Plasmodium Knowlesi Malaria: Assessing the Risk to the British Armed Forces

Abstract

Plasmodium knowlesi is a zoonosis and is now recognised as the fifth commonly occurring form of human malaria. It is endemic in South East Asia, including some areas previously declared malaria free or at low risk for malaria. The epidemiology of the disease is very different to other forms of malaria which are determined by transmission by anthrophilic mosquitoes from human reservoirs. In contrast Plasmodium knowlesi malaria has a monkey reservoir and disease is transmitted to humans by mosquitoes that normally feed on animals. People become accidentally infected when they enter the ranges of the vector mosquitoes and animal hosts. Improved and novel diagnostic methods have indicated that human disease is much more common than previously thought. Although the greatest disease burden falls on local populations living in endemic areas, visitors entering such zones are also at risk. The changing nature of tourism with deep jungle expeditions being more heavily marketed, and short visits to endemic zones now common, mean that new populations are increasingly recognised as being at risk. One such group are military personnel undergoing jungle training or deployed on Operations. The potential for severe disease in areas previously considered at low risk for malaria means that risk assessment needs to be reviewed, coupled with communication strategies to address prevention of a zoonotic form of the disease. The role of chemoprophylaxis in some specific groups may need to be considered.

Assessing the diagnostic performance of a novel RT-PCR fluorescence method for the detection of human plasmodium species

“…knowlesi ). In Africa, Plasmodium falciparum is the most common cause of malaria while, Plasmodium vivax is the most widely distributed species outside Africa [ 3 , 4 ].…”

“…Malaria in humans is exclusively caused by infection with one of the five distinct Plasmodium species (P. falciparum, P. vivax, P. ovale, P. malariae or P. knowlesi). In Africa, Plasmodium falciparum is the most common cause of malaria while, Plasmodium vivax is the most widely distributed species outside Africa [3,4].…”

Prevalence of malaria and associated risk factors among asymptomatic migrant laborers in West Armachiho District, Northwest Ethiopia

“…4 Among Plasmodium species that infect various species of vertebrates, five are known to infect humans, namely, Plasmodium falciparum , Plasmodium vivax , Plasmodium ovale , Plasmodium malariae , and Plasmodium knowlesi . 4 , 5 P. falciparum and P. vivax are the two most dominant malaria parasites in Ethiopia accounting for 60%–70% and 30%–40% of malaria cases, respectively. P. falciparum is the most dangerous species contributing high malarial deaths in Africa, including Ethiopia.…”

Re-evaluation of microscopy confirmed Plasmodium falciparum and Plasmodium vivax malaria by nested PCR detection in southern Ethiopia

“…Plasmodium falciparum is the most virulent species contributing to a larger extent to malarial deaths in Africa, including Ethiopia. Plasmodium vivax and P. ovale form resting stages in the liver as hypnozoites and can cause a clinical relapse [2]. …”