Detection of subpatent malaria among febrile mobile and migratory population individuals: a strategy for malaria elimination.

BACKGROUND

Imported malaria is a threat to malaria elimination. A case investigation (CI) with reactive active case detection (RACD) strategy is commonly used for the detection of malaria infections around the index cases.

METHODS

CI with RACD was conducted for detection of subpatent malaria among febrile mobile and migratory population (MMP) individuals around index cases in the state of Punjab in India, by microscopy, rapid diagnostic tests (RDTs) and nested PCR (nPCR). Glucose-6-phosphate dehydrogenase deficiency (G6PDd) was determined in Plasmodium vivax-positive patients.

RESULTS

A total of 119 malaria cases were reported, out of which 93.3% were P. vivax (111/119) and 6.7% (8/119) were Plasmodium falciparum. CI with RACD was initiated around 28 MMP index cases positive by RDT and microscopy. A total of 176 fingerprick samples were collected from febrile MMP individuals, from which 11 (11/176; 6.3%) infected individuals were detected: eight by RDT, microscopy and nPCR, and three (3/11; 27.3%) subpatent cases by only nPCR. None of the positive patients were found positive for G6PDd.

CONCLUSIONS

Subpatent malaria in MMP individuals can pose a challenge in malaria elimination. The RACD strategy around index cases may help to reduce the risk of spillover in the local population.