Abstract. Thrombocytopenia is a common finding in malaria, but its prognostic value has not been addressed in children. The relationship between thrombocytopenia (platelet count < 100,000/mm 3 on admission) and severity and outcome was investigated prospectively in children hospitalized with falciparum malaria in Dakar, Senegal, an area that is hypoendemic for malaria. Of 288 falciparum cases, 215 matched the 2000 World Health Organization definition of severe malaria. Median platelet counts were lower (98,000/mm 3 versus 139,000/mm 3 ; P < 0.02) among severe cases than in mild cases, and in children who died than among those who recovered (68,500/mm 3 versus 109,000/mm 3 ; P < 0.002). In severe cases, children presenting with a platelet count < 100,000/mm 3 were more likely to die (odds ratio [OR] ‫ס‬ 6.31, 95% confidence interval [CI] ‫ס‬ 2.0-26.0). Moreover, multivariate analysis identified thrombocytopenia as an independent predictor of death (OR ‫ס‬ 13.3, 95% CI ‫ס‬ 3.2-55.1). Our data show an association between thrombocytopenia and either severity or prognosis in childhood falciparum malaria.

HBV vaccine was introduced into the Expanded Programme on Immunization (EPI) in Senegal and Cameroon in 2005. We conducted a cross-sectional study in both countries to assess the HBV immune protection among children. All consecutive children under 4 years old, hospitalized for any reason between May 2009 and May 2010, with an immunisation card and a complete HBV vaccination, were tested for anti-HBs and anti-HBc. A total of 242 anti-HBc-negative children (128 in Cameroon and 114 in Senegal) were considered in the analysis. The prevalence of children with anti-HBs ≥10 IU/L was higher in Cameroon with 92% (95% CI: 87%–97%) compared to Senegal with 58% (95% CI: 49%–67%), (p<0.001). The response to vaccination in Senegal was lower in 2006–2007 (43%) than in 2008–2009 (65%), (p = 0.028). Our results, although not based on a representative sample of Senegalese or Cameroonian child populations, reveal a significant problem in vaccine response in Senegal. This response problem extends well beyond hepatitis B: the same children who have not developed an immune response to the HBV vaccine are also at risk for diphtheria, tetanus, pertussis (DTwP) and Haemophilus influenzae type b (Hib). Field biological monitoring should be carried out regularly in resource-poor countries to check quality of the vaccine administered.

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The relevance of WHO criteria for severe and complicated malaria has been debated for a while, especially as regards children. Recent data led WHO experts to modify the definition of severe malaria. The objective of this study was to evaluate retrospectively the significance of the new definition on severity, lethality and intensive care distribution in children admitted with falciparum malaria (in 1997-99) to Hôpital Principal de Dakar, Senegal. We used the paediatric risk of mortality score (PRISM) to compare the 2 definitions, WHO 2000 and WHO 1990. Finally, we evaluated the impact of the new definition in terms of major therapeutic interventions (MTIs): mechanical ventilation, haemodynamic support, transfusion, haemodialysis, and the use of sedatives. Among 311 patients, the frequencies of severe malaria cases and case-fatality rates thereof were 52% (n = 161) and 17% (n = 28) respectively using the 1990 WHO criteria, and 75% (n = 233) and 12% (n = 28) using the 2000 WHO criteria. Mean PRISM score among severe cases decreased with the new definition (6.5 versus 8.6). Both definitions predicted neurological sequelae and deaths with 100% sensitivity. One or more MTIs were required in severe malaria cases in 86% (n = 139) under the 1990 criteria and 73% (n = 170) under the 2000 criteria. In this area of low and seasonal transmission, the 2000 WHO definition of severe malaria proved broader and less specific, but was easier to apply and retained the high sensitivity of the earlier definition in identifying life-threatening infections.

This discrepancy observed in five classes of expected mortality (Hosmer-Lemeshow chi-square test, p < .001) may have been due to chance (sample size too small for a valid test), to a lower standard of care in Dakar than in the American hospitals where PRISM was designed, or to a failure of PRISM to classify risk in severe malaria.