TY - JOUR
T1 - Differential prevalence of plasmodium infections and cryptic plasmodium knowlesi malaria in humans in Thailand
AU - Putaporntip, Chaturong
AU - Hongsrimuang, Thongchai
AU - Seethamchai, Sunee
AU - Kobasa, Teerayot
AU - Limkittikul, Kriengsak
AU - Cui, Liwang
AU - Jongwutiwes, Somchai
N1 - Funding Information:
Financial support: National Research Council of Thailand (grant for fiscal years 2006–2007 to S.J. and C.P.); Thailand Research Fund (grant RMU5080002 to C.P.); Fogarty International Center, National Institutes of Health (grant D43TW006571 to C.P. and L.C.).
PY - 2009/4/15
Y1 - 2009/4/15
N2 - Background. A case of human infection with Plasmodium knowlesi has been recently discovered in Thailand. To investigate the prevalence of this malaria species, a molecular-based survey was performed. Methods. Blood samples from 1874 patients were tested for Plasmodium species by microscopy and nested polymerase chain reaction. P. knowlesi was characterized by sequencing the merozoite surface protein 1 gene (msp-1). Results. Of all Plasmodium species identified, P. falciparum, P. vivax, P. malariae, P. ovale, and P. knowlesi contributed 43.52%, 68.08%, 1.37%, 1.03%, and 0.57%, respectively. Mixed-species infections were more common in northwestern and southwestern regions bordering Myanmar (23%-24%) than in eastern and southern areas (3%- 5%). In northwestern and southwestern regions, mixed-species infections had a significantly higher prevalence in dry than in rainy seasons (P < .001). P. knowlesi was found in 10 patients, mostly from southern and southwestern areas-9 were coinfected with either P. falciparum or P. vivax. Most of the P. knowlesi Thai isolates were more closely related to isolates from macaques than to isolates from Sarawak patients. The msp-1 sequences of isolates from the same area of endemicity differed and possessed novel sequences, indicating genetic polymorphism in P. knowlesi infecting humans. Conclusions. This survey highlights the widespread distribution of P. knowlesi in Thailand, albeit at low prevalence and mostly occurring as cryptic infections.
AB - Background. A case of human infection with Plasmodium knowlesi has been recently discovered in Thailand. To investigate the prevalence of this malaria species, a molecular-based survey was performed. Methods. Blood samples from 1874 patients were tested for Plasmodium species by microscopy and nested polymerase chain reaction. P. knowlesi was characterized by sequencing the merozoite surface protein 1 gene (msp-1). Results. Of all Plasmodium species identified, P. falciparum, P. vivax, P. malariae, P. ovale, and P. knowlesi contributed 43.52%, 68.08%, 1.37%, 1.03%, and 0.57%, respectively. Mixed-species infections were more common in northwestern and southwestern regions bordering Myanmar (23%-24%) than in eastern and southern areas (3%- 5%). In northwestern and southwestern regions, mixed-species infections had a significantly higher prevalence in dry than in rainy seasons (P < .001). P. knowlesi was found in 10 patients, mostly from southern and southwestern areas-9 were coinfected with either P. falciparum or P. vivax. Most of the P. knowlesi Thai isolates were more closely related to isolates from macaques than to isolates from Sarawak patients. The msp-1 sequences of isolates from the same area of endemicity differed and possessed novel sequences, indicating genetic polymorphism in P. knowlesi infecting humans. Conclusions. This survey highlights the widespread distribution of P. knowlesi in Thailand, albeit at low prevalence and mostly occurring as cryptic infections.
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U2 - 10.1086/597414
DO - 10.1086/597414
M3 - Article
C2 - 19284284
AN - SCOPUS:65649123388
SN - 0022-1899
VL - 199
SP - 1143
EP - 1150
JO - Journal of Infectious Diseases
JF - Journal of Infectious Diseases
IS - 8
ER -