Ticked off

There tends to be a yearly rhythm to some of the health care news: flu shots in fall, Lyme disease in spring, West Nile virus in summer. Every so often, though, something new comes along to keep things interesting.

This time around, it’s the emergence of anaplasmosis as one of the leading tickborne diseases in Minnesota.

Figures released last week by the Minnesota Department of Health were quite surprising: The incidence of human anaplasmosis more than doubled in 2010. Most years, there are about 300 confirmed cases statewide; last year there were 720. About 30 percent of them resulted in hospitalization, and one person died. In some north central counties of Minnesota, anaplasmosis now rivals Lyme disease as one of the most common tickborne illnesses.

Most people probably haven’t heard much about anaplasmosis, so here’s a primer: It is a bacterial disease transmitted to humans through the bite of a deer tick, the same way Lyme disease is transmitted. Symptoms of infection include fever, severe headache, muscle aches, chills and shaking. There might also be nausea, vomiting, loss of appetite, weight loss, abdominal pain, diarrhea, joint pain and changes in mental status.

People who are aging or immune-compromised can be more vulnerable to severe disease. Among the serious complications of anaplasmosis are respiratory failure, kidney failure and secondary infections.

Treatment consists mainly of antibiotics.

Overall, potentially serious tickborne diseases are on the rise in Minnesota, a development that has state health officials concerned. Dave Neitzel, an epidemiologist who specializes in these diseases, calls it a “continuing and troubling trend.”

Cases have been popping up of Powassan virus disease and a new form of ehrlichiosis, both carried by the black-legged (or deer) tick. Neither of these diseases was seen in Minnesota before 2008.

The incidence of babesiosis, a tick-transmitted protozoan infection, also rose rather sharply last year, from 31 reported cases in 2009 to 56 last year.

The arrival of tick season doesn’t mean we should all be cowering indoors to stay safe. It should be noted that most of these diseases are still relatively uncommon. Prevention is the best medicine, though, and it starts with avoiding tick habitat as much as possible from late spring through midsummer, the time of year when ticks are most active. For those who need to spend time outdoors, repellents can help reduce their risk of being bitten by an infected tick.

The Minnesota Department of Health has more detailed information here and here.

Photo: Wikimedia Commons

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