education is essential to sustain VL elimination efforts.