Explained: Plasmodium ovale and other types of malaria

The soldier in Kerala is believed to have contracted Plasmodium ovale during his posting in Sudan, from where he returned nearly a year ago, and where Plasmodium ovale is endemic.

Malaria is caused by the bite of the female Anopheles mosquito, if the mosquito itself is infected with a malarial parasite. (Source: Wikimedia Commons)

A not very common type of malaria, Plasmodium ovale, has been identified in a jawan in Kerala. The soldier is believed to have contracted it during his posting in Sudan, from where he returned nearly 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 malarial parasite. There are five kinds of malarial parasites — Plasmodium falciparum, Plasmodium vivax (the commonest ones), Plasmodium malariae, Plasmodium ovale and Plasmodium knowlesi. Therefore, to say that someone has contracted the Plasmodium ovale type of malaria means that the person has been infected by that particular parasite.

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

Plasmodium ovale

Scientists said P ovale rarely causes severe illness and there is no need for panic because of the case detected in Kerala. Dr V S Chauhan, emeritus professor at the International Centre for Genetic Engineering and Biotechnology, New Delhi, said 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 it is for a person infected with P vivax. P ovale is no more dangerous than getting a viral infection, he said.

It is termed ovale as about 20% of the parasitised cells are oval in shape. Distinguishing between P vivax and P ovale may be tricky, Dr Chauhan said, but a good-quality lab should be able to differentiate between the two. 📣 Follow Express Explained on Telegram

Cases in India

According to scientists at the National Institute of Malaria Research (NIMR), the Kerala case could be an isolated one and there are no recorded cases of local transmission so far. Previously, too, isolated cases were reported in Gujarat, Kolkata, Odisha and Delhi. However, no local transmission has been recorded — which means 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 shortly after, he began experiencing fever and other symptoms. After Covid-19 tests returned negative, he was tested for malaria.

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

Dr Rajeevan said it was possible for the parasite to remain in the spleen or liver of the body for a long time, even years, after the mosquito bite, and the person could become symptomatic later.

Africa and elsewhere

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

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In a 2016 study on the China-Myanmar border, it was found that P ovale and P malariae occurred at very low prevalence, but were often misidentified. In another study, carried out in China’s Jiangsu Province, indigenous malaria cases decreased significantly over 2011-14, but imported cases of P ovale and P malariae had increased, and were often misdiagnosed.

— Inputs from Vishnu Varma in Kochi & ENS in New Delhi

Anuradha Mascarenhas

Anuradha Mascarenhas is a Senior Editor at The Indian Express, based in Pune. With a career spanning three decades, she is one of the most respected voices in Indian journalism regarding healthcare, science and environment and research developments. She also takes a keen interest in covering women's issues . Professional Background Education: A gold medalist in Communication and Journalism from Savitribai Phule Pune University and a Master’s degree in Literature. Author: She authored the biography At The Wheel Of Research, which chronicles the life and work of Dr. Soumya Swaminathan, the former Chief Scientist at the WHO. Key Focus: She combines scientific accuracy with storytelling, translating complex medical research into compelling public and human-interest narratives. Awards and Recognition Anuradha has won several awards including the Press Council of India's national award for excellence in journalism under the gender based reporting category in 2019 and the Laadli Media award (gender sensitivity -2024). A recipient of the Lokmat journalism award (gender category-2022), she was also shortlisted for the RedInk awards for excellence in journalism-2021. Her debut book At The Wheel Of Research, an exclusive biography of Dr Soumya Swaminathan the inaugural chief scientist of World Health Organisation was also nominated in the Popular Choice Category of JK Paper AUTHER awards. She has also secured competitive fellowships including the Laadli Media Fellowship (2022), the Survivors Against TB – New Research in TB Media Fellowship (2023) and is part of the prestigious 2025 India Cohort of the WomenLift Health Leadership Journey.” Recent Notable Articles (Late 2025) 1. Cancer & Specialized Medical Care "Tata Memorial finds way to kill drug-resistant cancer cells" (Nov 26, 2025): Reporting on a breakthrough for triple-negative breast cancer, one of the most aggressive forms of the disease. Discipline, diet and purpose; How a 97-year-old professor defies ageing'' (Nov 15, 2025) Report about Prof Gururaj Mutalik, the first Head of Department at Pune's B J Government Medical College who at 97 credits his longevity to healthy habits and a strong sense of purpose. 2. Environmental Health (The "Breathless Pune" Series) Long-term exposure even to 'moderate' air leads to chronic heart, lung, kidney issues" (Nov 26, 2025): Part of an investigative series highlighting that even "safe" pollution levels are damaging to vital organs. "For every 10 µg/m3 increase in PM2.5 level, there was 6-8% jump in medicine sales" (Nov 23, 2025): Using commercial data to prove the direct link between air quality and respiratory illnesses in Pune. 3. Lifestyle & Wellness News "They didn't let cancer, diabetes and heart disease stop them from travelling" (Dec 22, 2025): A collaborative piece featuring survivors who share practical tips for traveling with chronic conditions. At 17, his BP shot up to 200/120 mmHG; Lancet study flags why child and teen hypertension doubled between 2000 and 2020'' (Nov 12,2025)--A report that focusses on 17-year-old-boy's hypertensive crisis and reflects the rising global trend of high blood pressure among children and adolescents. 4. Scientific Recognition & Infrastructure For promoting sci-comm, gender diversity: IUCAA woman prof highlighted in Nature" (Nov 25, 2025): Covering the global recognition of Indian women scientists in gender studies and physics. Pune researchers find a spiral galaxy like the Milky Way from early universe'' (December 3, 2025)- A report on how Indian researchers discovered a massive galaxy that existed when the universe was just 1.5 billion years old , one of the earliest to have been observed so far. Signature Beat: Health, Science & Women in Leadership Anuradha is known for her COVID-19 reportage, where she was one of the first journalists to provide detailed insights into the Covishield and Covaxin trials. She has a dedicated interest in gender diversity in health and science, often profiling women researchers who are breaking the "leaky pipeline" in STEM fields. Her writing style is scrupulous, often featuring interviews with top-tier scientists and health experts from various institutions. ... Read More