A reassessment of the artificial infection of three predominant mosquito species with Plasmodium vivax in Shandong Province, China.
OBJECTIVE
Under certain ecological circumstances, pathogens are able to rapidly adapt to new vectors. The great capacity of Plasmodium spp. to adapt to new anopheline mosquito vectors on different continents and the continuous ecological changes attributed to humans might promote their adaptation to culicine vectors, which are known to infect humans. Based on our current knowledge, it is difficult to predict whether such adaptations will occur. This study was aimed to determine the infection susceptibility of Anopheles sinensis, Culex tritaeniorhynchus and Cx. pipiens pallens to Plasmodium vivax in Shandong Province of China.


METHODS
The susceptibility of the three predominant species of mosquitoes -An. sinensis, Cx. tritaeniorhynchus and Cx. pipiens pallens in Shandong Province was compared with a direct membrane feeding assay with 15 batches of Shandong strain mono-infected gametocyte-containing blood collected from Plasmodium vivax-infected patients. Infectivity was measured by dissecting the midguts and salivary glands of the mosquitoes. The presence of oocysts and sporozoites was determined by microscopy at 6 and 22 days post-blood feeding.


RESULTS
From the 15 batches of mosquitoes that were fed infected blood, oocysts and sporozoites were detected only in 7th, 13th and 15th batches of infection for An. sinensis, and no oocysts or sporozoites were detected in Cx. tritaeniorhynchus or Cx. pipiens pallens. The positive rate of An. sinensis infection was 21.2, 13 and 36.3% in the three batches of mosquitoes, with an average infection rate of 23.5%.


CONCLUSIONS
The susceptibility of An. sinensis to P. vivax was very high in Shandong Province. Cx. tritaeniorhynchus and Cx. pipiens pallens failed to exhibit susceptibility to P. vivax.
Department of Medical Entomology, Vector Biology Key Laboratory of Medicine and Health Shandong Province, Shandong Institute of Parasitic Diseases, Shandong Academy of Medical Sciences, Jining; Department of Collaborative Innovation Center for the Origin and Control of Emerging Infectious Diseases, Taishan Medical University, Taian, Shandong, China.
Chongxing
C
Zhang
Department of Medical Entomology, Vector Biology Key Laboratory of Medicine and Health Shandong Province, Shandong Institute of Parasitic Diseases, Shandong Academy of Medical Sciences, Jining, Shandong, China.
Guihong
G
Shi
Department of Medical Entomology, Vector Biology Key Laboratory of Medicine and Health Shandong Province, Shandong Institute of Parasitic Diseases, Shandong Academy of Medical Sciences, Jining, Shandong, China.
Peng
P
Cheng
Department of Medical Entomology, Vector Biology Key Laboratory of Medicine and Health Shandong Province, Shandong Institute of Parasitic Diseases, Shandong Academy of Medical Sciences, Jining, Shandong, China.
Haifang
H
Wang
Department of Medical Entomology, Vector Biology Key Laboratory of Medicine and Health Shandong Province, Shandong Institute of Parasitic Diseases, Shandong Academy of Medical Sciences, Jining, Shandong, China.
Hongmei
H
Liu
Department of Medical Entomology, Vector Biology Key Laboratory of Medicine and Health Shandong Province, Shandong Institute of Parasitic Diseases, Shandong Academy of Medical Sciences, Jining, Shandong, China.
Lijuan
L
Liu
Department of Medical Entomology, Vector Biology Key Laboratory of Medicine and Health Shandong Province, Shandong Institute of Parasitic Diseases, Shandong Academy of Medical Sciences, Jining, Shandong, China.
Xiuxia
X
Guo
Department of Medical Entomology, Vector Biology Key Laboratory of Medicine and Health Shandong Province, Shandong Institute of Parasitic Diseases, Shandong Academy of Medical Sciences, Jining, Shandong, China.
Maoqing
M
Gong
Department of Medical Entomology, Vector Biology Key Laboratory of Medicine and Health Shandong Province, Shandong Institute of Parasitic Diseases, Shandong Academy of Medical Sciences, Jining, Shandong, China.
Yong
Y
Huang
D000818:Animals; D000852:Anopheles / Q000469:parasitology* / Q000502:physiology*; D002681:China; D003465:Culex / Q000469:parasitology* / Q000502:physiology*; D041981:Gastrointestinal Tract / Q000469:parasitology; D008853:Microscopy; D033661:Oocysts / Q000254:growth & development; D010966:Plasmodium vivax / Q000254:growth & development*; D012469:Salivary Glands / Q000469:parasitology; D034101:Sporozoites / Q000254:growth & development