Schneider Petra, Bousema J Teun, Gouagna Louis C, Otieno Silas, van de Vegte-Bolmer Marga, Omar Sabah A, Sauerwein Robert W
Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
Am J Trop Med Hyg. 2007 Mar;76(3):470-4.
Submicroscopic Plasmodium falciparum gametocytemia (<5,000 gametocytes/mL) is common and may result in mosquito infection. We assessed the relation between gametocyte density and mosquito infection under experimental and field conditions using real-time quantitative nucleic acid sequence-based amplification (QT-NASBA) for gametocyte quantification. Serial dilutions of NF54 P. falciparum gametocytes showed a positive association between gametocyte density and the proportion of infected mosquitoes (beta=6.1; 95% confidence interval [CI], 2.7-9.6; P=0.001). Successful infection became unlikely below an estimated density of 250-300 gametocytes/mL. In the field, blood samples of 100 naturally infected children showed a positive association between gametocyte density and oocyst counts in mosquitoes (beta=0.38; 95% CI, 0.14-0.61; P=0.002). The relative contribution to malaria transmission was similar for carriers with submicroscopic and microscopic gametocytemia. Our results show that transmission occurs efficiently at submicroscopic gametocyte densities and that carriers harboring submicroscopic gametocytemia constitute a considerable proportion of the human infectious reservoir.
亚显微水平的恶性疟原虫配子体血症（<5000个配子体/毫升）很常见，可能导致蚊子感染。我们使用基于实时定量核酸序列扩增（QT-NASBA）的方法对配子体进行定量，评估了实验条件和野外条件下配子体密度与蚊子感染之间的关系。恶性疟原虫NF54株配子体的系列稀释显示，配子体密度与受感染蚊子的比例之间呈正相关（β=6.1；95%置信区间[CI]，2.7 - 9.6；P=0.001）。估计密度低于250 - 300个配子体/毫升时，成功感染的可能性不大。在野外，对100名自然感染儿童的血样检测显示，配子体密度与蚊子体内卵囊数量之间呈正相关（β=0.38；95%CI，0.14 - 0.61；P=0.002）。亚显微水平和显微水平配子体血症携带者对疟疾传播的相对贡献相似。我们的结果表明，在亚显微水平的配子体密度下也能有效传播，并且携带亚显微水平配子体血症的携带者在人类感染源中占相当大的比例。
