Prairie Dogs. Monkeypox. What’s Going On in Wisconsin?

Wisconsin has a new notoriety in the world of infectious diseases, giving us the potential to replace our standing as the Cryptosporidium hub of the US. A recent outbreak of monkeypox in the Midwest has health officials scrambling to find people who had contact with the sick prairie dogs that have been spreading the monkeypox virus to humans.

According to the CDC, monkeypox is a rare, smallpox-like virus that typically occurs in the rain forests of central and western Africa. The virus was discovered in laboratory monkeys in 1958, and later found in African rodents including squirrels, mice, rats and rabbits. The infection was reported in humans for the first time in the 1970s, but the current outbreak is the first time it's been found outside of Africa.

As of June 12, the CDC reported current investigation of 72 potential cases of monkeypox in humans, 21 of which are from Wisconsin. Indiana has 33 cases under investigation, Illinois has 17 and New Jersey has one.

Locally, Wisconsin cases of monkeypox have all been linked to a shipment of 38 prairie dogs that were sold as pets at two Milwaukee-area pet stores and at a Wausau swap meet. The Milwaukee distributor, SK Exotics, received the prairie dogs from an Illinois distributor, Phil’s Pocket Pets.

Mary Beth Graham, MD, Assistant Professor of Infectious Diseases at the Medical College of Wisconsin says that despite media reports emphasizing the role of the Gambian giant rat in transmission of the virus, there is no evidence that this is the case. “We’ve been able to track the animals from Africa, through an importer in Texas and to their arrival in the Midwest. During that process the prairie dogs might have had contact with many different species of animals, several of which could be the source of the virus. Currently there’s an ongoing investigation to determine the vector that brought the virus into this country.”

While monkeypox infection is reported to be fatal in 1% to 10% of victims in Africa, as of June 13 only one severe illness (encephalitis) and no deaths have been seen in the US, where nutrition, sanitation and access to medical care may improve outcomes. Many people recover completely from monkeypox, although some might have cosmetic effects such as scarring from skin lesions.

How Does it Spread? Current Cases Could Hold Key
Dr. Graham has seen 10 cases of monkeypox so far. “Four of the patients were hospitalized,” she reports, “and six were treated as outpatients. Only one of them was actually bitten, but all have had some contact with a sick prairie dog.” Some of the prairie dogs had skin lesions or respiratory secretions from which the virus might have been spread. All possible modes of transmission are being investigated by the CDC and individual investigators, but no definitive results have been verified as yet.

Because the mode or modes of transmission have not yet been positively identified, it’s important to avoid contact with the lesions or body fluids of an infected animal or person, or with items such as clothing or bedding that have been used patients already infected with the monkeypox virus.

“Our patients are being cared for with methods consistent with all possible avenues of transmission,” Dr. Graham says. “I’m exceedingly impressed with the staff at Froedtert & Medical College in their handling of this outbreak,” Dr. Graham concludes. “The nursing and house staff have been very calm, helpful and wonderfully professional.”

Symptoms
The symptoms of monkeypox vary from patient to patient, generally include some of the following:

• Fever
• Drenching sweats
• Sore throat
• Chills
• Headache
• Muscle pain
• Swollen lymph nodes

These initial symptoms are seen from 4 to 21 days after contact with an infected animal. Seventy-two hours to one week after the initial symptoms begin a rash erupts, and the raised bumps form lesions that crust over and fall off within a few weeks.

Treatment
“There is no official treatment for monkeypox,” says Dr. Graham. “I’ve been treating the patients’ constitutional symptoms, such as infected skin lesions and upper respiratory symptoms.” There are indications that the antiviral drug cidofovir may be efficacious in treating the illness, but it can interact poorly with a number of other drugs. In addition cidofovir can cause serious side effects, especially in the blood and kidneys.

Dr. Graham notes that sick animals also have the potential to carry other pathogens in addition to the monkeypox virus, and she has been watching (and testing) for symptoms that might indicate other animal-borne infections.

CDC Recommends Smallpox Vaccine
Although there is no treatment for monkeypox, the CDC issued a recommendation that people involved in investigating monkeypox outbreaks or caring for infected humans or animals should receive a smallpox vaccination to protect against the possibility of contracting monkeypox. The CDC is also recommending that people who have had close or intimate contact with individuals or animals confirmed to have monkeypox should be vaccinated. They can be vaccinated up to 14 days after their exposure to the sick person or animal.

But given the possible side effects of the smallpox vaccine and the relatively low risk of monkeypox, some health officials disagree with the recommendation. “It’s really up to the individual to decide,” says Dr. Graham. “The vaccine is safe for most people, and the 14-day period can give them enough time to decide which course of action to take.”

Precautions and Cautious Optimism
Dr. Graham warns that animals and rodents other than prairie dogs have the potential to carry the virus. In the meantime, the US government has banned the sale and transportation of prairie dogs and prohibited the importation of any African rodents into the country.

Pet owners, especially those with prairie dogs, are urged to be on the lookout for symptoms such as lesions or respiratory distress in their animals. Health officials say it is imperative that people with sick pets do not let them go, but take them to a veterinarian for evaluation.

Contact your health care provider or your local Health Department if you have had recent contact with a sick prairie dog or if you’ve had access to a person who has already been diagnosed with monkeypox and you have symptoms consistent with those listed above.

All in all, Dr. Graham says, if we continue to use common sense, good investigational methods and excellent precautions, there’s good reason to hope that we’ll contain the monkeypox virus before it spreads beyond its current limits.

This article includes information from the Medical College of Wisconsin Infectious Diseases Clinic and the Centers for Disease Control and Prevention (www.cdc.gov).

MCW Health News presents up-to-date information on patient care and medical research by the physicians of the Medical College of Wisconsin.