U.S. Blood Supply May Be Infected By Tick-borne Parasite

A tick-borne infection known as Babesiosis, which can cause severe disease and even death, is becoming a growing threat to the U.S. blood supply, according to a 31-year-old study led by government researchers.

U.S. Centers for Disease Control and Prevention found that the parasitic infection may be increasing across the country.

Babesia infections are marked by anemia, fever, chills and fatigue, but they can also cause organ failure and death, CDC officials said on Monday.

A recent study led by Dr. Barbara Herwaldt of the CDC, published in the Annals of Internal Medicine, found cases had occurred year-round and in states where Babesia parasites are not found - including as far away as Texas and Florida.

Babesiosis is a potentially life-threatening disease caused by intraerythrocytic parasites, which usually are tick-borne but also are transmissible by transfusion, wrote study authors in the journal.

The rare disease is known to occur naturally in seven U.S. states - Massachusetts, New York, Connecticut, Minnesota, Rhode Island, New Jersey and Wisconsin - during the spring and summer seasons.

Of the 162 cases of Babesia infection caused by blood transfusions between 1979 and 2009, nearly 80 percent occurred between 2000 and 2009.

Babesia microti has become the most frequently reported transfusion-transmitted parasite in the United States, CDC researchers wrote, far outpacing malaria infections, which accounted for 49 cases of transfusion-associated disease during the same period, including just five cases during 2000-2009.

In a separate study, published on Monday in the journal Pediatrics by a team at the University of Nebraska, researchers looked at seven cases of transfusion-associated Babesiosis in premature infants.

They found blood transfusions from two infected units of blood caused all seven of the cases of Babesiosis, where symptoms of the infection varied widely, but babies with the lowest weights at birth were at greatest risk of serious infection.

The authors warned doctors in areas in which Babesiosis occurs to be watchful for cases in premature infants exposed to blood transfusions.

They also concluded that Babesiosis should be included in the differential diagnosis of unexplained posttransfusion hemolytic anemia or fever, regardless of the season or U.S. region.

The CDC researchers called for better ways to prevent and detect cases of transfusion-associated Babesiosis.

Our findings underscore the year-round vulnerability of the U.S. blood supply - especially, but not only - in and near Babesiosis-endemic areas.

...They also highlight the importance of multi-agency collaborative efforts to detect, investigate, and document transfusion cases; to assess the risks for transfusion transmission; and, thereby, to inform the scope of prevention measures, health officials said.