Malaysia: Sabah farmers at higher risk of catching monkey malaria

The Star 11 Jun 17;

KOTA KINABALU: Adult male farmers are more than twice as likely to contract Plasmodium knowlesi (P. knowlesi) – a malaria parasite usually found only in monkeys – than other people in their communities, according to a report.

The study was conducted by the London School of Hygiene & Tropical Medicine, Menzies School of Health Research, Darwin, and the Sabah Health Department.

The research team found that farmers in Sabah who work in plantations, clear vegetation and take part in forestry work are the most at risk.

P. knowlesi is a zoonotic malaria parasite which is common in forest-dwelling macaque monkeys and transmitted between hosts by mosquitoes. It has a rapid growth rate in the blood that can lead to a high level of parasites in a short time and can cause severe and fatal disease.

Recent deforestation in the Sabah region has brought humans into closer contact with the forest.

P. knowlesi is now the most common form of human malaria in many areas of Malaysia, and has also been reported across South-East Asia.

In 2014, the Health Ministry reported that 2,584 out of the country’s 3,923 malaria cases derived from P. knowlesi, and that proportion is known to have risen further.

The researchers conducted a large case control study of more than 1,000 people in the Sabah districts of Kudat and Kota Marudu. Individuals with P. knowlesi were compared with those with other types of human malaria and a control group without malaria.

Detailed questionnaires recorded information on daily activities, residence and the frequency with which participants saw monkeys.

Men are four times more likely to have P. knowlesi infection than women, and although male farmers are more likely to contract monkey malaria, they are not at higher risk of contracting other types of malaria.

Indoor work such as shopkeeping, traditional female household duties, and studying are associated with a lower risk of P. knowlesi malaria in these communities.

The findings suggest that humans working on the fringes of the forest are at risk of contracting P. knowlesi, as well as in the forest itself when they carry out activities such as hunting.

A number of cases in women and children were also found which, along with the characteristics of mosquito and macaque populations, need further investigation.

Monkey malaria alert in Sabah
RUBEN SARIO The Star 11 Jun 17;

KOTA KINABALU: Health authorities in Sabah are intensifying their hunt for the Anopheles mosquitoes that are known for transmitting an emerging disease called Plasmodium knowlesi malaria from monkeys to humans.

Infectious Disease Society of Kota Kinabalu president Dr Timothy William said steps are being taken to reduce breeding sites of the mosquitoes apart from spraying insecticides where these insects are prevalent.

He said health officials were doing all things possible to optimise the treatment of Plasmodium knowlesi malaria or more commonly known as monkey malaria in humans through early detection.

“Those known to be suffering from this disease are given immediate treatment with Artemisinin combination therapy and early referral to tertiary care hospitals for severe cases.

“There is continuing research on this emerging disease,” said Dr William, the principal investigator of an international study on monkey malaria and co-author of the report that was recently published in The Lancet Planetary Health.

He was also the infectious disease consultant at the Queen Elizabeth Hospital here when the study was carried out in various parts of Sabah three years ago.

Chris Drakeley, Professor of Infection & Immunity from the London School of Hygiene & Tropical Medicine, and principal collaborator on the study, said P. knowlesi is a complex and potentially life-threatening parasite.

“Conventional approaches used to tackle malaria such as drugs or bed nets cannot be used to combat P. knowlesi as monkeys are the host and the risk is associated with outdoor work.

“Our study offers important insight into where social interventions are likely to have the biggest impact,” he said.

“We will continue to work with our colleagues in the Malaysian Health Ministry to improve awareness and education for local residents about areas of risk and how they can prevent mosquito bites,” he added.

Dr Matthew Grigg, Menzies Research fellow and lead author of the study, said: “Malaysia’s national malaria eradication plan is proving extremely effective in reducing case numbers of other types of malaria.

“However, we found that cases of P. knowlesi are on the rise due to a number of human behavioural factors such as farming, land clearing activities, working on oil palm plantations, and travelling or sleeping outside.”

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