Laura C. Steinhardt

The silent threat: asymptomatic parasitemia and malaria transmission

Scale-up of malaria control interventions has resulted in a substantial decline in global malaria morbidity and mortality. Despite this achievement, there is evidence that current interventions alone will not lead to malaria elimination in most malaria-endemic areas and additional strategies need to be considered. Use of antimalarial drugs to target the reservoir of malaria infection is an option to reduce the transmission of malaria between humans and mosquito vectors. However, a large proportion of human malaria infections are asymptomatic, requiring treatment that is not triggered by care-seeking for clinical illness. This article reviews the evidence that asymptomatic malaria infection plays an important role in malaria transmission and that interventions to target this parasite reservoir may be needed to achieve malaria elimination in both low- and high-transmission areas.

The Effect of Indoor Residual Spraying on Malaria and Anemia in a High-Transmission Area of Northern Uganda

Indoor residual spraying (IRS) with insecticide is now recommended for malaria control in high-transmission settings. However, concerns about insecticide resistance have increased. We conducted a cross-sectional household survey in high-transmission northern Uganda in two districts previously sprayed with pyrethroids before documentation of pyrethroid resistance and at least one round of carbamates and in one contiguous district that was not sprayed. Parasitemia prevalence among children < 5 years of age was lower in the two IRS districts compared with the non-sprayed district: 37.0% and 16.7% versus 49.8%, P < 0.001. Anemia prevalence was also significantly lower in the two IRS districts: 38.8% and 36.8% versus 53.0%, P < 0.001. Multivariable Poisson regression models indicated that a child living in a sprayed district had a 46% and 32% lower risk of parasitemia and anemia, respectively, than a child in a non-sprayed district (P < 0.001). Carefully managed IRS can significantly reduce malaria burden in high-transmission settings.

Quality of Malaria Case Management in Malawi: Results from a Nationally Representative Health Facility Survey

Background Malaria is endemic throughout Malawi, but little is known about quality of malaria case management at publicly-funded health facilities, which are the major source of care for febrile patients. Methods In April–May 2011, we conducted a nationwide, geographically-stratified health facility survey to assess the quality of outpatient malaria diagnosis and treatment. We enrolled patients presenting for care and conducted exit interviews and re-examinations, including reference blood smears. Moreover, we assessed health worker readiness (e.g., training, supervision) and health facility capacity (e.g. availability of diagnostics and antimalarials) to provide malaria case management. All analyses accounted for clustering and unequal selection probabilities. We also used survey weights to produce estimates of national caseloads. Results At the 107 facilities surveyed, most of the 136 health workers interviewed (83%) had received training on malaria case management. However, only 24% of facilities had functional microscopy, 15% lacked a thermometer, and 19% did not have the first-line artemisinin-based combination therapy (ACT), artemether-lumefantrine, in stock. Of 2,019 participating patients, 34% had clinical malaria (measured fever or self-reported history of fever plus a positive reference blood smear). Only 67% (95% confidence interval (CI): 59%, 76%) of patients with malaria were correctly prescribed an ACT, primarily due to missed malaria diagnosis. Among patients without clinical malaria, 31% (95% CI: 24%, 39%) were prescribed an ACT. By our estimates, 1.5 million of the 4.4 million malaria patients seen in public facilities annually did not receive correct treatment, and 2.7 million patients without clinical malaria were inappropriately given an ACT. Conclusions Malawi has a high burden of uncomplicated malaria but nearly one-third of all patients receive incorrect malaria treatment, including under- and over-treatment. To improve malaria case management, facilities must at minimum have basic case management tools, and health worker performance in diagnosing malaria must be improved.

Long-lasting insecticide-treated bed net ownership and use among children under five years of age following a targeted distribution in central Uganda

BackgroundUniversal coverage of long-lasting insecticide-treated bed nets (LLINs) for prevention of malaria was adopted by the Uganda National Malaria Control Programme in 2007. The first mass distribution of LLINs was implemented in 2010. Initially, a campaign targeted to households with pregnant women and children aged <five years was carried out, prior to a planned fill-in campaign to achieve universal LLIN coverage. This survey was conducted after the targeted distribution in central Uganda to assess progress in LLIN ownership and usage among children <five years.MethodsA two-stage, cluster-sample, cross-sectional household survey was carried out in early 2011 in Central region districts surveyed during the 2009 Malaria Indicator Survey (MIS). In the first sampling stage, 30 enumeration areas (EAs) were selected and all households were enumerated. Within each sampled EA, 20 households were randomly selected for interview using two questionnaires: a household questionnaire and a woman’s questionnaire for all women aged 15-49 years, both modified from the MIS.ResultsWhen compared to 2009 MIS results, household ownership of at least one LLIN increased by 47%, from 22 to 69% after the targeted campaign. LLIN use among children <five years increased by 40%, from 11 to 51%. Households with a child <six years old at the time of the survey, a proxy for those targeted, were significantly more likely to have received a campaign bed net (80.7 vs 35.2%, p < 0.001). LLIN ownership and use was equitable after the targeted campaign, with no significant differences by household wealth status.However, the proportion of households with at least one LLIN per two people was still low after the first campaign phase, increasing from 8.5 to 25.9%.ConclusionsThe first phase of the campaign led to substantial increases in both LLIN ownership and equitable use among children <five years in the Central region. However, access to an LLIN within the household was still low after the first phase of the campaign, indicating the need for the universal fill-in campaign.

Patient-, health worker-, and health facility-level determinants of correct malaria case management at publicly funded health facilities in Malawi: results from a nationally representative health facility survey

BackgroundPrompt and effective case management is needed to reduce malaria morbidity and mortality. However, malaria diagnosis and treatment is a multistep process that remains problematic in many settings, resulting in missed opportunities for effective treatment as well as overtreatment of patients without malaria.MethodsPrior to the widespread roll-out of malaria rapid diagnostic tests (RDTs) in late 2011, a national, cross-sectional, complex-sample, health facility survey was conducted in Malawi to assess patient-, health worker-, and health facility-level factors associated with malaria case management quality using multivariate Poisson regression models.ResultsAmong the 2,019 patients surveyed, 34% had confirmed malaria defined as presence of fever and parasitaemia on a reference blood smear. Sixty-seven per cent of patients with confirmed malaria were correctly prescribed the first-line anti-malarial, with most cases of incorrect treatment due to missed diagnosis; 31% of patients without confirmed malaria were overtreated with an anti-malarial. More than one-quarter of patients were not assessed for fever or history of fever by health workers. The most important determinants of correct malaria case management were patient-level clinical symptoms, such as spontaneous complaint of fever to health workers, which increased both correct treatment and overtreatment by 72 and 210%, respectively (p < 0.0001). Complaint of cough was associated with a 27% decreased likelihood of correct malaria treatment (p = 0.001). Lower-level cadres of health workers were more likely to prescribe anti-malarials for patients, increasing the likelihood of both correct treatment and overtreatment, but no other health worker or health facility-level factors were significantly associated with case management quality.ConclusionsIntroduction of RDTs holds potential to improve malaria case management in Malawi, but health workers must systematically assess all patients for fever, and then test and treat accordingly, otherwise, malaria control programmes might miss an opportunity to dramatically improve malaria case management, despite better diagnostic tools.

Review: Malaria Chemoprophylaxis for Travelers to Latin America

Because of recent declining malaria transmission in Latin America, some authorities have recommended against chemoprophylaxis for most travelers to this region. However, the predominant parasite species in Latin America, Plasmodium vivax, can form hypnozoites sequestered in the liver, causing malaria relapses. Additionally, new evidence shows the potential severity of vivax infections, warranting continued consideration of prophylaxis for travel to Latin America. Individualized travel risk assessments are recommended and should consider travel locations, type, length, and season, as well as probability of itinerary changes. Travel recommendations might include no precautions, mosquito avoidance only, or mosquito avoidance and chemoprophylaxis. There are a range of good options for chemoprophylaxis in Latin America, including atovaquone-proguanil, doxycycline, mefloquine, and--in selected areas--chloroquine. Primaquine should be strongly considered for nonpregnant, G6PD-nondeficient patients traveling to vivax-endemic areas of Latin America, and it has the added benefit of being the only drug to protect against malaria relapses.

Effectiveness of insecticide-treated bednets in malaria prevention in Haiti: a case-control study

BACKGROUND Insecticide-treated bednets (ITNs) are effective in preventing malaria where vectors primarily bite indoors and late at night, but their effectiveness is uncertain where vectors bite outdoors and earlier in the evening. We studied the effectiveness of ITNs following a mass distribution in Haiti from May to September, 2012, where the Anopheles albimanus vector bites primarily outdoors and often when people are awake. METHODS In this case-control study, we enrolled febrile patients presenting to outpatient departments at 17 health facilities throughout Haiti from Sept 4, 2012, to Feb 27, 2014, who were tested with malaria rapid diagnostic tests (RDTs), and administered questionnaires on ITN use and other risk factors. Cases were defined by positive RDT and controls were febrile patients from the same clinic with a negative RDT. Our primary analysis retrospectively matched cases and controls by age, sex, location, and date, and used conditional logistic regression on the matched sample. A sensitivity analysis used propensity scores to match patients on ITN use propensity and analyse malaria among ITN users and non-users. Additional ITN bioefficacy and entomological data were collected. FINDINGS We enrolled 9317 patients, including 378 (4%) RDT-positive cases. 1202 (13%) patients reported ITN use. Post-hoc matching of cases and controls yielded 362 cases and 1201 matched controls, 19% (333) of whom reported consistent campaign net use. After using propensity scores to match on consistent campaign ITN use, 2298 patients, including 138 (7%) RDT-positive cases, were included: 1149 consistent campaign ITN users and 1149 non-consistent campaign ITN users. Both analyses revealed that ITNs did not significantly protect against clinical malaria (odds ratio [OR]=0·95, 95% CI 0·68-1·32, p=0·745 for case-control analysis; OR=0·95, 95% CI 0·45-1·97, p=0·884 for propensity score analysis). ITN and entomological data indicated good ITN physical integrity and bioefficacy, and no permethrin resistance among local mosquitoes. INTERPRETATION We found no evidence that mass ITN campaigns reduce clinical malaria in this observational study in Haiti; alternative malaria control strategies should be prioritised. FUNDING The Global Fund to Fight AIDS, Tuberculosis, and Malaria, and the US-based Centers for Disease Control and Prevention (CDC).

Capacity Development through the US President’s Malaria Initiative–Supported Antimalarial Resistance Monitoring in Africa Network

Antimalarial drug resistance is an evolving global health security threat to malaria control. Early detection of Plasmodium falciparum resistance through therapeutic efficacy studies and associated genetic analyses may facilitate timely implementation of intervention strategies. The US President’s Malaria Initiative–supported Antimalarial Resistance Monitoring in Africa Network has assisted numerous laboratories in partner countries in acquiring the knowledge and capability to independently monitor for molecular markers of antimalarial drug resistance.

Universal versus conditional day 3 follow-up for children with non-severe unclassified fever at the community level in Ethiopia: A cluster-randomised non-inferiority trial

Background With declining malaria prevalence and improved use of malaria diagnostic tests, an increasing proportion of children seen by community health workers (CHWs) have unclassified fever. Current community management guidelines by WHO advise that children seen with non-severe unclassified fever (on day 1) should return to CHWs on day 3 for reassessment. We compared the safety of conditional follow-up reassessment only in cases where symptoms do not resolve with universal follow-up on day 3. Methods and findings We undertook a 2-arm cluster-randomised controlled non-inferiority trial among children aged 2–59 months presenting with fever and without malaria, pneumonia, diarrhoea, or danger signs to 284 CHWs affiliated with 25 health centres (clusters) in Southern Nations, Nationalities, and Peoples’ Region, Ethiopia. The primary outcome was treatment failure (persistent fever, development of danger signs, hospital admission, death, malaria, pneumonia, or diarrhoea) at 1 week (day 8) of follow-up. Non-inferiority was defined as a 4% or smaller difference in the proportion of treatment failures with conditional follow-up compared to universal follow-up. Secondary outcomes included the percentage of children brought for reassessment, antimicrobial prescription, and severe adverse events (hospitalisations and deaths) after 4 weeks (day 29). From December 1, 2015, to November 30, 2016, we enrolled 4,595 children, of whom 3,946 (1,953 universal follow-up arm; 1,993 conditional follow-up arm) adhered to the CHW’s follow-up advice and also completed a day 8 study visit within ±1 days. Overall, 2.7% had treatment failure on day 8: 0.8% (16/1,993) in the conditional follow-up arm and 4.6% (90/1,953) in the universal follow-up arm (risk difference of treatment failure −3.81%, 95% CI −∞, 0.65%), meeting the prespecified criterion for non-inferiority. There were no deaths recorded by day 29. In the universal follow-up arm, 94.6% of caregivers reported returning for reassessment on day 3, in contrast to 7.5% in the conditional follow-up arm (risk ratio 22.0, 95% CI 17.9, 27.2, p < 0.001). Few children sought care from another provider after their initial visit to the CHW: 3.0% (59/1,993) in the conditional follow-up arm and 1.1% (22/1,953) in the universal follow-up arm, on average 3.2 and 3.4 days later, respectively, with no significant difference between arms (risk difference 1.79%, 95% CI −1.23%, 4.82%, p = 0.244). The mean travel time to another provider was 2.2 hours (95% CI 0.01, 5.3) in the conditional follow-up arm and 2.6 hours (95% CI 0.02, 4.5) in the universal follow-up arm (p = 0.82); the mean cost for seeking care after visiting the CHW was 26.5 birr (95% CI 7.8, 45.2) and 22.8 birr (95% CI 15.6, 30.0), respectively (p = 0.69). Though this study was an important step to evaluate the safety of conditional follow-up, the high adherence seen may have resulted from knowledge of the 1-week follow-up visit and may therefore not transfer to routine practice; hence, in an implementation setting it is crucial that CHWs are well trained in counselling skills to advise caregivers on when to come back for follow-up. Conclusions Conditional follow-up of children with non-severe unclassified fever in a low malaria endemic setting in Ethiopia was non-inferior to universal follow-up through day 8. Allowing CHWs to advise caregivers to bring children back only in case of continued symptoms might be a more efficient use of resources in similar settings. Trial registration www.clinicaltrials.gov, identifier NCT02926625

Universal versus conditional day 3 follow-up for children with non-severe unclassified fever at the community level in the Democratic Republic of the Congo: A cluster-randomized, community-based non-inferiority trial

Background The World Health Organization’s integrated community case management (iCCM) guidelines recommend that all children presenting with uncomplicated fever and no danger signs return for follow-up on day 3 following the initial consultation on day 1. Such fevers often resolve rapidly, however, and previous studies suggest that expectant home care for uncomplicated fever can be safely recommended. We aimed to determine if a conditional follow-up visit was non-inferior to a universal follow-up visit for these children. Methods and findings We conducted a cluster-randomized, community-based non-inferiority trial among children 2–59 months old presenting to community health workers (CHWs) with non-severe unclassified fever in Tanganyika Province, Democratic Republic of the Congo. Clusters (n = 28) of CHWs were randomized to advise caregivers to either (1) return for a follow-up visit on day 3 following the initial consultation on day 1, regardless of illness resolution (as per current WHO guidelines; universal follow-up group) or (2) return for a follow-up visit on day 3 only if illness continued (conditional follow-up group). Children in both arms were assessed again at day 8, and classified as a clinical failure if fever (caregiver-reported), malaria, diarrhea, pneumonia, or decline of health status (development of danger signs, hospitalization, or death) was noted (failure definition 1). Alternative failure definitions were examined, whereby caregiver-reported fever was first restricted to caregiver-reported fever of at least 3 days (failure definition 2) and then replaced with fever measured via axillary temperature (failure definition 3). Study participants, providers, and investigators were not masked. Among 4,434 enrolled children, 4,141 (93.4%) met the per-protocol definition of receipt of the arm-specific advice from the CHW and a timely day 8 assessment (universal follow-up group: 2,210; conditional follow-up group: 1,931). Failure was similar (difference: –0.7%) in the conditional follow-up group (n = 188, 9.7%) compared to the universal follow-up group (n = 230, 10.4%); however, the upper bound of a 1-sided 95% confidence interval around this difference (−∞, 5.1%) exceeded the prespecified non-inferiority margin of 4.0% (non-inferiority p = 0.089). When caregiver-reported fever was restricted to fevers lasting ≥3 days, failure in the conditional follow-up group (n = 159, 8.2%) was similar to that in the universal follow-up group (n = 200, 9.1%) (difference: −0.8%; 95% CI: −∞, 4.1%; p = 0.053). If caregiver-reported fever was replaced by axillary temperature measurement in the definition of failure, failure in the conditional follow-up group (n = 113, 5.9%) was non-inferior to that in the universal follow-up group (n = 160, 7.2%) (difference: −1.4%; 95% CI: −∞, 2.5%; p = 0.012). In post hoc analysis, when the definition of failure was limited to malaria, diarrhea, pneumonia, development of danger signs, hospitalization, or death, failure in the conditional follow-up group (n = 108, 5.6%) was similar to that in the universal follow-up group (n = 147, 6.7%), and within the non-inferiority margin (95% CI: −∞, 2.9%; p = 0.017). Limitations include initial underestimation of the proportion of clinical failures as well as substantial variance in cluster-specific failure rates, reducing the precision of our estimates. In addition, heightened security concerns slowed recruitment in the final months of the study. Conclusions We found that advising caregivers to return only if children worsened or remained ill on day 3 resulted in similar rates of caregiver-reported fever and other clinical outcomes on day 8, compared to advising all caregivers to return on day 3. Policy-makers could consider revising guidelines for management of uncomplicated fever within the iCCM framework. Trial registration ClinicalTrials.gov NCT02595827