July 2003

---Philip A. Brunell, MD

There is a plague upon the land! As of June 18 there were 87 cases of suspected monkeypox affecting mainly Midwesterners, 20 of whom have been hospitalized. Twenty of the cases have had laboratory confirmation. One 11-year-old girl has encephalitis (www.cdc.gov/mmwr/preview/mmwrhtml/mm5223a1.htm).

However, prairie dogs that are potentially infected have been shipped to as many as 15 other states. One case, which had been reported in New Jersey, turned out to be a false alarm. One can offer some assurance that prairie dogs do not need to be disposed of if they are healthy and that vaccination of owners of such animals is not indicated. However, animals obtained after April 15 should be observed for evidence of disease particularly in areas where infected pets have been discovered. Most important, sick animals should not be released into the wild. Recommendations have been issued for containment of this outbreak including identification of affected animals and human cases, appropriate isolation procedures and for selective vaccination with smallpox vaccine (www.cdc.gov/mmwr/preview/mmwrhtml/mm5223a1.htm.)

David W. Fleming MD, deputy director for Public Health Science for the CDC, recommended that people who obtained prairie dogs or other small rodents since April 15 should observe their pets for signs of illness as well as consulting a physician should they become ill. One rabbit exposed to an infected prairie dog became infected and several gerbils have been exposed.

The disease may have been introduced into this country from Africa by five giant pouched rats from Gambia that ended up in the same Illinois pet store as the infected prairie dogs. Pet stores in Iowa and Wisconsin as well as swap meets might be the source of infected animals.

Owners should observe their pets for oozing eyes, breathing problems and a bumpy rash, which often can be detected while petting the animals. If you think your animal is infected you should contact your veterinarian. Transport of the animals should be carried out under instructions from a veterinarian to minimize the possibility of additional spread of infection. One particular prairie dog is suspected of infecting several humans and is believed to be a “super-spreader.”

Infected animals or those suspected of being infected should not be released into the wild. This could spread the disease to our rodent population and establish it as an endemic disease just as it is in Africa.

Prairie dogs are abundant in our Southwest. In 2001 alone, it was estimated that dealers in Texas captured 15,000 for the sole purpose for resale as pets.

Before the current outbreak, monkeypox did not exist in the Western Hemisphere. This virus is endemic in certain rodents in parts of Africa. Occasionally, a monkey or a human has been infected.

The two cases reported earlier of possible person-to-person spread (victim to health-care worker), in Wisconsin now appear to be doubtful. In Africa, where most cases have occurred, person-to-person spread is known to occur but the risk is debated. Precautions to prevent spread in offices can be found at www.cdc.gov/ncidod/monkeypox/infectioncontrol.htm.

Monkeypox was first described in Africa in the 1950s. It received a great deal of notoriety during the smallpox eradication program because of its resemblance to this disease. It was important to determine the etiology of illnesses with a vesicular rash to assess the need for additional smallpox vaccination in the area.

Chickenpox is a herpes virus, which also causes a vesicular rash, which is sometimes confused with monkeypox or smallpox. An 11-year-old boy from New Jersey who had been diagnosed as having monkeypox after visiting a family friend in Indiana who had two prairie dogs was later found to have had chickenpox.

Monkeypox resembles smallpox. Individuals who have had contact with a sick animal or a family member and subsequently develop fever, chills, muscle aches, or rash are advised to consult their doctor. Arrangement should be made to examine suspected cases with proper precautions in an isolation room. Significant lymphadenopathy is present in about half of the cases and respiratory symptoms are common. Physicians seeing suspected cases should consult www.cdc.gov/ncidod/monkeypox/casedefinition.htm for more detailed information on the clinical manifestations.

Smallpox vaccine has been shown to confer substantial protection against monkeypox, as these are related viruses. Vaccination is recommended in very limited situations in areas where monkeypox is present. Wisconsin has offered the vaccine to three groups of people: health-care workers and caregivers in contact with someone suspected of having monkeypox, people older than 1 year who have been in contact with animals sick with monkeypox or small mammals from dealers implicated in the outbreak; and people who are investigating suspected human and animal cases of monkeypox. There have been few takers. At least two other states with cases have not offered the vaccine. The recommendations from CDC can be found at www.phppo.cdc.gov/han/Documents/AlertDocs/146.asp.

To control spread there has been an embargo on rodents imported from Africa. There may be as many as 1,000 such animals imported annually. There also will be a ban on the sale or movement of these animals as well as for prairie dogs and their interstate sale. The original rats may have been imported by a Texas exotic pet dealer and sold to an Illinois pet shop where it is believed the prairie dogs first became infected.

There has been some praise and condemnation of how this has been handled. Some have been concerned about the delay in reporting what might have been smallpox to the CDC. Others have praised the alacrity of the response to the problem. There appeared to be a number of false alarms along the way. If there is a smallpox introduction, it will be important to identify it promptly so that an appropriate response can be mounted. There is a short window in which vaccination must take place. It also is important to prevent spread by isolation of suspected cases so that the number of exposures can be limited.

In the Institute of Medicine May report on smallpox preparedness, the importance of carefully examining the information obtained from the initial vaccination experience and to work on the infrastructure needed for an appropriate response was stressed. One thing that did not occur was a panic to vaccinate the entire population. This would not only create chaos but would result in injury to those vaccinated and some deaths.

Pets provide many benefits for kids but, perhaps, we need to be a bit more selective in choosing them. Exposures to pets have been associated with a lowered rate of development of allergy. When I was in practice I used to recommend that children get goldfish if their families had a history of atopic disease. Perhaps, this would be a good substitute for prairie dogs.