A new study has confirmed a drastic shift in the patterns of malaria occurrence in India, from widely reported cases of P. vivax (a mild form of malaria) to an increasing number of cases of P. falciparum (a virulent form of the disease). The research group has published its results in the scientific journal, PLOS ONE .
Malaria in humans, which spreads through the female Anopheles mosquito, is caused by one of the four different species (or types) of the Plasmodium parasite — P. falciparum , P. malariae , P. ovale and P. vivax . Of these, infection with P. falciparum causes a fatal form of malaria while that with P. vivax results in mild infection.
Samples from across India
In order to understand changes in the distribution of malaria cases, scientists at the ICMR-National Institute for Research in Tribal Health (NIRTH), Jabalpur, Madhya Pradesh, and their collaborators mapped the burden from different malaria infections from across India. They collected blood samples from over 2,300 patients having malaria-like symptoms from 11 different geographical locations. Researchers also observed a high proportion of cases of mixed infections or infection of a patient by two or more species of the malaria parasite.
The researchers collated data from publications over the past 13 years to analyse differential infection of malarial parasites based on an analysis of their DNA via a technique called the PCR diagnostic test.
“India is planning for malaria elimination by 2030. But a shift in malaria occurrence is really daunting for targeted malaria elimination,” says Prof. Aparup Das, Director, ICMR-NIRTH, who led the research.
Out of the positive malaria infections, 13% were found to be mixed infections due to P. falciparum and P. vivax . These were mostly located in the middle and the southwestern coast of India. The researchers consider mixed infections to be a daunting challenge as they are associated with severe malaria and the proper treatment protocol for these cases is not yet clearly defined.
Emerging challenge
Prof. Das has expressed concern over the emerging threat of another species of malaria, P. malariae . “Earlier it was confined to Odisha but our analyses suggest that it is spreading all over India and there are no defined treatment guidelines or diagnosis in the field for this species,” he notes.
“Considerable mixed malaria cases are reported, though not precisely due to technical and methodological challenges. The malaria elimination- and treatment-guidelines can be evaluated using such information and apprised to halt or delay the development of more resistant strains,” says Dr. Abhinav Sinha, a senior scientist at the National Institute of Malaria Research, Delhi, who was not connected with the study.
Larger studies have been planned for better understanding of the challenge. “A large-scale study encompassing all malaria endemic areas is to be performed utilising PCR diagnosis. This will reveal the real epidemiology of malaria and help in determining the different control measures that could be undertaken,” Prof. Das has told India Science Wire.
Aid pledge
In another development, at a high-level Malaria Summit in London, on April 18, collective commitments of $4.1 billion were secured from governments, the private sector, philanthropists and international organisations. The summit urged Commonwealth leaders to commit to halving malaria within five years. This would prevent 350 million cases of malaria and save 650,000 lives, predominantly children and pregnant women who are most at risk. — India Science Wire
With inputs by Vidya Krishnan
