Occurrence of Bordetella Infection in Pigs in Northern India

Bordetella bronchiseptica infection causing atrophic rhinitis in pigs is reported from almost all countries. In the present study, occurrence of Bordetella infection in apparently healthy pigs was determined in 392 pigs sampled to collect 358 serum samples and 316 nasal swabs from Northern India by conventional bacterioscopy, detection of antigen with multiplex polymerase chain reaction (mPCR), and detection of antibodies with microagglutination test (MAT) and enzyme linked immune-sorbent assay (ELISA). Bordetella bronchiseptica could be isolated from six (1.92%) nasal swabs. Although isolates varied significantly in their antimicrobial sensitivity, they had similar plasmid profile. The genus specific and species specific amplicons were detected from 8.2% and 4.4% nasal swabs using mPCR with alc gene (genus specific) and fla gene and fim2 gene (species specific) primers, respectively. Observations revealed that there may be other bordetellae infecting pigs because about 50% of the samples positive using mPCR for genus specific amplicons failed to confirm presence of B. bronchiseptica. Of the pig sera tested with MAT and ELISA for Bordetella antibodies, 67.6% and 86.3% samples, respectively, were positive. For antigen detection mPCR was more sensitive than conventional bacterioscopy while for detection of antibodies neither of the two tests (MAT and ELISA) had specificity in relation to antigen detection. Study indicated high prevalence of infection in swine herds in Northern India. 1. Introduction Bordetellosis caused by Bordetella bronchiseptica in pigs is an economically important disease, because infected pigs show a 6–10% reduced daily weight gain [1]. Although usually considered an opportunist or secondary invader [2], B. bronchiseptica can cause pneumonia and atrophic rhinitis in growing pigs [3–9]. Clinical signs of atrophic rhinitis or B. bronchiseptica infection are sneezing abnormal nasal discharge or epistaxis and shortening/deformity of snout. The pathogen is enzootic in many pig herds and pigs carry infection without any apparent signs of disease [10]. Bordetellosis in pigs is reported frequently from most of the countries; however, information is scant on B. bronchiseptica infection in pigs in India [11–13]. The disease is rarely reported in India except two outbreaks (on one farm) in Meghalaya, a North Eastern Indian State, in the recent past [12, 13]. Though piggery is much more common in other states of India, the disease is not reported. Besides a report of isolation from slaughtered pigs from Uttar Pradesh, North India [11], there is