Sunday, September 19

Sabah, Sarawak hotspots for malaria parasite transmission


KOTA KINABALU: Monkeybar, a multi-disciplinary, integrated research programme to investigate the epidemiology of the malaria parasite called Plasmodium knowlesi (P. knowlesi), has adopted an innovative approach by using drones to determine the possible correlation between land use, behaviour of macaques and the incidence of P. knowlesi infection in identified areas.

The planning for the Monkeybar project started in 2011 at Palawan Island, in the Philippines. The proposal for the five-year research programme was granted funding by the United Kingdom government and the project was subsequently launched in April 2012.

Monkeybar has identified two main sites for research, namely the Kudat and Kota Marudu areas in Sabah and the Palawan island.

Director of Malaria Research at the London School of Hygiene and Tropical Medicine, Professor Chris Drakeley, who is the principal investigator of the Monkeybar project, said the research examined environmental changes to wildlife and public health, as well as potential forestry implications.

It combines basic entomology and parasitology with clinical, primatology, social science and spatial epidemiological components.

Professor Drakeley said the conventional understanding of P. knowlesi transmission was men who worked in forests who were bitten by mosquitoes that fed on infected macaques.

However, he said observations done in Sabah found that P. knowlesi not only infected men who went to forests, but also housewives, driving instructors and young children, people who were not normally associated with going to forests.

In the areas where P. knowlesi transmission was present, Drakely said there has been notable changes in local environment as well as the increase in population.

“We have population increase all over Malaysia, Sabah is no exception.

“We see big changes in land use for plantation work, and we need to investigate whether this is associated with the increase in P. knowlesi,” he said at the Monkeybar project stakeholder meeting at Queen Elizabeth Hospital (QEH) here yesterday.

The reason drone was used in the research was to capture frequent environmental changes that happened over a short time and to be more in control of the location to capture the images that otherwise cannot be done with satellite imagery.

“The drone weighs 700 grams and can fly at an altitude of 400 metres for around 45 minutes.”

The researchers pre-programmed the area where the drone will fly to create a detailed image of areas they work in. In addition, the researchers fitted macaques with Global Positioning System (GPS) collars to study their behaviours and movements in order to determine where they are likely to be in contact with mosquitoes that bite them, and subsequently transmit malaria to humans.

Monkeybar researchers have also asked people to wear GPS tracker for approximately two weeks at different times of the year. The participants will have to make a note whenever they see a macaque, which will allow the researchers to study human-macaque interaction.

The image captured are then processed with computers to develop land cover maps that define ecotones and human-mosquitoes-macaque interaction sites.

In an updated risk map of P. knowlesi shown by Drakeley, Sabah and Sarawak are found to be hotspots for the malaria parasite transmission.

Historically, forest cover tip of Borneo was 86.5 per cent in 2000 but the figure declined to 80.2 per cent in 2008 and 75.4 per cent in 2012.

Since the Monkeybar research started 2.5 years ago, 330 malaria cases have been reported with 171 cases in Kudat and 159 in Kota Marudu, of which 214 are P.knowlesi mono infections.

The malaria patients aged between two and 73 but are primarily male between 25 and 50 years old. Ten per cent of the infected patients are less than 15 years old.

“Several household clusters of infection shows that forest is not the only transmission.”

Drakeley said the most striking observation was the increase in the number of malaria cases in Banggi Island as deforestation increased.

Based on the computer mapping that overlays macaques’ behaviour and land use in Kampung Paradason, one of the intensive sites in Kudat, it was found that macaques moved further away following significant land clearing.

While that alone cannot describe the significant increase of malaria cases, Drakeley said land clearing did cause movement in macaques.

Another ongoing work conducted by Monkeybar is carrying out surveys on the population in the areas the researchers work in to determine the level of malaria infection.

“In recent years, more people are infected with low level malaria infection than we thought.”

Moving onto the next phase, Drakeley said the research programme would examine if there was infection in other parts of Sabah.

Partners in the Monkeybar research programme include Danau Girang Field Centre, Liverpool School of Tropical Medicine, London School of Hygiene and Tropical Medicine, Malaysian Ministry of Health, Queen Elizabeth Hospital (QEH), Menzies School of Health Research, Research Institute for Tropical Medicine, Royal Veterinary College, Sabah Wildlife Department, Universiti Malaysia Sabah (UMS), University of Glasgow, University of Malaya, University of the Philippines Los Banos and Universiti Putra Malaysia.

Meanwhile, Dr Timothy William, Malaysian principal investigator of the Monkeybar project, said P. knowlesi infections have increased in the past 10 years.

“In 2013, 60 per cent of malaria cases are P. knowlesi.”

Dr Timothy said malaria almost never caused death and was benign, but P. knowlesi, on the other hand, had a mortality rate of up to three per cent.

Also present at the meeting were QEH director Dr Herric Corray and Ministry of Health Clinical Research Centre director Dr Goh Pik Pin.