Evaluation of the durability of long-lasting insecticidal nets in Guatemala.

BACKGROUND: Insecticide-treated bed nets (ITNs) are widely used for the prevention and control of malaria. In Guatemala, since 2006, ITNs have been distributed free of charge in the highest risk malaria-endemic areas and constitute one of the primary vector control measures in the country. Despite relying on ITNs for almost 15 years, there is a lack of data to inform the timely replacement of ITNs whose effectiveness becomes diminished by routine use. METHODS: The survivorship, physical integrity, insecticide content and bio-efficacy of ITNs were assessed through cross-sectional surveys conducted at 18, 24 and 32 months after a 2012 distribution of PermaNet® 2.0 in a malaria focus in Guatemala. A working definition of 'LLIN providing adequate protection' was developed based on the combination of the previous parameters and usage of the net. A total of 988 ITNs were analysed (290 at 18 months, 349 at 24 months and 349 at 32 months). RESULTS: The functional survivorship of bed nets decreased over time, from 92% at 18 months, to 81% at 24 months and 69% at 32 months. Independent of the time of the survey, less than 80% of the bed nets that were still present in the household were reported to have been used the night before. The proportion of bed nets categorized as "in good condition" per World Health Organization (WHO) guidelines of the total hole surface area, diminished from 77% to 18 months to 58% at 32 months. The portion of ITNs with deltamethrin concentration less than 10 mg/m2 increased over time. Among the bed nets for which bioassays were conducted, the percentage that met WHO criteria for efficacy dropped from 90% to 18 months to 52% at 32 months. The proportion of long-lasting insecticidal nets (LLINs) providing adequate protection was 38% at 24 months and 21% at 32 months. CONCLUSIONS: At 32 months, only one in five of the LLINs distributed in the campaign provided adequate protection in terms of survivorship, physical integrity, bio-efficacy and usage. Efforts to encourage the community to retain, use, and properly care for the LLINs may improve their impact. Durability assessments should be included in future campaigns.

Attrition, physical integrity and insecticidal activity of long-lasting insecticidal nets in sub-Saharan Africa and modelling of their impact on vectorial capacity.

BACKGROUND: Long-lasting insecticidal nets (LLINs) are the primary malaria prevention and control intervention in many parts of sub-Saharan Africa. While LLINs are expected to last at least 3 years under normal use conditions, they can lose effectiveness because they fall out of use, are discarded, repurposed, physically damaged, or lose insecticidal activity. The contributions of these different interrelated factors to durability of nets and their protection against malaria have been unclear. METHODS: Starting in 2009, LLIN durability studies were conducted in seven countries in Africa over 5 years. WHO-recommended measures of attrition, LLIN use, insecticidal activity, and physical integrity were recorded for eight different net brands. These data were combined with analyses of experimental hut data on feeding inhibition and killing effects of LLINs on both susceptible and pyrethroid resistant malaria vectors to estimate the protection against malaria transmission-in terms of vectorial capacity (VC)-provided by each net cohort over time. Impact on VC was then compared in hypothetical scenarios where one durability outcome measure was set at the best possible level while keeping the others at the observed levels. RESULTS: There was more variability in decay of protection over time by country than by net brand for three measures of durability (ratios of variance components 4.6, 4.4, and 1.8 times for LLIN survival, use, and integrity, respectively). In some countries, LLIN attrition was slow, but use declined rapidly. Non-use of LLINs generally had more effect on LLIN impact on VC than did attrition, hole formation, or insecticide loss. CONCLUSIONS: There is much more variation in LLIN durability among countries than among net brands. Low levels of use may have a larger impact on effectiveness than does variation in attrition or LLIN degradation. The estimated entomological effects of chemical decay are relatively small, with physical decay probably more important as a driver of attrition and non-use than as a direct cause of loss of effect. Efforts to maximize LLIN impact in operational settings should focus on increasing LLIN usage, including through improvements in LLIN physical integrity. Further research is needed to understand household decisions related to LLIN use, including the influence of net durability and the presence of other nets in the household.

Assessing bed net damage: comparisons of three measurement methods for estimating the size, shape, and distribution of holes on bed nets.

BACKGROUND: Measuring the physical condition of long-lasting insecticidal nets (LLINs) under field conditions is of great importance for malaria control programmes to guide decisions on how frequently to replace LLINs. Current guidelines by the World Health Organization Pesticide Evaluation Scheme (WHOPES) propose a proportionate hole index (pHI) for assessing LLIN condition by counting the number of holes the size of a thumb, fist, head, and larger than a head. However, this method does not account for irregular hole shapes or exact hole sizes which could result in inaccurate decisions about when to replace LLINs. METHODS: LLINs were collected during a 2013 health facility-based malaria case control study in Machinga District, Malawi. To evaluate the accuracy of the pHI, the physical condition of 277 LLINs was estimated by the WHOPES method and then compared with two more thorough measurement methods: image analysis of digital photographs of each LLIN side; and for 10 nets, ruler measurements of the length, width, and location of each hole. Total hole counts and areas per net were estimated by each method, and detailed results of hole shapes and composite pictures of hole locations were generated using image analysis. RESULTS: The WHOPES method and image analysis resulted in similar estimates of total hole counts, each with a median of 10 (inter-quartile range (IQR) 4-24 and 4-23, respectively; p = 0.004); however, estimated hole areas were significantly larger using the WHOPES method (median 162 cm2, IQR 28-793) than image analysis (median 13 cm2, IQR 3-101; p < 0.0001). The WHOPES method classified fewer LLINs in 'good condition' compared to image analysis (42% vs 74%). The ruler method detected significantly more holes than image analysis did (p = 0.002) in 10 LLINs; however, total hole area was not significantly different (p = 0.16). Most holes were not circular but roughly 2-5 times longer in one direction. The lower quarter of LLIN sides was found to have the most holes. CONCLUSIONS: The WHOPES method overestimated total hole area, likely because holes are elongated rather than circular, suggesting further adjustments to the pHI formula may be warranted when considering LLIN replacement strategies.

Health worker adherence to malaria treatment guidelines at outpatient health facilities in southern Malawi following implementation of universal access to diagnostic testing.

BACKGROUND: Appropriate diagnosis and treatment are essential for reducing malaria mortality. A cross-sectional outpatient health facility (HF) survey was conducted in southern Malawi from January to March 2015 to determine appropriate malaria testing and treatment practices four years after implementation of a policy requiring diagnostic confirmation before treatment. METHODS: Enrolled patients were interviewed, examined and had their health booklet reviewed. Health workers (HWs) were asked about training, supervision and access to the 2013 national malaria treatment guidelines. HFs were assessed for malaria diagnostic and treatment capacity. Weighted descriptive analyses and logistic regression of patient, HW and HF characteristics related to testing and treatment were performed. RESULTS: An evaluation of 105 HFs, and interviews of 150 HWs and 2342 patients was completed. Of 1427 suspect uncomplicated malaria patients seen at HFs with testing available, 1072 (75.7%) were tested, and 547 (53.2%) tested positive. Testing was more likely if patients spontaneously reported fever (odds ratio (OR) 2.6; 95% confidence interval (CI) 1.7-4.0), headache (OR 1.5; 95% CI 1.1-2.1) or vomiting (OR 2.0; 95% CI 1.0-4.0) to HWs and less likely if they reported skin problems (OR 0.4; 95% CI 0.2-0.6). Altogether, 511 (92.7%) confirmed cases and 98 (60.3%) of 178 presumed uncomplicated malaria patients (at HFs without testing) were appropriately treated, while 500 (96.6%) of 525 patients with negative tests did not receive anti-malarials. Only eight (5.7%) suspect severe malaria patients received appropriate pre-referral treatment. Appropriate treatment was more likely for presumed uncomplicated malaria patients (at HFs without testing) with elevated temperature (OR 1.5/1 °C increase; 95% CI 1.1-1.9), who reported fever to HWs (OR 5.7; 95% CI 1.9-17.6), were seen by HWs with additional supervision visits in the previous 6 months (OR 1.2/additional visit; 95% CI 1.0-1.4), or were seen by older HWs (OR 1.1/year of age; 95% CI 1.0-1.1). CONCLUSIONS: Correct testing and treatment practices were reasonably good for uncomplicated malaria when testing was available. Pre-referral treatment for suspect severe malaria was unacceptably rare. Encouraging HWs to elicit and appropriately respond to patient symptoms may improve practices.

A longitudinal study of the durability of long-lasting insecticidal nets in Zambia.

BACKGROUND: A key goal of malaria control is to achieve universal access to, and use of, long-lasting insecticidal nets (LLINs) among people at risk for malaria. Quantifying the number of LLINs needed to achieve and maintain universal coverage requires knowing when nets need replacement. Longitudinal studies have observed physical deterioration in LLINs well before the assumed net lifespan of 3 years. The objective of this study was to describe attrition, physical integrity and insecticide persistence of LLINs over time to assist with better quantification of nets needing replacement. METHODS: 999 LLINs distributed in 2011 in two highly endemic provinces in Zambia were randomly selected, and were enrolled at 12 months old. LLINs were followed every 6 months up to 30 months of age. Holes were counted and measured (finger, fist, and head method) and a proportional hole index (pHI) was calculated. Households were surveyed about net care and repair and if applicable, reasons for attrition. Functional survival was defined as nets with a pHI <643 and present for follow-up. At 12 and 24 months of age, 74 LLINs were randomly selected for examination of insecticidal activity and content using bioassay and chemical analysis methods previously described by the World Health Organization (WHO). RESULTS: A total of 999 LLINs were enrolled; 505 deltamethrin-treated polyester nets and 494 permethrin-treated polyethylene nets. With 74 used to examine insecticide activity, 925 were available for full follow-up. At 30 months, 325 (33 %) LLINs remained. Net attrition was primarily due to disposal (29 %). Presence of repairs and use over a reed mat were significantly associated with larger pHIs. By 30 months, only 56 % of remaining nets met criteria for functional survival. A shorter functional survival was associated with having been washed. At 24 months, nets had reduced insecticidal activity (57 % met WHO minimal criteria) and content (5 % met WHO target insecticide content). CONCLUSIONS: The median functional survival time for LLINs observed the study was 2.5-3 years and insecticide activity and content were markedly decreased by 2 years. A better measure of net survival incorporating insecticidal field effectiveness, net physical integrity, and attrition is needed.

Survey of obstetrician-gynecologists in the United States about toxoplasmosis: 2012 update.

PURPOSE: Toxoplasmosis, caused by the parasite Toxoplasma gondii, can have serious impacts on fetal development in the setting of acute maternal primary infection. The American College of Obstetricians and Gynecologists (ACOG) sought to determine current knowledge, practices, opinions, and educational preferences regarding T. gondii infection in pregnancy among ACOG members practicing prenatal care. METHODS: ACOG sent a survey to 1,056 members chosen by stratified random sampling from membership lists, including 370 participants and 686 non-participants in the Collaborative Ambulatory Research Network (CARN). Mailings were sent up to four times to nonresponders. RESULTS: Survey minimum response rates were 40.3% (CARN) and 19.7% (non-CARN); response rates adjusted for imputed non-eligibility were 59.7% (CARN) and 22.6% (non-CARN). Among providers, 80.2% had diagnosed no acute maternal T. gondii infections in the past 5 years, 12.7% correctly identified the screening role of the Toxoplasma avidity test, 42.6% performed serologic T. gondii screening for at least some asymptomatic pregnant women, and 62.1% of those who so did used appropriate approaches. Providers in the northeastern United States were 2.02 times more likely to routinely screen than those in the west (p = 0.025) and female providers were 1.48 times more likely than male providers (p = 0.047). The potential educational interventions considered useful by the most practitioners were updated ACOG guidelines on screening (81.4%) and management (71.7%) for acute T. gondii infection in pregnancy. CONCLUSIONS: ACOG members would benefit from educational efforts targeted at risk factor counseling and screening approaches.

Effect of the Expanded Program on Immunization Contact Method of data collection on health behaviors in Mali.

BACKGROUND: The Expanded Program on Immunization Contact Method (EPI-CM) is a proposed monitoring and program management tool for developing countries. The method involves health workers tallying responses to questions about health behaviors during routine immunizations and providing targeted counseling. We evaluated whether asking caretakers about health behaviors during EPI visits led to changes in those behaviors. METHODS: We worked in 2 districts in Mali: an intervention district where during immunization visits workers asked about 4 health behaviors related to bed net use, fever, respiratory disease, and diarrhea, and a control district where workers conducted routine immunization activities without health behavior questions. To evaluate the effect of EPI-CM, we conducted a cross-sectional household survey at baseline and 1 year postintervention. We used multivariate logistic regression to compare between districts the change over 1 year in 4 health behaviors: use of insecticide-treated nets, appropriate fever treatment, care-seeking for respiratory complaints, and appropriate diarrhea treatment. RESULTS: There were no significant differences between the 2 districts in the change in the 4 health behaviors when controlling for age, sex, maternal education and occupation, immunization history, and wealth. CONCLUSIONS: We found no evidence that EPI-CM increases healthy behaviors. Further evaluation of other potential benefits and costs of EPI-CM is warranted.

Validity of Expanded Program on Immunization Contact Method health behavior estimates in Mali.

BACKGROUND: In the developing world, household surveys provide high-quality health behavior data integral to public health program management. The Expanded Program on Immunization Contact Method (EPI-CM) is a proposed, less resource-intensive method in which health center staff incorporate health behavior questions into routine vaccination activities. No systematic evaluation of EPI-CM validity has yet been conducted. METHODS: We used concurrent household survey and EPI-CM to collect data on 4 infant health behaviors in Mali at 2 time points (8 total comparisons). Studied health behaviors were bednet use, obtaining care for fever, obtaining care for a respiratory complaint, and using oral rehydration solution for diarrhea. Household survey and EPI-CM estimates were considered equivalent if a 95% confidence interval about the difference in estimated proportions fell within the interval (-.10, .10). RESULTS: EPI-CM estimates were higher than household survey estimates for 7 of 8 unadjusted paired estimates; estimates of bednet use in 2009 met a priori equivalence criteria in a setting of high bednet use (90.5%). When we restricted household survey data to infants up-to-date on vaccinations, estimates for behaviors other than bednet use remained substantially different. CONCLUSIONS: We were unable to demonstrate that EPI-CM, as implemented, consistently produces data comparable with household survey data.

Improved equity in measles vaccination from integrating insecticide-treated bednets in a vaccination campaign, Madagascar.

OBJECTIVE: To evaluate the effect of integrating ITN distribution on measles vaccination campaign coverage in Madagascar. METHODS: Nationwide cross-sectional survey to estimate measles vaccination coverage, nationally, and in districts with and without ITN integration. To evaluate the effect of ITN integration, propensity score matching was used to create comparable samples in ITN and non-ITN districts. Relative risks (RR) and 95% confidence intervals (CI) were estimated via log-binomial models. Equity ratios, defined as the coverage ratio between the lowest and highest household wealth quintile (Q), were used to assess equity in measles vaccination coverage. RESULTS: National measles vaccination coverage during the campaign was 66.9% (95% CI 63.0-70.7). Among the propensity score subset, vaccination campaign coverage was higher in ITN districts (70.8%) than non-ITN districts (59.1%) (RR=1.3, 95% CI 1.1-1.6). Among children in the poorest wealth quintile, vaccination coverage was higher in ITN than in non-ITN districts (Q1; RR=2.4, 95% CI 1.2-4.8) and equity for measles vaccination was greater in ITN districts (equity ratio=1.0, 95% CI 0.8-1.3) than in non-ITN districts (equity ratio=0.4, 95% CI 0.2-0.8). CONCLUSION: Integration of ITN distribution with a vaccination campaign might improve measles vaccination coverage among the poor, thus providing protection for the most vulnerable and difficult to reach children.

Temporal trends of sulphadoxine-pyrimethamine (SP) drug-resistance molecular markers in Plasmodium falciparum parasites from pregnant women in western Kenya.

BACKGROUND: Resistance to sulphadoxine-pyrimethamine (SP) in Plasmodium falciparum parasites is associated with mutations in the dihydrofolate reductase (dhfr) and dihydropteroate synthase (dhps) genes and has spread worldwide. SP remains the recommended drug for intermittent preventive treatment for malaria in pregnancy (IPTp) and information on population prevalence of the SP resistance molecular markers in pregnant women is limited. METHODS: Temporal trends of SP resistance molecular markers were investigated in 489 parasite samples collected from pregnant women at delivery from three different observational studies between 1996 and 2009 in Kenya, where SP was adopted for both IPTp and case treatment policies in 1998. Using real-time polymerase chain reaction, pyrosequencing and direct sequencing, 10 single-nucleotide polymorphisms (SNPs) of SP resistance molecular markers were assayed. RESULTS: The prevalence of quintuple mutant (dhfr N51I/C59R/S108N and dhps A437G/K540E combined genotype) increased from 7% in the first study (1996-2000) to 88% in the third study (2008-2009). When further stratified by sample collection year and adoption of IPTp policy, the prevalence of the quintuple mutant increased from 2.4% in 1998 to 44.4% three years after IPTp policy adoption, seemingly in parallel with the increase in percentage of SP use in pregnancy. However, in the 1996-2000 study, more mutations in the combined dhfr/dhps genotype were associated with SP use during pregnancy only in univariable analysis and no associations were detected in the 2002-2008 and 2008-2009 studies. In addition, in the 2008-2009 study, 5.3% of the parasite samples carried the dhps triple mutant (A437G/K540E/A581G). There were no differences in the prevalence of SP mutant genotypes between the parasite samples from HIV + and HIV- women over time and between paired peripheral and placental samples. CONCLUSIONS: There was a significant increase in dhfr/dhps quintuple mutant and the emergence of new genotype containing dhps 581 in the parasites from pregnant women in western Kenya over 13 years. IPTp adoption and SP use in pregnancy only played a minor role in the increased drug-resistant parasites in the pregnant women over time. Most likely, other major factors, such as the high prevalence of resistant parasites selected by the use of SP for case management in large non-pregnant population, might have contributed to the temporally increased prevalence of SP resistant parasites in pregnant women. Further investigations are needed to determine the linkage between SP drug resistance markers and efficacy of IPTp-SP.

Detecting Malaria Hotspots in Haiti, a Low-Transmission Setting.

In 2006, Haiti committed to malaria elimination when the transmission was thought to be low, but before robust national parasite prevalence estimates were available. In 2011, the first national population-based survey confirmed the national malaria parasite prevalence was < 1%. In both 2014 and 2015, Haiti reported approximately 17,000 malaria cases identified passively at health facilities. To detect malaria transmission hotspots for targeting interventions, the National Malaria Control Program (NMCP) piloted an enhanced geographic information surveillance system in three departments with relatively high-, medium-, and low-transmission areas. From October 2014-September 2015, NMCP staff abstracted health facility records of confirmed malaria cases from 59 health facilities and geo-located patients' households. Household locations were aggregated to 1-km2 grid cells to calculate cumulative incidence rates (CIRs) per 1,000 persons. Spatial clustering of CIRs were tested using Getis-Ord Gi* analysis. Space-time permutation models searched for clusters up to 6 km in distance using a 1-month malaria transmission window. Of the 2,462 confirmed cases identified from health facility records, 58% were geo-located. Getis-Ord Gi* analysis identified 43 1-km2 hotspots in coastal and inland areas that overlapped primarily with 13 space-time clusters (size: 0.26-2.97 km). This pilot describes the feasibility of detecting malaria hotspots in resource-poor settings. More data from multiple years and serological household surveys are needed to assess completeness and hotspot stability. The NMCP can use these pilot methods and results to target foci investigations and malaria interventions more accurately.

Comparison of anaemia and parasitaemia as indicators of malaria control in household and EPI-health facility surveys in Malawi.

BACKGROUND: The World Health Organization has recommended that anaemia be used as an additional indicator to monitor malaria burden at the community level as malaria interventions are nationally scaled up. To date, there are no published evaluations of this recommendation. METHODS: To evaluate this recommendation, a comparison of anaemia and parasitaemia among 6-30 month old children was made during two repeated cross-sectional household (HH) and health facility (HF) surveys in six districts across Malawi at baseline (2005) and in a follow-up survey (2008) after a scale up of malaria control interventions. RESULTS: HH net ownership did not increase between the years (50.5% vs. 49.8%), but insecticide treated net (ITN) ownership increased modestly from 41.5% (95% CI: 37.2%-45.8%) in 2005 to 45.3% (95% CI: 42.6%-48.0%) in 2008. ITN use by children 6-30 months old, who were living in HH with at least one net, increased from 73.6% (95% CI:68.2%-79.1%) to 80.0% (95% CI:75.9%-84.1%) over the three-year period. This modest increase in ITN use was associated with a decrease in moderate to severe anaemia (Hb <8 g/dl) from 18.4% (95% CI:14.9%-21.8%) in 2005 to 15.4% (13.2%-17.7%) in 2008, while parasitaemia, measured as positive-slide microscopy, decreased from 18.9% (95% CI:14.7%-23.2%) to 16.9% (95% CI:13.8%-20.0%), a relative reduction of 16% and 11%, respectively. In HF surveys, anaemia prevalence decreased from 18.3% (95% CI: 14.9%-21.7%) to 15.4% (95% CI: 12.7%-18.2%), while parasitaemia decreased from 30.6% (95% CI: 25.7%-35.5%) to 13.2% (95% CI: 10.6%-15.8%), a relative reduction of 15% and 57%, respectively. CONCLUSION: Increasing access to effective malaria prevention was associated with a reduced burden of malaria in young Malawian children. Anaemia measured at the HF level at time of routine vaccination may be a good surrogate indicator for its measurement at the HH level in evaluating national malaria control programmes.

Assessing bed net use and non-use after long-lasting insecticidal net distribution: a simple framework to guide programmatic strategies.

BACKGROUND: Insecticide-treated nets (ITNs) are becoming increasingly available to vulnerable populations at risk for malaria. Their appropriate and consistent use is essential to preventing malaria, but ITN use often lags behind ITN ownership. In order to increase ITN use, it is necessary to devise strategies that accurately identify, differentiate, and target the reasons and types of non-use. METHODS: A simple method based on the end-user as the denominator was employed to classify each individual into one of four ITN use categories: 1) living in households not owning an ITN; 2) living in households owning, but not hanging an ITN; 3) living in households owning and hanging an ITN, but who are not sleeping under one; and 4) sleeping under an ITN. This framework was applied to survey data designed to evaluate long-lasting insecticidal nets (LLINs) distributions following integrated campaigns in five countries: Togo, Sierra Leone, Madagascar, Kenya and Niger. RESULTS: The percentage of children <5 years of age sleeping under an ITN ranged from 51.5% in Kenya to 81.1% in Madagascar. Among the three categories of non-use, children living in households without an ITN make up largest group (range: 9.4%-30.0%), despite the efforts of the integrated child health campaigns. The percentage of children who live in households that own but do not hang an ITN ranged from 5.1% to 16.1%. The percentage of children living in households where an ITN was suspended, but who were not sleeping under it ranged from 4.3% to 16.4%. Use by all household members in Sierra Leone (39.9%) and Madagascar (60.4%) indicate that integrated campaigns reach beyond their desired target populations. CONCLUSIONS: The framework outlined in this paper provides a helpful tool to examine the deficiencies in ITN use. Monitoring and evaluation strategies designed to assess ITN ownership and use can easily incorporate this approach using existing data collection instruments that measure the standard indicators.

Impact of mass distribution of free long-lasting insecticidal nets on childhood malaria morbidity: the Togo National Integrated Child Health Campaign.

BACKGROUND: An evaluation of the short-term impact on childhood malaria morbidity of mass distribution of free long-lasting insecticidal nets (LLINs) to households with children aged 9-59 months as part of the Togo National Integrated Child Health Campaign. METHODS: The prevalence of anaemia and malaria in children aged zero to 59 months was measured during two cross-sectional household cluster-sample surveys conducted during the peak malaria transmission, three months before (Sept 2004, n=2521) and nine months after the campaign (Sept 2005, n=2813) in three districts representative of Togo's three epidemiological malaria transmission regions: southern tropical coastal plains (Yoto), central fertile highlands (Ogou) and northern semi-arid savannah (Tone). RESULTS: In households with children<5 years of age, insecticide-treated net (ITN) ownership increased from <1% to >65% in all 3 districts. Reported ITN use by children during the previous night was 35.9%, 43.8% and 80.6% in Yoto, Ogou and Tone, respectively. Rainfall patterns were comparable in both years. The overall prevalence of moderate to severe anaemia (Hb<8.0 g/dL) was reduced by 28% (prevalence ratio [PR] 0.72, 95% CI 0.62-0.84) and mean haemoglobin was increased by 0.35 g/dL (95% CI 0.25-0.45).The effect was predominantly seen in children aged 18-59 months and in the two southern districts: PR (95% CI) for moderate to severe anaemia and clinical malaria: Yoto 0.62 (0.44-0.88) and 0.49 (0.35-0.75); Ogou 0.54 (0.37-0.79) and 0.85 (0.57-1.27), respectively. Similar reductions occurred in children<18 months in Ogou, but not in Yoto. No effect was seen in the semi-arid northern district despite a high malaria burden and ITN coverage. CONCLUSIONS: A marked reduction in childhood malaria associated morbidity was observed in the year following mass distribution of free LLINs in two of the three districts in Togo. Sub-national level impact evaluations will contribute to a better understanding of the impact of expanding national malaria control efforts.

Polymorphisms in genes of interleukin 12 and its receptors and their association with protection against severe malarial anaemia in children in western Kenya.

BACKGROUND: Malarial anaemia is characterized by destruction of malaria infected red blood cells and suppression of erythropoiesis. Interleukin 12 (IL12) significantly boosts erythropoietic responses in murine models of malarial anaemia and decreased IL12 levels are associated with severe malarial anaemia (SMA) in children. Based on the biological relevance of IL12 in malaria anaemia, the relationship between genetic polymorphisms of IL12 and its receptors and SMA was examined. METHODS: Fifty-five tagging single nucleotide polymorphisms covering genes encoding two IL12 subunits, IL12A and IL12B, and its receptors, IL12RB1 and IL12RB2, were examined in a cohort of 913 children residing in Asembo Bay region of western Kenya. RESULTS: An increasing copy number of minor variant (C) in IL12A (rs2243140) was significantly associated with a decreased risk of SMA (P = 0.006; risk ratio, 0.52 for carrying one copy of allele C and 0.28 for two copies). Individuals possessing two copies of a rare variant (C) in IL12RB1 (rs429774) also appeared to be strongly protective against SMA (P = 0.00005; risk ratio, 0.18). In addition, children homozygous for another rare allele (T) in IL12A (rs22431348) were associated with reduced risk of severe anaemia (SA) (P = 0.004; risk ratio, 0.69) and of severe anaemia with any parasitaemia (SAP) (P = 0.004; risk ratio, 0.66). In contrast, AG genotype for another variant in IL12RB1 (rs383483) was associated with susceptibility to high-density parasitaemia (HDP) (P = 0.003; risk ratio, 1.21). CONCLUSIONS: This study has shown strong associations between polymorphisms in the genes of IL12A and IL12RB1 and protection from SMA in Kenyan children, suggesting that human genetic variants of IL12 related genes may significantly contribute to the development of anaemia in malaria patients.

Bed net ownership in Kenya: the impact of 3.4 million free bed nets.

BACKGROUND: In July and September 2006, 3.4 million long-lasting insecticide-treated bed nets (LLINs) were distributed free in a campaign targeting children 0-59 months old (CU5s) in the 46 districts with malaria in Kenya. A survey was conducted one month after the distribution to evaluate who received campaign LLINs, who owned insecticide-treated bed nets and other bed nets received through other channels, and how these nets were being used. The feasibility of a distribution strategy aimed at a high-risk target group to meet bed net ownership and usage targets is evaluated. METHODS: A stratified, two-stage cluster survey sampled districts and enumeration areas with probability proportional to size. Handheld computers (PDAs) with attached global positioning systems (GPS) were used to develop the sampling frame, guide interviewers back to chosen households, and collect survey data. RESULTS: In targeted areas, 67.5% (95% CI: 64.6, 70.3%) of all households with CU5s received campaign LLINs. Including previously owned nets, 74.4% (95% CI: 71.8, 77.0%) of all households with CU5s had an ITN. Over half of CU5s (51.7%, 95% CI: 48.8, 54.7%) slept under an ITN during the previous evening. Nearly forty percent (39.1%) of all households received a campaign net, elevating overall household ownership of ITNs to 50.7% (95% CI: 48.4, 52.9%). CONCLUSIONS: The campaign was successful in reaching the target population, families with CU5s, the risk group most vulnerable to malaria. Targeted distribution strategies will help Kenya approach indicator targets, but will need to be combined with other strategies to achieve desired population coverage levels.

Seroprevalence of Measles, Rubella, Tetanus, and Diphtheria Antibodies among Children in Haiti, 2017.

In Haiti, measles, rubella, and maternal and neonatal tetanus have been eliminated, but a diphtheria outbreak is ongoing as of 2019. We conducted a nationally representative, household-based, two-stage cluster survey among children aged 5-7 years in 2017 to assess progress toward maintenance of control and elimination of selected vaccine-preventable diseases (VPDs). We stratified Haiti into West region (West department, including the capital city) and non-West region (all other departments). We obtained vaccination history and dried blood spots, and measured antibody concentrations to VPDs on a multiplex bead assay. Among 1,146 children, national seropositivity was 83% (95% CI: 80-86%) for tetanus, 83% (95% CI: 81-85%) for diphtheria, 87% (95% CI: 85-89%) for measles, and 84% (95% CI: 81-87%) for rubella. None of the children had long-term immunity to tetanus or diphtheria (IgG concentration ≥ 1 international unit/mL). Seropositivity in the West region was lower than that in the non-West region. Vaccination coverage was 68% (95% CI: 61-74%) for ≥ 3 doses of tetanus- and diphtheria-containing vaccine (DTP3), 84% (95% CI: 80-87%) for one dose of measles-rubella vaccine (MR1), and 20% (95% CI: 16-24%) for MR2. The seroprevalence of measles, rubella, and diphtheria antibodies is lower than population immunity levels needed to prevent disease transmission, particularly in the West region; reintroduction of these diseases could lead to an outbreak. To maintain VPD control and elimination, Haiti should achieve DTP3 and MR2 coverage ≥ 95%, and include tetanus and diphtheria booster doses in the routine immunization schedule.

Prevalence of Chronic Hepatitis B Virus Infection among Children in Haiti, 2017.

In 2016, the World Health Assembly endorsed the Global Health Sector Strategy on Viral Hepatitis, which calls for elimination of hepatitis B virus (HBV) by 2030 (definition: ≤ 0.1% hepatitis B surface antigen [HBsAg] prevalence among children aged 5 years). The burden of chronic HBV infection among children in Haiti is unknown. We conducted a nationally representative cross-sectional serological survey among 5- to 7-year-old children based on a two-stage cluster design with two strata: West (includes metropolitan Port-au-Prince) and non-West (all other departments). We collected demographic, socioeconomic, and vaccination history data and tested for HBsAg using a rapid point-of-care test. We estimated HBsAg prevalence and evaluated the association of HBV infection with vaccination history, demographics, and socioeconomic characteristics. Of the 1,152 children, seven (0.5%, 95% CI: 0.2-1.2) were HBsAg positive. The HBsAg prevalence varied by region (West: 0.1%, 95% CI: 0.01-0.9; non-West: 0.7%, 95% CI: 0.2-1.9) (P = 0.1), gender (males: 0.7%, 95% CI: 0.2-2.4; females: 0.2%, 95% CI: 0.05-1.1) (P = 0.3), and caregiver's education level (none: 0.8%, 95% CI: 0.2-3.1; some or completed primary: 0.5%, 95% CI: 0.1-1.8; some secondary: 0.4%, 95% CI: 0.1-1.8; secondary and higher: 0.0%, 95% CI: 0-0), although the differences were not statistically significant. None of the HBsAg-positive children had documented vaccination with hepatitis B vaccine (HepB). Haiti's chronic HBV infection prevalence among children is low; however, it is above the elimination target. To reach elimination, Haiti needs to achieve high coverage with the three HepB doses and introduce a HepB birth dose.

Insecticide-treated net ownership and usage in Niger after a nationwide integrated campaign.

OBJECTIVES: In December 2005 and March 2006, Niger conducted nationwide integrated campaigns to distribute polio vaccine and long lasting insecticide-treated nets (LLINs) to children <5 years of age. We evaluated the campaign effectiveness, net retention, insecticide-treated net (ITN) ownership, and usage. METHODS: Two nationwide cross-sectional surveys in January 2006 (dry season) and September 2006 (rainy season), using a stratified two-stage cluster sampling design. We mapped selected communities, selected households by simple random sampling, and administered questionnaires by interviewers using personal digital assistants. RESULTS: The first survey showed that ITN ownership in all households was 6.3% prior to the campaign, increasing to 65.1% after the campaign in the second survey. The second survey also showed that 73.4% of households with children <5 received an LLIN and that 97.7% of households that received > or = one LLIN retained it. The wealth equity ratio for ITN ownership in households with children <5 increased from 0.17 prior to the campaign to 0.79 afterward. During the dry season, 15.4% of all children <5 and 11.3% of pregnant women slept under an ITN, while during rainy season, 55.5% of children <5 and 48.2% of pregnant women slept under an ITN. CONCLUSIONS: Free distribution during the integrated campaign rapidly increased ITN ownership and decreased inequities between those in the highest and lowest wealth quintiles. Retention of ITNs was very high, and usage was high during malaria transmission season. However, ITN ownership and usage by vulnerable groups continues to fall short of RBM targets, and additional strategies are needed to increase ownership and usage.

Use of handheld computers with global positioning systems for probability sampling and data entry in household surveys.

We introduce an innovative method that uses personal digital assistants (PDAs) equipped with global positioning system (GPS) units in household surveys to select a probability-based sample and perform PDA-based interviews. Our approach uses PDAs with GPS to rapidly map all households in selected areas, choose a random sample, and navigate back to the sampled households to conduct an interview. We present recent field experience in two large-scale nationally representative household surveys to assess insecticide-treated bed net coverage as part of malaria control efforts in Africa. The successful application of this method resulted in statistically valid samples; quality-controlled data entry; and rapid aggregation, analyses, and availability of preliminary results within days of completing the field work. We propose this method as an alternative to the Expanded Program on Immunization cluster sample method when a fast, statistically valid survey is required in an environment with little census information at the enumeration area level.