Lyme Disease
It’s Lyme season in the United States and the risk of infection by the black-legged ticks that carry it is growing, especially with half of Americans now living on tick infested territory. Lyme disease is the most common vector-borne disease in the Northern Hemisphere.
Without immediate antibiotic treatment, Lyme disease can cause debilitating heart and nervous system issues, arthritis, and other complications, making it difficult to cure. Although several vaccines are in development, the rising number of cases have reached epidemic levels: in the U.S., some 476,000 cases are reported each year accounting for about $1 billion in medical costs
With several vaccines in development, researchers are optimistic they will be able to prevent the disease within just a few years. A human vaccine developed by Pfizer and its French biotech partner, Valneva, is in Phase 3 trials. Moderna is working on an mRNA version. Researchers at MassBiologics of UMass Chan Medical School are developing an anti-Lyme antibody treatment.
Ticks pick up the bacteria while feeding on infected hosts, including white-footed mice (the primary disease reservoir), other small mammals, and white-tailed deer. B. burgdorferi then sits in a tick’s intestine for months until the arthropod latches onto a new victim for its next meal. With the influx of blood into the tick’s gut, the bacteria transform. They stop producing an outer surface protein, OspA, that anchors them to the intestine, which allows them to move to the tick’s salivary glands. The bacteria then pass through the wound and into their new host.
The process from bite to transmission typically takes 36 to 48 hours—so finding and removing a tick quickly after being bitten is critical.
What happens next isn’t always predictable. A signature bull’s eye rash may signal infection, but not always. The bacteria may initially remain localized, or rapidly disseminate throughout the body
There are things people can do now to protect themselves until new preventions are available: using repellents, showering after time outdoors, and cleaning up yard leaf litter. It’s also important to know the signs of tick-borne illness—an unexplained fever or a rash—and seek medical care, Mead says. “The great majority of Lyme disease cases can be treated pretty effectively with antibiotics, if you recognize it [early].”
Outside Magazine, May 2023
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