Foot-and-mouth disease is a threat

Planning for the worst | With outbreaks around the world, North America is lucky to be free of FMD, says USDA official

LOUISVILLE, Ky. — The World Organization of Animal Health received 119 reports of foot-and-mouth disease outbreaks last year.

“FMD is out there and it is really rather amazing that we have not had it for so long in our country or on the North American continent,” said Jon Zack, director of veterinary services with the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service.

North American authorities continue to plan for the possibility of an outbreak with strategies that involve slaughter, surveillance and biosecurity. Flexibility is critical in a region as big as North America.

“Choosing alternative strategies is a complex decision. It is a state, federal and tribal decision. It involves everyone,” Zack said during a foot-and-mouth forum at the National Institute for Animal Agriculture conference held in Louisville April 15-18.

“You don’t lock yourself into a strategy where the response is worse than the disease itself,” he said.

One of the problems is the interdependence of the North American livestock system with cattle, pigs, sheep and goats moving from Canada to Mexico. All three countries have large animal inventories and an infection of any one of them is likely to change the status for all.

“If there was an outbreak in Mexico, what would that do to our status internationally,” Zack said.

APHIS has written guidelines because tough choices may have to be made during an outbreak.

All movement stops in a designated area of infection, trading partners are notified and emergency plans start within the first 24 hours of a confirmed case.

Decisions are needed for the status of non-infected areas, and agreement is needed on who is in charge.

Zack conceded that there will be regulatory interventions and resistance from other states and tribal councils. Local knowledge will have to be respected.

Strategy will depend on the ability to detect, control and contain FMD animals as quickly as possible. The goal is to quickly eradicate the disease while protecting the food supply, economy and public health.

The guidelines call for a co-ordinated public information campaign. There are also plans to create secure supplies of eggs, milk, turkey, broilers and pork.

“Stamping out” is the most common approach to disease eradication, in which infected and susceptible animals are euthanized and disposed of appropriately.

This works best if the outbreak is contained to a jurisdictional area in which FMD can be readily contained and further spread is unlikely.

The jurisdiction may decide on the “stamping out” approach and to use emergency vaccination before slaughtering animals.

Another ploy is the “stamping out” approach with modified emergency vaccination, which allows animals to live.

Emergency vaccination to live without “stamping out” protects susceptible animals. This strategy is reserved for an outbreak in which FMD is widely disseminated across the country.

There will also be swift quarantine and movement controls. Rapid diagnosis and reporting along with epidemiological investigation and tracing are needed.

There will also be increased surveillance and stepped up biosecurity measures.

The United States participates in the North American FMD Vaccine bank with Canada and Mexico, but only limited amounts are stored.

No single dose of a FMD vaccine provides complete immunity to prevent all future infections.

Seven serotypes of foot-and-mouth disease and 65 strains are available. Cross protection between these types varies based on antigenic similarity.

Quarantine areas will have specific boundaries but could spread as the crisis deepens.

The minimum-sized infected zone should be at least three kilometres beyond the perimeters of presumption or confirmed infected premises. Buffer zone should be at least seven km beyond the perimeter of the infected zone.

The control area should be at least 10 km beyond the perimeter of the closest infected premise. This may change as the outbreak continues.

Nearly six million animals would be in the affected area if the disease was found in three counties in the states of Texas, Oklahoma and Kansas. About 10.5 million animals would be affected if it spread to six counties and 17. 8 million animals if 12 counties were involved.

About the author



Stories from our other publications