Utility of Health Facility-based Malaria Data for Malaria Surveillance

Abstract

BackgroundCurrently, intensive malaria control programs are being implemented in Africa to reduce the malaria burden. Clinical malaria data from hospitals are valuable for monitoring trends in malaria morbidity and for evaluating the impacts of these interventions. However, the reliability of hospital-based data for true malaria incidence is often questioned because of diagnosis accuracy issues and variation in access to healthcare facilities among sub-groups of the population. This study investigated how diagnosis and treatment practices of malaria cases in hospitals affect reliability of hospital malaria data.Methodology/Principal FindingsThe study was undertaken in health facilities in western Kenya. A total of 3,569 blood smears were analyzed after being collected from patients who were requested by clinicians to go to the hospital’s laboratory for malaria testing. We applied several quality control measures for clinical malaria diagnosis. We compared our slide reading results with those from the hospital technicians. Among the 3,390 patients whose diagnoses were analyzed, only 36% had clinical malaria defined as presence of any level of parasitaemia and fever. Sensitivity and specificity of clinicians’ diagnoses were 60.1% (95% CI: 61.1−67.5) and 75.0% (95% CI: 30.8−35.7), respectively. Among the 980 patients presumptively treated with an anti-malarial by the clinicians without laboratory diagnosis, only 47% had clinical malaria.Conclusions/SignificanceThese findings revealed substantial over-prescription of anti-malarials and misdiagnosis of clinical malaria. More than half of the febrile cases were not truly clinical malaria, but were wrongly diagnosed and treated as such. Deficiency in malaria diagnosis makes health facility data unreliable for monitoring trends in malaria morbidity and for evaluating impacts of malaria interventions. Improving malaria diagnosis should be a top priority in rural African health centers.

Clinical performance of an automated reader in interpreting malaria rapid diagnostic tests in Tanzania

“…It is well known that microscopy is an imperfect subjective diagnostic method with multiple factors affecting interpretation of blood smears, such as variability in techniques of blood film preparation, staining, reading standards, and most importantly high dependency on the level of expertise of the examining microscopists [17,22-26]. Therefore, to limit these difficulties, microscopy in this study was performed by experienced technicians in a single referral centre who analysed films independently and were blinded to the RDT results.…”

Seasonal dynamics and microgeographical spatial heterogeneity of malaria along the China–Myanmar border

“…Trained nurses collected blood samples by a standard finger-prick method, and thick and thin smears were prepared on labeled slides for parasite species identification. A clinical malaria case was defined as an individual with malaria-related symptoms (fever, i.e., axillary temperature ≥ 37.5°C, chills, severe malaise, headache or vomiting) at the time of examination or 1-2 days prior to the examination with a Plasmodium -positive blood smear (Afrane et al, 2013; Zhou et al, 2015). Parasites were identified microscopically by two experienced technologists.…”

“…Parasites were identified microscopically by two experienced technologists. For quality control purpose, a third microscopist confirmed parasite identification by random analysis of ~ 5% of the slides (Afrane et al, 2013; Zhou et al, 2015). …”

High Levels of Asymptomatic and Subpatent Plasmodium falciparum Parasite Carriage at Health Facilities in an Area of Heterogeneous Malaria Transmission Intensity in the Kenyan Highlands

“…In addition, the experience of the laboratory and clinical personnel, quality of microscopy, particular brand or availability of RDTs, and time dedicated to malaria testing are also important potential sources of bias, making results difficult to compare. 6,7 Health facility-based cross-sectional surveys that sample from all individuals presenting at the facility as well as any accompanying individuals (as distinct from sampling only among individuals with suspected malaria) have been shown to be a useful tool for measuring malaria transmission intensity. 8,9 Health facility surveys provide an operationally attractive method to estimate malaria prevalence in the wider catchment population, because the inclusion of all health facility attendees mitigates against some of the biases associated with passive case detection.…”

“…8,9 Health facility surveys provide an operationally attractive method to estimate malaria prevalence in the wider catchment population, because the inclusion of all health facility attendees mitigates against some of the biases associated with passive case detection. 7,10 However, most health facility malaria surveys have relied on diagnosis by microscopy or RDT, both of which have a limited ability to detect parasitemia at low parasite densities. 8,11,12 The number of malaria infections detected through these surveys is, therefore, likely to have been substantially lower than would have been achieved using a more sensitive diagnostic approach, such as polymerase chain reaction (PCR).…”