The Mexican SENASICA (equivalent to the USDA-APHIS) has reported an outbreak of Exotic Newcastle disease (velogenic viscerotropic Newcastle disease) in the state of Baja California. The report dated January 26 indicated that mortality occurred in a flock of approximately 21,000 mature chickens, which suffered 40% mortality within a few days before diagnosis, followed by depletion of the survivors.
According to Mexican authorities, the previous reported outbreak in this area occurred in 1982.
Vaccination
Reports claiming that one or more states in Mexico are free of END have always been viewed with suspicion by U.S. poultry veterinarians. Claims to this effect are based more on political considerations than substance. It is common knowledge that poultry producers in Mexico employ intensive vaccination programs incorporating live attenuated vaccines in combination with inactivated oil emulsion products to establish immunity. If the disease was not endemic in many poultry-producing areas in Mexico, integrators and farmers would not expend money on vaccines and vaccinations and suffer the deleterious effect on performance of these intensive programs.
It is presumed that the affected flock was improperly vaccinated and as with other flocks in the region was exposed to END and because of deficient immunity demonstrated clinical disease and high mortality.
Biosecurity precautions
The significance of this outbreak relates to the fact that due to proximity and movement of personnel, END can be introduced into the U.S. poultry industry. Egg production operations located in boarder states are extremely vulnerable to introduction of infection by workers returning from visits to their home country.
Standard biosecurity precautions, if they exist in other than name on U.S. farms, are inadequate to exclude HPAI and END, creating a risk of introduction of infection. Given the movement of nest-run eggs among complexes operated by large multi-state egg producers, dissemination on a national scale could occur, rapidly resulting in devastation of the U.S. industry since the resources of the USDA-APHIS are inadequate to deal with simultaneous multiple outbreaks of END in diverse areas.
The basic precautions that should be taken to exclude END include:
- Employing only documented aliens
- Ensuring that workers returning from their homeland should be restricted from either direct or indirect contact with poultry for at least 48 hours after re-entry into the U.S.
- All workers should park their vehicles in a designated area at least 100 yards from the perimeter of a poultry farm.
- Workers should doff their outer clothing and shoes in a dedicated change room and don company-supplied clothing including coverall, caps and footwear.
- All employees should have the opportunity to thoroughly decontaminate their hands by washing in soap and water and applying an alcohol gel before entering houses.
- Footbaths containing an active disinfectant should be placed at the entry point to farms and in hallways between adjacent houses on an in-line complex
- Special precautions should be applied to non-company work crews contracted for vaccination, beak trimming and flock movement.
- Managers should inspect flocks daily and review production records and water consumption to detect any sign of disease. In the event of any deviation from normal parameters, appropriate professional diagnostic procedures should be initiated.
