In this sense S. malayensis has retained the ancestral character state being, like S. sinensium, a parasite

primarily of rodents ( Attwood et al., 2008). Consequently, studies of S. malayensis may be useful in understanding the processes of host-switching in the evolution of Schistosoma. SE Asia has been spared devastating vector borne zoonotic Raf inhibition protozoa such as trypanosoma which cause enormous harm to public health in Africa and South America. Indeed, the most important vector-borne zoonotic protozoan in SE Asia, Plasmodium knowlesi, was only discovered as a common human pathogen in 2004. Other vector-borne protozoa, which have not yet been recorded in SE Asia but occur in adjacent regions, include Babesia spp. in Japan, Taiwan, Korea and China ( Shih et al., 1997, Homer et al., 2000 and Marathe et al., 2005) and Trypanosoma evansi in central India

( Joshi et al., 2005). Further research may demonstrate these pathogens in SE Asia. P. knowlesi was identified in 1931, by Professor R. Knowles and Assistant Surgeon B.M. Das Gupta, of the Calcutta School of Tropical Medicine and Hygiene ( Knowles and Das Gupta, 1932). There was confusion as to the species of primate in whose blood selleck products the parasite was found (initially said to be the African species Cercopithecus pygerythrus), but it was eventually determined to be the long-tailed macaque Macaca fascicularis ( Eyles, 1963 and Singh et al., 2004). It is the only primate malaria with a 24-h asexual blood-stage cycle and, unlike P. vivax and P. ovale, P. knowlesi is not known to have a hypnozoite stage. The genome has been sequenced ( Pain et al., 2008). The parasite was used in the 1930s as a fever-inducing agent for the treatment of neurosyphilis ( Knowles and Das Gupta, 1932). It was

recognized that P. knowlesi parasites at different stages in human erythrocytes were difficult to Electron transport chain distinguish from P. falciparum and P. malariae by microscopy. The first natural human infection of P. knowlesi was reported in 1965 in a man who returned to the USA from peninsular Malaysia. A further report in 1971 described human P. knowlesi infection, also contracted in peninsular Malaysia. Mosquito borne monkey-to-human and human-to-human transmission of P. knowlesi can occur under experimental conditions. Singh et al. (2004) demonstrated, for the first time, the public health importance of P. knowlesi during an investigation of what was thought to be human P. malariae infection in Sarawak, eastern Malaysia. On finding that the laboratory and clinical features of these infections were atypical and a nested PCR assay failed to identify P. malariae DNA they demonstrated the parasites to be P. knowlesi. By PCR assay, 120 (58%) of 208 malaria patients tested positive for P. knowlesi, whereas none were positive for P. malariae. Most of the P. knowlesi infections were in rural adults without clustering within communities.