An outbreak of Salmonella Typhimurium in pigs in a faro with persistent PCV-2 associated diseases.

VIGO G., ; LEOTTA G., ; CAFFER M.I., ; SANGUINETTI H.R.,; PIÑEYRO P., ; CAPUCCIO J., ; PERFUMO C.J.

Foz do Iguazu, PR, Brasil

Congreso; 2° Congreso Latinoamericano de Suinocultura. 4° Congreso de Suinocultura del Mercosur.; 2004

Salmonella enterica subespecies enterica serovar Typhimurium is an important pathogen for swine which had emerged worldwide during the last two decades. Enterocolitis caused by S. Typhimurium occurs with greater than expected in high-health herds. In contrast to S. Choleraesuis, S. Typhimurium it is not host specific and can be isolated from birds, rodents, cows, feed or water. In, a study carried-out from 1994 to 1996 showed that salmonellae were isolated from 11%, 9% and 58% of pneumonic, enteric or septicemic samples respectively while a report of 2001, the frequency was 1.3%, 9% and 7.8% from the same source samples. The objective of this work were describe the clinical, pathological and bacteriological studies of an outbreak of salmonellosis in pigs in a farm with persistent porcine circovirus type 2 associated diseases as well as the results of control strategy. On March 2004, an increased mortality at the growing/fattener phase (approx. 2300 pigs) was reported in a 330 sow?s inventory 3 sites farm. Fourth barns were filled with 575 growing pigs each (30-40 kg) coming from a nursery facility. The feeder barns, poultry adapted houses, had a deep straw bed with water and feed provided in a wet/dry feeder. The feed was a soybean/com/meat meal formulated with the addition of 110 ppm of tylosine. The batch of pigs started with no problems, however 3 weeks later, and during 4 months, mortality reached, from a historical figure of 1% to 2.6%, 3.7%, 2% and 2.7% on March, April, May and June respectively. Besides an equivalent number of poor doing pigs were culled. The affected pigs showed a yellow-green-watery diarrhea lasting for 3-4 days with lost of condition. In total, 19 pigs were postmortem examinated. At the begining of the outbreak 7 dead pigs a 1 severely affected were studied and on july, 9 dead pigs and 2 with clinical illness (fever). From them, routine istopathological and bacteriological studies were carried-out. Besides, rectal swabs from 6 diarrheic pigs were sampled. The isolated Salmonella strains were serotyped according the Standard International Scheme for Salmonella Serotyping at the National Reference laboratory of Enterobacteria INEI-ANLIS Dr. Carlos G. Malbrán. In the first group, the pathological diagnosis were: in 3 pigs bronchopneumonia with more than 25% of the lung involvement with associated lesions of post-weaning multisystemic wasting syndrome (PMWS), 1 pig with porcine dermatitis and nephropathy syndrome (PDNS), 1 pig with purulent bronchopneumonia and 3 with fibrinonecrotic cecitis and colitis. In the second group, 5 with PMWS, 2 with PDNS and 1 each with the diagnosis of torsion, systemic infection, septic polyarthritis and pneumonia. From the first necropsy group, Salmonella was isolated from colon, spleen and rectal swab from 2 pigs with fibrinonecrotic colitis and 1 from bronchopneumonia and PMWS. The antigenic formulae obtained were 4, 12:i1, 2 corresponding to Salmonella Typhimurium var. Copenhagen. Before the confirmatory diagnosis, all pigs were medicated with chlortetracycline 300 ppm and carbadox 50 ppm via feed during 2 weeks; besides the meat meal was replaced with soybean meal and pigs moved to a slatted floor accommodation. Currently in Argentina, PMWS is the most prevalent viral disease. In lymph-nodes PCV-2 infect lymphocytes, monocytes and macrophages with the development of lymphocyte depletion, monocytic infiltration and associated ammunosuppression allowing the coinfection with other virus or bacteria. Among them, P. multocida, S. suis and clinical salmonellosis covered statistical significance related with PMWS. In Argentina, Salmonella serovar Typhimurium var. Copenhagen have been isolated from food, mammals and human being, although neither isolation nor associated with enterocolitis lesion were reported in pigs. Salmonella Typhimurium enterocolitis is the results of the rapid and non-specific cellular invasion in less than 10 minutes of M cells, globlet cells, and enterocytes. Concurrent debilitating infection or poor hygiene was considered risk factors for Salmonella infection. Therefore, in the study case a previously clinical PMWS might have triggered the concurrent infection and pathological manifestation of Salmonella Typhimurium var. Copenhagen. However, when specific therapy, skilled management (moved from hay bed to slated floor), and replaced meat meal were applied toward controlling salmonellosis, neither enterocolitis nor isolation of the bacteria were successful, even though PCV-2 associated diseases were still found