The footprints of relapsing malaria in southwest Delhi, India

Control of vivax malaria is challenging due to persistence of hypnozoites causing relapses and safety concerns with primaquine in G6PD deficient individuals. We present the epidemiology of malaria with emphasis on recurrence of vivax malaria over a period of four years in southwest Delhi among patients reporting to malaria clinic.

Microscopic examination of stained blood smears of fever patients attending malaria clinic was performed. Confirmed malaria cases were treated as per the national treatment guidelines. The epidemiological data of confirmed malaria cases including demographic characteristics, age, gender and past history of malaria were analysed. Patients were asked to report in case of occurence of fever.

From January 2011 to December 2014, 429 Plasmodium vivax, 24 P. falciparum and three mixed infection cases were reported to the Malaria Clinic at National Institute of Malaria Research, New Delhi. Malaria cases peaked in the months of August and September during all the four years. Recurrent episodes of vivax malaria were observed in 14.72% patients to whom primaquine was not dispensed, while the prevalence was 4.02% among those who received primaquine. The relapsing patterns observed were of both short as well as long latency P. vivax phenotypes. The entomological survey of area from where malaria patients reported, showed prevalence of Anopheles stephensi.

The study showed presence of persistent P. vivax malaria with strains causing both frequent and long latency recurrences (probable relapses) in southwest Delhi. This highlights the need to evaluate primaquine regimens against both these strains and formulate strategies to improve compliance to 14-days primaquine treatment.