Jambou R, Tombo M L, Raharimalala L, Rakotonjanabelo A, Rabe T, Laventure S, Boisier P
Laboratoire du paludisme, Institut Pasteur de Madagascar, Antananarivo, Madagascar.
Sante. 1998 Jul-Aug;8(4):257-64.
Antananarivo has a population of close to one million inhabitants and is located in the highlands of Madagascar. The capital was, until some years ago, thought to be a malaria transmission-free zone. However, between 1985 and 1990, several malaria cases occurred in the suburbs of Antananarivo, along the Ikopa river (the Betsimitatatra Plain), suggesting that local transmission was occurring. Numerous malaria cases have since been reported by health workers each year, but there is insufficient epidemiological information about the cause and origin of the transmission, because cases are rarely confirmed by parasitological examination. The National Malaria Control Management in Madagascar has, after four years of intensive DDT spraying campaigns in the highlands, stopped this specific method of control. Epidemiological follow-up studies will be carried out to evaluate the effects on malaria transmission of this cessation of control measures. The transmission of malaria in Antananarivo was studied from 1995 to 1996. Patients from nine health centers in various suburbs of Antananarivo were included in the study, with the presence of fever used as the sole inclusion criterion. Children randomly selected from schools in the same area were included in a second study group. A blood sample was obtained from each participant to determine the parasite index and the prevalence of antibodies against P. falciparum. The splenic index was also determined. A second assessment was performed for the school children six months later, using the same markers of malaria infection. Nine hundred and thirty two patients from the health center group were referred for participation in the study. This represented 10% of all patients and 74% of the patients with fever. The school group included 1,545 children. The splenic index was similarly low (0.5%) in the health center and school groups, as was the overall parasite index (2.6% for the health center group and 0.8% in the school group). The prevalence of antibodies against P. falciparum was also low, but with a seasonal variation: 2.5% in June 1995 and 11.6% in January 1996. Almost all the cases confirmed by parasitological examination were due to the patient having stayed in an area with hyperendemic malaria or having been in contact with an individual who had been to an area with a high level of transmission. Our findings confirm that Antananarivo is now in a post-epidemic situation. Malaria cases are mostly associated with a history of travel in areas with high levels of malaria transmission, particularly the coastal regions of Madagascar. Nevertheless, a low level of transmission may persist and lead to further outbreaks of malaria in the future, due to the presence in the area of Anopheles arabiensis.
塔那那利佛拥有近百万人口，位于马达加斯加的高地。直到几年前，这座首都还被认为是无疟疾传播区。然而，在1985年至1990年间，塔那那利佛郊区沿伊科帕河（贝齐米萨拉卡平原）出现了几例疟疾病例，这表明当地存在疟疾传播。此后，卫生工作者每年都报告大量疟疾病例，但由于病例很少通过寄生虫学检查得到确诊，关于传播原因和起源的流行病学信息不足。在马达加斯加高地进行了四年的滴滴涕密集喷洒运动后，该国国家疟疾控制管理部门已停止了这种特定的控制方法。将开展流行病学跟踪研究，以评估停止控制措施对疟疾传播的影响。1995年至1996年对塔那那利佛的疟疾传播情况进行了研究。来自塔那那利佛各郊区九个卫生中心的患者被纳入研究，以发热作为唯一的纳入标准。从同一地区学校中随机挑选的儿童被纳入第二个研究组。从每个参与者身上采集血样，以确定寄生虫指数和抗恶性疟原虫抗体的流行率。还测定了脾脏指数。六个月后，对学童进行了第二次评估，使用相同的疟疾感染指标。卫生中心组有932名患者被转诊参与研究。这占所有患者的10%，发热患者的74%。学校组包括1545名儿童。卫生中心组和学校组的脾脏指数同样较低（0.5%），总体寄生虫指数也是如此（卫生中心组为2.6%，学校组为0.8%）。抗恶性疟原虫抗体的流行率也较低，但有季节性变化：1995年6月为2.5%，1996年1月为11.6%。几乎所有通过寄生虫学检查确诊的病例都是因为患者曾在疟疾高度流行地区停留，或与去过疟疾传播高发地区的人有过接触。我们的研究结果证实，塔那那利佛目前处于疫情后状态。疟疾病例大多与在疟疾传播高发地区的旅行史有关，特别是马达加斯加的沿海地区。然而，由于该地区存在阿拉伯按蚊，可能仍存在低水平的传播，并可能导致未来疟疾的进一步爆发。
