Incidence Of Malaria Cases Research Articles

Increased uptake of intermittent preventive treatment for malaria in pregnant women in Zambia (2006–2012): Potential determinants and highlight of lessons learnt

ObjectiveTo assess potential determinants of uptake and highlight lessons learnt from the implementation of intermittent preventive treatment (IPTp), given to pregnant women as early as possible during the second trimester in Zambia. MethodsData from four national malaria surveys (2006, 2008, 2010, 2012) were reviewed, and proportions of pregnant women attending antenatal clinics (ANCs) who received two or more doses of sulfadoxine–pyrimethamine (IPTp2) were compared by place of residence, education level, and wealth status. Malaria cases and deaths in pregnant women, from Health Information Management System 2011–2013, were analyzed to determine malaria burden in pregnancy in Zambia. A multiple logistic regression model was applied to identify potential determinants of IPTp uptake. ResultsThe proportion of pregnant women who took IPTp at ANCs increased from near zero at inception in 2001 to 61.9% in 2006; and to 72% by 2012 (P < 0.001), and overall the uptake was 1.41 times higher in 2012 compared to 2006. From 2006 to 2012, IPTp2 uptake among women with no formal education increased from 51% to 68% (P < 0.1). Likewise, uptake among pregnant women with the lowest wealth index increased from 58.2% to 61.2%. By 2012, IPTp uptake among pregnant women within the lowest wealth index increased to a similar level as the women with high wealth index (P = 0.05). Incidence of malaria cases, hospital admissions and mortality during pregnancy decreased between 2011 and 2013. Overall, increased IPTp uptake was associated with being in urban areas (OR = 1.56, 95% CI: 1.39–1.74), having college (OR = 1.83, 95% CI: 1.25–2.75) or secondary education (OR = 1.68, 95% CI: 1.44–1.96) or of being of higher wealth status (OR = 1.86, 95% CI: 1.60–2.17). ConclusionsZambia has increased IPTp uptake through ANC for all women. The malaria control program has contributed to increasing access to health services and reducing demographic and socioeconomic disparities.

Malaria surveillance in low-transmission areas of Zambia using reactive case detection.

BackgroundRepeat national household surveys suggest highly variable malaria transmission and increasing coverage of high-impact malaria interventions throughout Zambia. Many areas of very low malaria transmission, especially across southern and central regions, are driving efforts towards sub-national elimination.Case descriptionReactive case detection (RCD) is conducted in Southern Province and urban areas of Lusaka in connection with confirmed incident malaria cases presenting to a community health worker (CHW) or clinic and suspected of being the result of local transmission. CHWs travel to the household of the incident malaria case and screen individuals living in adjacent houses in urban Lusaka and within 140 m in Southern Province for malaria infection using a rapid diagnostic test, treating those testing positive with artemether–lumefantrine.DiscussionReactive case detection improves access to health care and increases the capacity for the health system to identify malaria infections. The system is useful for targeting malaria interventions, and was instrumental for guiding focal indoor residual spraying in Lusaka during the 2014/2015 spray season. Variations to maximize impact of the current RCD protocol are being considered, including the use of anti-malarials with a longer lasting, post-treatment prophylaxis.ConclusionThe RCD system in Zambia is one example of a malaria elimination surveillance system which has increased access to health care within rural communities while leveraging community members to build malaria surveillance capacity.

Progress toward malaria elimination in Jazan Province, Kingdom of Saudi Arabia: 2000-2014.

BackgroundThe draft Global Technical Strategy for malaria aims to eliminate malaria from at least 10 countries by 2020. Yemen and Saudi Arabia remain the last two countries on the Arabian Peninsula yet to achieve elimination. Over the last 50 years, systematic efforts to control malaria in the Kingdom of Saudi Arabia has successfully reduced malaria cases to a point where malaria is now constrained largely to Jazan Province, the most south-western area along the Red Sea. The progress toward elimination in this province is reviewed between 2000 and 2014.MethodsData were obtained from the Ministry of Health case-reporting systems, activity reports, unpublished consultants reports, and relevant scientific published papers. Sub-provincial population data were obtained the national household censuses undertaken in 2004 and 2010. Rainfall data were obtained from the Meteorological Department in Jazan.ResultsBetween 2000 and 2014 there were 5522 locally acquired cases of malaria and 9936 cases of imported malaria. A significant reduction in locally acquired malaria cases was observed from 2000 to 2014, resulting in an average annual incidence (2010–2014) of 0.3 cases per 10,000 population. Conversely imported cases, since 2000, remain consistent and higher than locally acquired cases, averaging between 250 and 830 cases per year. The incidence of locally acquired cases is heterogeneous across the Province, with only a few health districts contributing the majority of the cases. The overall decline in malaria case incidence can be attributed to coincidental expansion of control efforts and periods of exceptionally low rainfall.ConclusionsJazan province is poised to achieve malaria elimination. There is a need to change from a policy of passive case detection to reactively and proactively detecting infectious reservoirs that require new approaches to surveillance. These should be combined with advanced epidemiological tools to improve the definitions of epidemiological receptive and hotspot malaria risk mapping. The single largest threat currently remains the risks posed by imported infections from Yemen.

Spatial patterns of incident malaria cases and their household contacts in a single clinic catchment area of Chongwe District, Zambia.

BackgroundReactive case detection (RACD) for malaria is a strategy that may be used to complement passive surveillance, as passive surveillance fails to identify infections that are asymptomatic or do not seek care. The spatial and seasonal patterns of incident (index) cases reported at a single clinic in Chongwe District were explored.MethodsA RACD strategy was implemented from June 2012 to June 2013 in a single catchment area in Chongwe District. Incident (index) cases recorded at the clinic were followed up at their household, and all household contacts were tested for malaria using rapid diagnostic tests (RDTs). GPS coordinates were taken at each index household. Spatial analyses were conducted to assess characteristics related to clustering, cluster detection and spatial variation in risk of index houses. Effects of season (rainy versus dry), distance to the clinic and distance to the main road were considered as modifying factors. Lastly, logistic regression was used to identify factors associated with the proportion of household contacts testing RDT positive.ResultsA total of 426 index households were enrolled, with 1,621 household contacts (45% RDT positive). Two space–time clusters were identified in the rainy season, with ten times and six times higher risk than expected. Significantly increased spatial clustering of index households was found in the rainy season as compared to the dry season (based on K-function methodology). However, no seasonal difference in mapped spatial intensity of index households was identified. Logistic regression analysis identified two main factors associated with a higher proportion of RDT positive household contacts. There was a 41% increased odds of RDT positive household contacts in households where the index case was under 5 years of age [OR = 1.41, 95% confidence intervals (1.15, 1.73)]. For every 500-m increase in distance from the road, there was a 5% increased odds of RDT positive household contacts [OR = 1.05 (1.02, 1.07)], controlling for season.DiscussionAreas of increased report of malaria persist after controlling for distance to the clinic and main road. Clinic-based interventions will miss asymptomatic, non-care seeking infections located farther from the road. RACD may identify additional infections missed at the clinic.

A methodological framework for the improved use of routine health system data to evaluate national malaria control programs: evidence from Zambia.

BackgroundDue to challenges in laboratory confirmation, reporting completeness, timeliness, and health access, routine incidence data from health management information systems (HMIS) have rarely been used for the rigorous evaluation of malaria control program scale-up in Africa.MethodsWe used data from the Zambia HMIS for 2009–2011, a period of rapid diagnostic and reporting scale-up, to evaluate the association between insecticide-treated net (ITN) program intensity and district-level monthly confirmed outpatient malaria incidence using a dose–response national platform approach with district-time units as the unit of analysis. A Bayesian geostatistical model was employed to estimate longitudinal district-level ITN coverage from household survey and programmatic data, and a conditional autoregressive model (CAR) was used to impute missing HMIS data. The association between confirmed malaria case incidence and ITN program intensity was modeled while controlling for known confounding factors, including climate variability, reporting, testing, treatment-seeking, and access to health care, and additionally accounting for spatial and temporal autocorrelation.ResultsAn increase in district level ITN coverage of one ITN per household was associated with an estimated 27% reduction in confirmed case incidence overall (incidence rate ratio (IRR): 0 · 73, 95% Bayesian Credible Interval (BCI): 0 · 65–0 · 81), and a 41% reduction in areas of lower malaria burden.ConclusionsWhen improved through comprehensive parasitologically confirmed case reporting, HMIS data can become a valuable tool for evaluating malaria program scale-up. Using this approach we provide further evidence that increased ITN coverage is associated with decreased malaria morbidity and use of health services for malaria illness in Zambia. These methods and results are broadly relevant for malaria program evaluations currently ongoing in sub-Saharan Africa, especially as routine confirmed case data improve.Electronic supplementary materialThe online version of this article (doi:10.1186/s12963-014-0030-0) contains supplementary material, which is available to authorized users.

Environmental determinant of malaria cases among travellers

BackgroundApproximately 125 million travellers visit malaria-endemic countries annually and about 10,000 cases of malaria are reported after returning home. Due to the fact that malaria is insect vector transmitted, the environment is a key determinant of the spread of infection. Geo-climatic factors (such as temperature, moisture, water quality) determine the presence of Anopheles breeding sites, vector densities, adult mosquito survival rate, longevity and vector capacity. Several studies have shown the association between environmental factors and malaria incidence in autochthonous population. The association between the incidence of clinical malaria cases among non-immune travellers and environmental factors is yet to be evaluated. The objective of the present study was to identify, at a country scale (Ivory Coast), the environmental factors that are associated with clinical malaria among non-immune travellers, opening the way for a remote sensing-based counselling for malaria risk prevention among travellers.MethodsThe study sample consisted in 87 cohorts, including 4,531 French soldiers who travelled to Ivory Coast, during approximately four months, between September 2002 and December 2006. Their daily locations were recorded during the entire trip. The association between the incidence of clinical malaria and other factors (including individual, collective and environmental factors evaluated by remote sensing methods) was analysed in a random effect mixed Poisson regression model to take into account the sampling design.ResultsOne hundred and forty clinical malaria cases were recorded during 572,363 person-days of survey, corresponding to an incidence density of 7.4 clinical malaria episodes per 1,000 person-months under survey. The risk of clinical malaria was significantly associated with the cumulative time spent in areas with NDVI > 0.35 (RR = 2,42), a mean temperature higher than 27°C (RR = 2,4), a longer period of dryness during the preceding month (RR = 0,275) and the cumulative time spent in urban areas (RR = 0,52).ConclusionsThe present results suggest that remotely-sensed environmental data could be used as good predictors of the risk of clinical malaria among vulnerable individuals travelling through African endemic areas.

Progress towards malaria control targets in relation to national malaria programme funding

BackgroundMalaria control has been dramatically scaled up the past decade, mainly thanks to increasing international donor financing since 2003. This study assessed progress up to 2010 towards global malaria impact targets, in relation to Global Fund, other donor and domestic malaria programme financing over 2003 to 2009.MethodsAssessments used domestic malaria financing reported by national programmes, and Global Fund/OECD data on donor financing for 90 endemic low- and middle-income countries, WHO estimates of households owning one or more insecticide-treated mosquito net (ITN) for countries in sub-Saharan Africa, and WHO-estimated malaria case incidence and deaths in countries outside sub-Saharan Africa.ResultsGlobal Fund and other donor funding is concentrated in a subset of the highest endemic African countries. Outside Africa, donor funding is concentrated in those countries with highest malaria mortality and case incidence rates over the years 2000 to 2003. ITN coverage in 2010 in Africa, and declines in case and death rates per person at risk over 2004 to 2010 outside Africa, were greatest in countries with highest donor funding per person at risk, and smallest in countries with lowest donor malaria funding per person at risk. Outside Africa, all-source malaria programme funding over 2003 to 2009 per case averted ($56-5,749) or per death averted ($58,000-3,900,000) over 2004 to 2010 tended to be lower (more favourable) in countries with higher donor malaria funding per person at risk.ConclusionsIncreases in malaria programme funding are associated with accelerated progress towards malaria control targets. Associations between programme funding per person at risk and ITN coverage increases and declines in case and death rates suggest opportunities to maximize the impact of donor funding, by strategic re-allocation to countries with highest continued need.

Commencement of the Meningococcal Vaccination for the Republic of Korea Army

Commencement of the Meningococcal Vaccination for the Republic of Korea Army

Utilising malariometric data in Real Time: a strategy to roll back malaria and sustain local elimination

Current scale up strategies for malaria control are based on massive input of resources as well as expertise from major donors from a variety of sources but long term sustainability is insecure. Objectives are not always based on public health principles, and outcomes are measured on an immediate scale of demographic or logistic estimates rather than epidemiological indices. If the objective is to reduce transmission as well as to reduce mortality and disease in endemic communities, new strategies sustained through local infrastructure and expertise must be developed. There is a need to focus on empowering local infrastructure to collect data from rural areas, process them in real time, analyze for outbreak conditions and mobilize the local health system to intervene strategically in place and time. In Zambia, the rural health service is doing this on a pilot scale. In endemic areas where transmission is less than holoendemic (or stable), transmission is seasonal with peaks during the rainy season and troughs when the weather is cold or hot and dry. During the peak malaria season malaria is widespread, but during the low transmission season malaria can be quite restricted and focal with a high proportion of asymptomatic infections. If a major vector control intervention is implemented, then transmission becomes reduced both during the peak but also during the dry season. This has been show clearly in the Macha district of Zambia where data on malaria case incidence rates has been collected weekly since August 2008. Staff at 14 rural health centres (RHC) report weekly by SMS texting to the research institute at Macha the number of cases diagnosed positive by rapid diagnostic test (RDT) during the previous week. During the low transmission season, it becomes clear just where residual foci occur and what appear to be salient risk factors for low season transmission. It is also clear how and when the case positivity rate spreads after the advent of the rains. Using GIS it is clear where the foci persist and where the parasite reservoir would be vulnerable to attack. These foci were identified by following cases diagnosed in RHC during the low transmission period in 2010 to their homestead, and by examining other residents of the homestead by RDT and PCR for asymptomatic cases. There were significantly more malaria infections detected at these homesteads than in homes selected randomly. We propose to target such foci in real time using RHC staff on bicycle during low transmission and treat all contacts with regular anti malaria treatment without additional diagnosis. This will concentrate the attack in place and time. With preparation, this paradigm can be integrated into the health system, would be locally sustained and in time will eliminate foci and the parasite reservoir and reduce dependence on major donations from other countries and donors whose priorities may change.

Dry Season Determinants of Malaria Disease and Net Use in Benin, West Africa

BackgroundTo achieve malaria eradication, control efforts have to be sustained even when the incidence of malaria cases becomes low during the dry season. In this work, malaria incidence and its determinants including bed net use were investigated in children of under 5 years of age in 28 villages in southern Benin during the dry season.Methods and FindingsMean malaria clinical incidence was measured in children aged 0–5 years by active case detection in 28 villages of the Ouidah-Kpomasse-Tori Bossito sanitary district between November 2007 and March 2008. Using Poisson mixed-effect models, malaria incidence was assessed according to the level of transmission by different vector species, and Long-Lasting Insecticide-treated mosquito Nets (LLIN) use and ownership. Then, a Binomial mixed-effect model was developed to assess whether nighttime temperature (derived from MODIS remote sensing data), biting nuisance and LLIN ownership are good predictors of LLIN use >60%. Results suggested that Anopheles funestus (Incidence Rates Ratio (IRR) = 3.38 [IC95 1.91–6]) rather than An. gambiae s.s. is responsible for malaria transmission. A rate of LLIN use >60% was associated with a lower risk of malaria (IRR = 0.6 [IC95 0.37–0.99]). Low nocturnal temperature and high biting nuisance were good predictors of LLIN use >60%.ConclusionsAs recommended by the Malaria Eradication (MalERA) Consultative Group on Modelling, there is a need to understand better the effects of seasonality on malaria morbidity. This study highlights the need to take into account the specificity of malaria epidemiology during the dry-hot season and get a better understanding of the factors that influence malaria incidence and net use. These findings should help National Malaria Control Programmes to implement more effective and sustainable malaria control strategies in Africa.

Study of some epidemological aspects of Malaria in a tribal district (Nandurbar), Maharashtra

Background : Ten percent of the total population of the State of Maharashtra belongs to tribal population groups. These groups remain isolated, living in remote forest and hilly areas far from civilization. Nandurbar district has been a newly carved tribal district (July 1998). Objective : To find out the prevalence of various type of malaria and to see the correlation between rainfall and incidence of malaria cases. Materials and Methods : It was a retrospective, cross sectional study carried out during 1999 to 2004. The reports from the years, 1999 to 2004, were taken from district health office and district malaria office, respectively. Results : There were total 5228 cases of malaria; out of these, 3237 were Plasmodium vivax (PV) cases, and 2001 were Plasmodium falciparum (PF) malarial cases, during the years, 1999 to 2004. In the years, 1999 to 2002, percentage of PV malaria was more than PF malaria. Majority of PV malaria cases was observed in the year 1999. In the year 2004, the PV malaria started showing an upward trend in Nandurbar district, Maximum numbers of cases were reported in rainy season as compared to winter and summer seasons. It was observed that the PF cases were increased during the months of July to October, every year. It was also observed that as rain fall increases, the number of malaria cases also increases. Conclusion : There is an upward trend of malarial cases in the tribal block. Incidence of malarial cases closely correlates with the rainfall.

Indoor residual spraying for preventing malaria.

BACKGROUND: Primary malaria prevention on a large scale depends on two vector control interventions: indoor residual spraying (IRS) and insecticide-treated mosquito nets (ITNs). Historically, IRS has reduced malaria transmission in many settings in the world, but the health effects of IRS have never been properly quantified. This is important, and will help compare IRS with other vector control interventions. OBJECTIVES: To quantify the impact of IRS alone, and to compare the relative impacts of IRS and ITNs, on key malariological parameters. SEARCH STRATEGY: We searched the Cochrane Infectious Diseases Group Specialized Register (September 2009), CENTRAL (The Cochrane Library 2009, Issue 3), MEDLINE (1966 to September 2009), EMBASE (1974 to September 2009), LILACS (1982 to September 2009), mRCT (September 2009), reference lists, and conference abstracts. We also contacted researchers in the field, organizations, and manufacturers of insecticides (June 2007). SELECTION CRITERIA: Cluster randomized controlled trials (RCTs), controlled before-and-after studies (CBA) and interrupted time series (ITS) of IRS compared to no IRS or ITNs. Studies examining the impact of IRS on special groups not representative of the general population, or using insecticides and dosages not recommended by the World Health Organization (WHO) were excluded. DATA COLLECTION AND ANALYSIS: Two authors independently reviewed trials for inclusion. Two authors extracted data, assessed risk of bias and analysed the data. Where possible, we adjusted confidence intervals (CIs) for clustering. Studies were grouped into those comparing IRS with no IRS, and IRS compared with ITNs, and then stratified by malaria endemicity. MAIN RESULTS: IRS versus no IRSStable malaria (entomological inoculation rate (EIR) 1): Two studies; for incidence and prevalence, the malaria rates were higher in the IRS group compared to the ITN group in one study. Malaria incidence was higher in the IRS arm in India (risk ratio IRS:ITN = 1.48) and in South Africa (risk ratio 1.34 but the cluster unadjusted CIs included 1). For malaria prevalence, ITNs appeared to give better protection against any infection compared to IRS in India (risk ratio IRS:ITN = 1.70) and also for both P. falciparum (risk ratio IRS:ITN = 1.78) and P. vivax (risk ratio IRS:ITN = 1.37). AUTHORS' CONCLUSIONS: Historical and programme documentation has clearly established the impact of IRS. However, the number of high-quality trials are too few to quantify the size of effect in different transmission settings. The evidence from randomized comparisons of IRS versus no IRS confirms that IRS reduces malaria incidence in unstable malaria settings, but randomized trial data from stable malaria settings is very limited. Some limited data suggest that ITN give better protection than IRS in unstable areas, but more trials are needed to compare the effects of ITNs with IRS, as well as to quantify their combined effects

Estimating unreported malaria cases in England: a capture–recapture study

A capture-recapture study was undertaken to estimate the incidence and likely total burden of malaria cases in England. Cases diagnosed by the national Malaria Reference Laboratory (MRL) between July 2003 and December 2004 were matched with cases reported to Hospital Episode Statistics using demographic, geographical, parasitological, and temporal information. A total of 3861 cases were recorded in one or both datasets; the 'unknown population' was estimated as 746 cases (95% CI 677-822) giving a total of 4607 cases (95% CI 4446-4767) over 18 months. Eighty-four percent (95% CI 83-85) of cases were recorded in one or both datasets. Fifty-six percent (95% CI 54-58) of cases were captured by the MRL surveillance system; ascertainment for Plasmodium falciparum and London cases was higher at 66% and 62%, respectively. Improving case ascertainment will facilitate effective measures to reduce the burden of this preventable disease in the UK.

Low-high season variation inPlasmodium falciparumerythrocyte binding antigen 175 (eba-175) allelic forms in malaria endemic area of Burkina Faso

To assess the impact of seasonal variation on the distribution of the eba-175 allelic forms in the area where malaria transmission is markedly seasonal. Blood samples were collected from 291 and 239 children under 5 years of age during the low and the high malaria transmission season, respectively, in four villages named Dawelgué, Kounda, Tanghin and Watenga of Saponé Health District, then screened for eba 175 F- and C- alleles by nested PCR analysis. F- alleles were more prevalent than C-alleles in the low [0.66 vs. 0.34 (P < 0.0001)] and high transmission season [0.67 vs. 0.33 (P < 0.0001)]. No significant seasonal variation was observed in the distribution of the two alleles. However, according to Sewall Wright rules, the population pairwise F(ST) values, between Dawelgué and Tanghin during the low transmission season (F(ST_) value = 0.10415, P-value = 0.0090 and during the high season (F(ST_)value = 0.08244, P-value < 0.00001), between Tanghin and Watenga during the low season (F(ST) value = 0.07414, P-value = 0.009) indicated a moderate but statistically significant genetic differentiation. Although there was a moderate but significant genetic differentiation between some study villages at different times of the year, this study result in the seasonal stability of eba-175 allele's distribution in the study area.

Reimbursement of malaria chemoprophylaxis for travellers from Europe to Sub-Saharan Africa: Cost-effectiveness analysis from the perspective of the French national health insurance system

Among Western countries, France has the highest incidence of imported malaria cases, mostly from travellers visiting Sub-Saharan Africa (SSA). Despite related high costs of imported malaria assumed by the public French national health insurance system (FHS), the latter does not reimburse travellers for malaria chemoprophylaxis (MC). This study aims to analyzes, from the FHS perspective, the cost-effectiveness of a 65% reimbursement of MC costs (MC 65%) for French resident travellers, under the assumption that this reimbursement would lead to increased recourse to MC. For that purpose, a decision tree model was developed with variables obtained from the literature, including incidence of malaria among travellers in the absence of MC, probabilities of recourse to MC, MC effectiveness and costs and medical expenses for a case of imported malaria. Data analysis of 1,434,675 travellers to SSA in 2005 estimated, for MC 65% vs. MC 0%, incidence of malaria cases to be 3836 malaria cases (21 deaths)/year vs. 6321 cases (34 deaths)/year, respectively, and cost of Euro 47,071,687/year vs. Euro 17,416,955/year. Incremental cost of MC 65% related to MC 0% was Euro 11,933 per malaria case prevented and Euro 2,281,133 per malaria-related death prevented. Results generated by this model, which can be adapted for other European countries, should be an incentive for the FHS to favourably consider MC 65% for French residents travelling to SSA.

Abundance, biting behaviour and parous rate of anopheline mosquito species in relation to malaria incidence in gold‐mining areas of southern Venezuela

A longitudinal entomological and epidemiological study was conducted in five localities of southern Venezuela between January 1999 and April 2000 to determine the abundance, biting behaviour and parity of anopheline mosquitoes (Diptera: Culicidae) in relation to climate variables and malaria incidence. A total of 3685 female anopheline mosquitoes, representing six species, were collected. The most abundant species were Anopheles marajoara Galvão & Damasceno (60.7%) and Anopheles darlingi Root (35.1%), which together represented 95.8% of the total anophelines collected. Abundance and species distribution varied by locality. Malaria prevalence varied from 12.5 to 21.4 cases per 1000 population. Transmission occurred throughout the year; the annual parasite index (API) for the study period was 813.0 cases per 1000 population, with a range of 71.6-2492 per 1000 population, depending on locality. Plasmodium vivax (Grassi & Feletti) (Coccidia: Plasmodiidae) accounted for 78.6% of cases, Plasmodium falciparum (Welch) for 21.4% and mixed infections (Pv+Pf) for < 0.1%. Anopheles marajoara and An. darlingi were more abundant during the rainy season (April-September). There was no significant correlation (P > 0.05) between mosquito abundance and rainfall. Correlations between malaria incidence by parasite species and mosquito abundance were not significant (P > 0.05). Monthly parous rates were similar for An. marajoara and An. darlingi throughout the year, with two peaks that coincided with the dry-rainy transition period and the period of less rain. Peaks in the incidence of malaria cases were observed 1 month after major peaks in biting rates of parous anophelines. Anopheles darlingi engages in biting activity throughout the night, with two minor peaks at 23.00-00.00 hours and 03.00-04.00 hours. Anopheles marajoara has a different pattern, with a biting peak at 19.00-21.00 hours and 76.6% of biting occurring before midnight. Although both vectors bite indoors and outdoors, they showed a highly significant (P < 0.01) degree of exophagic behaviour. The present study constitutes the first effort to characterize the bionomics of anophelines in malaria endemic foci in different ecological situations in relation to malaria transmission in southern Venezuela and to provide relevant information to be considered when planning and implementing vector control programmes.

Epidemiologic aspects of the malaria transmission cycle in an area of very low incidence in Brazil

BackgroundExtra-Amazonian autochthonous Plasmodium vivax infections have been reported in mountainous regions surrounded by the Atlantic Forest in Espírito Santo state, Brazil.MethodsSixty-five patients and 1,777 residents were surveyed between April 2001 and March 2004. Laboratory methods included thin and thick smears, multiplex-PCR, immunofluorescent assay (IFA) against P. vivax and Plasmodium malariae crude blood-stage antigens and enzyme-linked immunosorbent assay (ELISA) for antibodies against the P. vivax-complex (P. vivax and variants) and P. malariae/Plasmodium brasilianum circumsporozoite-protein (CSP) antigens.ResultsAverage patient age was 35.1 years. Most (78.5%) were males; 64.6% lived in rural areas; 35.4% were farmers; and 12.3% students. There was no relevant history of travel. Ninety-five per cent of the patients were experiencing their first episode of malaria. Laboratory data from 51 patients were consistent with P. vivax infection, which was determined by thin smear. Of these samples, 48 were assayed by multiplex-PCR. Forty-five were positive for P. vivax, confirming the parasitological results, while P. malariae was detected in one sample and two gave negative results. Fifty percent of the 50 patients tested had IgG antibodies against the P. vivax-complex or P. malariae CSP as determined by ELISA. The percentages of residents with IgM and IgG antibodies detected by IFA for P. malariae, P. vivax and Plasmodium falciparum who did not complain of malaria symptoms at the time blood was collected were 30.1% and 56.5%, 6.2% and 37.7%, and 13.5% and 13%, respectively. The same sera that reacted to P. vivax also reacted to P. malariae. The following numbers of samples were positive in multiplex-PCR: 23 for P. vivax; 15 for P. malariae; 9 for P. falciparum and only one for P. falciparum and P. malariae. All thin and thick smears were negative. ELISA against CSP antigens was positive in 25.4%, 6.3%, 10.7% and 15.1% of the samples tested for "classical" P. vivax (VK210), VK247, P. vivax-like and P. malariae, respectively. Anopheline captures in the transmission area revealed only zoophilic and exophilic species.ConclusionThe low incidence of malaria cases, the finding of asymptomatic inhabitants and the geographic separation of patients allied to serological and molecular results raise the possibility of the existence of a simian reservoir in these areas.

Is molecular biology the best alternative for diagnosis of malaria to microscopy? A comparison between microscopy, antigen detection and molecular tests in rural Kenya and urban Tanzania

To assess the agreement of different diagnostic methods for the diagnosis and confirmation of the clinical suspicion of Plasmodium infection in children in Tanzania and Kenya. Blood samples were collected by the finger prick method from 338 children. Blood samples were collected from 338 children with the clinical suspicion of uncomplicated malaria in health clinics in Tanzania and Kenya. The presence of Plasmodium parasites was assessed with microscopy, rapid diagnostic tests (RDTs) and the molecular assays, quantitative nucleic acid sequence based amplification (QT-NASBA) and polymerase chain reaction (PCR). The results were compared and analysed for agreement. There was a high degree of agreement (88.6-100%) between RDTs or molecular tests and microscopy. In rural Kenya, with a high incidence of malaria cases, the correlation coefficient ranged from 0.94 for RDTs to 0.76 for PCR. In urban Tanzania, where there was a low incidence of cases, R for RDTs was 1.0 but only 0.25 for PCR and 0.33 for NASBA. Malaria is overestimated if the diagnosis is based solely on clinical signs. Therefore, laboratory confirmation is essential. Microscopy is a reliable method in rural areas where malaria is prevalent, but RDTs offer a good alternative with the advantage that it is an easy and rapid method. Molecular tests are more sensitive but difficult to implement in rural areas. In areas with lower incidence, molecular tests detect a significantly higher number of Plasmodium infections than RDTs or microscopy. Although implementation of molecular tools can be difficult, the prospect of an easy and cheap detection system makes them promising tools for the near future.

Imported malaria in Kuwait (1985-2000).

The objective of this study was to document the status of malaria infection and effect of preventive measures on the epidemiologic profile of imported malaria cases in Kuwait during 1985-2000. The study included screening of two groups of individuals for malaria infection by microscopy; (1) all migrant workers from malaria-endemic countries on their first entry to Kuwait; and (2) all suspected malaria cases already residing in the country. The study period was divided into pre-war (1985-1990), postwar (1992-1997) and proactive preventive (1998-2000) periods. During the proactive preventive period, the home countries were also involved in screening for malaria infection in all prospective immigrants to Kuwait. The annual incidence of malaria cases detected during the pre-war, postwar and proactive preventive periods ranged between 465 and 1,229, 654 and 1,379, and 248 and 393, respectively. Plasmodium vivax infection was detected in 71% of the cases and P. falciparum in 27%. The number of malaria cases detected increased to >1,300 after the war during 1992-1993. However, the number of malaria cases dropped significantly to less than 400 during 1998-2000 (p80%) of malaria patients were young male adults between 21 and 40 years of age. The data on drug resistance were not well defined, due to limited testing. This study suggests that the proactive preventive program to screen all prospective immigrants for malaria infection in their home countries significantly reduced the numbers of imported infections to <400 cases/year, a drop of 52.6%. In addition, it also identified a group of settled immigrants, the majority of whom were at high risk for acquisition of malaria infection during their visit to home countries. There is an urgent need to target this group for prevention strategies such as education/information and other preventive measures against malaria infection.

Spatial targeting of interventions against malaria.

Malaria transmission is strongly associated with location. This association has two main features. First, the disease is focused around specific mosquito breeding sites and can normally be transmitted only within certain distances from them: in Africa these are typically between a few hundred metres and a kilometre and rarely exceed 2-3 kilometres. Second, there is a marked clustering of persons with malaria parasites and clinical symptoms at particular sites, usually households. In localities of low endemicity the level of malaria risk or case incidence may vary widely between households because the specific characteristics of houses and their locations affect contact between humans and vectors. Where endemicity is high, differences in human/vector contact rates between different households may have less effect on malaria case incidences. This is because superinfection and exposure-acquired immunity blur the proportional relationship between inoculation rates and case incidences. Accurate information on the distribution of malaria on the ground permits interventions to be targeted towards the foci of transmission and the locations and households of high malaria risk within them. Such targeting greatly increases the effectiveness of control measures. On the other hand, the inadvertent exclusion of these locations causes potentially effective control measures to fail. The computerized mapping and management of location data in geographical information systems should greatly assist the targeting of interventions against malaria at the focal and household levels, leading to improved effectiveness and cost-effectiveness of control.