FOREIGN ANIMAL DISEASE ALERT
Investigation Uncovers First Outbreak of Monkeypox Infection in Western Hemisphere
Updated: June 23, 2003
Public health officials from the Centers for Disease Control and Prevention (CDC) have confirmed the first outbreak of monkeypox in the United States and in the Western Hemisphere. To date, human cases have developed in residents of Illinois, Indiana, Kansas, Missouri, Ohio, and Wisconsin. Most affected persons in the US outbreak have had direct contact with recently purchased ill prairie dogs (including bites, handling, household contact, or handling of cages and bedding).
Human monkeypox is a rare, zoonotic, viral disease that occurs primarily in the rain forest countries of Central and West Africa. Monkeypox virus is an orthopoxvirus. In humans, infection with monkeypox virus usually results in a prodomal phase consisting of flu-like symptoms followed by a pustular rash similar to, but less infectious than, that resulting from infection with smallpox virus. Monkeypox in humans is not usually fatal. The incubation period for people is about 12 days, but can range from 4 to 20 days. Animal species known to be susceptible to monkeypox virus include nonhuman primates, rabbits, and some rodents; however, the extent of animal susceptibility is not completely understood and caution dictates that all mammals be considered susceptible. Person-to-person transmission of monkeypox has been reported to occur at a rate of 1 to 10%.
Illinois state officials have determined the source of the infected prairie dogs to be an exotic pet dealer in Villa Park, Illinois. The prairie dogs appear to have been exposed to the virus through contact with Gambian rats imported from Africa that were intended to be sold as pets. A Texas distributor imported the rats together with rope squirrels, dormice, and other small mammals.
Once arriving in Illinois, the exposed prairie dogs were held in close proximity with other animals of numerous species, some of which might be susceptible to infection with orthopoxviruses. The following animals were on the Illinois premises: hamsters, gerbils, chinchillas, squirrels, mice, pygmy hedgehogs, jerboas, mole rats, degus, and Brazilian possums. In addition, the dealer had recently sold wallabies, armadillos, short-tailed opossums, raccoons, sugar gliders, and possibly nonhuman primates.
At this point in the US investigation, the only animals found to have exhibited clinical signs of monkey pox are prairie dogs, a Gambian rat, and a rabbit. The rabbit was housed in a veterinary clinic with an ill prairie dog. Gambian giant pouched rats have previously been associated with transmission of orthopoxvirus. Clinical signs seen in the affected animals include listlessness, ocular and nasal discharges, cough, loss of appetite, lymph node enlargement, loss of hair with or without scabs, and pneumonia. Veterinarians should also be alert to the development of illness in other animal species that may have been housed with ill prairie dogs or Gambian rats.
Pet owners who believe their pet may have contracted monkeypox should immediately isolate the animal from humans and other animals and contact their veterinarian and their local or state public health department for direction. In most cases, evaluation by a veterinarian will be recommended. Before transporting the animal to the veterinary clinic, owners should notify their veterinarian so that specific infection control precautions may be undertaken.
Veterinarians examining or treating sick rodents, rabbits, and exotic pets such as prairie dogs and Gambian rats, should consider the possibility of monkeypox and are advised to use isolation precautions and personal protective equipment, including gloves, gowns, eye protection, and a surgical mask or N-95 respirator. If an animal is reported or brought to a veterinary clinic that has been exposed to or is showing signs of monkeypox, veterinarians should immediately contact their public health department for further information and handling instructions. Owners should not abandon animals at shelters or release them into the wild.
The CDC has recommended vaccinia (smallpox) vaccination for veterinarians and other laboratory workers who directly and regularly handle cultures or animals infected with monkeypox virus. Individuals caring for anyone infected with monkeypox have also been advised to consider vaccination. Previous vaccination against smallpox may lessen the severity of contacted disease.
Monkeypox is included in the list of select agents published by HHS. Veterinarians, healthcare providers, and public health personnel must report suspect cases of monkeypox in animals and humans to their public health department immediately.
The CDC and the FDA have issued a joint order prohibiting the importation of rodents from Africa and banning the distribution, sale, and transport of prairie dogs and 6 species of African rodents within the United States.
More information from the AVMA:
Monkeypox backgrounder (PDF) (updated June 23, 2003)
More information from the CDC:
Questions and answers about monkeypox:
http://www.cdc.gov/ncidod/monkeypox/qa.htm
Case count:
http://www.cdc.gov/od/oc/media/monkeypx.htm
Guidance for veterinarians:
www.cdc.gov/ncidod/monkeypox/animalguidance.htm
Interim field collection specimen form:
http://www.cdc.gov/ncidod/monkeypox/pdf/specimenform.pdf (PDF)
Guidance for pet owners and animal handlers:
http://www.cdc.gov/ncidod/monkeypox/petownerfacts.htm
http://www.cdc.gov/ncidod/monkeypox/animalhandlers.htm
Information on the embargo order:
http://www.cdc.gov/ncidod/monkeypox/pdf/embargo.pdf (PDF)
http://www.cdc.gov/ncidod/monkeypox/embargoqa.htm
Human clinical photos and micrographs of the virus:
http://research.marshfieldclinic.org/crc/monkeypox.asp
Smallpox vaccine and monkeypox:
http://www.cdc.gov/ncidod/monkeypox/smallpoxvaccine_mpox.htm
 Top
|
= AVMA/SAVMA Members Only