Did you know that getting bit by a tick is not the only way you can be exposed to a tick-borne illness? A portion of the U.S. blood supply is infected with the tick-borne parasite known as Babesia. As alarming at it sounds, this is not new information.
The CDC has known since 1979 that this pathogen can be transmitted via blood transfusions, although it was not officially considered a reportable illness until 2011. Recent investigations, in addition growing concerns over the spread of Lyme disease in recent years, have highlighted the need for interventions that will protect the public from receiving contaminated blood.
Babesia is a protozoan parasite that is transmitted by Ixodes ticks. Commonly known as “deer ticks,” these are the same type that carry Lyme disease. It is the most common co-infection associated with Lyme disease and can cause a malaria-type illness. Symptoms include fever, fatigue, headache, sweats, loss of appetite, shortness of breath, anemia, and depression and usually appear anywhere between 1 and 9 weeks after exposure. The first known case of Babesiosis in the United States was in San Francisco, CA in 1966.
Babesia microti is the most common strain in the U.S., but 5 other strains have been discovered and are also known to cause infection in humans. The pathogen infects the red blood cells. Babesiosis is not normally life-threatening and even asymptomatic in some, but it can be serious and even fatal in those who have no spleen, those who are immunocompromised, and the very old or very young. In 2015, former first lady of New York, Jean Bryne, died from the disease at the age of 88.
Prevalence in Blood Supply
Last year, a study published in the New England Journal of Medicine laid out the findings of research conducted by the American Red Cross between 2012 and 2014 on the prevalence of Babesia in the U.S. Blood Supply. Samples from blood donors in 4 states were tested for Babesia microti. Out of 80,000 samples that were tested, 335 were positive. While this may seem like a small percentage, Babesia is thought to be the biggest infectious disease threat transmitted by blood transfusions. This is due in part to the findings of a retrospective study by the CDC revealing that 70% of Babesia cases contracted in this way occurred after the year 2000, so it is clearly on the rise. It is estimated to be responsible for roughly 38% of fatalities tied to microbial contamination of blood transfusions.
Transmission rates have been studied in animals, revealing that infection can occur 50% of the time from Babesia-contaminated blood. However, this transmission rate occurred in healthy animals. Since individuals receiving blood transfusions often have serious health problems, the rate of transmission may be much higher in humans. Additionally, this study only tested for one strain of Babesia. If all strains were tested, the prevalence of infected blood would most likely have been higher.
The Pressing Need for Screening Programs
As if this data wasn’t concerning enough, experts are predicting that 2017 could be the worse year yet for Lyme disease. This is due to the resurgence of the mouse population in the Northeast last year. Mice carry Lyme disease and transmit it to ticks, who then infect other animals and humans. Mice are a double threat – not only are they like magnets for ticks, but the infection rate is also extremely high (about 95%). Since the same kind of ticks that carry Borrelia burgdorferi (the bacteria that causes Lyme disease) also carry Babesia, this spells bad news for the U.S. blood supply in the near future.
This is especially concerning considering there is no universal screening process in place yet. The American Red Cross does state that infection with Babesia disqualifies an individual from giving blood, but donors are not specifically asked if they have a history of tick bites or Lyme disease. Even if they were asked, many people are either asymptomatic or not aware that they have a tick-borne illness. Steps are being made to inform the public and begin implementing more screening, but progress is happening slowly.
In the past year, the CDC published an article titled “Babesiosis and the U.S. Blood Supply” which states that Babesia can be transmitted by ticks, through a blood transfusion, or from mother to baby (congenital transmission). A pilot program was recently started to screen for Babesia in donated blood in Massachusetts. Hopefully, screening will begin in other high risk states as well, which some experts estimate would reduce Babesia in the blood supply by up to 95%. This would still be inadequate because it would only address one strain of Babesia, but it’s a start. In 2015, the FDA recommended year-round antibody screening until a universal screening test can be put into place.
While the general public should continue to take the proper precautions to avoid tick bites, in the case of blood transfusions, these precautions would of course be useless. Recipients of blood transfusions have no control over the quality of the donated blood. And given the spike expected this year in Lyme disease and presumably other tick-borne illnesses like Babesia, there is certainly an urgency to the situation.