The effectiveness of older insecticide-treated bed nets (ITNs) to prevent malaria infection in an area of moderate pyrethroid resistance: results from a cohort study in Malawi.

BACKGROUND: A previous cohort study in Malawi showed that users of new insecticide-treated bed nets (ITNs) were significantly protected against malaria compared to non-users, despite moderate levels of pyrethroid resistance among the primary mosquito vectors. The present study investigated whether ITNs that were 1-2 years old continued to protect users in the same area with moderate pyrethroid resistance. METHODS: One year following a baseline cross-sectional malaria parasitaemia prevalence survey and universal distribution of deltamethrin ITNs (May 2012), a fixed cohort of 1223 children aged 6-59 months was enrolled (April 2013). Children were tested for parasitaemia at monthly scheduled visits and at unscheduled sick visits from May to December 2013 using rapid diagnostic tests. ITN use the prior night and the condition of ITNs (based on presence of holes) was assessed by caregiver self-report. The incidence rate ratio (RR) comparing malaria infection among users and non-users of ITNs was modelled using generalized estimating equations adjusting for potential confounders and accounting for repeated measures on each child. The protective efficacy (PE) of ITN use was calculated as 1 - RR. RESULTS: In this cohort, self-reported ITN use remained consistently high (> 95%) over the study period. Although users of ITNs were slightly more protected compared to non-users of ITNs, the difference in incidence of infection was not statistically significant (RR 0.83, 95% confidence interval [CI] 0.54-1.27). Among ITN users, malaria incidence was significantly lower in users of ITNs with no holes (of any size) compared to users of ITNs with ≥ 1 hole (RR 0.82, 95% CI 0.69-0.98). CONCLUSIONS: There was no significant PE of using 1-2 year-old ITNs on the incidence of malaria in children in an area of moderate pyrethroid resistance, but among ITN users, the authors found increased protection by ITNs with no holes compared to ITNs with holes. Given the moderate levels of pyrethroid resistance in the primary malaria vector and recent evidence of added benefits of ITNs with synergists or non-pyrethroid insecticides, next-generation ITNs may be a useful strategy to address pyrethroid resistance and should be further explored in Malawi.

The Effect of Text Message Reminders to Health Workers on Quality of Care for Malaria, Pneumonia, and Diarrhea in Malawi: A Cluster-Randomized, Controlled Trial.

The use of mobile technologies in medicine, or mHealth, holds promise to improve health worker (HW) performance, but evidence is mixed. We conducted a cluster-randomized controlled trial to evaluate the effect of text message reminders to HWs in outpatient health facilities (HFs) on quality of care for malaria, pneumonia, and diarrhea in Malawi. After a baseline HF survey (2,360 patients) in January 2015, 105 HFs were randomized to three arms: 1) text messages to HWs on malaria case management; 2) text messages to HWs on malaria, pneumonia, and diarrhea case management (latter two for children < 5 years); and 3) control arm (no messages). Messages were sent beginning April 2015 twice daily for 6 months, followed by an endline HF survey (2,536 patients) in November 2015. An intention-to-treat analysis with difference-in-differences binomial regression modeling was performed. The proportion of patients with uncomplicated malaria managed correctly increased from 42.8% to 59.6% in the control arm, from 43.7% to 55.8% in arm 1 (effect size -4.7%-points, 95% confidence interval (CI): -18.2, 8.9, P = 0.50) and from 30.2% to 50.9% in arm 2 (effect size 3.9%-points, 95% CI: -14.1, 22.0, P = 0.67). Prescription of first-line antibiotics to children < 5 years with clinically defined pneumonia increased in all arms, but decreased in arm 2 (effect size -4.1%-points, 95% CI: -42.0, 33.8, P = 0.83). Prescription of oral rehydration solution to children with diarrhea declined slightly in all arms. We found no significant improvements in malaria, pneumonia, or diarrhea treatment after HW reminders, illustrating the importance of rigorously testing new interventions before adoption.

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.

The effect of holes in long-lasting insecticidal nets on malaria in Malawi: results from a case-control study.

BACKGROUND: Long-lasting insecticidal nets (LLINs) are a cornerstone of malaria prevention. Holes develop in LLINs over time and compromise their physical integrity, but how holes affect malaria transmission risk is not well known. METHODS: After a nationwide mass LLIN distribution in July 2012, a study was conducted to assess the relationship between LLIN damage and malaria. From March to September 2013, febrile children ages 6-59 months who consistently slept under LLINs (every night for 2 weeks before illness onset) were enrolled in a case-control study at Machinga District Hospital outpatient department. Cases were positive for Plasmodium falciparum asexual parasites by microscopy while controls were negative. Digital photographs of participants' LLINs were analysed using an image-processing programme to measure holes. Total hole area was classified by quartiles and according to the World Health Organization's proportionate hole index (pHI) cut-offs [< 79 cm2 (good), 80-789 cm2 (damaged), and > 790 cm2 (too torn)]. Number of holes by location and size, and total hole area, were compared between case and control LLINs using non-parametric analyses and logistic regression. RESULTS: Of 248 LLINs analysed, 97 (39%) were from cases. Overall, 86% of LLINs had at least one hole. The median number of holes of any size was 9 [interquartile range (IQR) 3, 22], and most holes were located in the lower halves of the nets [median 7 (IQR 2, 16)]. There were no differences in number or location of holes between LLINs used by cases and controls. The median total hole area was 10 cm2 (IQR 2, 125) for control LLINs and 8 cm2 (IQR 2, 47) for case LLINs (p = 0.10). Based on pHI, 109 (72%) control LLINs and 83 (86%) case LLINs were in "good" condition. Multivariable modeling showed no association between total hole area and malaria, controlling for child age, caregiver education, and iron versus thatched roof houses. CONCLUSIONS: LLIN holes were not associated with increased odds of malaria in this study. However, most of the LLINs were in relatively good condition 1 year after distribution. Future studies should examine associations between LLIN holes and malaria risk with more damaged nets.

Quality of Case Management for Pneumonia and Diarrhea Among Children Seen at Health Facilities in Southern Malawi.

Pneumonia and diarrhea are leading causes of child deaths in Malawi. Guidelines to manage childhood illnesses in resource-poor settings exist, but studies have reported low health-care worker (HCW) adherence to guidelines. We conducted a health facility survey from January to March 2015 to assess HCW management of pneumonia and diarrhea in children < 5 years of age in southern Malawi, and to determine factors associated with case management quality. Descriptive statistics and multivariable logistic regression models examined patient, HCW, and health facility factors associated with recommended pneumonia and diarrhea management, using Malawi's national guidelines as the gold standard. Of 694 surveyed children 2-59 months of age at 95 health facilities, 132 (19.0%) met survey criteria for pneumonia; HCWs gave recommended antibiotic treatment to 90 (68.2%). Of 723 children < 5 years of age, 222 (30.7%) had uncomplicated diarrhea; HCWs provided recommended treatment to 94 (42.3%). In multivariable analyses, caregivers' spontaneous report of children's symptoms was associated with recommended treatment of both pneumonia (odds ratio [OR]: 2.8, 95% confidence interval [CI]: 1.2-6.8, P = 0.023) and diarrhea (OR: 24.2, 95% CI: 6.0-97.0, P < 0001). Malaria diagnosis was negatively associated with recommended treatment (OR for pneumonia: 0.5, 95% CI: 0.2-1.0, P = 0.046; OR for diarrhea: 0.3, 95% CI: 0.1-0.6, P = 0.003). To improve quality of care, children should be assessed systematically, even when malaria is suspected. Renewed efforts to invigorate such a systematic approach, including HCW training, regular follow-up supervision, and monitoring HCW performance, are needed in Malawi.

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.

In vivo efficacy of artemether-lumefantrine and artesunate-amodiaquine for uncomplicated Plasmodium falciparum malaria in Malawi, 2014.

BACKGROUND: Malaria causes significant morbidity in Malawi, with an estimated 5 million cases in 2014. Artemether-lumefantrine (AL) and artesunate-amodiaquine (ASAQ) are the first- and second-line treatments for uncomplicated malaria, respectively, but emerging resistance threatens their efficacy. In order to understand whether AL and ASAQ remain efficacious for the treatment of uncomplicated Plasmodium falciparum malaria in Malawi, a therapeutic efficacy trial was conducted. METHODS: During March-July 2014, febrile children aged 6-59 months with microscopy-confirmed uncomplicated P. falciparum malaria (1000-200,000 parasites/µL) were enrolled in a 28-day randomized in vivo efficacy trial at three sites: one each in northern (Karonga), central (Nkhotakota) and southern (Machinga) Malawi. The study was powered to estimate site-specific efficacy for AL and overall efficacy for ASAQ, with 3:1 randomization to AL or ASAQ. Blood was collected for malaria microscopy and molecular testing on days 0-3, 7, 14, 21, and 28. Recrudescence and reinfection were differentiated using polymerase chain reaction (PCR) genotyping of merozoite surface protein. The primary outcome was the PCR-corrected day 28 Kaplan-Meier cumulative success rate. RESULTS: A total of 452 children were enrolled; 303/338 (89 %) and 98/114 (86 %) reached a study endpoint in AL and ASAQ arms, respectively. All treatment failures occurred after day 3. The day 28 uncorrected cumulative success rate was 97.1 % (95 % confidence interval [CI]: 93.9-100 %) for ASAQ and 76.8 % (95 % CI 72.1-81.5 %) for AL, with 82.5 % (95 % CI 75.4-89.7 %), 69 % (95 % CI 59.9-78.1 %), and 78.2 % (95 % CI 70.2-86.3 %) success in the northern, central, and southern regions, respectively. The day 28 PCR-corrected cumulative success rate was 99 % (95 % CI 97.2-100 %) in the ASAQ arm and 99.3 % (95 % CI 98.3-100 %) in the AL arm, with 98-100 % efficacy in each site. CONCLUSIONS: As evidenced by the day 28 PCR-corrected cumulative success rates, both AL and ASAQ remain efficacious treatments for uncomplicated malaria in Malawi. The lower uncorrected efficacy in the AL arm compared to ASAQ may be explained by the shorter half-life of lumefantrine (3-6 days) compared to amodiaquine (9-18 days). The high reinfection rate suggests that there is a continued need to scale-up effective malaria prevention interventions.

Clinical outcomes among febrile children aged 2 to 59 months with negative malaria rapid diagnostic test results in Mchinji District, Malawi.

BACKGROUND: Malawi malaria treatment guidelines recommend a definitive diagnosis, using a malaria rapid diagnostic test (mRDT), for all patients with fever or history of fever. Improving the management and outcomes of febrile children with negative mRDT results should be a priority. METHODS: Through a prospective cohort study designed to investigate clinical outcomes of children treated at the community level, we followed, for 7 days, children aged 2 to 59 months, who had negative mRDT results and were treated with antipyretic medication. Clinical outcomes were assessed on days 3 and 7 post-recruitment. RESULTS: The median age of recruited children was 19 months. Of the 285 children enrolled, 139 (48.8%) were females. Of the children for whom data were available for analysis, 95/236 (40.3%) had fever (temperature ≥ 37.5°C) at enrolment, and almost half of the sick children (125/268; 46.6%) had symptoms of upper respiratory tract infection. Most sick children (89.6%; 95% confidence interval, CI = 84.2 to 93.3) recovered, while 10.4% (95% CI: 6.7 to 15.8) were still sick by day 7 of follow-up. There were no deaths reported during the 7 days of follow-up. Being afebrile at enrolment (odds ratio, OR = 2.5; 95% CI = 1.1 to 6.0; P = 0.027) and sleeping under an insecticide-treated net (ITN) (OR = 2.7; 95% CI = 1.2 to 6.2; P = 0.011) were associated with recovery by day 7. In multivariable analysis, sleeping under an ITN the previous night was the only factor associated with recovery by day 7. Microscopy did not detect any malaria parasites in the blood of recruited children, at recruitment or on day 7. CONCLUSIONS: In this community-level study, the majority of febrile children with negative mRDT results recovered within 7 days of health worker consultation for a febrile illness, having only taken antipyretics.

The effectiveness of long-lasting, insecticide-treated nets in a setting of pyrethroid resistance: a case-control study among febrile children 6 to 59 months of age in Machinga District, Malawi.

BACKGROUND: The escalating level of mosquito resistance to pyrethroid insecticides threatens the effectiveness of insecticide-treated nets (ITNs) for malaria control in Malawi. An evaluation of the effectiveness of ITNs for preventing malaria in children aged 6-59 months old, after 1 year of mass distribution of LLINs was conducted in Machinga District, Malawi, an area of moderate pyrethroid resistance. METHODS: A facility-based, case-control study among children 6-59 months was conducted in an area of pyrethroid resistance between March and September 2013 in Machinga District. Cases and controls were children with fever who sought care from the same hospital and tested positive and negative, respectively, for malaria parasites by microscopy. RESULTS: A high proportion of both cases (354 of 404 or 87.6 %) and controls (660 of 778 or 84.8 %) slept under an ITN the night before the survey. In univariable logistic regression, older age (24-59 months versus 6-23 months, p < 0.001), sleeping on the floor versus a mattress (p < 0.001), and open versus closed house eaves (p = 0.001) were associated with increased odds of malaria, whilst secondary education of the caretaker, having windows on multiple walls, and being in the least poor wealth quintile (p < 0.001 for each) reduced the odds of malaria; ITN use was not associated with malaria (p = 0.181). In multivariable analysis, older age (p < 0.001) and secondary education of the caregiver (p = 0.011) were the only factors significantly associated with malaria. CONCLUSION: This study did not find a significant personal protective effect of ITNs. However, high use of ITNs in the community and recent findings of lower malaria incidence in ITN users compared to bed net non-users from a cohort study in the same area suggest that ITNs provide community protection to both users and non-users alike in this area.

The use of intermittent preventive treatment in pregnancy and insecticide-treated bed nets for malaria prevention by women of child-bearing age in eight districts in Malawi.

BACKGROUND: Intermittent preventive treatment in pregnancy (IPTp) and insecticide-treated bed nets (ITNs) can reduce the morbidity and mortality associated with malaria in pregnancy. Although the coverage for both IPTp and ITN use have been described in Malawi, the analysis of factors associated with IPTp receipt and ITN use is lacking. This analysis was conducted to assess IPTp and ITN use and predictors of use by women of child-bearing age (WOCBA). METHODS: A two-stage cluster-sample cross-sectional survey was conducted April 16-30, 2009 in eight districts across Malawi. Information on receipt of two or more doses of IPTp, ITN ownership, and ITN use the night before the survey was collected. Multivariate logistic regression was used to assess predictors of IPTp and ITN use. RESULTS: Data were collected from 7407 households containing 6985 WOCBA and 3213 recently pregnant women (women who reported a completed pregnancy in the 2 years before the survey). Most recently pregnant women (96 %) had at least one antenatal care (ANC) clinic visit; 91 % reported receiving at least one dose of IPTp, and 72 % reported receiving two or more doses of IPTp. Women in Phalombe, Rumphi, and Lilongwe were more likely to receive two doses of IPTp than those in Blantyre [adjusted odds ratio (aOR) 2.5 (95 % CI 1.5-4.5), 2.5 (95 % CI 1.5-4.3), and 2.0 (95 % CI 1.2-3.1), respectively]. Educated women were more likely to have received IPTp compared to women with no education [aOR 1.6 (95 % CI 1.0-2.6) for those who completed primary school, aOR1.9 (95 % CI 1.1-3.3) for some secondary school, and aOR 4.1 (95 % CI 1.9-8.7) for completed secondary school or above], and women in the poorest socioeconomic status quintile were less likely to receive IPTp than those in the least poor quintile [aOR 0.68 (95 % CI 0.48-0.97)]. In all, 53 % of WOCBA used an ITN the previous night. Women in Nkhotkhota and Phalombe were less likely to have slept under an ITN the previous night compared to those in Blantyre [aOR 0.52 (95 % CI 0.39-0.69) and aOR 0.67 (95 % CI 0.47-0.95), respectively]. In addition, age [aOR 0.61 (95 % CI 0.45-0.83) for women 15-19 years old], and either being currently pregnant [aOR 1.5 (95 % CI 1.2-2.0)] or having been pregnant in the previous 2 years [aOR 2.4, (95 % CI 2.1-2.8)] were associated with ITN use. CONCLUSION: In Malawi in 2009, IPTp and ITN use in WOCBA fell short of national and international goals. Adoption of new guidelines encouraging administration of IPTp at every scheduled ANC visit might increase IPTp use. Increasing health promotion activities to encourage earlier attendance at ANC clinics and create demand for IPTp and ITNs might improve overall IPTp and ITN use.

In vivo efficacy of sulphadoxine-pyrimethamine for the treatment of asymptomatic parasitaemia in pregnant women in Machinga District, Malawi.

BACKGROUND: The effectiveness of sulphadoxine-pyrimethamine (SP) intermittent preventive treatment of malaria in pregnancy (IPTp) might be compromised by high prevalence of resistance-associated Plasmodium falciparum dihydrofolate reductase (dhfr) and dihydropteroate synthase (dhps) mutations. As a proxy for IPTp-SP effectiveness, the in vivo efficacy of SP to clear parasitaemia and prevent reinfection in asymptomatic parasitaemic pregnant women in an area with high SP resistance prevalence was assessed. METHODS: Pregnant women 16-26 weeks' gestation with asymptomatic parasitaemia presenting for antenatal care were given IPTp-SP and followed for 42 days. The primary outcome was polymerase chain reaction (PCR) uncorrected 42-day survival rate; the per cent of patients without recrudescence or reinfection by day 42. PCR was used to distinguish recrudescence from reinfection. DNA was sequenced to detect resistance-associated dhfr and dhps mutations. RESULTS: Of 245 pregnant women included in the intention-to-treat analysis, 93.9% cleared their parasitaemia by day 7. The day 42 PCR-uncorrected survival rate was 58.1% (95% confidence interval (CI) 51.5-65.7) and day 42 PCR-corrected survival was 68.7% (CI 61.4-76.0). Recrudescence was more common among primi- than among multigravid women; recrudescence rate 33.3% (CI 25.1-42.4%) versus 21.4% (CI 15.0-29.0%) (log rank test p-value 0.006). The quintuple mutant was present in nearly all samples (95%), while 2% were sextuple mutants with an additional mutation at dhps A581G. CONCLUSIONS: SP efficacy for acute malaria treatment has been compromised by resistance, but SP retains partial activity among pregnant women with asymptomatic parasitaemia, and thus might be useful for IPTp. Nonetheless, research on non-SP IPTp regimens should continue. TRIAL REGISTRATION: ClinicalTrials.gov NCT01120145 .

Home visits to assess the reliability of caregiver-reported use of insecticide-treated bednets by children in Machinga District, Malawi.

A malaria cohort study was conducted among young children in Machinga District, Malawi, following distribution of insecticide-treated bednets (ITNs) in May 2012. To assess ITN use, two independently sampled subsets of children (211 during survey 1 [December 2012-January 2013] and 325 during survey 2 [September-October 2013]) were randomly selected to compare the proportions of positive and negative agreement between caregiver verbal reports at monthly interviews with visual observation of the ITN at home visits. Caregiver-reported ITN use was consistently high during both surveys (98.1% and 96.0%, respectively; P = 0.17). Home visit-based ITN use fell significantly (P < 0.001) from survey 1 (98.6%) to survey 2 (88.6%). The proportions of positive agreement between caregiver report and home visit in the first and second surveys were 98.8% (95% confidence interval [CI] 97.6-99.8%) and 93.3% (95% CI 91.2-95.3%), respectively. The proportions of negative agreement in the first and second surveys were 28.6% (95% CI 0-75.0%) and 20.0% (95% CI 0.1-35.0%), respectively. ITN use by children was high in Machinga District, and caregiver reports and home visits with visual confirmation of the net demonstrated a high level of agreement for use of ITNs, but a low level of agreement when ITNs were not used.

The A581G Mutation in the Gene Encoding Plasmodium falciparum Dihydropteroate Synthetase Reduces the Effectiveness of Sulfadoxine-Pyrimethamine Preventive Therapy in Malawian Pregnant Women.

BACKGROUND: The A581 G: mutation in the gene encoding Plasmodium falciparum dihydropteroate synthase (dhps), in combination with the quintuple mutant involving mutations in both dhps and the gene encoding dihydrofolate reductase (dhfr), the so-called sextuple mutant, has been associated with increased placental inflammation and decreased infant birth weight among women receiving intermittent preventive treatment with sulfadoxine-pyrimethamine (IPTp-SP) during pregnancy. METHODS: Between 2009 and 2011, delivering women without human immunodeficiency virus infection were enrolled in an observational study of IPTp-SP effectiveness in Malawi. Parasites were detected by polymerase chain reaction (PCR); positive samples were sequenced to genotype the dhfr and dhps loci. The presence of K540 E: in dhps was used as a marker for the quintuple mutant. RESULTS: Samples from 1809 women were analyzed by PCR; 220 (12%) were positive for P. falciparum. A total of 202 specimens were genotyped at codon 581 of dhps; 17 (8.4%) harbored the sextuple mutant. The sextuple mutant was associated with higher risks of patent infection in peripheral blood (adjusted prevalence ratio [aPR], 2.76; 95% confidence interval [CI], 1.82-4.18) and placental blood (aPR 3.28; 95% CI, 1.88-5.78) and higher parasite densities. Recent SP use was not associated with increased parasite densities or placental pathology overall and among women with parasites carrying dhps A581 G: . CONCLUSIONS: IPTp-SP failed to inhibit parasite growth but did not exacerbate pathology among women infected with sextuple-mutant parasites. New interventions to prevent malaria during pregnancy are needed urgently.

A cohort study of the effectiveness of insecticide-treated bed nets to prevent malaria in an area of moderate pyrethroid resistance, Malawi.

BACKGROUND: Insecticide-treated bed nets (ITNs) are the cornerstone of malaria control in sub-Saharan Africa but their effectiveness may be compromised by the spread of pyrethroid resistance among malaria vectors. The objective of this investigation was to assess the effectiveness of ITNs to prevent malaria in an area of Malawi with moderate pyrethroid resistance. METHODS: One deltamethrin ITN was distributed in the study area for every two individuals in each household plus one extra ITN for households with an odd number of residents. A fixed cohort of 1,199 children aged six to 59 months was seen monthly for one year and at sick visits to measure malaria infection and use of ITNs. Insecticide resistance among malaria vectors was measured. The effect of ITN use on malaria incidence was assessed, adjusting for potential confounders using generalized estimating equations accounting for repeated measures. RESULTS: There were 1,909 infections with Plasmodium falciparum over 905 person-years at risk (PYAR), resulting in an observed incidence of 2.1 infections per person-year (iPPY). ITNs were used during 97% of the PYAR. The main vector was Anopheles funestus: mortality in WHO tube assays after exposure to 0.05% deltamethrin was 38% (95% confidence interval (CI) 29-47), and resistance was due to elevated oxidase enzymes. After adjusting for potential confounders, the incidence of malaria infection among ITN users was 1.7 iPPY (95% CI 1.5-2.1) and among non-bed net users was 2.6 iPPY (95% CI 2.0-3.3). Use of ITNs reduced the incidence of malaria infection by 30% (rate ratio 0.7; 95% CI, 0.5-0.8) compared to no bed nets. CONCLUSION: ITNs significantly reduced the incidence of malaria infection in children in an area with moderate levels of pyrethroid resistance and considerable malaria transmission. This is the first study to show that ITNs provide protection in areas where pyrethroid-resistant An. funestus is the major malaria vector. Malaria control programmes should continue to distribute and promote ITNs in areas with low to moderate pyrethroid resistance; however, insecticide resistance may intensify further and it is not known whether ITNs will remain effective at higher levels of resistance. There is an urgent need to identify or develop new insecticides and technologies to limit the vulnerability of ITNs to insecticide resistance.

Pooled PCR testing strategy and prevalence estimation of submicroscopic infections using Bayesian latent class models in pregnant women receiving intermittent preventive treatment at Machinga District Hospital, Malawi, 2010.

BACKGROUND: Low malaria parasite densities in pregnancy are a diagnostic challenge. PCR provides high sensitivity and specificity in detecting low density of parasites, but cost and technical requirements limit its application in resources-limited settings. Pooling samples for PCR detection was explored to estimate prevalence of submicroscopic malaria infection in pregnant women at delivery. Previous work uses gold-standard based methods to calculate sensitivity and specificity of tests, creating a challenge when newer methodologies are substantially more sensitive than the gold standard. Thus prevalence was estimated using Bayesian latent class models (LCMs) in this study. METHODS: Nested PCR (nPCR) for the 18S rRNA gene subunit of Plasmodium falciparum was conducted to detect malaria infection in microscopy-negative Malawian women on IPTp. Two-step sample pooling used dried blood spot samples (DBSs) collected from placenta or periphery at delivery. Results from nPCR and histology as well as previously published data were used to construct LCMs to estimate assay sensitivity and specificity. Theoretical confidence intervals for prevalence of infection were calculated for two-step and one-step pooling strategies. RESULTS: Of 617 microscopy-negative Malawian women, 39 (6.3%) were identified as actively infected by histology while 52 (8.4%) were positive by nPCR. One hundred forty (22.7%) individuals had past infection assessed by histology. With histology as a reference, 72% of women in the active infection group, 7.1% in the past infection group and 3.2% in histology-negative group were nPCR positive. Using latent class models without a gold standard, histology had a median sensitivity of 49.7% and specificity of 97.6% for active infection while PCR had a median sensitivity of 96.0% and specificity of 99.1%. The true prevalence of active infection was estimated at 8.0% (CI: 5.8-10.5%) from PCR. PCR also had similar sensitivity for detecting either peripheral or placental malaria for submicroscopic infections. One-step pooling would give similar confidence intervals for pool sizes less than 20 while reducing the number of tests performed. CONCLUSIONS: Pooled nPCR testing was a sensitive and resource-efficient strategy and LCMs provided precise prevalence estimates of submicroscopic infections. Compared to two-step pooling, one-step pooling could provide similar prevalence estimates at population levels with many fewer tests required.

Elevated dry-season malaria prevalence associated with fine-scale spatial patterns of environmental risk: a case-control study of children in rural Malawi.

BACKGROUND: Understanding the role of local environmental risk factors for malaria in holo-endemic, poverty-stricken settings will be critical to more effectively implement- interventions aimed at eventual elimination. Household-level environmental drivers of malaria risk during the dry season were investigated in rural southern Malawi among children < five years old in two neighbouring rural Traditional Authority (TA) regions dominated by small-scale agriculture. METHODS: Ten villages were randomly selected from TA Sitola (n = 6) and Nsamala (n = 4). Within each village, during June to August 2011, a census was conducted of all households with children under-five and recorded their locations with a geographic position system (GPS) device. At each participating house, a nurse administered a malaria rapid diagnostic test (RDT) to children under five years of age, and a questionnaire to parents. Environmental data were collected for each house, including land cover within 50-m radius. Variables found to be significantly associated with P. falciparum infection status in bivariate analysis were included in generalized linear models, including multivariate logistic regression (MLR) and multi-level multivariate logistic regression (MLLR). Spatial clustering of RDT status, environmental factors, and Pearson residuals from MLR and MLLR were analysed using the Getis-Ord Gi* statistic. RESULTS: Of 390 children enrolled from six villages in Sitola (n = 162) and four villages in Nsamala (n = 228), 45.6% tested positive (n = 178) for Plasmodium infection by RDT. The MLLR modelled the statistical relationship of Plasmodium positives and household proximity to agriculture (<25-m radius), controlling for the child sex and age (in months), bed net ownership, elevation, and random effects intercepts for village and TA-level unmeasured factors. After controlling for area affects in MLLR, proximity to active agriculture remained a significant predictor of positive RDT result (OR 2.80, 95% CI 1.41-5.55). Mapping of Pearson residuals from MLR showed significant clustering (Gi* z > 2.58, p < 0.01) predominantly within TA Sitola, while residuals from MLLR showed no such clustering. CONCLUSION: This study provides evidence for significant, dry-season heterogeneity of malaria prevalence strongly linked to peridomestic land use, and particularly of elevated risk associated with nearby crop production.

Effectiveness of intermittent preventive treatment with sulfadoxine-pyrimethamine during pregnancy on maternal and birth outcomes in Machinga district, Malawi.

BACKGROUND: Malaria during pregnancy is associated with low birth weight and increased perinatal mortality, especially among primigravidae. Despite increasing prevalence of malarial parasite resistance to sulfadoxine-pyrimethamine (SP), SP continues to be recommended for intermittent preventive treatment in pregnancy (IPTp). METHODS: Women without human immunodeficiency virus infection were enrolled upon delivery. Data on the number of SP doses received during pregnancy were recorded. The primary outcome was placental infection demonstrated by histologic analysis. Secondary outcomes included malaria parasitemia (in peripheral, placental, cord blood specimens) at delivery and composite birth outcome (small for gestational age, preterm delivery, or low birth weight). RESULTS.: Of 703 women enrolled, 22% received <2 SP doses. Receipt of ≥ 2 SP doses had no impact on histologically confirmed placental infection. IPTp-SP was associated with a dose-dependent protective effect on composite birth outcome in primigravidae, with an adjusted prevalence ratio of 0.50 (95% confidence interval [CI], .30-.82), 0.30 (95% CI, .19-.48), and 0.18 (95% CI, .05-.61) for 1, 2, and ≥ 3 doses, respectively, compared with 0 doses. CONCLUSIONS: IPTp-SP did not reduce the frequency of placental infection but was associated with improved birth outcomes. Few women received no SP, so the true effect of IPTp-SP may be underestimated. Malawian pregnant women should continue to receive IPTp-SP, but alternative strategies and antimalarials for preventing malaria during pregnancy should be investigated.

Impact of indoor residual spraying with lambda-cyhalothrin on malaria parasitemia and anemia prevalence among children less than five years of age in an area of intense, year-round transmission in Malawi.

Little is known about the impact of indoor residual spraying (IRS) in areas with intense malaria transmission such as sub-Saharan Africa. In Malawi, IRS with lambda-cyhalothrin has been applied annually in an area of intense year-long transmission since 2007. We evaluated the impact of IRS on parasitemia and anemia prevalence in children less than five years of age by using a cross-sectional household survey conducted in 2009, six months after the second IRS spray round. We measured malaria parasitemia and anemia (hemoglobin level < 11 g/dL) in 899 children less than five years of age and used binomial regression to assess the impact of IRS by comparing children living in a household sprayed with IRS (direct IRS) with those in a household not sprayed with IRS, but in an IRS area (indirect IRS) and those living in a household not sprayed with IRS and not in an IRS area (no IRS). In the IRS area, 77% of households reported receiving IRS. Adjusting for bed net use, house construction, and socioeconomic status, we found that receiving direct IRS and indirect IRS were significantly associated with a 33% (95% confidence interval [CI] = 1-54%) and 46% (95% CI = 20-64%) reduction in parasitemia and a 21% (95% CI = 4-34%) and 30% (95% CI = 12-45%) reduction in anemia prevalence, respectively.

Adherence to treatment with artemether-lumefantrine for uncomplicated malaria in rural Malawi.

BACKGROUND: In 2007, Malawi replaced the first-line medication for uncomplicated malaria, sulfadoxine-pyrimethamine-a single-dose regimen-with artemether-lumefantrine (AL)-a 6-dose, 3-day regimen. Because of concerns about the complex dosing schedule, we assessed patient adherence to AL 2 years after routine implementation. METHODS: Adults and children with uncomplicated malaria were recruited at 3 health centers. We conducted both pill counts and in-home interviews on medication consumption 72 hours after patients received AL. Complete adherence was defined as correctly taking all 6 AL doses, as assessed by pill count and dose recall. We used logistic regression to identify factors associated with complete adherence. RESULTS: Of 386 patients, 65% were completely adherent. Patients were significantly more likely to be completely adherent if they received their first dose of AL as directly observed therapy at the health center (odds ratio [OR], 2.4; P < .01), received instructions using the medication package as a visual aid (OR, 2.5; P = .02), and preferred AL over other antimalarials (OR, 2.7; P < .001). In contrast, children <5 years of age were significantly less likely to be adherent (OR, 0.5; P = .05). CONCLUSIONS: Adherence to AL treatment for uncomplicated malaria was moderate, and children, who are the most likely to die of malaria, were less adherent than adults. Efforts to improve adherence should be focused on this vulnerable group. Interventions including the introduction of child-friendly antimalarial formulations, direct observation of the first dose, use of the AL package as a visual aid for instructions, and enhancing patient preference for AL could potentially increase AL adherence and overall effectiveness.

Impact of health facility-based insecticide treated bednet distribution in Malawi: progress and challenges towards achieving universal coverage.

BACKGROUND: High levels of insecticide treated bednet (ITN) use reduce malaria burden in countries with intense transmission such as Malawi. Since 2007 Malawi has implemented free health facility-based ITN distribution for pregnant women and children <5 years old (under-5s). We evaluated the progress of this targeted approach toward achieving universal ITN coverage. METHODS: We conducted a cross-sectional household survey in eight districts in April 2009. We assessed household ITN possession, ITN use by all household members, and P. falciparum asexual parasitemia and anemia (hemoglobin <11 grams/deciliter) in under-5s. RESULTS: We surveyed 7,407 households containing 29,806 persons. Fifty-nine percent of all households (95% confidence interval [95% CI]: 56-62), 67% (95% CI: 64-70) of eligible households (i.e., households with pregnant women or under-5s), and 40% (95% CI: 36-45) of ineligible households owned an ITN. In households with at least one ITN, 76% (95% CI: 74-78) of all household members, 88% (95% CI: 87-90) of under-5s and 90% (95% CI: 85-94) of pregnant women used an ITN the previous night. Of 6,677 ITNs, 92% (95% CI: 90-94) were used the previous night with a mean of 2.4 persons sleeping under each ITN. In multivariable models adjusting for district, socioeconomic status and indoor residual spraying use, ITN use by under-5s was associated with a significant reduction in asexual parasitemia (adjusted odds ratio (aOR) 0.79; 95% CI: 0.64-0.98; p-value 0.03) and anemia (aOR 0.79; 95% CI 0.62-0.99; p-value 0.04). Of potential targeted and non-targeted mass distribution strategies, a campaign distributing 1 ITN per household might increase coverage to 2.1 household members per ITN, and thus achieve near universal coverage often defined as 2 household members per ITN. CONCLUSIONS: Malawi has substantially increased ITN coverage using health facility-based distribution targeting pregnant women and under-5s, but needs to supplement these activities with non-targeted mass distribution campaigns to achieve universal coverage and maximum public health impact.