TWiP 277: Rif-ing on river blindness

This Week in Parasitism Episode 277 dives into two major parasitic diseases: Chagas disease and onchocerciasis (river blindness). Christina Naula opens with a detailed analysis of a landmark Global Burden of Disease study on Chagas, highlighting a significant decline in global prevalence, deaths, and disability-adjusted life years (DALYs) from 1990 to 2023—particularly in endemic regions like Southern and Andean Latin America. Despite this progress, she raises concerns about underreporting due to stigma, especially in countries like Panama that deny the disease's presence, and a growing burden in non-endemic regions like the U.S. and Europe due to migration. The paper underscores the need for better screening and targeted treatment in immigrant populations. Daniel Griffin then presents findings from a phase 2A trial comparing antibiotic regimens for onchocerciasis, showing that six weeks of doxycycline (100 or 200 mg) is highly effective at depleting Wolbachia endosymbionts and sterilizing adult worms, while shorter courses of rifampicin or combination therapy were less effective. He emphasizes the potential to shift from annual mass drug administration with ivermectin to curative, shorter treatments, especially in areas where ivermectin poses risks due to loa-loa co-infection. Both guests stress the importance of community engagement, particularly with local leaders, and the need for larger phase 3 trials to optimize dosing and expand access to curative therapies. Key takeaways include: 1) Chagas disease burden is declining globally but remains under-recognized in non-endemic areas; 2) Stigma prevents accurate reporting and treatment in endemic countries; 3) Doxycycline is a highly effective, potentially curative treatment for onchocerciasis when administered for six weeks; 4) Shorter regimens with rifampicin are less effective, possibly due to underdosing; 5) Community trust and leadership are essential for successful parasitic disease control programs; 6) Targeted screening of migrant populations is critical to prevent congenital transmission; 7) Wolbachia-targeting therapies offer a promising path toward true cure for filarial infections; 8) The shift from lifelong ivermectin to curative antibiotic regimens could transform global elimination efforts.