title: Plasmodium knowlesi and human malaria parasites in Khan Phu, Vietnam: Gametocyte production in humans and frequent co-infection of mosquitoes.
abstract: Four species of malaria parasite, Plasmodium falciparum, Plasmodium vivax, Plasmodium malariae and Plasmodium knowlesi infect humans living in the Khanh Phu commune, Khanh Hoa Province, Vietnam. The latter species also infects wild macaque monkeys in this region. In order to understand the transmission dynamics of the three species, we attempted to detect gametocytes of the three species in the blood of infected individuals, and sporozoites in the salivary glands of mosquitoes from the same region. For the detection of gametocyte-specific mRNA, we targeted region 3 of pfg377, pvs25, pmg and pks25 as indicators of the presence of P. falciparum, P. vivax, P. malariae and P. knowlesi gametocytes, respectively. Gametocyte-specific mRNA was present in 37, 61, 0 and 47% of people infected with P. falciparum (n = 95), P. vivax (n = 69), P. malariae (n = 6) or P. knowlesi (n = 32), respectively. We found that 70% of mosquitoes that had P. knowlesi in their salivary glands also carried human malaria parasites, suggesting that mosquitoes are infected with P. knowlesi from human infections.
authors.affiliation: Department of Virology and Parasitology,Fujita Health University School of Medicine,Toyoake,Aichi,Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Maeno
authors.affiliation: Malaria Unit,Department of Pathology,Institute of Tropical Medicine,Nagasaki University,Nagasaki,Nagasaki,Japan.
authors.forename: R
authors.initials: R
authors.lastname: Culleton
authors.affiliation: Khanh Phu Malaria Research Unit,Medical Committee Netherlands-Viet Nam,Nha Trang,Khanh Hoa Province,Viet Nam.
authors.forename: N T
authors.initials: NT
authors.lastname: Quang
authors.affiliation: Laboratory of Tropical Medicine and Parasitology,Dokkyo Medical University,Mibu,Tochigi,Japan.
authors.forename: S
authors.initials: S
authors.lastname: Kawai
authors.affiliation: Khanh Phu Malaria Research Unit,Medical Committee Netherlands-Viet Nam,Nha Trang,Khanh Hoa Province,Viet Nam.
authors.forename: R P
authors.initials: RP
authors.lastname: Marchand
authors.affiliation: Department of Protozoology,Institute of Tropical Medicine,Nagasaki University,Nagasaki,Nagasaki,Japan.
authors.forename: S
authors.initials: S
authors.lastname: Nakazawa
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D002648:Child; D009033:Culicidae / Q000469:parasitology*; D005260:Female; D006801:Humans; D008288:Malaria / Q000453:epidemiology / Q000469:parasitology*; D008297:Male; D016790:Plasmodium knowlesi; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016053:RNA, Protozoan / Q000235:genetics; D014744:Vietnam / Q000453:epidemiology; D055815:Young Adult
chemical_list: D012333:RNA, Messenger; D016053:RNA, Protozoan
keywords: 
                 Plasmodium knowlesi
              ; 
                 pfg377
              ; 
                 pks25
              ; 
                 pvs25
              ; dried blood spot; gametocytes; human; malaria; mosquito