An uncommon type of malaria, caused by the malarial parasite, Plasmodium ovale, was identified in a jawan in Kerala, according to a report in December 2020. The soldier is believed to have contracted it during his posting in Sudan, from where he returned in January 2020. In November, he began showing symptoms after his arrival from Delhi to Kerala. The jawan was discharged from hospital within a week after full recovery, after he received treatment and preventive measures in accordance with the protocol laid out as part of Kerala’s integrated diseases surveillance programme (IDSP). The Plasmodium ovale is endemic to tropical Western Africa.
Earlier, a rapid antigen test to detect the strain of the parasite had given negative results for both Plasmodium falciparum and Plasmodium vivax, the common types of parasites found in India.
According to scientists at the National Institute of Malaria Research (NIMR), the Kerala case could be an isolated one; there have not been cases of local transmission. Previously, too, isolated cases of the disease had been reported in Gujarat, Kolkata, Odisha, and Delhi but there had been no local transmission on record.
It is possible for the parasite to remain in the spleen or liver of the human body for a long time, even years, after the mosquito bite and become symptomatic later. That is what could have happened in the case of the jawan. P. ovale rarely causes severe illness.
About the Parasites
Malaria is caused by the bite of the female Anopheles mosquito, when the mosquito is infected with a malarial parasite. The malarial parasites identified are of five kinds: Plasmodium vivax, Plasmodium falciparum, Plasmodium malariae, Plasmodium ovale and Plasmodium knowlesi.
- ovale is like P. vivax, and both generally do not result in death of the infected (it is like a viral infection). The symptoms in their case is fever for 48 hours, headache, and nausea; the treatment modality is the same as well. It could be tricky distinguishing between the two unless the lab performing the tests is well-equipped.
- ovale is called so, as about 20 per cent of the parasitised cells are oval in shape. It is rarely to be found outside of Africa, relatively speaking; where found, it comprises less than 1 per cent of the isolates, say scientists. It has been detected in the Philippines, Indonesia, and Papua New Guinea, though rarely. P. ovale and P. malariae were found at very low prevalence on the China-Myanmar border, but were often misidentified, according to a 2016 study. In another study, in Jiangsu Province, China, indigenous malaria cases decreased significantly over 2011–14, but imported cases of P. ovale and P. malariae had increased, and had been misdiagnosed often.
India
About 19 countries in sub-Saharan Africa and India together have 85 per cent of the global malaria infections (2019).
In India, the states where malaria is most spread are Chhattisgarh, Jharkhand, Madhya Pradesh, Meghalaya, and Odisha. Out of 1.57 lakh malaria cases, in 2019, 1.1 lakh cases (70 per cent) were cases of P. falciparum. In 2018, the National Vector-borne Disease Control Programme (NVBDCP) estimated that about 5 lakh people suffering from malaria, i.e., 63 per cent, were cases of P. falciparum, even as researchers writing in the Malaria Journal of BMC felt the numbers could be an underestimate. Overall, in India, malaria cases have seen a drop from about 20 million in 2000 to about 5.6 million in 2019 (World Malaria Report 2020).