Retinal Changes in Uncomplicated and Severe Plasmodium knowlesi Malaria

Area of Science:

• Ophthalmology
• Infectious Diseases
• Tropical Medicine

Background:

• Plasmodium knowlesi causes severe malaria, but its pathogenesis remains unclear.
• Retinal changes are known indicators of severe falciparum malaria pathogenesis.
• Retinal manifestations in knowlesi malaria have not been previously studied.

Purpose of the Study:

• To investigate and characterize retinal changes in adults with knowlesi malaria.
• To compare retinal findings between severe and non-severe knowlesi malaria cases.
• To explore potential differences in pathogenesis compared to Plasmodium falciparum malaria.

Main Methods:

• An observational study involving 44 Malaysian adults hospitalized with knowlesi malaria.
• Indirect ophthalmoscopy and fundus photography were used to examine retinal changes.
• Patients were categorized into severe (n=20) and non-severe (n=24) disease groups.

Main Results:

• Retinal changes were detected in 92% of severe and 82% of non-severe cases via photography.
• Common findings included nonspecific retinal whitening, hemorrhages, retinal pigment epithelium changes, and drusen.
• No significant differences in the type or severity of retinal changes were observed between severe and non-severe knowlesi malaria. Patients with hemorrhages had lower platelet counts.

Conclusions:

• The observed retinal changes in knowlesi malaria are generally mild and nonspecific.
• The lack of severe retinopathy contrasts with findings in falciparum malaria, suggesting different pathogenetic mechanisms.
• Microvascular sequestration, a key feature in severe falciparum malaria, may not be a major factor in severe knowlesi malaria.