Minnesota Department of Health (MDH) Bug Bytes

June 19, 2003
Vol. 4: No. 7

Topics in this Issue:
1. Monkeypox
2. West Nile Virus is Here

1. Monkeypox
Last week, CDC reported on an outbreak of monkeypox in humans involving 53 persons in Illinois, Indiana, and Wisconsin (at http://www.cdc.gov/mmwr/preview/
). Since that time additional cases have been reported in Kansas, Ohio, and Missouri for a total of 87 suspect or confirmed cases. Human cases have resulted direct or close contact with prairie dogs, a Gambian giant rat, or a rabbit that became ill after exposure to an ill prairie dog at a veterinary clinic. Traceback investigations have been initiated to identify the source of monkeypox virus introduced into the U.S. and have identified a common distributor where prairie dogs and Gambian giant rats were housed together in Illinois. A search of imported animal records revealed that Gambian giant rats were shipped from Ghana in April to a wildlife importer in Texas and subsequently were sold to the Illinois distributor. The shipment contained approximately 800 small mammals of nine different species that might have been the actual source of introduction of monkeypox.

We have not documented any human cases in Minnesota nor are we aware of any infected animals. We did evaluate a suspect vesicular rash in a 15 year-old who presented to an emergency room; specimens collected tested positive for varicella zoster virus in our laboratory by PCR. Clinicians seeing suspect cases should call us for consultation and for the collection of specimens for testing by us.

2. West Nile Virus is Here
As West Nile Virus (WNV) continued to spread rapidly across the central U.S. during the summer of 2002, Minnesota recorded its first 48 human cases (0 fatalities), and 992 equine cases. The virus was reported in humans, birds, horses, and/or mosquitoes in all counties except for Lake and Cook. Nationally, WNV was found in 44 states and the District of Columbia resulting in 4,156 human cases (284 fatalities). Additional information is at:

The arbovirus transmission season is just getting underway in the U.S. with low numbers of reports of WNV-positive birds, mosquitoes, and horses from 23 states. The first probable human WNV case of the year was reported this week in a South Carolina resident. In Minnesota, we had an early equine case (onset 4/14) in Crow Wing County, and two additional horse cases reported within the last week (Washington and Sherburne Counties). We have no reports of WNV-positive birds or mosquitoes in the state to date. The public is encouraged to report dead/dying birds to us via our website (listed above). As in past years, we still expect the greatest risk to humans to be from mid-July through mid-September.

Priority for WNV Clinical Testing at MDH Public Health Laboratory:
We are encouraging the submission of serum and/or CSF for arbovirus testing, but are concentrating testing efforts and resources on patients who meet any of the following criteria:
- presumptive viral encephalitis/meningo-encephalitis or aseptic meningitis
- fever and headache that warrants a lumbar puncture and/or hospitalization
- presumed Guillain-Barre syndrome or acute flaccid paralysis

We do not have the resources to test potential mild cases, i.e., those that have headache, fever, chills, or rash, but do
NOT require a lumbar puncture and/or hospitalization. Please see the CDC website for further Clinical Guidance:

Physicians should call us at 651-201-5414 or 1-877-676-5414, to report suspect cases of WNV.

The MDH Laboratory conducts serology (IgM and IgG EIA) and real-time PCR for WNV, LaCrosse encephalitis (LAC), Eastern equine encephalitis (EEE), Western equine encephalitis (WEE), and St. Louis encephalitis (SLE). In addition, Vero cell culture is also performed which can detect these agents and other viral agents of encephalitis.


Bug Bytes is a combined effort of the Infectious Disease Epidemiology, Prevention and Control Division and the Public Health Laboratory Division of MDH. We provide Bug Bytes as a way to say THANK YOU to the infection control professionals, laboratorians, local public health professionals, and health care providers who assist us.

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Updated Friday, November 19, 2010 at 02:16PM