Epidemiology of Plasmodium vivax Malaria Infection in Nepal

Malaria is endemic in the southern plain of Nepal which shares a porous border with India. More than 80% cases of malaria in Nepal are caused by Plasmodium vivax. The main objective of this study was to review the epidemiology of P. vivax malaria infections as recorded by the national malaria control program of Nepal between 1963 and 2016. National malaria data were retrieved from the National Malaria program in the Ministry of Health, Government of Nepal. The epidemiological trends and malariometric indicators were analyzed. Vivax malaria has predominated over falciparum malaria in the past 53 years, with P. vivax malaria comprising 70-95% of the annual malaria infections. In 1985, a malaria epidemic occurred with 42,321 cases (82% P. vivax and 17% Plasmodium falciparum). Nepal had experienced further outbreaks of malaria in 1991 and 2002. Plasmodium falciparum cases increased from 2005 to 2010 but since then declined. Analyzing the overall trend between 2002 (12,786 cases) until 2016 (1,009 cases) shows a case reduction by 92%. The proportion of imported malaria cases has increased from 18% of cases in 2001 to 50% in 2016. The current trends of malariometric indices indicate that Nepal is making a significant progress toward achieving the goal of malaria elimination by 2025. Most of the cases are caused by P. vivax with imported malaria comprising an increasing proportion of cases. The malaria control program in Nepal needs to counter importation of malaria at high risk areas with collaborative cross border malaria control activities.