Malaria parasite density and splenic status by ultrasonography in stable sickle-cell anaemia (HbSS) children.

ABSTRACT

BACKGROUND: To determine the relationship, if any, between malaria parasitaemia, parasite density and presence/size of the spleen, using abdominal ultrasonography in stable sickle cell anaemia subjects aged 6 to 15 years. METHODS: A prospective study of one hundred consecutive sickle cell anaemia (SCA) and 100 matched healthy HbAA controls aged 6 to 15 years was undertaken. The presence of malaria parasite, and parasite density were determined using thick blood film. Splenic status was determined by using abdominal ultrasound. None of the children was symptomatic for malaria. RESULTS: The prevalence of autosplenectomy and splenomegaly were 20% and 27% respectively in SCA subjects compared to 0% and 4% respectively in HbAA controls. Thirty percent and 34% of the SCA and controls respectively had malaria parasitaemia. In SCA subjects, the parasite density ranged from 33 to 4000 per microl with a mean of 1071.10 +/- 895.5 per microl. In HbAA controls, the parasite density ranged from 180 to 5150 per microl with a mean of 1759 +/- 1382.87 per microl. The difference in parasite density between SCA subjects and HbAA was significant p<0.05. The parasite densities were relatively higher among SCA with splenomegaly and normal spleen sizes compared to SCA subjects with autosplenectomy. CONCLUSIONS: The prevalence of malaria parasitaemia is lower in healthy SCA subjects than in HBAA controls. Sickle cell anaemia subjects have lower malaria parasite density. Autosplenectomy may be a positive adaptation in SCA subjects with effective innate immunity to malaria.