COVID-19: Possible Cause of Induction of Relapse of Plasmodium vivax Infection.

To the Editor: In ongoing pandemic of novel corona virus disease (COVID-19), clinicians are observing atypical manifestations of the disease. We hereby report a case of COVID-19 co-infection with vivax malaria in a 10-y-old boy, who previously had received incomplete radical cure with primaquine for vivax infection, suggesting a possible role of COVID-19 in inducing current malarial relapse.

A 10-y-old boy, resident of Delhi, presented to the pediatric emergency department of a tertiary care hospital with history of high grade fever with chills and rigors, headache, cold, cough and pain abdomen. Past history revealed admission with a similar episode of febrile illness six months back. Medical records from previous admission revealed that he was diagnosed with P. vivax infection and had not completed primaquine therapy as per history. At presentation, child was febrile with fever of 104° F, maintained saturation of 97–98% on room air. Rest of systemic examination was normal. Investigations revealed Hb of 11.7/dl, total leucocyte count (TLC) of 4500/mm3 with 15% neutrophils, 53% lymphocytes and 28% eosinophils (absolute eosinophil count of 1260/mm3), and platelet count of 52,000/mm3. Rapid diagnostic test for malaria was faintly positive for pan antigen and smear examination showed all stages of Plasmodium vivax (P. vivax), confirming it to be malaria. Nasal and pharyngeal swabs RT-PCR for corona virus 2 (SARS-CoV-2) were positive. Other investigations were normal.

The child was admitted and treated for malaria and supportive care for COVID-19 infection [1]. Primaquine eradication therapy was given for 14 d after ruling out G6PD deficiency. He was discharged after complete recovery.

This boy had been diagnosed with P. vivax infection six months back and had now reactivation of malaria. Relapse rates after P. vivax infection vary geographically from 8 to 80%, with considerable proportion of population harboring dormant but activatable hypnozoites in endemic areas [2]. Exact mechanism causing this activation is though unclear, associated cytokine response with systemic illness has been postulated in P vivax relapse [3]. COVID-19 leads to a cytokine storm, which is responsible for the more severe manifestations of the disease [4, 5]. Hence, we postulate that the COVID-19 infection, with its cytokine response was responsible for induction of P. vivax relapse in our patient. Our hypothesis is based on circumstantial evidence in form of documented malaria in past, a possibility of re-activation in natural course or re-infection cannot be ruled out.