Detection of Mycobacterium avium subspecies paratuberculosis by nested-PCR of ovine fecal samples

Abstract

PARATUBERCULOSIS IS A CHRONIC GRANULOMATOUS ENTERITIS CAUSED BY MYCOBACTERIUM AVIUM SUBSPECIES PARATUBERCULOSIS (MAP), WHICH AFFECTS WILD AND DOMESTIC RUMINANTS. MAP IS SHED IN FECES FROM INFECTED ANIMALS. TRANSMISSION OF THE INFECTION TAKES PLACE BY ORAL INGESTION OF THE BACTERIUM FROM CONTAMINATED FOOD AND WATER WITH FECES. WITH THE OBJECTIVE TO ESTABLISH A PARATUBERCULOSIS DIAGNOSIS IN OVINE BY NESTED-PCR FROM FECAL SAMPLES, 204 FECAL AND SERUM OVINE SAMPLES WERE STUDIED. FECES WERE EVALUATED BY NESTED-PCR AND BACTERIAL CULTURE, SERUM SAMPLES WERE ANALYZED BY AGAR GEL IMMUNODIFFUSION (AGID). NESTED-PCR YIELDED A 210 BP AMPLIFICATION PRODUCT THAT CORRESPONDS TO MAP-IS900, IN 61 OUT OF 204 SAMPLES. FROM THESE, 43 WERE FROM AGID POSITIVE ANIMALS AND 18 FROM NEGATIVE ANIMALS. SEVENTEEN MAP STRAINS WERE ISOLATED BY BACTERIAL CULTURE AND AGID DETECTED 91 POSITIVE ANIMALS. NESTED-PCR ALLOWED TO DETECT, SOONER, GREATER NUMBER OF ANIMALS SHEDDING BACILLUS, EVEN WHEN THEY HAD RESULTED NEGATIVE TO THE SEROLOGICAL TEST. THIS RESULT IS CONSIDERED IMPORTANT BECAUSE GENERALLY THESE ANIMALS, WHILE REMAINING IN THE FARM, CONSTITUTE THE MAIN SOURCE OF INFECTION FOR THE HERD. NESTED-PCR SHOULD BE CONSIDERED AS AN ALTERNATIVE, WHEN A PROMPT RESULT IS REQUIRED TO KNOW THE HEALTH STATUS OF THE HERD WITH RESPECT TO PARATUBERCULOSIS.