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London School of Hygiene & Tropical Medicine Malaria Centre


Image of monkey. Picture copyright

Image of monkey. Picture copyright

“MONKEYBAR”: Defining the biomedical, environmental and social risk factors for human infection with Plasmodium knowlesi; opportunities for prevention and control of an emerging zoonotic infection

LSHTM investigators:
Chris Drakeley, Jonathan Cox and Kimberly Fornace
External collaborators:
Benoit Goossens, Senthilvel Nathan, Milena Salgado-Lynn (Danau Girang Field Centre / Sabah Wildlife Department, Malaysia); Timothy William (Infectious Disease Society Kota Kinabalu Sabah, Malaysia); Steve Torr (Liverpool School of Tropical Medicine, UK); Malaysian Ministry of Health; Nick Anstey (Menzies School of Health Research, Australia); Fe Espino, Ferdinand Salazar (Research Institute for Tropical Medicine, Philippines); Royal Veterinary College, UK; Indra Vythilingam (University of Malaya, Malaysia); Chua Tock Hing, Kntayya Mariappan, Paul Porodong (Universiti Malaysia Sabah, Malaysia); Heather Ferguson, Rowland Kao (University of Glasgow, UK); Judeline Dimalibot (University of the Philippines Los Baños); Martha Betson (University of Surrey, UK)
Funding body:
We acknowledge the Medical Research Council, Natural Environment Research Council, Economic and Social Research Council, and Biotechnology and Biological Sciences Research Council for the funding received for this project through the Environmental & Social Ecology of Human Infectious Diseases Initiative (ESEI) (Grant ref. G1100796)

In the last decade, reports have emerged from Malaysia of naturally acquired human infections of Plasmodium knowlesi, a malaria parasite that was previously thought only to infect certain species of monkeys (largely long-tailed and pig-tailed macaques) in Southeast Asia. 

This is a potentially serious public health problem as P. knowlesi exhibits a rapid 24-hour replication cycle in humans (resulting in mortality from severe malaria) and requires prompt diagnosis and optimal treatment, the guidelines for which currently do not exist.

Factors determining the emergence of this zoonotic infection are largely undescribed. It is hypothesised that environmental change is driving P. knowlesi malaria into certain human populations. 

Using an interdisciplinary network of researchers in the UK, the Philippines and Malaysia, this work seeks to characterise the environment (socio-economic and natural) that supports P. knowlesi infection in its hosts and vectors, to determine the risk factors for exposure in humans and to inform and target control measures.

The 5-year project focuses on research sites in Sabah, Malaysia and Palawan Island, The Philippines, and consists of two phases:

  1. Years 1-3 (2012-2015): Clinical monitoring of the number of human cases of P. knowlesi together with a case control study in Sabah; with a concurrent disease dynamics assessment including entomology, primatology and social science components. This work is underpinned by detailed land use surveys and laboratory support for assessing infections in monkeys, humans and mosquitoes.
  2. Years 4-5 (2015-2017): Large scale epidemiological surveys, mathematical model development and analysis.

Current survey work in Sabah, Malaysia

We are now in phase 2 of the project, with a large scale malaria survey currently taking place in Sabah, Malaysia. The survey is being conducted in four districts (Kudat (including Pulau Banggi), Pitas, Kota Marudu and Ranau) and must be completed within a short time frame, during the months of September – December 2015.

The survey involves taking small blood samples from a total of around 10,000 people in 170 kampungs, and administering a short questionnaire. To date, samples have been collected from over 7000 people and the field teams are working hard to collect the remaining 3000 samples needed to complete the study in November.

The survey teams and project investigators are working closely with the district hospitals in Sabah, local health clinics and public health teams. The research has been approved by the Malaysian National Medical Research Ethics Committee, under the Malaysian Ministry of Health, and the London School of Hygiene & Tropical Medicine Ethics Committee.

We would like to inform inhabitants of the selected kampungs and potential survey participants, that participation in the survey is entirely voluntary and you have the right to choose whether or not to take part. We would also like to provide reassurance that the samples and data collected from the survey will only be used for malaria research activities as approved by the relevant LSHTM and Malaysian ethics committees.  Our intention for this research is solely to improve malaria control and public health in the region. We greatly appreciate the cooperation of all the selected kampungs and participants and their huge contribution to making this project a success.

For more information, visit the Monkeybar Research Sabah Facebook page, follow the project on Twitter, or contact the Project Administrator, elisabeth [dot] downe [at] lshtm [dot] ac [dot] uk (subject: Monkeybar%20project%20enquiry) (Beth Downe).