Evaluacion de algunos factores que pudieron influir en el incremento de la fiebre porcina clásica en el Estado de México, México, durante 1997

Abstract

THE CONTROL AREA OF CLASSICAL SWINE FEVER (CSF) IS LOCATED IN THE CENTRAL AND SOUTHERN PARTS OF MEXICO WHERE VACCINATION OF SWINE HAS BEEN CONTINUED, AND CSF CASES ARE STILL REPORTED. THE NUMBER OF OUTBREAKS INCREASED IN 1997, AND 87% OF THOSE OCCURRED IN BACKYARD PIG PREMISES. TO DETERMINE SOME OF THE FACTORS RESPONSIBLE FOR THE INCREASE OF OUTBREAKS IN 1997, A SURVEY WAS DONE IN 424 BACKYARD PREMISES, OF FOUR MUNICIPALITIES, FOUR ANIMAL MARKETS, FOUR SLAUGHTERHOUSES AND SIXTEEN FARROW-TO FINISH FARMS IN THE WESTERN PART OF THE STATE OF MEXICO WITHIN THE CONTROL AREA. IN BACKYARD PREMISES AN AVERAGE OF 25% OF THE PIGS HAD BEEN VACCINATED, AND THE SEROLOGICAL SURVEY SHOWED THAT 43% HAD ANTIBODIES. AN AVERAGE OF 37% OF THE PIGS WERE SOLD AND REPLACED EVERY THREE MONTHS. AT THE FARROW-TO FINISH FARMS, 12% THE ANIMALS WERE NOT VACCINATED. AT THE ANIMAL MARKETS, AN AVERAGE OF 40% OF SWINE CAME FROM THE ERADICATION AREA, AND THE REST, 60% OF THE CONTROL AREA. THE VETERINARIANS IN CHARGE AT THE FOUR SLAUGHTERHOUSES REPORTED THAT THERE HAD BEEN ANIMALS CONDEMNED WITH LESIONS SUGGESTIVE OF CSF. IT WAS CONCLUDED THAT SOME OF THE FACTORS THAT INCREASED THE NUMBER OF OUTBREAKS IN 1997 IN THE BACKYARD PIG POPULATION, WERE THE LARGE AMOUNT OF SUSCEPTIBLE PIGS THAT CAME INTO THE CSF ENDEMIC CONTROL AREA, AND WERE MIXED WITH OTHER PIGS IN ANIMALS MARKETS, THE HIGH MOBILITY OF THE ANIMALS AND LOW HERD IMMUNITY, AND SICK AND VIREMIC ANIMALS WERE SEND TO THE SLAUGHTERHOUSES AND TRUCKS AND DRIVERS BECAME CONTAMINATED AND CARRIED OUT THE VIRUS BACK TO THE SWINE PREMISES.