Assessment of sow herd frequency of PCV-2 using placental umbilical cord serum and serology in 18 breeding farms in Brazil.

Porcine circovirus type 2 (PCV-2) is the agent of one of the most important diseases in the swine industry. Although it has been controlled through vaccination, viremic piglets at birth may represent a risk by reducing vaccination efficacy. Since there are few reports on the viremic status of pre-suckling piglets regarding PCV-2 infection, we assessed the PCV-2 frequency in sows housed in 18 breeding farms with no history of clinical PCVAD in Brazil, using placental umbilical cord serum (PUCS). The selection criteria were: breeding farms with more than 1,000 sows; sows not vaccinated for PCV-2 at least for 2 years prior to the study; farms with no history of PCV-2 clinical disease in the last 12 months; and production systems with a maximum of two sites. Blood from the umbilical cords in sow placenta or directly from piglet's immediately after birth was collected from 30 litters on each farm for PCR. In addition, blood from 538 sows was collected for PCV-2 antibody detection. A total of 17.29% of the PUCS tested positive. The PCV-2 DNA was detected in PUCS from 94.4% of all farms. A total of 94.8% of the sows was positive for PCV-2 antibodies. However, seronegative sows were detected in 44.4% of farms. All 18 farms had at least 46.9% seropositive dams. A higher percentage of seronegative sows was observed for farms with more than 10% of PCV-2-positive litters compared to those with ≤10% of PCV-2 positive litters (8.9 +/-1.7% vs. 1.5 +/- 0.7%, p < 0.01, respectively).

Matched case-control study evaluating the frequency of the main agents associated with neonatal diarrhea in piglets / Estudo caso-controle pareado avaliando a frequência dos principais agentes causadores de diarréia neonatal em suínos no Rio Grande do Sul

A case-control study was carried out in litters of 1 to 7-day-old piglets to identify the main infectious agents involved with neonatal diarrhea in pigs. Fecal samples (n=276) from piglets were collected on pig farms in the State of Rio Grande do Sul, Brazil, from May to September 2007. Litters with diarrhea were considered cases (n=129) and normal litters (n=147) controls. The samples were examined by latex agglutination test, PAGE, conventional isolating techniques, ELISA, PCR, and microscopic methods in order to detect rotavirus, bacterial pathogens (Escherichia coli, Clostridium perfringens type A and C, and Clostridium difficile), and parasites (Coccidian and Cryptosporidium spp.). Outbreaks of diarrhea were not observed during sampling. At least one agent was detected in fecal samples on 25 out of 28 farms (89.3 percent) and in 16 farms (57.1 percent) more than one agent was found. The main agents diagnosed were Coccidia (42.86 percent) and rotavirus (39.29 percent). The main agents identified in litters with diarrhea were Clostridium difficile (10.6 percent), Clostridium perfringens type A (8.8 percent) and rotavirus (7.5 percent); in control litters, Clostridium difficile (16.6 percent) and Coccidian (8.5 percent). Beta hemolytic Escherichia coli and Clostridium perfringens type C were not detected. When compared with controls, no agent was significantly associated with diarrhea in case litters. These findings stress the need for caution in the interpretation of laboratorial diagnosis of mild diarrhea in neonatal pigs, as the sole detection of an agent does not necessarily indicate that it is the cause of the problem.

Um estudo de caso-controle em leitegadas de um a sete dias de idade foi realizado com o objetivo de identificar os principais agentes infecciosos envolvidos na diarreia neonatal de leitões. As amostras de fezes (n=276) foram coletadas em granjas de suínos no Estado do Rio Grande do Sul, Brasil, no período de maio a setembro de 2007. Leitegadas com diarreia foram consideradas casos (n=147) e leitegadas normais, controles (n=129). As amostras foram examinadas através do teste de aglutinação em látex, PAGE, cultivo, ELISA, PCR e métodos microscópicos para a excreção dos principais agentes de diarreia: virais (rotavirus), bacterianos (Escherichia coli, Clostridium perfringens tipos A e tipo C e Clostridium difficile) e parasitários (coccídeos e Cryptosporidium spp.). Durante o período do estudo não foram observados surtos e a diarréia, quando presente, apresentou-se leve. Pelo menos um agente foi identificado nas amostras fecais de 25 entre 28 granjas (89,3 por cento) analisadas e em 16 granjas (57,1 por cento) mais de um agente foi detectado. Os principais agentes encontrados nas granjas foram coccídeos (42,86 por cento) e rotavírus (39,29 por cento). Os principais agentes detectados nas leitegadas com diarreia foram Clostridium difficile (10,6 por cento), Clostridium perfringens tipo A (8,8 por cento) e rotavírus (7,5 por cento). Por outro lado, nas leitegadas controle os agentes mais prevalentes foram Clostridium difficile (16,6 por cento) e coccídeos (8,5 por cento). E. coli Beta hemolítica e Clostridium perfringens tipo C não foram detectados. O presente estudo de caso-controle demonstrou que nenhum agente infeccioso esteve associado significativamente com diarreia (p>0.05). Esses achados reforçam a necessidade de que haja cuidado na interpretação de resultados de exames laboratoriais em materiais coletados de leitões com diarreia neonatal leve, pois a detecção isolada de um agente infeccioso não indica necessariamente que o mesmo seja a causa do problema.