A groundbreaking study overturns previous assumptions about the anti-malarial properties of blood groups, revealing that even individuals with the "silent Duffy blood group system" are susceptible to infection. This finding highlights the complexity of malaria drug resistance and the importance of advanced diagnostics in a changing global health environment.

People with blood traits thought to make them naturally immune to the disease still became infected. The question now is: How could this happen?

Researchers who have been working for decades to find a cure for malaria believe they have found a blood type that appears to protect against malaria. However, a recent article published in the journal Cell Host & Microbe reveals that even people with this so-called protective blood type can become infected. The question now is, how did they become infected?

"This could mean that the specific genetic mutation associated with this blood type doesn't completely prevent malaria, or that the parasite may have found another way to get into blood cells," said Peter Zimmerman, a professor of pathology at Case Western Reserve University School of Medicine and senior author of the study. "That's a big deal because it could change the way we try to get rid of this parasite."

"This malaria parasite, called Plasmodium vivax, was once common in Northeast Ohio. This summer, it spread within the U.S. states of Florida and Texas for the first time in 20 years," said study co-investigator Christopher King, a professor of pathology. "We already know that the U.S. is at risk of reintroduction of malaria with climate change and increasing immigration and travel from malaria-endemic areas."

Collaborators on the study include researchers from France (Célia Dechavanne and Benoit Gamain, National Institute of Blood Transfusion, CNMR/University Paris Diderot) and Madagascar (Arsène Ratsimbasoa, Université Fianarantsoa).

"For more than 100 years, malaria researchers have been trying to understand resistance and susceptibility to Plasmodium vivax infections in Africans," Zimmerman said. "More than 2.5 billion people may live in Africa and Southeast Asia, where this parasite is found. Hundreds of thousands of people die from malaria every year. Overall, malaria is one of the top three health infectious diseases worldwide - malaria, tuberculosis and HIV/AIDS."

The research team is studying a specific blood type (Fy-negative) found in the blood of most Africans and people of African descent, known as the "silent Duffy blood type." The DNA code for the Duffy-negative blood group (GATA-1) is mutated, resulting in a protein that cannot be expressed on the surface of red blood cells.

The researchers conducted experiments using lab-grown blood cells and cells extracted from bone marrow to study Tamiflu-silenced blood types.

"Surprisingly, we found that even if people lack the DNA encoding for GATA-1, Duffy protein is sometimes present on their red blood cells," Zimmerman said. "Our results suggest that the bone marrow and other places where blood cells are initially made are important for Plasmodium to find red blood cells with Duffy protein, grow, and cause disease."

In other experiments in the lab, they examined the blood of people with the silent blood type Tamiflu. They note that infection with P. vivax is often detected using a special test rather than the usual microscopic test.

This means that people with Tamiflu's silent blood type can still be infected, but it won't be easily detected on routine blood tests. In other words, they found that P. vivax could invade the red blood cells of patients with Tamiflu-silenced blood types. Additionally, if their bone marrow becomes infected, it can produce parasites that can be transmitted. Mosquitoes can acquire this parasite and infect others.

"This finding raises questions about how the malaria parasite causes infection and disease, especially since some infected people don't show many signs in the blood," Zimmerman said. "We need to look more closely at the blood to better understand how common and severe this type of malaria is in people with Duffy-silent traits."

Compiled source: ScitechDaily