Malaria Infection in Patients with Sickle Cell Disease in Nigeria: Association with Markers of Hyposplenism.

Malaria is considered an important cause of morbidity and mortality among people living with sickle cell disease (SCD). This has partly been attributed to the loss of splenic function that occurs early in the disease process. We conducted a cross-sectional study and determined the frequency of malaria infection among SCD patients and explored the association with spleen's presence on ultrasonography and spleen function assessed using the frequency of Howell-Jolly bodies (HJBs). A total of 395 participants consisting of 119 acutely-ill SCD patients, 168 steady-state SCD controls, and 108 healthy non-SCD controls were studied. The prevalence of Plasmodium falciparum parasitemia was 51.3% in acutely-ill SCD patients, 31.7% in steady-state SCD controls, and 11.0% in the healthy non-SCD controls; however, the mean parasite density was significantly higher in the non-SCD controls compared to both SCD groups (p = 0.0001). Among the acutely-ill SCD patients, the prevalence of clinical malaria and severe malaria anemia were highest in children <5 years of age. The prevalence of parasitemia (p = 0.540) and parasite density (p = 0.975) showed no association with spleen presence or absence on ultrasonography. Similarly, the frequency of HJB red cells was not associated with the presence of parasitemia (p = 0.183). Our study highlights the frequency and role of malaria infection in acutely-ill SCD patients, especially in those younger than five years. Although we have found no evidence of an increased risk of malaria parasitemia or parasite density with markers of hyposplenism, the role played by an underlying immunity to malaria among SCD patients in malaria-endemic region is not clear and needs further studies.