Is malaria control a priority? Evidence from Nepal

The research reported here assessed the value of malaria control through a cost-effectiveness study of the vertically-organized malaria control programme in Nepal. It presents a methodological framework for analysing cost-effectiveness which includes resource-saving consequences as well as health consequences. The methods used to collect data on control costs, cases and deaths prevented, treatment costs averted and production gains are described and the assumptions required by the analysis are made explicit. A variety of cost-effectiveness ratios are calculated, sensitivity analysis applied and the policy implications of the results considered. The results from Nepal are compared to estimates for parasitic disease and other health programmes in other countries: it is concluded that the Nepalese programme appears no less cost-effective than many other health interventions. It can also be justified by reference to the population groups benefiting from malaria control.     

Spatiotemporal patterns of malaria incidence in northern Thailand

We present a detailed analysis of long-term time series of malaria incidence in northern Thailand. Positive cases for Plasmodium falciparum and P. vivax have been recorded monthly from 1977-2002 at 13 provinces in the region. Time series statistical methods are used to examine the long-term trends and seasonal dynamics of malaria incidence at regional and provincial scales. Both malarial types are declining throughout the region, except in the two provinces that share a large border with Myanmar. The rate of decline in P. vivax has decreased across the region since the end of the 1980s, and this may be a signal of developing resistance or changing vector potential. Both species display a two-peak annual seasonality that may be attributed to patterns of vector occurrence, farming practice and migration of individuals across international borders. In a number of provinces, the importance of the first seasonal peak has grown in recent years, possibly owing to increases in vector densities. The medium-term fluctuations of both species exhibit a clear spatial organisation. There is some evidence of a subtle close to 4-year super annual cycle in P. falciparum, which we suggest is driven by extrinsic factors relating to the climate of the region.     

海南省疟疾发病情况及利用气象因子进行发病率拟合的研究

目的 探索海南省气候因素与疟疾流行之间的关系并建立能够表达疟疾发病率变化的气象因子拟合模型，以用于预测海南省疟疾发病率。方法 收集1995～2000年海南省月度气象资料(温度、湿度和降雨量)和月度疟疾发病率资料，应用Spearman等级相关分析气象因子与疟疾发病率之间的相关关系，用逐步回归建立气象因子拟合发病率变化的拟合模型。结果 气温和降雨量与疟疾发病率有相关性。应用逐步回归分析得到的拟合模型为：全省，I=-1.041 0．061t0.2，r^2=0．590(I：全省月发病率，t02：当前月及其前两个月期间的平均气温)；中南部高发地区，I=-5．701 0．382t02-0．147t02min，r^2=0．626，(t02/min：当前月及其前两个月期间的平均最低气温)。而如果引入I2(2个月前发病率)时，可以得到拟合效果更好的回归模型：全省，I=-1．701 0．064t4.2 0．47I2 0．025d2，r^2=0．72(d2:2个月前最高气温和最低气温之差)；中南部高发地区，I=-4．754 0．179t0.2 0．447I2 0．063d2，r^2=0．73。结论 气候因素能够影响疟疾的流行，可以利用气象因子拟合疟疾流行趋势并应用拟合模型对人群未来疟疾发病率进行预测。     

The economic consequences of malaria for households: a case-study in Nepal

Increased attention has recently been paid to the impact of illness on the well-being of households in developing countries. This has been a particular theme in the case of malaria, but relatively little evidence is available on how households react to malaria and on its impact on expenditure and time allocation patterns. This paper reports the results of a study designed to investigate the economic consequences of malaria for households in Nepal. A household survey of malaria cases in two districts provided information on use of various sources of treatment, their cost to households, time lost by the person with malaria, the extent to which others inside or outside the household provided assistance with the normal work of the malaria patient, the time spent caring for a child with malaria and any financial losses associated with the malaria episode. Out-of-pocket expenditure on treatment differed greatly between the two districts, for reasons associated with the choice of public or private sources of treatment and the number of visits made per episode. The majority of households appeared to cope without great difficulty with the reduction in labour supply caused by a malaria episode, by drawing largely on the time of adult family members. Caution is advised in extrapolating the results to other situations, given the extent to which local factors are likely to influence the impact on households. Moreover, the findings relate to a situation where a malaria control programme is in place: a relatively greater impact per household would occur in the absence of control. However, it is argued that such surveys have value in informing health policy, particularly in relation to setting priorities and treatment policy.     

Circumsporozoite antibodies and falciparum malaria incidence in children living in a malaria endemic area

In a case—control study we examined the association of Plasmodium falciparum circumsporozoite antibodies (anti-R32tet32) with subsequent P. falciparum infections. A study population of 140 children living in an endemic area was followed longitudinally for 25 weeks with weekly blood smears for malaria parasites and, once every two weeks, serum samples for circumsporozoite antibody determinations. From the malaria cases, antibody measurements occurring between two and six weeks prior to the onset of parasitaemia were utilized. For each case, two controls were selected. The results from 17 cases and 34 controls failed to show a statistically significant difference in antibody levels prior to the infection (P=0.07, one-tailed Student''s t-test). However, 8 of the 17 cases had antibody present, indicating a level that was not protective against patent infection.     

State transition detection in the spatio-temporal incidence of malaria

Mosquito-borne disease spread might exhibit irregular epidemic fronts caused by ecological heterogeneity in the risk factors. To determine Plasmodium vivax infection spread in north-eastern Venezuela, we used the State Transition Index (STI) to detect the spatial locations of malaria incidence boundaries and their dynamics over time. Then, we evaluated the role of population size on disease persistence. Boundary locations of malaria were found to be highly spatially variable. Waves of infection were observed in the spatial mosaics of large and small nearby localities due to a strong asynchrony in the epidemic dynamics between both host populations. Our results suggest that the epidemic spatial diffusion follows a hierarchy from large, populated villages (with few or no seasonal parasite fadeouts) to smaller, less populated localities, where infection outbreak was irregular or disease dynamics showed frequent fadeouts. Our findings stress the importance of malaria surveillance and control in these larger communities.     

Willingness to pay and determinants of choice for improved malaria treatment in rural Nepal

A logit model is used to estimate provider choice from six types by malaria patients in rural Nepal. Patient characteristics that influence choice include travel costs, income category, household size, gender, and severity of malaria. Income effects are introduced by assuming the marginal utility of money is a step function of expenditures on the numeraire. This method of incorporating income effects is ideally suited for situations when exact income data is not available. Significant provider characteristics include wait time for treatment and wait time for laboratory results. Household willingness to pay (wtp) is estimated for increasing the number of providers and for providing more sites with blood testing capabilities. Wtp estimates vary significantly across households and allow one to assess how much different households would benefit or lose under different government proposals.     

The economic evaluation of malaria control technologies: the case of Nepal.

This paper illustrates the methodological issues arising from the use of economic evaluation in a developing country context, and how economic evaluation can be applied in developing countries to draw conclusions of relevance to policy-makers. The paper reports research on the cost-effectiveness of the malaria control programme in Nepal. It outlines the heirarchy of choices presented by malaria control and concentrates on the evaluation of the mix of routine strategies employed by the programme, particularly for vector control and case detection and treatment. A social perspective is taken, and emphasis placed on identifying costs falling on households, namely private expenditure on treatment and loss of days of work. Conclusions are drawn relating to the application of economic evaluation methodology to disease control programmes in developing countries.     

When to seek health care: a duration analysis for malaria patients in Nepal

We find that the log-normal distribution of care-seeking time - the number of days from the onset of symptoms of malaria to when a patient seeks treatment from a provider - best described the treatment-seeking behavior of malaria patients in rural areas of two districts of Nepal. The care-seeking rate, or the probability of seeking care, was low on the first day of the symptoms; it increased sharply over the first five days and then gradually declined. Since at the time of the research there was a system of malaria workers taking monthly surveillance rounds of each house to detect and treat malaria cases, patients, instead of traveling to a provider for care, generally waited for malaria workers to arrive at home when the wait for malaria workers was short. But, the probability of seeking care on any day rose if the wait was longer. Women generally tended to wait longer for the malaria workers in order to receive treatment at home. Patient's age, household size, education, and the type of malaria species infecting the patient had no significant effect on care-seeking rate. Given an assumption that a wait of 100 days for a malaria worker would effectively represent total absence of surveillance program, the estimated model predicted higher care-seeking rates under no surveillance program than under the monthly surveillance program.     

安徽省疟疾发病地理信息系统研究

目的建立疟疾发病地理信息系统模型，对疟疾发病情况进行空间分析。方法收集1950～2005年疟疾发病资料，使用EpiInfo3．3．2软件建立数据库并拟合地理信息系统模型。结果1970～1999年，疟疾发病率最高达到12156．42／10万，最低仅为1．32／10万，总体呈逐年下降趋势，平均下降速度为27．01％；2000～2005年，疫情出现回升，6年间疟疾发病率平均上升速度61．91％。结论安徽省疟疾历史上严重流行区在长江以北，重点在沿淮淮北地区；现阶段疟疾高发地区仍然徘徊在淮河流域及其以北地区，但发病范围可能有所扩大。     

Increasing incidence of malaria in the Negro River basin, Brazilian Amazon

Malaria in Brazil is virtually restricted to the Amazon Region, where it has a heterogeneous geographic distribution. We reviewed secondary data in order to describe the regional and temporal distribution of 8018 malaria cases seen between 2003 and 2007 in Santa Isabel do Rio Negro, a municipality in the northwest Brazilian Amazon. A significant rise in malaria incidence, mainly in the Yanomami Indian reservation, was observed during this time. Anopheline breeding sites were also mapped and entomological data were obtained through the capture of larval and adult mosquitoes. Thirty-three potential breeding sites were identified in the urban and periurban areas, 28 of which were positive for anopheline larvae. Anopheles darlingi specimens were captured in both intra- and peridomicile locations in the urban areas. Demographic data were also assessed via a sectional survey, revealing that the majority of dwellings were vulnerable to mosquitoes. This study suggests that urban and periurban areas of this municipality are highly susceptible to epidemic malaria, which is endemic in the Yanomami Indian reservation near the city. In addition, transmission can be perpetuated autochthonously in the urban area, drawing attention to the continuous need for preventative measures such as controlling adult and aquatic stages of mosquitoes and improving housing.     

上海市浦东新区2008-2010年疟疾发病情况分析

疟疾是一种严重危害人类健康的世界范围性疾病,传播快,易反复。我国政府决定在2010年全面开展消除疟疾工作,上海市也拟定在2015年达到消除疟疾目标。为了解浦东新区疟疾发病情况,从而为制订后期防控策略提供参考,我们对2008-2010年浦东新区疟疾发病情况进行了分析,现报告如下。     

Underreporting of malaria incidence in The Netherlands: results from a capture-recapture study

The aim of this study was to estimate the completeness of notification of malaria by physicians and laboratories in the Netherlands in 1996. We used a capture-recapture (CRC) analysis of three incomplete, partially overlapping registers of malaria cases: a laboratory survey, the Notification Office and the hospital admission registration. The response of the laboratories was 83.2%. In 1996 the laboratories microscopically identified 535 cases of malaria, 330 patients with malaria were admitted to hospital and physicians notified 311 malaria cases. 667 malaria cases were recorded in at least one register. CRC analysis estimated the total number of malaria cases at 774 (95 % CI of 740-821). This implies a completeness of notification of 40.2% for physicians and 69.1% for the laboratories. It can be concluded that laboratory-based notification can considerably increase the number of officially reported malaria cases as compared to notification by physicians. However, possibly one-third of the cases may still go unreported.