Presence of neoehrlichiosis confirmed in Switzerland

By Helen Albert, Senior medwireNews Reporter

Researchers have confirmed the presence of a novel tick-borne disease known as neoehrlichiosis in Switzerland.

Neoehrlichiosis, caused by the tick-borne bacterium Candidatus Neoehrlichia mikurensis, was first discovered in Asia in 1999 and seven cases have been reported in China and eight in Europe to date.

The condition results in relapsing high fever, weight loss, and general malaise, but can be treated using antibiotics.

Three of the European patients are resident in the Zurich area of Switzerland and the authors of the current study, published in the Journal of Clinical Microbiology, developed a diagnostic multiplex realtime polymerase chain reaction assay after the first Swiss case, which was then used to diagnose the second and third cases in October 2011 and January 2012. The assay uses a 282 base pair fragment of the Candidatus N. mikurensis genome to accurately identify those infected with the bacterium.

Guido Bloemberg (University of Zurich, Switzerland) and colleagues also used the assay to test 1916 ticks collected from four forests in the Zurich area within 3 km of the residences of the Swiss patients.

They found that Candidatus N. mikurensis was present in 3.5-8.0% of the ticks in all the areas sampled, which suggests a "strong geographic association between the three patients and the assumed vector."

The majority of patients infected with neoehrlichiosis so far have been immunocompromised in some way, but there have been cases of people with a healthy immune system contracting the disease.

"Our study shows that the greater Zurich region is a risk area for neoehrlichiosis, especially for immunocompromised people," explained co-author Florian Maurer, also from the University of Zurich, in a press statement.

Bloemberg added that the advantage of the new test is that is can detect the infection quickly. "Because the bacteria that cause neoehrlichiosis couldn't be bred in the lab until now and thus no rapid tests were available, many infections might have remained undetected," he said.

"How well the bacterium is transmitted to humans via a bite from an infected tick, however, still needs to be researched," he concluded.

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