Severity of malaria and level of Plasmodium falciparum transmission

Mathematical modeling of the impact of malaria vaccines on the clinical epidemiology and natural history of Plasmodium falciparum malaria: Overview

We report a major project to develop integrated mathematical models for predicting the epidemiologic and economic effects of malaria vaccines both at the individual and population level. The project has developed models of the within-host dynamics of Plasmodium falciparum that have been fitted to parasite density profiles from malaria therapy patients, and simulations of P. falciparum epidemiology fitted to field malariologic datasets from a large ensemble of settings across Africa. The models provide a unique platform for predicting both the short- and long-term effects of malaria vaccines on the burden of disease, allowing for the temporal dynamics of effects on immunity and transmission. We discuss how the models can be used to obtain robust cost-effectiveness estimates for a wide range of malaria vaccines and vaccination delivery strategies in different eco-epidemiologic settings. This paper outlines for a non-mathematical audience the approach we have taken and its underlying rationale.

Polyuria in association with Plasmodium falciparum malaria in a region of unstable transmission

During a recent epidemic of Plasmodium falciparum malaria in Hlabisa district, KwaZulu Natal, polyuria was recognized in a subset of adults presenting to hospital with severe disease. In January to May 2000, following consent, cases of severe malaria provided blood spots for HIV testing, clinical data, and blood and urine samples for investigation of the polyuria. Four hundred and eleven adults with malaria were admitted, of whom 175 had severe malaria and 37 had polyuria (21% of severe cases). In those with polyuria the mean 24-h urine output was 3018 ml or 2.85 ml/kg/h. Ten of 15 (66%) patients investigated had urine and plasma osmolalities consistent with diabetes insipidus. There was no significant association between polyuria and sex, age, HIV status or features of severe malaria. Whether the polyuria in these non-immune adults is a localized problem unrelated to malaria, or a hitherto unrecognized complication of severe malaria is not clear. Physicians are alerted to this observation, and the need for more clinical and pathophysiological studies.

HIV infection as a cofactor for severe falciparum malaria in adults living in a region of unstable malaria transmission in South Africa

BACKGROUND

Malaria and HIV are two of the most important diseases facing Africa. It remains uncertain whether HIV-related immunosuppression adversely affects the clinical outcome of malaria.

OBJECTIVE

To measure the association between HIV status and outcome from malarial infection in adults living in a region of unstable malaria transmission.

DESIGN

Observational cohort study.

SETTING

Four community clinics and the Government hospital in Hlabisa district, KwaZulu-Natal, South Africa; a region of high HIV prevalence.

METHODS

Consecutive febrile adults were screened for malaria with a rapid antigen test. Those with malaria provided blood spots for HIV testing, a thick blood film for confirmation of malaria and clinical data. Outcome was established following management according to South African government guidelines.

RESULTS

Malaria was microscopically confirmed in 613. HIV prevalence was 29.9% (180/613); 110 (18%) had severe/complicated malaria and 28 (4.6%) died. HIV-infected patients were more likely to vomit or be confused and were more likely to be admitted to hospital (P = 0.05). In patients admitted to hospital, HIV infection was associated with severe/complicated malaria [adjusted odds ratio (OR) 2.3; 95% confidence interval (CI), 1.4-3.9] and with death (OR 7.5; 95% CI, 2.2-25.1). Acidosis and coma were also strong independent risk factors for death.

CONCLUSION

HIV infection had an unexpectedly large association with the outcome of falciparum malaria in a region of unstable transmission. Both diseases are widespread in Africa and these results add to the body of knowledge suggesting an interaction of significant public health importance between HIV and malaria in Africa.

Childhood malaria in a region of unstable transmission and high human immunodeficiency virus prevalence

BACKGROUND

Malaria and HIV are important pediatric problems in sub-Saharan Africa. It is uncertain how HIV-related immunosuppression and malaria interact in children. We aimed to describe associations among HIV status, presentation and outcome from malaria in children from Hlabisa district, KwaZulu-Natal, South Africa, a region of high HIV prevalence and unstable Plasmodium falciparum transmission.

METHODS

Consecutive febrile children were screened for malaria with a rapid antigen test. After consent was given, clinical data were recorded, and blood spots were obtained for HIV antibody testing. Cases were managed according to national guidelines.

RESULTS

Malaria was diagnosed in 663 children, of whom 10.1% were HIV antibody-positive. Semiquantitative asexual and sexual stage parasitemia densities were unrelated to HIV status. Overall 161 children were hospitalized; 19 (12%) were <1 year old; and 41 (25%) had severe/complicated malaria. Severe disease presented more frequently in HIV antibody-positive than in HIV-uninfected children (P = 0.05), particularly in those >1 year old with coma (P = 0.02) and hypoglycemia (P = 0.05). Receiving parenteral antibiotics was associated with severe disease (odds ratio, 3.0; 95% confidence interval, 1.3 to 6.7) whereas a low white blood cell count (<4 x 10(6)/l) was associated with nonsevere disease (odds ratio, 0.4; 95% confidence interval, 0.2 to 0.8). Seven children (4.3%) died. Coma, age <1 year and low white blood cell count were the clearest predictors of poor outcome.

CONCLUSION

HIV infection was associated with severe/complicated malaria, although the magnitude of the effect may be relatively small. Given that both malaria and HIV are widespread in Africa, even small effects may generate significant morbidity and mortality and major public health consequences.