Research

Malaria misdiagnosis in Uganda – implications for policy change

Joan Nankabirwa¹ , Dejan Zurovac^2,3,4 , Julius N Njogu² , John B Rwakimari⁵ , Helen Counihan⁶ , Robert W Snow^2,3 and James K Tibenderana^1,7

¹  Malaria Consortium, Africa Regional Office, Sturrock Road, Kampala, Uganda

²  Malaria Public Health and Epidemiology Group, KEMRI/Wellcome Trust Research Programme, PO Box 43640, 00100 GPO, Nairobi, Kenya

³  Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, CCVTM, Oxford, UK

⁴  Center for International Health and Development, Boston University School of Public Health, Crosstown 3rd floor, 801 Massachusetts Ave, Boston, MA 02118, USA

⁵  Ministry of Health, National Malaria Control Programme, Kampala, Uganda

⁶  Malaria Consortium, Development House, 56-64 Leonard Street, London EC2A 4LT

⁷  London School of Hygiene and Tropical Medicine, Keppel Street, WC1E 7HT, UK

author email corresponding author email

Malaria Journal 2009, 8:66doi:10.1186/1475-2875-8-66

Published:	16 April 2009

Abstract

Background

In Uganda, like in many other countries traditionally viewed as harbouring very high malaria transmission, the norm has been to recommend that febrile episodes are diagnosed as malaria. In this study, the policy implications of such recommendations are revisited.

Methods

A cross-sectional survey was undertaken at outpatient departments of all health facilities in four Ugandan districts. The routine diagnostic practices were assessed for all patients during exit interviews and a research slide was obtained for later reading. Primary outcome measures were the accuracy of national recommendations and routine malaria diagnosis in comparison with the study definition of malaria (any parasitaemia on expert slide examination in patient with fever) stratified by age and intensity of malaria transmission. Secondary outcome measures were the use, interpretation and accuracy of routine malaria microscopy.

Results

1,763 consultations undertaken by 233 health workers at 188 facilities were evaluated. The prevalence of malaria was 24.2% and ranged between 13.9% in patients ≥5 years in medium-to-high transmission areas to 50.5% for children <5 years in very high transmission areas. Overall, the sensitivity and negative predictive value (NPV) of routine malaria diagnosis were high (89.7% and 91.6% respectively) while the specificity and positive predictive value (PPV) were low (35.6% and 30.8% respectively). However, malaria was under-diagnosed in 39.9% of children less than five years of age in the very high transmission area. At 48 facilities with functional microscopy, the use of malaria slide examination was low (34.5%) without significant differences between age groups, or between patients for whom microscopy is recommended or not. 96.2% of patients with a routine positive slide result were treated for malaria but also 47.6% with a negative result.

Conclusion

Current recommendations and associated clinical practices result in massive laria over-diagnosis across all age groups and transmission areas in Uganda. Yet, under-diagnosis is also common in children <5 years. The potential benefits of malaria microscopy are not realized. To address malaria misdiagnosis, Uganda's policy shift from presumptive to parasitological diagnosis should encompass introduction of malaria rapid diagnostic tests and substantial strengthening of malaria microscopy.