(CNN) -- The US Centers for Disease Control and Prevention said Monday it will suspend the import of dogs from more than 100 countries where rabies still spreads among dogs.

The decision will affect dog rescue missions, imports from dog breeders and people bringing in pets, the CDC said.

It's because of a combination of factors -- the pandemic, a lack of facilities for quarantining dogs safely and three recent incidents of infected dogs that were brought into the country, the CDC said.

"This suspension applies to all dogs, including puppies, emotional support dogs, and dogs that traveled out of the United States and are returning from a high-risk country," the CDC said in a statement.

"This action is necessary to ensure the health and safety of dogs imported into the United States and to protect the public's health against the reintroduction of canine rabies virus variants (dog rabies). The suspension is temporary and will be reviewed periodically."

Rabies is the deadliest virus known to people and to dogs alike. There's no reliable cure, although vaccines can prevent it after exposure.

The CDC's list of high-risk countries is on its website.

"If these dogs coming from high-risk countries haven't been properly vaccinated, there is a risk they could bring it into the country," Dr. Emily Pieracci, a veterinary medical officer in CDC's Division of Global Migration and Quarantine, told CNN.

"I think it is important to stress that this is a temporary suspension. We recognize that this is not the long-term solution," she said. The initial suspension is likely to be 12 months, she said.

But, she said, the pandemic has disrupted vaccination programs for animals and people alike, and the risk of bringing in a dog infected with rabies is greater than before.

Plus, CDC resources are stretched thin and it will be hard to be inspecting paperwork and animals at points of entry when CDC experts are needed for other matters.

And CDC isn't the only organization stretched thin. "The pandemic created an unsafe environment for dogs," Pieracci said. With fewer flights scheduled, and fewer staff at airports, dogs often waited for long periods in their crates in unsafe conditions -- especially if they were rejected because owners could not document they had been properly vaccinated.

"They were having to face prolonged and extended waiting times before being returned to their country of origin," she said. Some were sick, and some even died.

Unlike countries such as Britain that routinely quarantine animals being imported to make sure they are not infected with rabies, the US lacks safe quarantine facilities for imported dogs.

The suspension will affect dog rescue missions and could affect soldiers bringing back rescue dogs from, say Afghanistan, Pieracci said.

"There are a limited number of exemptions for Department of Defense personnel who are relocating to the US who are moving their personal pets. It is not for them to bring back rescue dogs," she said.

But they'll have to apply for the exemption and follow strict protocols. That will include certifying the vaccination certificates and getting a blood test for the dog to show it has antibodies to rabies. "We are going to make sure the dogs are microchipped so dogs are not switched out at the last minute," Pieracci said.

Rabies is not a trivial concern. It kills more than 99% of people known to have been infected. Once people begin to show symptoms, they are almost certain to die. Only a very few children have been saved with a complex treatment regime.

Rabies kills an estimated 59,000 people every year in 150 countries, with 95% of cases in Africa and Asia, according to the World Health Organization. It says 99% of cases come from dog bites.

"Due to underreporting and uncertain estimates, this number is likely a gross underestimate," WHO says.

The CDC declared the US free of canine rabies in 2007. That's only one strain of rabies; strains infecting bats, raccoons and other animals remain common in the US, and just about any strain can infect any mammal.

"It could cost millions of dollars to eliminate it again," Pieracci said. In the US, one to three human cases are reported every year, mostly people infected by bats.

The US requires evidence of rabies vaccination to import animals from countries where the virus still circulates, but a few have slipped through.

"Since 2015 there been three separate importations of rabid dogs. All of these dogs were rescue dogs that had what appeared to be valid rabies vaccination certification on importation," Pieracci said.

Each case cost public health officials $500,000 to track down and follow up any people or animals that could have been exposed to the dogs, the CDC said.

"There were a number of dogs that had contact with the rabid dogs and had to be put in quarantine for anywhere from four to six months," Pieracci said. "It is a very costly and very time-consuming event whenever there is a rabid dog that has been imported."

Rabies is passed through saliva. Vaccination can prevent symptoms if the vaccine is given in time, but once symptoms begin, there's almost no hope.

The suspension will only affect about 6% of the 1 million or so dogs that are imported into the US.

"This is not going to affect most people that want to travel with their dogs," Pieracci said.

"We are animal lovers. We support people wanting to import dogs from overseas, but we really want to make sure that it's done safely. This is not our end goal. We don't want this to be the permanent answer," she added.

"But we do need some time to figure out a better system so that we can make sure that rabies is not re-introduced into the United States."

The CDC suspension will be posted in the Federal Register and a 30-day comment period will run through July 14 before the suspension takes effect.

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