Infectious bronchitis serological survey using SIN6/YUC/ MEX/96 virus in backyard chickens from 30 communities in the State of Yucatan in Mexico

Abstract

INFECTIOUS BRONCHITIS (IB) IS CONSIDERED ONE OF THE MOST IMPORTANT CAUSES OF ECONOMICAL LOSS PRODUCING HIGH MORTALITY, REDUCED GROWTH RATES IN CHICKS, AND LESIONS TO THE OVIDUCT OF LAYING HENS IMPAIRING EGG PRODUCTION. ONE THOUSAND AND SEVENTY SIX CHICKENS WERE RANDOMLY SELECTED, AND SAMPLED FROM 30 COMMUNITIES IN FOUR REGIONS OF THE STATE OF YUCATAN IN MEXICO. SERUM SAMPLES WERE RUN USING THE HAEMAGGLUTINATION INHIBITION TEST. SERA WITH TITRES EQUAL OR HIGHER THAN 25 (1/32) WERE CONSIDERED POSITIVE. SEROPREVALENCE WAS CALCULATED BY DIVIDING THE NUMBER OF POSITIVE SERA BY THE TOTAL NUMBER OF SAMPLES. SEROPREVALENCE WAS 74.9% (CI 95%, 68.9%-80%). NINE COMMUNITIES (TIXMEUAC, SOTUTA, CHAN SAN ANTONIO, XBEC, DZOYAXCHE, CUZAMA, RUINAS DE AKE, XTEPEN AND YOBAIN) HAD SEROPREVALENCES ABOVE 90%. ONLY FOUR COMMUNITIES (MACMAY-CATMIS, KANXOC, ESPITA AND BACA) HAD SEROPREVALENCES OF 50% OR BELOW. SEROPREVALENCE WITH THE IB SIN6/YUC/MEX/96 VIRUS WAS HIGHER THAN THE SEROPREVALENCE PREVIOUSLY REPORTED WITH THE M41 STRAIN IN THE STATE OF YUCATAN IN MEXICO, INDICATING THAT THE VIRUS SIN6/YUC/MEX/96 IS PRESENT AND WELL DISTRIBUTED IN THE STUDIED COMMUNITIES. HOWEVER, IN THOSE REGIONS WHERE SEROPREVALENCE WAS SIMILAR WITH BOTH VIRUSES USED AS AN ANTIGEN, OR WAS HIGHER WITH THE M41 STRAIN, IT IS PROBABLE THAT THE PRESENCE OF A DIFFERENT IB VIRUS OR A COMBINATION OF DIFFERENT TYPES INDUCED CROSS REACTION.