Department of Pathobiological Sciences, University of Wisconsin, Madison, Wisconsin, United States of America.
PLoS Negl Trop Dis. 2013 Sep 12;7(9):e2433. doi: 10.1371/journal.pntd.0002433. eCollection 2013.
The relationship between mosquito vectors and lymphatic filariasis (LF) parasites can result in a range of transmission outcomes. Anophelines are generally characterized as poor vectors due to an inability to support development at low densities. However, it is important to understand the potential for transmission in natural vectors to maximize the success of elimination efforts. Primary vectors in Papua New Guinea (n = 1209) were dissected following exposure to microfilaremic blood (range 8-233 mf/20 µl). We examined density dependent and species-specific parasite prevalence, intensity and yield, barriers to parasite development as well as impacts on mosquito survival. We observed strikingly different parasite prevalence and yield among closely related species. Prevalence of infective stage larvae (L3s) ranged from 4.2% to 23.7% in An. punctulatus, 24.5% to 68.6% in An. farauti s.s. and 61.9% to 100% in An. hinesorum at low and high density exposures, respectively. Injection experiments revealed the greatest barrier to parasite development involved passage from the midgut into the hemocoel. The ratio of L3 to ingested mf at low densities was higher in An. hinesorum (yield = 1.0) and An. farauti s.s. (yield = 0.5) than has been reported in other anopheline vectors. There was a negative relationship between mosquito survival and bloodmeal mf density. In An. farauti s.s., increased parasite yield and survival at low densities suggest greater competence at low microfilaremias. In Papua New Guinea the likelihood of transmission will be strongly influenced by vector composition and changes in the mf reservoir as a result of elimination efforts. Global elimination efforts will be strengthened by the knowledge of transmission potential in the context of current control measures.
蚊虫媒介与淋巴丝虫病（LF）寄生虫之间的关系会导致一系列不同的传播结果。按蚊通常被认为是传播能力差的媒介，因为它们无法在低密度下支持寄生虫的发育。然而，了解自然媒介中的潜在传播能力对于最大限度地提高消除工作的成功率至关重要。在巴布亚新几内亚（n = 1209），对暴露于微丝蚴血症血液（范围 8-233 mf/20 µl）后的主要媒介进行了解剖。我们检查了密度依赖性和种特异性寄生虫的流行率、强度和产量、寄生虫发育的障碍以及对蚊子生存的影响。我们观察到密切相关的物种之间存在显著不同的寄生虫流行率和产量。在低密度和高密度暴露下，感染期幼虫（L3）的流行率在斑蚊（An. punctulatus）中为 4.2%至 23.7%，在远东山蚊（An. farauti s.s.）中为 24.5%至 68.6%，在赫氏按蚊（An. hinesorum）中为 61.9%至 100%。注射实验表明，寄生虫发育的最大障碍是从中肠进入血腔。在低密度下，L3 与摄入的微丝蚴的比值在赫氏按蚊（产量 = 1.0）和远东山蚊（产量 = 0.5）中比其他按蚊媒介中报道的更高。蚊子的存活率与血餐微丝蚴密度之间呈负相关。在远东山蚊中，低密度下寄生虫产量和存活率的增加表明在低微丝蚴血症时的传播能力更强。在巴布亚新几内亚，由于消除工作，媒介组成和微丝蚴库的变化将强烈影响传播的可能性。在当前控制措施的背景下，了解传播潜力将增强全球消除工作的力度。
