Explained: Plasmodium ovale and other types of malaria

Written by Anuradha Mascarenhas | Pune |

December 12, 2020 4:45:24 am

Malaria is caused by the bite of the female Anopheles mosquito, if the mosquito itself is infected with a malaria parasite. (File / Representative)

A rare type of malaria, Plasmodium ovale, has been identified in a jawan in Kerala. The soldier is believed to have contracted it during his post in Sudan, from where he returned almost a year ago and where Plasmodium ovale is endemic.

Types of malaria

Malaria is caused by the bite of the female Anopheles mosquito, if the mosquito itself is infected with a malaria parasite. There are five types of malaria parasites: Plasmodium falciparum, Plasmodium vivax (the most common), Plasmodium malariae, Plasmodium ovale, and Plasmodium knowlesi. Therefore, to say that someone has contracted Plasmodium ovale type of malaria means that the person has been infected by that particular parasite.

In India, out of 1.57 lakh of malaria cases in the high burden states of Odisha, Chhattisgarh, Jharkhand, Meghalaya and Madhya Pradesh in 2019, 1.1 lakh of cases (70%) were falciparum malaria cases, according to a statement from the Ministry of Health. on December 2. In 2018, the National Vector Borne Disease Control Program (NVBDCP) estimated that approximately 5 lakh of people suffered from malaria (63% were from Plasmodium falciparum); Researchers writing in the Malaria Journal of BMC felt that the numbers might be underestimated. The recent World Malaria Report 2020 said that cases in India fell from about 20 million in 2000 to about 5.6 million in 2019.

Plasmodium ovale

The scientists said that Povale rarely causes serious illness and there is no need to panic over the case found in Kerala. Dr VS Chauhan, Emeritus Professor at the International Center for Genetic Engineering and Biotechnology, New Delhi, said that P ovale is very similar to P. vivax, which is not a killer form. Symptoms include fever for 48 hours, headache, and nausea, and the treatment modality is the same as for a person infected with P. vivax. Povale is no more dangerous than getting a viral infection, he said.

It is called oval because approximately 20% of the parasitized cells are oval in shape. Distinguishing between P. vivax and P ovale can be tricky, Dr. Chauhan said, but a good-quality lab should be able to differentiate between the two.

Cases in India

According to scientists from the National Malaria Research Institute (NIMR), the Kerala case could be isolated and there are so far no recorded cases of local transmission. Previously, isolated cases were also reported in Gujarat, Kolkata, Odisha and Delhi. However, no local transmission has been recorded, which means that these cases have been acquired.

The jawan had returned to India from Sudan in January this year and was in Delhi. A month ago, he went to Kerala and soon after, he began to experience fever and other symptoms. After she tested negative for Covid-19, she was tested for malaria.

And on the slide, we could see the parasite inside the red blood cell sample. In Kerala, we usually see types of malaria like Plasmodium falciparum and Plasmodium vivax. So we did a rapid antigen test to detect the strain and found that it was negative for both types. When we investigated further, we diagnosed it as Plasmodium ovale, ”said Dr. Rajeevan, medical superintendent of the Kannur district hospital, where the jawan was treated. 📣 Follow Express explained on Telegram

Dr. Rajeevan said that the parasite may remain in the body’s spleen or liver for a long time, even years, after the mosquito bite, and the person may develop symptoms later.

Africa and other places

P oval malaria is endemic to tropical West Africa. According to NIMR scientists, P ovale is relatively rare outside of Africa and, where it is found, it comprises less than 1% of isolates. It has also been detected in the Philippines, Indonesia and Papua New Guinea, but it is still relatively common in these areas.

In a 2016 study on the China-Myanmar border, P ovale and P malariae were found to occur with very low prevalence, but were often misidentified. In another study, conducted in China’s Jiangsu province, indigenous malaria cases decreased significantly between 2011 and 2014, but imported cases of P ovale and P. malariae had increased and were often misdiagnosed.

Contributions of Vishnu Varma in Kochi and ENS in New Delhi

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