Zhu Guoding, Xia Hui, Zhou Huayun, Li Julin, Lu Feng, Liu Yaobao, Cao Jun, Gao Qi, Sattabongkot Jetsumon
Parasit Vectors. 2013 Jun 14;6:176. doi: 10.1186/1756-3305-6-176.
Anopheles sinensis, Anopheles anthropophagus, Anopheles minimus and Anopheles dirus are the major vectors of malaria transmission in China. Anopheles sinensis is considered a secondary vector due to its relatively low malaria-transmission ability. However, in 2005, an outbreak of over 40,000 Plasmodium vivax malaria cases was reported in areas where Anopheles sinensis was the only major vector. Therefore, it is necessary to reassess the malaria transmission ability of this vector species in China.
Laboratory colonies of An. sinensis and An. anthropophagus, and first-generation progeny (F1) of An. sinensis that had been collected in central China, were infected by direct membrane feeding assay with mono-vivax gametocyte-containing blood collected from vivax-infected patients. The mosquitoes were kept for 7 to 14 days post-blood feeding to allow parasites to develop into oocysts and sporozoites. Infectivity was measured by dissecting midguts and salivary glands. The presence of oocysts and sporozoites was determined by microscopy at 7 and 14 days post-blood feeding, and the numbers of gametocytes and asexual parasites, as well as mosquito parasite infections, were determined.
The positive oocyst and sporozoite feed rates of the 142 pairs of lab-colony An. sinensis and An. anthropophagus were not significantly different, and the same results were found with the 10 pairs of laboratory and F1 An. sinensis. An. sinensis had more oocysts/midgut at 7 days post-feeding than An. anthropophagus, but the gametocytemia, asexual parasitemia, and ratio of macrogametocytes to microgametocytes, did not correlate with either oocyst or sporozoite infection. However, in the oocyst-positive mosquitoes, there was a correlation between gametocytemia and the average oocyst number/midgut.
The susceptibility of An. sinensis (both laboratory and F1) to P. vivax-infected blood is similar to Anopheles anthropophagus, when evaluated by membrane feeding assay under laboratory conditions. In recent years, in central China, the vivax malaria transmission ability of An. sinensis has probably been underestimated. Further studies of this species in other regions are needed. An. sinensis could also be a good candidate vector for evaluating candidate malaria transmission-blocking vaccines (TBV).
中华按蚊、嗜人按蚊、微小按蚊和大劣按蚊是中国疟疾传播的主要媒介。中华按蚊因其相对较低的疟疾传播能力被视为次要媒介。然而，2005年，在中国一些地区报告了超过4万例间日疟原虫疟疾病例的暴发，而这些地区中华按蚊是唯一的主要媒介。因此，有必要重新评估该媒介在中国的疟疾传播能力。
将中华按蚊和嗜人按蚊的实验室种群，以及在中国中部采集的中华按蚊第一代子代（F1），通过直接膜饲法用从间日疟感染患者采集的含间日疟配子体的血液进行感染。在吸血后将蚊子饲养7至14天，以使寄生虫发育成卵囊和子孢子。通过解剖中肠和唾液腺来测量感染性。在吸血后7天和14天通过显微镜检查确定卵囊和子孢子的存在，并确定配子体和无性寄生虫的数量以及蚊子的寄生虫感染情况。
142对实验室种群的中华按蚊和嗜人按蚊的卵囊阳性和子孢子感染率无显著差异，10对实验室中华按蚊和F1中华按蚊也得到相同结果。吸血后7天，中华按蚊中肠的卵囊数比嗜人按蚊多，但配子体血症、无性疟原虫血症以及大配子体与小配子体的比例与卵囊或子孢子感染均无相关性。然而，在卵囊阳性的蚊子中，配子体血症与中肠平均卵囊数之间存在相关性。
在实验室条件下通过膜饲法评估时，中华按蚊（实验室种群和F1）对间日疟感染血液的易感性与嗜人按蚊相似。近年来，在中国中部，中华按蚊的间日疟传播能力可能被低估了。需要在其他地区对该物种进行进一步研究。中华按蚊也可能是评估候选疟疾传播阻断疫苗（TBV）的良好候选媒介。
