Changes in malaria burden and transmission in sentinel sites after the roll-out of long-lasting insecticidal nets in Papua New Guinea
Changes in malaria burden and transmission in sentinel sites after the roll-out of long-lasting insecticidal nets in Papua New Guinea
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DOI：
10.1186/s13071-016-1635-x
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发表时间：
2016-06-14
影响因子：
3.2
通讯作者：
Mueller, Ivo
中科院分区：
文献类型：
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作者：
Hetzel, Manuel W.;Reimer, Lisa J.;Mueller, Ivo
背景：由于疟疾寄生虫、蚊子媒介、人类宿主及其自然环境的多样性，巴布亚新几内亚表现出复杂的疟疾流行病学。疟疾在不同规模的传播和负担的不均一性可能影响疟疾控制干预措施的成功，反之亦然。本文评估了全国首次发放长效杀虫蚊帐后哨点疟疾流行、发病率和传播的变化。方法：在分发长效杀虫蚊帐前后，有目的地选择6个哨点进行数据收集，包括当地卫生机构的临床监测、家庭调查和昆虫学调查。并不是所有的活动都在所有地点进行。蚊子是通过人类着陆器捕捉到的。结果：疟疾月平均发病率由13/千人下降至2/千人(发病率比=0.12；95%CI：0.09~0.17；P<；0.001)。疟疾的平均人群患病率从LLIN前的15.7%下降到LLIN后的4.8%(调整后的优势比=0.26；95%CI：0.20-0.33；P<；0。001)。总体而言，恶性疟原虫感染的发病率和患病率的下降比间日疟原虫感染更明显。其他发病率指标(贫血、脾肿大、自报发热)在大多数地点显示出下降的趋势。按蚊平均叮人率由干预前的83次/人/晚下降到干预后的31次(P=0.008)。不同地点的按蚊物种组成不同，但在LLIN之后，各地的多样性都较低。两地间日疟原虫感染LLIN后均呈下降趋势，而恶性疟原虫感染呈上升趋势。结论：LLIN在恶性疟原虫和间日疟原虫中的分布有明显影响。间日疟原虫较高的复原力可能归因于催眠虫的复发和其他有利于间日疟原虫传播的生物学特性。对媒介物种组成的影响因地点不同而不同，这可能会影响LLIN的有效性。需要进行深入和长期的流行病学和昆虫学调查，以了解残留传播发生的时间和地点，以及观察到的变化是否持续。
Background: Papua New Guinea exhibits a complex malaria epidemiology due to diversity in malaria parasites, mosquito vectors, human hosts, and their natural environment. Heterogeneities in transmission and burden of malaria at various scales are likely to affect the success of malaria control interventions, and vice-versa. This manuscript assesses changes in malaria prevalence, incidence and transmission in sentinel sites following the first national distribution of long-lasting insecticidal nets (LLINs).Methods: Before and after the distribution of LLINs, data collection in six purposively selected sentinel sites included clinical surveillance in the local health facility, household surveys and entomological surveys. Not all activities were carried out in all sites. Mosquitoes were collected by human landing catches. Diagnosis of malaria infection in humans was done by rapid diagnostic test, light microscopy and PCR for species confirmation.Results: Following the roll-out of LLINs, the average monthly malaria incidence rate dropped from 13/1,000 population to 2/1,000 (incidence rate ratio = 0.12; 95 % CI: 0.09-0.17; P < 0.001). The average population prevalence of malaria decreased from 15.7 % pre-LLIN to 4.8 % post-LLIN (adjusted odds ratio = 0.26; 95 % CI: 0.20-0.33; P < 0. 001). In general, reductions in incidence and prevalence were more pronounced in infections with P. falciparum than with P. vivax. Additional morbidity indicators (anaemia, splenomegaly, self-reported fever) showed a decreasing trend in most sites. Mean Anopheles man biting rates decreased from 83 bites/person/night pre-LLIN to 31 post-LLIN (P = 0.008). Anopheles species composition differed between sites but everywhere diversity was lower post-LLIN. In two sites, post-LLIN P. vivax infections in anophelines had decreased but P. falciparum infections had increased despite the opposite observation in humans.Conclusions: LLIN distribution had distinct effects on P. falciparum and P. vivax. Higher resilience of P. vivax may be attributed to relapses from hypnozoites and other biological characteristics favouring the transmission of P. vivax. The effect on vector species composition varied by location which is likely to impact on the effectiveness of LLINs. In-depth and longer-term epidemiological and entomological investigations are required to understand when and where residual transmission occurs and whether observed changes are sustained.