title: Humans frequently exposed to a range of non-human primate malaria parasite species through the bites of Anopheles dirus mosquitoes in South-central Vietnam.
abstract: BACKGROUND
  Recent studies have described natural human infections of the non-human primate parasites Plasmodium knowlesi and Plasmodium cynomolgi. In Southeast Asia, mosquitoes of the Anopheles leucosphyrus group bite both humans and monkeys in the forest and thus offer a possible route for Plasmodium species to bridge the species barrier. In this study we analysed the species composition of malarial sporozoites infecting the salivary glands of Anopheles dirus in order to determine their potential role as bridge vectors of Plasmodium parasites from monkeys to humans.
  
  
  METHODS
  Mosquitoes were collected in the forest and forest fringe area of Khanh Phu commune by human-baited landing collection. Anopheles species were determined on the basis of morphologic features. Sporozoite-infected salivary glands were applied to filter paper and dried in an ambient atmosphere, before storage in closed vials at 4-6 °C. Detection and identification of Plasmodium species in salivary glands were carried out by nested-PCR of the small subunit ribosomal RNA gene.
  
  
  RESULTS
  Six species of Plasmodium parasites were detected by PCR, of which P. vivax was the most common, followed by P. knowlesi, P. inui, P. cynomolgi, P. coatneyi and P. falciparum. Twenty-six of the 79 sporozoite infected mosquitoes showed multiple infections, most of which were a combination of P. vivax with one or more of the non-human primate Plasmodium species.
  
  
  CONCLUSIONS
  These results suggest that humans overnighting in this forest are frequently inoculated with both human and non-human primate malaria parasites, leading to a situation conducive for the emergence of novel zoonotic malaria.
authors.affiliation: Department of Virology and Parasitology, Fujita Health University School of Medicine, 1-98 Kutsukake, Toyoake, Aichi, 470-1192, Japan. ymaeno@fujita-hu.ac.jp.
authors.forename: Yoshimasa
authors.initials: Y
authors.lastname: Maeno
authors.affiliation: Khanh Phu Malaria Research Unit, Medical Committee Netherlands-Viet Nam, Nha Trang, Khanh Hoa province, Viet Nam. kpmalaria@gmail.com.
authors.forename: Nguyen Tuyen
authors.initials: NT
authors.lastname: Quang
authors.affiliation: Malaria Unit, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Nagasaki, Japan. richard@nagasaki-u.ac.jp.
authors.forename: Richard
authors.initials: R
authors.lastname: Culleton
authors.affiliation: Laboratory of Tropical Medicine and Parasitology, Dokkyo Medical University, Mibu, Tochigi, Japan. skawai@dokkyomed.ac.jp.
authors.forename: Satoru
authors.initials: S
authors.lastname: Kawai
authors.affiliation: The Graduate School of Global Environmental Studies, Kyoto University, Kyoto, Kyoto, Japan. masuda.gaku.2a@kyoto-u.ac.jp.
authors.forename: Gaku
authors.initials: G
authors.lastname: Masuda
authors.affiliation: Department of Protozoology, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Nagasaki, Japan. nakazawa@nagasaki-u.ac.jp.
authors.forename: Shusuke
authors.initials: S
authors.lastname: Nakazawa
authors.affiliation: Khanh Phu Malaria Research Unit, Medical Committee Netherlands-Viet Nam, Nha Trang, Khanh Hoa province, Viet Nam. ronmarch@gmail.com.
authors.forename: Ron P
authors.initials: RP
authors.lastname: Marchand
mesh_terms: D000818:Animals; D000852:Anopheles / Q000469:parasitology*; D001483:Base Sequence; D016054:DNA, Protozoan / Q000737:chemistry / Q000235:genetics; D005260:Female; D006801:Humans; D007303:Insect Vectors / Q000469:parasitology*; D008288:Malaria / Q000453:epidemiology / Q000469:parasitology / Q000635:transmission*; D010961:Plasmodium / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000502:physiology; D016133:Polymerase Chain Reaction; D011323:Primates / Q000469:parasitology; D012335:RNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D012469:Salivary Glands / Q000469:parasitology; D017422:Sequence Analysis, DNA; D014744:Vietnam / Q000453:epidemiology
chemical_list: D016054:DNA, Protozoan; D012335:RNA, Ribosomal; D012337:RNA, Ribosomal, 18S