Babesia Microti DNA

Babesia microti is a microscopic parasite that infects red blood cells and causes babesiosis, an illness resembling malaria. Unlike many infections where symptoms are obvious, B. microti often hides at very low levels in the blood. This makes molecular testing, which looks for the parasite’s DNA, essential for diagnosis and for ensuring the safety of the blood supply.

The most reliable way to detect B. microti DNA is through polymerase chain reaction (PCR), a method that makes millions of copies of specific genetic sequences so they can be measured. PCR tests can find as few as three to six infected red blood cells in a milliliter of blood, far more sensitive than a microscope slide or antibody testing. This sensitivity is particularly important in people who carry the parasite without symptoms, where traditional tests may appear normal but the person can still transmit infection to others through a tick bite or a blood transfusion.

Genomic studies, mapping all of the parasite’s DNA, have shown that B. microti has one of the smallest genomes among parasites in its group. Researchers have identified genes that vary across strains and proteins that trigger strong immune responses, which may serve as new diagnostic targets or even guide future therapies. These insights help improve detection, especially when different Babesia species need to be distinguished.

The clinical implications are significant. Someone may test negative by antibody testing if the infection is recent or if their immune system does not mount a strong response, but DNA testing can still reveal the parasite. Conversely, a person who had an infection years ago may continue to have antibodies, yet no active infection, which is another reason DNA testing is crucial for telling apart current versus past infection. The presence of Babesia DNA in otherwise healthy, asymptomatic donors is a major reason nucleic acid testing is being incorporated into blood bank screening. Even very low levels of parasites can cause severe illness in recipients, particularly in newborns, older adults, or people with weakened immunity.