Jul 10, 2003 (CIDRAP News) – The number of possible human monkeypox cases dropped in the past week as investigators ruled out 11 cases while confirming three, the Centers for Disease Control and Prevention (CDC) announced today.
As of Jul 8, 35 cases were confirmed by laboratory tests and another 36 possible cases remained under investigation, for a total of 71 cases, the CDC reports in the Jul 11 issue of Morbidity and Mortality Weekly Report. Confirmed cases include 17 in Wisconsin, 8 in Illinois, 7 in Indiana, 2 in Missouri, and 1 in Kansas. The agency had reported 81 cases, including 32 confirmed, on Jul 2.
Eighteen of the 71 patients were hospitalized at some point with the disease, but some were admitted for isolation only, the CDC reports. Two children who suffered serious illness have recovered.
The CDC says all 35 confirmed cases of monkeypox have been linked to prairie dogs that were sold by an Illinois animal distributor. The prairie dogs apparently were infected through contact with African rodents, including Gambian giant rats and dormice, that the Illinois distributor bought from a Texas importer Apr 21.
Investigators have traced 93 infected or potentially infected prairie dogs from the Illinois animal distributor to six other states (Wisconsin, Indiana, Missouri, Michigan, Kansas, and South Carolina), the report says. An unknown number of other prairie dogs died or were sold at animal swap meets.
The Texas animal distributor who sold African rodents to the Illinois distributor imported about 800 small mammals, including 762 rodents, from Ghana on Apr 9, the CDC reports. As announced previously, the CDC confirmed monkeypox in six rodents from that shipment.
Investigators have traced 584 of the 762 African rodents to other animal distributors in six states (Texas, New Jersey, Iowa, Illinois, Minnesota, and Wisconsin) but could not trace the other 178, according to the report. However, no possible or confirmed cases of human monkeypox have been attributed to direct contact with the African rodents. In addition, no monkeypox cases have been seen in animals exposed to the African rodents, other than the prairie dogs linked to the Illinois distributor, the article states. Of the 584 rodents that were traced, about 465 are dead.
The CDC says public health measures to contain the monkeypox outbreak "appear to have been effective in reducing exposure of humans to infected animals, with few cases reported" since the measures were announced Jun 11. The control steps include a federal ban on importation and movement of the implicated animal species, state restrictions on intrastate animal transport and trade, quarantines on premises, and euthanasia of animals.
Rodents from the Apr 9 shipment pose a continued infection risk to other animals and humans, the CDC warns. The agency recommends euthanasia for those rodents and any prairie dogs that were exposed to them. In addition, mammals that were in facilities that housed a rodent from the Apr 9 shipment should be quarantined for 6 weeks from the last date the rodent was present.
CDC. Update: multistate outbreak of monkeypox—Illinois, Indiana, Kansas, Missouri, Ohio, and Wisconsin, 2003. MMWR 2003;52(27):642-6 [Full text]