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Last Updated

14 Jun 2003

Source: Milwaukee Journal Sentinel (WI), June 14, 2003

Smallpox vaccine to fight virus

Shots offered to those exposed to monkeypox


Wisconsin officials will start giving smallpox shots Saturday to health care workers, veterinary staffers and others who have been in close contact with people or animals with monkeypox.

The shots are voluntary and are not recommended for the general public because the vaccine carries significant risks of its own, and very little is known about its usefulness against monkeypox. But state and federal officials said the risks of the disease outweigh the dangers of the shot for a small group of people likely to be exposed to the germ.

"Monkeypox can be a very serious illness. We must do all that we can to keep the number of cases to a minimum," said Ken Baldwin, administrator of the Wisconsin Division of Public Health.

"I want to emphasize that the number of people that would need to be vaccinated in these circumstances is going to be a very small number," added state epidemiologist Jeffrey Davis.

Monkeypox is a viral cousin of smallpox, though far less deadly. It had never been seen in the Western Hemisphere until the outbreak came to light in Wisconsin last week.

The source is thought to be pet prairie dogs who became infected when kept with or near rodents imported from Africa, the only place monkeypox was previously seen.

At least 87 possible human cases are being investigated in four states - 34 in Wisconsin, 33 in Indiana, 19 in Illinois and one in New Jersey. Thirteen cases have been confirmed so far by the Centers for Disease Control and Prevention, including four in Wisconsin; tests are pending on the rest.

Of Wisconsin's other 30 cases, 10 are considered probable cases and the remaining 20, suspected. The distinction depends on the nature and severity of the rash that people have developed and how consistent it is with monkeypox, Davis said.

Person-person spread unlikely

The good news is that two health care workers probably don't have monkeypox and that there's no evidence of person-to-person spread yet in the United States.

"The illnesses in both of those individuals has been quite mild. I would go so far as to say it's highly likely that neither one has monkeypox," though lab tests are still pending, Davis said.

Thirteen possible cases in Wisconsin were reported from Wednesday evening to Friday, and "the majority of those are veterinary health workers," showing the need for such people to take strong infection control measures to protect themselves, Davis said. People should call veterinarians before bringing in sick animals so precautions can be taken to avoid spreading the virus.

Eight cases being investigated in Wisconsin involve people who work at or visited pet stores. At least two had no known contact with prairie dogs. One had been in the store for a significant amount of time and bought a reptile, Davis said. Another didn't have contact with prairie dogs but had contact with another species and was scratched.

"There are other animals that will be examined, tested, just to see whether or not they could have been infected within this shipment of exotic animals," Davis said. "Because we want to be aggressive, there may be other animals tested, as well."

Smallpox shots will be offered to people in direct contact with confirmed, probable or suspected monkeypox cases. The vaccine will be free, but those receiving it won't be eligible for federal smallpox injury compensation or worker's compensation if they're harmed by the vaccine.

"There is no evidence that the smallpox vaccine prevents monkeypox after a person has been exposed," but the shots are 85% effective at preventing monkeypox when given before exposure to the virus, according to state health officials.

Experience with the smallpox vaccine suggests that when given three to four days after exposure to that germ, disease can be prevented or made less severe, so officials are hoping it will do the same after exposure to monkeypox.

Experimental use

But the vaccine has never been used for this purpose, and state officials are concerned that people understand the relative risks.

"It's an investigational new drug when used in this way. That means it's experimental. It's like a drug trial," said Herb Bostrom, director of the state's Bureau of Communicable Diseases.

Before routine smallpox vaccination ended in the 1970s, about 40 of every 1 million people receiving the vaccine for the first time had a life-threatening complication, and one or two died. Heart problems have come to light during recent efforts to vaccinate military and health care workers as part of bioterrorism preparedness.

"It is not the world's cleanest or safest vaccine," and people considering it for monkeypox must carefully and thoughtfully consider the risks, said Milwaukee Health Commissioner Seth Foldy.

But G. Richard Olds, chairman of medicine at the Medical College of Wisconsin, said one or two deaths out of 1 million from the vaccine are far fewer than one to 10 for every 100 cases of monkeypox that occurred in Africa.

"We should not have a cavalier attitude about anything with a mortality rate," he said.

"I have doctors and nurses and people who have been exposed. The longer we delay, the worse this equation of risk versus benefits gets," he said.

Robert Belshe, the St. Louis University doctor who led government testing on the potency of the government's stockpiled smallpox vaccine last year, agreed.

"In the face of a monkeypox outbreak, it makes sense if you're exposed to go ahead and have the smallpox vaccine," Belshe said.

Meanwhile, officials are still trying to track animals that may be involved in the outbreak, including a prairie dog sold at a Wausau swap meet May 11 and four prairie dogs sold by Hoffer's Tropic Life Pets in Milwaukee.

Acting state veterinarian Robert Ehlenfeldt asked owners to contact health officials so they can complete their investigation and make sure no one else is at risk. He also urged people to obey the expanded ban the state imposed Thursday against selling, displaying or swapping prairie dogs or any mammals, even cats and dogs, that may have been in contact with prairie dogs since April 1.

"Clearly, this is a human health risk, and I would expect people to step up and follow the rules," he said.