Malaria Incidence Rate Research Articles

An observational analysis of the impact of indoor residual spraying with non-pyrethroid insecticides on the incidence of malaria in S\xe9gou Region, Mali: 2012\u20132015

BackgroundSégou Region in Central Mali is an area of high malaria burden with seasonal transmission, high access to and use of long-lasting insecticidal nets (LLINs), and resistance to pyrethroids and DDT well documented in Anopheles gambiae s.l. (the principal vector of malaria in Mali). Ségou has recently received indoor residual spraying (IRS) supported by Mali’s collaboration with the US President’s Malaria Initiative/Africa Indoor Residual Spraying programme. From 2012 to 2015, two different non-pyrethroid insecticides: bendiocarb in 2012 and 2013 and pirimiphos-methyl in 2014 and 2015, were used for IRS in two districts. This report summarizes the results of observational analyses carried out to assess the impact of these IRS campaigns on malaria incidence rates reported through local and district health systems before and after spraying.MethodsA series of retrospective time series analyses were performed on 1,382,202 rapid diagnostic test-confirmed cases of malaria reported by district routine health systems in Ségou Region from January 2012 to January 2016. Malaria testing, treatment, surveillance and reporting activities remained consistent across districts and years during the study period, as did LLIN access and use estimates as well as An. gambiae s.l. insecticide resistance patterns. Districts were stratified by IRS implementation status and all-age monthly incidence rates were calculated and compared across strata from 2012 to 2014. In 2015 a regional but variable scale-up of seasonal malaria chemoprevention complicated the region-wide analysis; however IRS operations were suspended in Bla District that year so a difference in differences approach was used to compare 2014 to 2015 changes in malaria incidence at the health facility level in children under 5-years-old from Bla relative to changes observed in Barouéli, where IRS operations were consistent.ResultsDuring 2012–2014, rapid reductions in malaria incidence were observed during the 6 months following each IRS campaign, though most of the reduction in cases (70% of the total) was concentrated in the first 2 months after each campaign was completed. Compared to non-IRS districts, in which normal seasonal patterns of malaria incidence were observed, an estimated 286,745 total fewer cases of all-age malaria were observed in IRS districts. The total cost of IRS in Ségou was around 9.68 million USD, or roughly 33.75 USD per case averted. Further analysis suggests that the timing of the 2012–2014 IRS campaigns (spraying in July and August) was well positioned to maximize public health impact. Suspension of IRS in Bla District after the 2014 campaign resulted in a 70% increase in under-5-years-old malaria incidence rates from 2014 to 2015, significantly greater (p = 0.0003) than the change reported from Barouéli District, where incidence rates remained the same.ConclusionsFrom 2012 to 2015, the annual IRS campaigns in Ségou are associated with several hundred thousand fewer cases of malaria. This work supports the growing evidence that shows that IRS with non-pyrethroid insecticides is a wise public health investment in areas with documented pyrethroid resistance, high rates of LLIN coverage, and where house structures and population densities are appropriate. Additionally, this work highlights the utility of quality-assured and validated routine surveillance and well defined observational analyses to rapidly assess the impact of malaria control interventions in operational settings, helping to empower evidence-based decision making and to further grow the evidence base needed to better understand when and where to utilize new vector control tools as they become available.

Impact of the 2013 Floods on the Incidence of Malaria in Almanagil Locality, Gezira State, Sudan.

Background: Heavy rain hit Sudan in August 2013 with subsequent flash floods in different parts of the country. This study investigated the impact of the flooding on incidence of malaria in Almanagil Locality in central Sudan.Methods: This observational retrospective study compared malaria data sets during rainfall seasons in the Almanagil Locality in the year of flooding (2013) with those of corresponding rainfall seasons of previous two non-flood years (2011 and 2012).Results: A marked increase of new malaria cases and incidence rate was observed in the 13 sentinel malaria notification sites in the locality (IR increased from 6.09 per 100,000 person­days in 2011 [95 % CI: 5.93-6.26] and 6.48 in 2012 [95 % CI: 6.31-6.65] to 8.24 in 2013 [95 % CI: 8.05-8.43] ; P< 0.0001), with a peaking of the incidence rate in the under-5-years age group (IR for this age group jumped from 9.80 per 100,000 person­days in 2011 [95 % CI: 9.29­10.32] and 10.00 in 2012 [95 % CI: 9.52­10.49] to 15.02 in 2013 [95 % CI: 14.41­15.64]). A noticeable increase in the slide positivity rate (P< 0.0001) was observed in the 12-week period of 2013 (SPR = 20.86% [95 % CI: 20.40 ­21.32%]) compared with the same periods in 2011 (SPR = 8.72% [95 % CI: 8.36 ­9.08%]) and 2012 (SPR = 12.62% [95 % CI: 12.24 ­13.01%]), with a more marked rise of the SPR in the under-5-year age group. Hospital data showed increase in both the inpatient and outpatient incidence proportions in the study period of 2013 compared to those of the years 2011 and 2012. Hospital OPD incidence proportion in 2013 was 19.7% (95% CI: 19.24­20.18%) compared to 12.85% (95% CI: 12.48­13.23%) in 2011, and 12.16% (95% CI: 11.82­12.51%) in 2012. The < 5 year old groups were responsible for the overall rise in the proportion of malaria cases in 2013 , particularly the < 1 year old group which more than doubled in the 2013 period compared to both 2011 and 2012 periods (Age­specific proportion of the outpatient malaria cases of the < 1 year old group in 2013 was19.5% [95% CI: 18.5­20.6%] compared to 7.7% [95% CI: 6.9­8.6%] in 2011 and 8.1% [95% CI: 7.3­8.9%] in 2012. Incidence proportion of severe malaria cases (inpatients) increased to 22.5 % (95 % CI: 21.5 to 23.6 %) in the study period of 2013 compared to 19.8 % (95 % CI: 18.6 to 21.0 %) in 2011 and 18.4 % (95 % CI: 17.4 to 19.5) in 2012. The increase in the proportion of severe malaria cases was mainly due to a higher proportion of children < 5 years of age and especially to a higher proportion of children < 1 year of age.Conclusion: The study revealed a significant increase in the incidence rate of malaria in Almanagil Locality following the flash flood of August 2013. The flooding had the highest impact on the malaria incidence of the under-5-years age group, and particularly of the under-1-year age group.Keywords: Flood, Flooding, Malaria, Disaster, Sudan, Gezira, Almanagil

Spatial Distribution of Malaria Incidence in Sabah from 2012 to 2016

Objective: Malaria is a significant public health problem in developing countries. Spatial pattern of malaria was developed by geospatial tools from other countries were proven as an effective ways in malaria control programme especially to curb the disease spread. This study aims to observe spatial distribution and patternsexplicitly in Sabah from year 2012 to 2016. From this we can provide explanation on malaria patterns and its spatial variations. Methods: Yearly dataset on malaria cases was used in this study from 2012 to 2016 which was compiled by Sabah Health State Department, Ministry of Health Malaysia. Kriging interpolation method in Geographical Information System (GIS) was applied to analyze the 5-year study period. Moran’s I was used to determinethe spatial autocorrelation between districts in Sabah. Results: The incidence rate of malaria in Sabah shows reducing trend during the 5-year study period. The highest incidence rate involved the central and western of Sabah with more than 200 per 100,000 populations. Moran’s I statistics for all the years indicates that incidence of malaria is clustered (p-value<0.05). Conclusion: Geospatial analysis is a useful tool in order to investigate the relationship between malaria incidences and shows spatial variations. This information helps the health authorities to emphasize the specific area in intervening malaria problem.

Novel use Of Hydroxyurea in an African Region with Malaria (NOHARM): a trial for children with sickle cell anemia

AbstractHydroxyurea treatment is recommended for children with sickle cell anemia (SCA) living in high-resource malaria-free regions, but its safety and efficacy in malaria-endemic sub-Saharan Africa, where the greatest sickle-cell burden exists, remain unknown. In vitro studies suggest hydroxyurea could increase malaria severity, and hydroxyurea-associated neutropenia could worsen infections. NOHARM (Novel use Of Hydroxyurea in an African Region with Malaria) was a randomized, double-blinded, placebo-controlled trial conducted in malaria-endemic Uganda, comparing hydroxyurea to placebo at 20 ± 2.5 mg/kg per day for 12 months. The primary outcome was incidence of clinical malaria. Secondary outcomes included SCA-related adverse events (AEs), clinical and laboratory effects, and hematological toxicities. Children received either hydroxyurea (N = 104) or placebo (N = 103). Malaria incidence did not differ between children on hydroxyurea (0.05 episodes per child per year; 95% confidence interval [0.02, 0.13]) vs placebo (0.07 episodes per child per year [0.03, 0.16]); the hydroxyurea/placebo malaria incidence rate ratio was 0.7 ([0.2, 2.7]; P = .61). Time to infection also did not differ significantly between treatment arms. A composite SCA-related clinical outcome (vaso-occlusive painful crisis, dactylitis, acute chest syndrome, splenic sequestration, or blood transfusion) was less frequent with hydroxyurea (45%) than placebo (69%; P = .001). Children receiving hydroxyurea had significantly increased hemoglobin concentration and fetal hemoglobin, with decreased leukocytes and reticulocytes. Serious AEs, sepsis episodes, and dose-limiting toxicities were similar between treatment arms. Three deaths occurred (2 hydroxyurea, 1 placebo, and none from malaria). Hydroxyurea treatment appears safe for children with SCA living in malaria-endemic sub-Saharan Africa, without increased severe malaria, infections, or AEs. Hydroxyurea provides SCA-related laboratory and clinical efficacy, but optimal dosing and monitoring regimens for Africa remain undefined. This trial was registered at www.clinicaltrials.gov as #NCT01976416.

Novel Use of Hydroxyurea in an African Region with Malaria (NOHARM): A Randomized Controlled Trial

▪Background. Hydroxyurea treatment is recommended for children with sickle cell anemia (SCA) living in high-resource malaria-free regions, but its safety and efficacy in malaria-endemic settings such as sub-Saharan Africa, where the greatest sickle cell burden exists, remain unknown. In vitro studies suggest hydroxyurea could increase malaria severity, through upregulation of intracellular adhesion molecule 1 (ICAM-1) that facilitates parasite adhesion to endothelium. In addition, hydroxyurea-associated neutropenia could worsen infections that occur in low-resource settings.Methods. NOHARM (NCT01976416) was a randomized, double-blinded, placebo-controlled trial conducted in malaria-endemic Uganda. Children between the ages of 1.00-3.99 years were enrolled, and then received 12-months of blinded treatment with either hydroxyurea or placebo at 20 ± 2.5 mg/kg/day, with dose adjustments in both arms for weight gain and hematological toxicities. All participants received standard care for SCA including folic acid, penicillin prophylaxis, and pneumococcal vaccination. For malaria prophylaxis, children received insecticide-treated mosquito nets and monthly sulphadoxine-pyrimethamine. The primary outcome was incidence of clinical malaria. Secondary outcomes included SCA-related adverse events, clinical and laboratory effects, and hematological toxicities. After completing the blinded treatment phase, all participants were offered open-label hydroxyurea, as per local Ethics Committee recommendations.Results. Study participants (median age 2.2 years) received either hydroxyurea (N=104) or placebo (N=103) for 12-months. Malaria occurred at a low rate throughout the study. The malaria incidence did not differ between children on hydroxyurea [0.05 episodes/child/year, 95% CI (0.02, 0.13)] versus placebo [0.07 episodes/child/year (0.03, 0.16)]. The hydroxyurea/placebo malaria incidence rate ratio was 0.7 [(0.2, 2.7), p=0.61], and time to infection did not differ significantly between treatment arms. A composite SCA-related clinical outcome (vaso-occlusive painful crisis, dactylitis, acute chest syndrome, splenic sequestration, or blood transfusion) was less frequent with hydroxyurea (45%) than placebo (69%, p=0.001). For individual clinical events, vaso-occlusive pain and hospitalizations were significantly less frequent with hydroxyurea than placebo; the number needed to treat to prevent one hospitalization was 6.4, while the number needed to treat to prevent a SCA-related event was 2.5. Serious adverse events, sepsis episodes, and dose-limiting toxicities were similar between treatment arms. Specifically, low hemoglobin (<6.0 g/dL) occurred more frequently in children receiving placebo than hydroxyurea, while the frequencies of neutropenia, thrombocytopenia and reticulocytopenia did not differ significantly between treatment arms. Three deaths occurred (two hydroxyurea, one placebo, none from malaria). Children receiving hydroxyurea had significantly increased hemoglobin concentration and fetal hemoglobin, along with decreased leukocytes, neutrophils, and reticulocytes.Conclusions. In this prospective randomized double-blinded placebo-controlled trial of young children with SCA living in Uganda, hydroxyurea therapy was both safe and efficacious. Based on these NOHARM data, hydroxyurea treatment appears safe for children with SCA living in malaria-endemic sub-Saharan Africa, without increased risk for severe malaria, infections, or adverse events. Hydroxyurea provides predicted SCA-related laboratory and clinical efficacy, but the optimal dosing and monitoring regimens for affected children in Africa remain undefined. DisclosuresWare:Agios: Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Research Funding; Addmedica: Research Funding; Nova Laboratories: Consultancy; Global Blood Therapeutics: Consultancy.

Malaria cases in Switzerland from 2005 to 2015 and recent rise of imported Plasmodium vivax malaria.

Reporting cases of malaria to the Federal Office of Public Health has been mandatory in Switzerland since 1974. We analysed notifications of imported confirmed malaria cases between 2005 and 2015 in Switzerland or Liechtenstein. Data for previously visited countries, nationality and reason for travelling were analysed. In contrast with the impressive drop of malaria cases reported worldwide since 2000, we found that the number of malaria cases imported yearly in Switzerland doubled in 2014 and 2015 compared to the average for the preceding decade. Since 2014, Plasmodium vivax infection represented 36% of all diagnosed malaria cases in Switzerland, compared to 11% in the decade leading to 2013. Most of the vivax malaria patients originated from the Horn of Africa, especially from Eritrea. This rise in cases was a consequence not only of an increase in the number of Eritrean refugees, but also their vivax malaria incidence rate, which jumped from 1-3‰ previously to 12‰ in 2014. This is a trend that is not matched by national statistics in Eritrea. An unreported increased incidence in the country of origin (Eritrea) might be the cause of the rise of Pv cases imported into Switzerland, but infections are also likely to occur along the harsh and long migration journey. This epidemiology highlights the need to register and use primaquine for the treatment of latent-phase P. vivax malaria in Switzerland, a medicine currently neither marketed nor systematically reimbursed. Moreover, general practitioners should be aware of this specific epidemiological situation in order to avoid misdiagnosis of febrile Eritreans even months after they reach Switzerland.

Prevalence of polymorphisms in glucose-6-phosphate dehydrogenase, sickle haemoglobin and nitric oxide synthase genes and their relationship with incidence of uncomplicated malaria in Iganga, Uganda

BackgroundHost genetics play an important role in Plasmodium falciparum malaria susceptibility. However, information on host genetic factors and their relationships with malaria in the vaccine trial site of Iganga, Uganda is limited. The main objective of this study was to determine the prevalence of selected host genetic markers and their relationship to malaria incidence in the vaccine trial site of Iganga, Uganda. In a 1-year longitudinal cohort study, 423 children aged below 9 years were recruited and their malaria episodes were investigated. Host genetic polymorphisms were assessed by PCR–RFLP, haemoglobin electrophoresis and DNA sequencing. Using a multivariate negative binomial regression model, estimates of the impact of human genetic polymorphisms on malaria incidence were performed. In all statistical tests, a P value of <0.05 was considered as significant.ResultsThe prevalences of sickle cell haemoglobin trait, G6PD c.202 G>A (rs 1050828) and NOS2 −954 G>C (rs 1800482) variants were 26.6, 22.7 and 17.3%, respectively. Inducible nitric oxide synthase 2 (NOS2 −954 G>C; rs 1800482) heterozygosity was associated with lower incidence of malaria in all age groups {Adjusted incident rates ratio (aIRR) 0.59; 95% CI [0.386–0.887]; P = 0.012)}. About 4% of study subjects had co-existence of sickle cell Hb trait and G6PD deficiency. Sickle cell Hb heterozygotes (Hb AS) aged less than 1 year experienced significantly more malaria episodes annually than children with normal haemoglobin (Hb AA) {aIRR = 1.98; 95% CI [1.240–3.175]; P = 0.004}. There was no significant influence of the sickle cell trait on malaria incidence among older children of 1–9 years.ConclusionsMutation (NOS2 −954 G>C; rs 1800482) of nitric oxide synthase 2 gene promoter was associated with a lower incidence of acute malaria. The normal haemoglobin (wild genotype; HbAA) was associated with reduced malaria incidence rates during the first year of life. More understanding of the interplay between host genetics and malaria susceptibility is required.

Incidence, prevalence and mortality rates of malaria in Ethiopia from 1990 to 2015: analysis of the global burden of diseases 2015

BackgroundIn Ethiopia there is no complete registration system to measure disease burden and risk factors accurately. In this study, the 2015 global burden of diseases, injuries and risk factors (GBD) data were used to analyse the incidence, prevalence and mortality rates of malaria in Ethiopia over the last 25 years.MethodsGBD 2015 used verbal autopsy surveys, reports, and published scientific articles to estimate the burden of malaria in Ethiopia. Age and gender-specific causes of death for malaria were estimated using cause of death ensemble modelling.ResultsThe number of new cases of malaria declined from 2.8 million [95% uncertainty interval (UI) 1.4–4.5 million] in 1990 to 621,345 (95% UI 462,230–797,442) in 2015. Malaria caused an estimated 30,323 deaths (95% UI 11,533.3–61,215.3) in 1990 and 1561 deaths (95% UI 752.8–2660.5) in 2015, a 94.8% reduction over the 25 years. Age-standardized mortality rate of malaria has declined by 96.5% between 1990 and 2015 with an annual rate of change of 13.4%. Age-standardized malaria incidence rate among all ages and gender declined by 88.7% between 1990 and 2015. The number of disability-adjusted life years lost (DALY) due to malaria decreased from 2.2 million (95% UI 0.76–4.7 million) in 1990 to 0.18 million (95% UI 0.12–0.26 million) in 2015, with a total reduction 91.7%. Similarly, age-standardized DALY rate declined by 94.8% during the same period.ConclusionsEthiopia has achieved a 50% reduction target of malaria of the millennium development goals. The country should strengthen its malaria control and treatment strategies to achieve the sustainable development goals.

A study on the epidemiological characteristics and infectious forecast model of malaria at Guangzhou Airport among Chinese returnees from Africa

BackgroundCross-border malaria transmission in China is a major component of Chinese imported malaria cases. Such cases mostly are travellers returning from malaria endemic countries in Africa. By investigating malaria infectious status among Chinese worker in Africa, this study analysed the malaria risk factors, in order to establish infectious forecast model.MethodsChinese returnees data from Africa were collected at Guangzhou Baiyun International Airport, Guangzhou, China between August 2015 and March 2016 and were included in the cross-sectional and retrospective survey.ResultsA total of 1492 respondents were included in the study with the majority consisting of junior middle school educated male. Most of them are manual and technical workers hired by companies, with average of 37.04 years of age. Overall malaria incidence rate of the population was 8.98% (134/1492), and there were no significant differences regarding age, gender, occupation, or team. Forecast model was developed on the basis of malaria risk factors including working country, local ecological environment type, work duration and intensity of mosquito bite prevention.ConclusionsThe survey suggested that malaria incidence was high among Chinese travellers who had worked in Africa countries of heavy malaria burden. Further research on the frequency and severity of clinical episodes among Chinese travellers having worked in Africa is needed.

Using selected global health indicators to assess public health status of population displaced by natural and man-made disasters

The United Nations proclaimed the 1990s as the International Decade for Natural Disaster Reduction (IDNDR). Since then the scientific community has undertaken significant research linked to disaster management, primarily focusing on geophysical hazards, risks, vulnerabilities, and early warning systems. However, limited research is available regarding the health status of a population on the move due to natural and manmade disasters, and how disasters influence key public health indicators. Key health indicators include, but are not limited to, immunization coverage, malaria incidence rate, measles incidence rate, malnutrition, and births attended by trained healthcare professionals. The objective of this research is to assess the health status of a disaster-induced displaced population with respect to specific public health indicators. A retrospective analysis of purposely-selected thirty camps of a displaced population in the Khyber Pakhtunkhwa Province of Pakistan is performed by means of an outpatient registry database. The study's findings reveal that the levels of risks and vulnerabilities of camps vary regarding different kinds of indicators. Therefore, there is high probability that if the same programs and interventions are undertaken for all camps, the desired goals may not be possible to achieve.

Malaria incidence during early childhood in rural Burkina Faso: Analysis of a birth cohort protected with insecticide-treated mosquito nets

BackgroundEven in the high transmission areas of sub-Saharan Africa (SSA), the incidence of falciparum malaria varies greatly depending on factors such as age, rainfall pattern, distance to breeding places, quality of houses, and existing vector control measures. Insecticide-treated mosquito nets (ITN) have now become the vector control standard in nearly all of SSA. This study aims to describe and analyse the incidence of malaria in a cohort of young children protected with ITN in rural West Africa. MethodsData of a subsample from a large community trial in rural north-western Burkina Faso consisting of 420 children were analysed. The main aim of the trial was to evaluate the long-term effects of ITNs in two groups of new-borns; Group A was protected with ITN from birth onwards while Group B was protected only from month six onwards. The primary objective of this study was to describe malaria incidence in detail with an analysis of the impact of potentially relevant determinants of malaria incidence, in particular age, sex, ITN protection, village, month and season as secondary objective. Bivariate negative binomial regression analysis was used to calculate incidence rate ratios of malaria incidence. Moreover, relevant variables were included in a multivariate negative binomial regression model to examine possible risk factors for malaria. ResultsOut of the 420 study children 387 (92.1%) developed a total of 1822 falciparum malaria episodes; the malaria incidence rate was 7.6 per 1000 child days. Group A children had lower malaria incidence rates compared to group B, but only in early infancy. Malaria incidence varied significantly between villages and increased with age, but no sex-specific differences were observed; these findings were confirmed in the multi-variate analysis. Malaria incidence peaked sharply towards the end of the rainy season in September but there were no differences in the seasonal pattern by study group. ConclusionsThe study, carried out in a high-transmission West African area, shows that malaria incidence remains high in spite of maximum ITN coverage.

EFFICACY AND TOLERABILITY OF REPEATED ADMINISTRATION OF ACTS OVER A PERIOD OF TWO YEARS IN CHILDREN AND ADULT PATIENTS WITH ACUTE UNCOMPLICATED MALARIA IN BURKINA FASO

BackgroundAccording to the guidelines of the Burkina Faso National Malaria Control Programme, artesunate-amodiaquine (ASAQ) and artemether-lumefantrine (AL) are the first-line drugs for uncomplicated malaria treatments. However, in some contexts where...

Spatiotemporal epidemic characteristics and risk factor analysis of malaria in Yunnan Province, China

BackgroundMalaria remains an important public health concern in China and is particularly serious in Yunnan, a China’s provincial region of high malaria burden with an incidence of 1.79/105 in 2012. This study aims to examine the epidemiologic profile and spatiotemporal aspects of epidemics of malaria, and to examine risk factors which may influence malaria epidemics in Yunnan Province.MethodsThe data of malaria cases in 2012 in 125 counties of Yunnan Province was used in this research. The epidemical characteristics of cases were revealed, and time and space clusters of malaria were detected by applying scan statistics method. In addition, we applied the geographically weighted regression (GWR) model in identifying underlying risk factors.ResultsThere was a total of 821 cases of malaria, and male patients accounted for 83.9% (689) of the total cases. The incidence in the group aged 20–30 years was the highest, at 3.00/105. The majority (84.1%) of malaria cases occurred in farmers and migrant workers, according to occupation statistics. On a space-time basis, epidemics of malaria of varying severity occurred in the summer and autumn months, and the high risk regions were mainly distributed in the southwest counties. Annual average temperature, annual cumulative rainfall, rice yield per square kilometer and proportion of rural employees mainly showed a positive association with the malaria incidence rate, according to the GWR model.ConclusionsMalaria continues to be one of serious public health issues in Yunnan Province, especially in border counties in southwestern Yunnan. Temperature, precipitation, rice cultivation and proportion of rural employees were positively associated with malaria incidence. Individuals, and disease prevention and control departments, should implement more stringent preventative strategies in locations with hot and humid environmental conditions to control malaria.

Geographical patterns of malaria transmission based on serological markers for falciparum and vivax malaria in Ratanakiri, Cambodia.

BackgroundMalaria transmission is highly heterogeneous, especially in low endemic countries, such as Cambodia. This results in geographical clusters of residual transmission in the dry, low transmission season, which can fuel the transmission to wider areas or populations during the wet season. A better understanding of spatial clustering of malaria can lead to a more efficient, targeted strategy to reduce malaria transmission. This study aims to evaluate the potential of the use of serological markers to define spatial patterns in malaria exposure.MethodsBlood samples collected in a community-based randomized trial performed in 98 high endemic communities in Ratanakiri province, north-eastern Cambodia, were screened with a multiplex serological assay for five serological markers (three Plasmodium falciparum and two Plasmodium vivax). The antibody half-lives range from approximately six months until more than two years. Geographical heterogeneity in malaria transmission was examined using a spatial scan statistic on serology, PCR prevalence and malaria incidence rate data. Furthermore, to identify behavioural patterns or intrinsic factors associated with malaria exposure (antibody levels), risk factor analyses were performed by using multivariable random effect logistic regression models. The serological outcomes were then compared to PCR prevalence and malaria incidence data.ResultsA total of 6502 samples from two surveys were screened in an area where the average parasite prevalence estimated by PCR among the selected villages is 3.4 %. High-risk malaria pockets were observed adjacent to the ‘Tonle San River’ and neighbouring Vietnam for all three sets of data (serology, PCR prevalence and malaria incidence rates). The main risk factors for all P. falciparum antigens and P. vivax MSP1.19 are age, ethnicity and staying overnight at the plot hut.ConclusionIt is possible to identify similar malaria pockets of higher malaria transmission together with the potential risk factors by using serology instead of PCR prevalence or malaria incidence data. In north-eastern Cambodia, the serological markers show that malaria transmission occurs mainly in adults staying overnight in plot huts in the field. Pf.GLURP.R2 showed a shrinking pocket of malaria transmission over time, and Pf.MSP1.19, CSP, PvAMA1 were also informative for current infection to a lesser extent. Therefore, serology could contribute in future research. However, further in-depth research in selecting the best combination of antigens is required.Electronic supplementary materialThe online version of this article (doi:10.1186/s12936-016-1558-1) contains supplementary material, which is available to authorized users.

Spatial change in the risks of Plasmodium vivax and Plasmodium falciparum malaria in China, 2005–2014

Abstract Objective Despite the declining trend of malaria incidence over the last decade, Plasmodium falciparum malaria has increased in China both in terms of the number of case and geographical coverage. Thus, to improve the control intervention, we examined the change in the risk of both Plasmodium vivax and Plasmodium falciparum malaria across China during 2005–2014. Methods We applied logistic regression model to understand change in the risk of Plasmodium vivax and Plasmodium falciparum malaria in each county across the study period, and linear regression model to examine annual change in longitude and latitude of affected areas. Results The risk of Plasmodium falciparum malaria significantly increased with latitude and longitude, indicating that the incidence rate of Plasmodium falciparum malaria increased in the northern and eastern, or decreased in south and western China. Similarly, latitude and longitude of counties with Plasmodium falciparum significantly associated with year, showing annual increase in P. falciparum affected counties within the north and east. For Plasmodium vivax, the risk increased with latitude and longitude, but the longitude significantly decreased, and no significant change in latitude. Conclusion The risk of both Plasmodium falciparum and Plasmodium vivax malaria increased in the northern and eastern China, and was more noticeable for P. falciparum. An underlying cause of the increased malaria risk needs further investigation.

Correlation between malaria epidemic incidence and some natural and social factors in high incidence areas of Shandong Province

To explore the association between malaria epidemic situation and some natural and social factors in high-incidence areas of Shandong Province, so as to provide evidences for malaria elimination in these areas. Twenty towns of 10 counties (cities, districts,) in the high incidence areas of malaria in Shandong Province were selected as the study sites, and the residents in the study sites were investigated by questionnaires with one household as a unit, so as to understand the related natural and social factors. In addition, the malaria epidemic data in the study sites from 2006 to 2010 were collected, and the correlation between these factors and the epidemic situation of malaria was analyzed by Spearman rank correlation and multiple stepwise regression. The square root of malaria incidence rate (Y) was negatively related to the rate of households using insecticide (X3), and the rate of households using screen doors and windows (X4) (both P < 0.05), but was positively related to the rate of housing surrounding water environment and exposure ratio (X6) (both P < 0.05). The regression equation established was Y = 0.032X5 + 0.048X6-0.495, R2 = 0.973. Malaria incidence is obviously associated with some natural and social factors. The measures such as clearing the breeding place of mosquito, protecting the exposure population at nightfall, as well as using door-window screen and repellents correctly, can effectively control malaria.

Impact of interventions on malaria in internally displaced persons along the China-Myanmar border: 2011-2014.

BackgroundInternally displaced persons (IDP) represent vulnerable populations whose public health conditions merit special attention. In the China–Myanmar border area, human movement and resettlements of IDP can influence malaria transmission. Comparison of disease incidence and vector densities between IDP camps and surrounding local villages allows for better understanding of current epidemiology and to evaluate the effectiveness of interventions in the region.MethodsMalaria and vector surveillance was conducted in three IDP camps and three local villages neighbouring the camps along the China–Myanmar border in Myanmar. Clinical malaria cases were collected from seven hospitals/clinics from April 2011 to December 2014. Malaria vector population dynamics were monitored using CDC light traps. The use of malaria preventive measures and information on aid agencies and their activities was obtained through questionnaire surveys.ResultsMalaria was confirmed in 1832 patients. Of these cases, 85.4 % were Plasmodium vivax and 11.4 % were Plasmodium falciparum malaria. Annual malaria incidence rates were 38.8 and 127.0 cases/1000 person year in IDP camps and local villages, respectively. Older children of 5–14 years had the highest incidence rate in the camps regardless of gender, while male adults had significantly higher incidence rates than females in local villages and females child-bearing age had significantly lower risk to malaria in IDP camps compare to local villages. Seasonal malaria outbreaks were observed both in the IDP camps and in the local villages from May to August 2013. The proportion of P. vivax remained unchanged in local villages but increased by approximately tenfold in IDP camps from 2011 to 2014. Anopheles vector density was tenfold higher in local villages compared to IDP camps (2.0:0.2 females/trap/night). Over 99 % of households in both communities owned bed nets. While long-lasting insecticidal nets accounted for 61 % of nets used in IDPs, nearly all residents of local villages owned regular nets without insecticide-impregnation. There were more active aid agencies in the camps than in local villages.ConclusionMalaria in IDP camps was significantly lower than the surrounding villages through effective control management. The observation of P. vivax outbreaks in the study area highlights the need for increased control efforts. Expansion of malaria intervention strategies in IDP camps to local surrounding villages is critical to malaria control in the border area.Electronic supplementary materialThe online version of this article (doi:10.1186/s12936-016-1512-2) contains supplementary material, which is available to authorized users.

The impact of long-lasting microbial larvicides in reducing malaria transmission and clinical malaria incidence: study protocol for a cluster randomized controlled trial.

BackgroundThe massive scale-up of insecticide-treated nets (ITNs) and indoor residual spraying (IRS) has led to a substantial increase in malaria vector insecticide resistance as well as in increased outdoor transmission, both of which hamper the effectiveness and efficiency of ITN and IRS. Long-lasting microbial larvicide can be a cost-effective new supplemental intervention tool for malaria control.Methods/designWe will implement the long-lasting microbial larvicide intervention in 28 clusters in two counties in western Kenya. We will test FourStar controlled release larvicide (6 % by weight Bacillus thuringiensis israelensis and 1 % Bacillus sphaerius) by applying FourStar controlled release granule formulation, 90-day briquettes, and 180-day briquettes in different habitat types. The primary endpoint is clinical malaria incidence rate and the secondary endpoint is malaria vector abundance and transmission intensity. The intervention will be conducted as a two-step approach. First, we will conduct a four-cluster trial (two clusters per county, with one of the two clusters randomly assigned to the intervention arm) to optimize the larvicide application scheme. Second, we will conduct an open-label, cluster-randomized trial to evaluate the effectiveness and cost-effectiveness of the larvicide. Fourteen clusters in each county will be assigned to intervention (treatment) or no intervention (control) by a block randomization on the basis of clinical malaria incidence, vector density, and human population size per site. We will treat each treatment cluster with larvicide for three rounds at 4-month intervals, followed by no treatment for the following 8 months. Next, we will switch the control and treatment sites. The former control sites will receive three rounds of larvicide treatment at appropriate time intervals, and former treatment sites will receive no larvicide. We will monitor indoor and outdoor vector abundance using CO2-baited CDC light traps equipped with collection bottle rotators. Clinical malaria data will be aggregated from government-run malaria treatment centers.DiscussionSince current first-line vector intervention methods do not target outdoor transmission and will select for higher insecticide resistance, new methods beyond bed nets and IRS should be considered. Long-lasting microbial larviciding represents a promising new tool that can target both indoor and outdoor transmission and alleviate the problem of pyrethroid resistance. It also has the potential to diminish costs by reducing larvicide reapplications. If successful, it could revolutionize malaria vector control in Africa, just as long-lasting bed nets have done.Trial registrationU.S. National Institute of Health, study ID NCT02392832. Registered on 3 February 2015.

Malaria Incidence Rates from Time Series of 2-Wave Panel Surveys.

Methodology to estimate malaria incidence rates from a commonly occurring form of interval-censored longitudinal parasitological data—specifically, 2-wave panel data—was first proposed 40 years ago based on the theory of continuous-time homogeneous Markov Chains. Assumptions of the methodology were suitable for settings with high malaria transmission in the absence of control measures, but are violated in areas experiencing fast decline or that have achieved very low transmission. No further developments that can accommodate such violations have been put forth since then. We extend previous work and propose a new methodology to estimate malaria incidence rates from 2-wave panel data, utilizing the class of 2-component mixtures of continuous-time Markov chains, representing two sub-populations with distinct behavior/attitude towards malaria prevention and treatment. Model identification, or even partial identification, requires context-specific a priori constraints on parameters. The method can be applied to scenarios of any transmission intensity. We provide an application utilizing data from Dar es Salaam, an area that experienced steady decline in malaria over almost five years after a larviciding intervention. We conducted sensitivity analysis to account for possible sampling variation in input data and model assumptions/parameters, and we considered differences in estimates due to submicroscopic infections. Results showed that, assuming defensible a priori constraints on model parameters, most of the uncertainty in the estimated incidence rates was due to sampling variation, not to partial identifiability of the mixture model for the case at hand. Differences between microscopy- and PCR-based rates depend on the transmission intensity. Leveraging on a method to estimate incidence rates from 2-wave panel data under any transmission intensity, and from the increasing availability of such data, there is an opportunity to foster further methodological developments, particularly focused on partial identifiability and the diversity of a priori parameter constraints associated with different human-ecosystem interfaces. As a consequence there can be more nuanced planning and evaluation of malaria control programs than heretofore.

Major decline in malaria morbidity and mortality in the Union of Comoros between 2010 and 2014: The effect of a combination of prevention and control measures.

Malaria remains a public health challenge in sub-Saharan Africa. In response to this, many countries are working towardsachieving the World Health Assembly and Roll Back Malaria Partnership target of a 75% decline in malaria incidence. To assess trends in malaria morbidity and mortality in the three islands of the Comoros Archipelago from 2010 to 2014. This was a retrospective study in which all confirmed malaria cases and deaths recorded between 2010 and 2014 were accessedfrom the national malaria control database. Trends and comparisons in malaria incidence and case fatality rates for all age groups, includingunder-5 children and pregnant women, were analysed using Microsoft Excel and SPSS version 16. A substantial decline in malaria incidence was observed for each island between 2010 and 2014; from 75.98 cases per 1 000 populationin 2010 to 0.14 in 2014 in Moheli, 60.60 to 0.02 in Anjouan and 235.36 to 5.47 in Grand Comoro. Additionally, a general reduction in malariacase fatalities was observed. In Moheli, there were no case fatalities between 2010 and 2014, while there was a decline in the case fatality rate inAnjouan (from 1.20 fatalities per 1 000 cases to 0) and Grand Comoros (0.51 to 0). There were also significant differences (p&lt;0.05) in malariaincidence and case fatalities between the three islands. A similar trend was observed for pregnant women and under-5 children. Our study indicates a significant decline in malaria morbidity and mortality in the islands of Moheli, Anjouan and GrandComoro from 2010 to 2014. This considerable reduction is attributed to a combination of malaria prevention and control interventionsimplemented during the study period.