Babesiosis and Malaria in the United States: Epidemiology, Research Funding, Medical Progress, & Recommendations for Improvement.

BACKGROUND: Babesiosis and malaria are infectious diseases caused by the intraerythrocytic parasites Babesia and Plasmodium, respectively. While no human red blood cell (RBC) receptors have been shown to be essential for B. microti (Bm) invasion, Duffy (ACKR1) was reported to be essential for P. knowlesi and P. vivax invasion in 1975 and 1976, respectively. This suggests additional medical progress is needed for babesiosis, warranting a detailed analysis. METHODS: Given similarities in the target cell of infection, data about babesiosis and malaria cases in the US were obtained from the Centers for Disease Control and Prevention (CDC). Research funding was quantified using National Institutes of Health (NIH) data, and medical progress was evaluated through a literature review. RESULTS: Over the 5-year span of 2018-22, there were 9799 and 7722 confirmed babesiosis and malaria cases, respectively. Confirmed babesiosis cases exceeded malaria cases in 4 of 5 years. In 2022, babesiosis and malaria data were either not reported or unavailable to the CDC by ten and one US state(s), respectively. Regarding babesiosis, it is likely that the vast majority of cases were due to domestically acquired Bm, in the context of no chemoprophylaxis. Concerning malaria, >90% of US cases were imported from foreign locations, ~95% of cases were linked with not taking chemoprophylaxis, and P. falciparum (Pf) was the most common cause. From 2018-22, babesiosis and malaria were the underlying cause of death for 70 and 32 US residents, respectively. NIH funding estimates suggest ~$4 million in support of babesiosis and ~$169 million for malaria in 2024. There are many malaria-inspired medications, two malaria vaccines, and hundreds of characterized Plasmodium proteins, while these measures of medical progress are far behind for babesiosis. Outside of the US, there are >200 million malaria cases per year, while babesiosis is rare. CONCLUSIONS: In the US from 2018-22, there were more babesiosis cases and deaths than malaria. Decades of robust CDC and NIH funding for malaria led to its elimination from the US, improved medical knowledge and interventions, and reduced foreign morbidity and mortality. These data suggest that leveraging similar approaches used for malaria, including increased NIH and CDC funding for babesiosis, would likely lead to progress (e.g., improved treatment). Babesiosis qualifies as both a rare and an orphan disease.