Hyposplenism revealed by Plasmodium malariae infection

Abstract

Background: Hyposplenism, due to splenectomy, inherited red blood cell disorders or acquired conditions such as celiac disease, has an important impact on the severity of malaria, especially in non-immune patients. Conversely, that malaria may reveal functional hyposplenism has not been described previously.

Methods: A 31-year old gardener was diagnosed with an uncomplicated attack of Plasmodium malariae 11 years after leaving the endemic area. In addition to trophozoites and schizonts, thick and thin smears also showed Howell-Jolly bodies, pointing to functional hyposplenism. This was later confirmed by the presence of a calcified spleen in the context of S/β + sickle-cell syndrome in a patient previously unaware of this condition.

Conclusion: Malaria may reveal hyposplenism. Although Howell-Jolly bodies are morphologically similar to nuclei of young Plasmodium trophozoite, distinction on smears is based on the absence of cytoplasm and irregular size of Howell-Jolly bodies. In the patient reported here, hyposplenism was revealed by the occurrence of P. malariae infection relatively late in life. Timely diagnosis of hyposplenism resulted in the implementation of appropriate measures to prevent overwhelming infection with capsulated bacteria. This observation highlights the importance of diagnosing hyposplenism in patients with malaria despite the morphological similarities between ring nuclei and Howell-Jolly bodies on thick smears.

Figure 1

Diagnosis of Plasmodium malariae infection and presence of Howell-Jolly bodies. Thick (A) and thin (B) smear at admission (original magnification ×1000, Giemsa –R staining). In red squares, a sample of P. malariae rings showing morphological similarities between ring nuclei and Howell-Jolly bodies. The absence of cytoplasm is key for the differential diagnosis. A. Two leukocyte nuclei, the rosette-like aspect (vertical arrow) of the schizont (Plasmodium malariae), and several Howell-Jolly bodies (red arrows). B. Small size of the erythrocyte hosting a P. malariae gametocyte (vertical arrow) and unifected red blood cells showing microcytosis, anisochromasia, and target aspect.

Figure 2

Abdominal CT-scan identify a small calcified spleen (yellow arrow).