Salako L A, Ajayi F O, Sowunmi A, Walker O
Clinical Pharmacology Unit, University College Hospital, Ibadan, Nigeria.
Ann Trop Med Parasitol. 1990 Oct;84(5):435-45. doi: 10.1080/00034983.1990.11812493.
The frequency of asymptomatic malaria parasitaemia was investigated in rural and urban school-children aged six to 12 years in southwestern Nigeria between January 1987 and October 1988. Asymptomatic parasitaemia was detected in the rural school-children all year round with the lowest parasite rate in January and the highest in July, corresponding to the mid-dry and wet seasons respectively. Asymptomatic parasitaemia was also common amongst urban school-children, but the frequency was lower than in the rural children. Parasite density was less than or equal to 1000 microliters-1 in 42% of parasite-positive asymptomatic children and was greater than 10,000 microliters-1 in only 20% of them. Mass treatment with chloroquine, to which the parasites were fully sensitive, was followed by the same rate of re-infection in the parasite-positive and parasite-negative groups. Of 7713 patients clinically diagnosed as having malaria 4425 were found to have parasitologically-proven malaria, and of these 4239 had pure Plasmodium falciparum malaria. Of the patients with falciparum malaria only 4.6% were below the age of one year. In 47% the parasite count was less than or equal to 1000 microliters-1, and it was over 10,000 microliters-1 in 37% and over 250,000 microliters-1 in 16%. There was no significant difference between the asymptomatic children and the acutely ill patients in the percentage with parasite densities less than or equal to 1000 microliters-1, but the percentage with parasite densities greater than 10,000 microliters-1 was significantly greater in the acute malaria patients than in those with asymptomatic parasitaemia.
1987年1月至1988年10月期间，对尼日利亚西南部6至12岁的城乡学童无症状疟疾寄生虫血症的发生率进行了调查。农村学童全年均检测到无症状寄生虫血症，1月份寄生虫率最低，7月份最高，分别对应旱季中期和雨季。城市学童中无症状寄生虫血症也很常见，但发生率低于农村儿童。42%的寄生虫阳性无症状儿童的寄生虫密度小于或等于1000微升-1，只有20%的儿童寄生虫密度大于10000微升-1。对寄生虫完全敏感的氯喹进行大规模治疗后，寄生虫阳性组和寄生虫阴性组的再感染率相同。在7713例临床诊断为疟疾的患者中，4425例经寄生虫学证实患有疟疾，其中4239例为单纯恶性疟原虫疟疾。在患恶性疟原虫疟疾的患者中，只有4.6%年龄在1岁以下。47%的患者寄生虫计数小于或等于1000微升-1，37%的患者超过10000微升-1，16%的患者超过250000微升-1。无症状儿童和急性病患者中寄生虫密度小于或等于1000微升-1的百分比没有显著差异，但急性疟疾患者中寄生虫密度大于10000微升-1的百分比显著高于无症状寄生虫血症患者。
