Researchers identify emerging tick-borne illness in Sweden

Dec 8, 2011 | Katharina Schwan | Outbreak News

On July 3, 2009, a 77-year old Swedish man went out kayaking when he suddenly developed acute diarrhea, followed by fever, chills and loss of consciousness.  After being hospitalized, doctors discovered the patient also suffered from deep vein thrombosis (DVT), or blood clots deep within the body, in the lower leg and groin.

One week later, the man was discharged from the hospital after being treated with antibiotics and an anticoagulant, to help thin his blood. Over the next couple of months however, the patient, who also had chronic lymphocytic leukemia, was readmitted to the hospital for a variety of reasons, including the emergence of a rash, anemia and persistent fever. Finally on October 1st, researchers at the University of Gothenburg’s Sahlgrenska Academy were able to identify the bacterial microbe causing the infection.

This patient was the first human to be infected with Candidatus Neoehrlichia mikurensis, which was first isolated in rats from Mikura Island, Japan in 2004. However, the bacteria have never before been detected in Sweden: not in ticks, rats, or humans.

It is believed that the bacteria are spread from wild animals to humans via ticks. However, person-to-person transmission is unlikely. The peak season for ticks-borne illnesses occurs during the summer months, which correlates to the initial patients’ manifestation of symptoms.

Clinical symptoms of Ca. Neoehrlichia mikurensis infection resemble influenza and may include high fever, headache, feelings of discomfort and muscle pain. Severe symptoms are more likely in the elderly and immunocompromised, as seen with the index case. Further research must be conducted to better understand the formation of blood clots in the veins and lungs as a possible symptom of the disease.

The bacteria have infected eight patients thus far; three in Sweden, and the rest scattered throughout Germany, Switzerland and the Czech Republic. Its widespread range across Europe suggests that Ca. Neoehrlichia mikurensis could be an emerging pathogen.

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