Abstract：
OBJECTIVE: A 15-month longitudinal study was conducted to determine the duration and infectivity of asymptomatic qPCR-detected Plasmodium falciparum and Plasmodium vivax infections in Ethiopia.
METHODS: Total parasite and gametocyte kinetics were determined by molecular methods; infectivity to Anopheles arabiensis mosquitoes by repeated membrane feeding assays. Infectivity results were contrasted with passively recruited symptomatic malaria cases.
RESULTS: For P. falciparum and P. vivax infections detected at enrolment, median durations of infection were 37 days (95% confidence interval [CI], 15-93) and 60 days (95% CI, 18-213), respectively. P. falciparum and P. vivax parasite densities declined over the course of infections. From 47 feeding assays on 22 asymptomatic P. falciparum infections, 6.4% (3/47) were infectious and these infected 1.8% (29/1579) of mosquitoes. No transmission was observed in feeding assays on asymptomatic P. vivax mono-infections (0/56); one mixed-species infection was highly infectious. Among the symptomatic cases, 4.3% (2/47) of P. falciparum and 73.3% (53/86) of P. vivax patients were infectious to mosquitoes.
CONCLUSIONS: The majority of asymptomatic infections were of short duration and low parasite density. Only a minority of asymptomatic individuals were infectious to mosquitoes. This contrasts with earlier findings and is plausibly due to the low parasite densities in this population.
METHODS: Total parasite and gametocyte kinetics were determined by molecular methods; infectivity to Anopheles arabiensis mosquitoes by repeated membrane feeding assays. Infectivity results were contrasted with passively recruited symptomatic malaria cases.
RESULTS: For P. falciparum and P. vivax infections detected at enrolment, median durations of infection were 37 days (95% confidence interval [CI], 15-93) and 60 days (95% CI, 18-213), respectively. P. falciparum and P. vivax parasite densities declined over the course of infections. From 47 feeding assays on 22 asymptomatic P. falciparum infections, 6.4% (3/47) were infectious and these infected 1.8% (29/1579) of mosquitoes. No transmission was observed in feeding assays on asymptomatic P. vivax mono-infections (0/56); one mixed-species infection was highly infectious. Among the symptomatic cases, 4.3% (2/47) of P. falciparum and 73.3% (53/86) of P. vivax patients were infectious to mosquitoes.
CONCLUSIONS: The majority of asymptomatic infections were of short duration and low parasite density. Only a minority of asymptomatic individuals were infectious to mosquitoes. This contrasts with earlier findings and is plausibly due to the low parasite densities in this population.
摘要：
目的：进行了为期15个月的纵向研究，以确定埃塞俄比亚无症状qPCR检测的恶性疟原虫和间日疟原虫感染的持续时间和传染性。
方法：通过分子方法确定总寄生虫和配子细胞动力学；通过重复的膜摄食测定对阿拉伯按蚊的感染性。感染性结果与被动招募的有症状疟疾病例形成对比。
结果：对于在登记时检测到的恶性疟原虫和间日疟原虫感染，中位感染持续时间为37天(95%置信区间[CI]，15-93)和60天(95%CI，18-213)，分别。恶性疟原虫和间日疟原虫的密度在感染过程中下降。通过对22种无症状恶性疟原虫感染的47种喂养试验，6.4％（3/47）具有传染性，这些感染了1.8％（29/1579）的蚊子。在无症状间日疟原虫单感染的喂养试验中未观察到传播（0/56）；一种混合物种感染具有高度传染性。在有症状的病例中，4.3%(2/47)的恶性疟原虫和73.3%(53/86)的间日疟原虫患者感染蚊子。
结论：大多数无症状感染持续时间短，寄生虫密度低。只有少数无症状的个体感染了蚊子。这与早期的发现相反，并且可能是由于该种群的寄生虫密度低。
方法：通过分子方法确定总寄生虫和配子细胞动力学；通过重复的膜摄食测定对阿拉伯按蚊的感染性。感染性结果与被动招募的有症状疟疾病例形成对比。
结果：对于在登记时检测到的恶性疟原虫和间日疟原虫感染，中位感染持续时间为37天(95%置信区间[CI]，15-93)和60天(95%CI，18-213)，分别。恶性疟原虫和间日疟原虫的密度在感染过程中下降。通过对22种无症状恶性疟原虫感染的47种喂养试验，6.4％（3/47）具有传染性，这些感染了1.8％（29/1579）的蚊子。在无症状间日疟原虫单感染的喂养试验中未观察到传播（0/56）；一种混合物种感染具有高度传染性。在有症状的病例中，4.3%(2/47)的恶性疟原虫和73.3%(53/86)的间日疟原虫患者感染蚊子。
结论：大多数无症状感染持续时间短，寄生虫密度低。只有少数无症状的个体感染了蚊子。这与早期的发现相反，并且可能是由于该种群的寄生虫密度低。
