Duffy antigen absence and thalassemia traits convey partial resistance to which mosquito-borne disease?

• A. Dengue
• B. Lyme disease
• C. Chagas disease
• D. Malaria

Answer: (D)

The traits described affect how red blood cells interact with malaria parasites, so they give partial resistance to malaria, a disease spread by Anopheles mosquitoes. The Duffy antigen absence means red blood cells lack a receptor that the parasite Plasmodium vivax uses to invade cells. Without that receptor, P. vivax has a harder time entering and infecting red blood cells, reducing infection risk. Thalassemia traits alter red blood cell properties—like size, shape, and how long the cells circulate—which makes the environment less favorable for parasite growth and replication, further lowering disease risk and severity. These protective effects are specific to malaria because the parasites rely on these red blood cell features to thrive, and they don’t generally confer resistance to diseases like dengue (a viral illness transmitted by mosquitoes of a different genus), Lyme (tick-borne), or Chagas (spread by kissing bugs).