PCV2 Associated Enteritis
Cases of PCV2-associated enteritis are relatively uncommon. Most of the PCV2-associated enteritis cases are from grow-finish pigs. PCV2-associated enteritis cases often clinically and grossly resemble subacute or chronic ileitis. The intestinal mucosa is grossly thickened and mesenteric lymph nodes are enlarged. Microscopic examination confirms the presence of ganulomatous enteritis which can be associated with abundant PCV2-antigen by IHC (Halbur and Opriessnig, 2004). Kim et al. (2004a) diagnosed PCV2-associated enteritis in six weanling pigs. PMWS or PDNS were not seen in the herd of origin and the six pigs had no lymphoid depletion or histiocytic replacement of follicles in lympoid tissues. The authors proposed that diagnosis PCV2-associated enteritis occur only (1) if diarrhea is present, (2) if characteristic lesions are present in Peyer’s patches but not in other lymph nodes, and (3) if PCV2-antigen or nucleic acids are present within the lesions (Kim et al., 2004a).
There are many reports of concurrent infections with PCV2-associated enteritis. Cryptosporidium parvum and PCV2 were demonstrated in a 3-month-old Iberian pig (Núňez et al., 2003). Since Cryptosporidium parvum is a rare primary intestinal pathogen in post-weaning and growing pigs, the authors speculated that concurrent PCV2 infection caused immunosuppression (Núňez et al., 2003). Granulomatous enteritis was observed in Iberian pigs naturally infected with PCV2 and Lawsonia intracelllularis (Segalés et al., 2001b). Intestinal chlamydial infection concurrent with PMWS was observed in a 12-week-old Spanish pig (Carrasco et al., 2000). Finally, Jung et al. (2006) identified PCV2 in pig naturally infected with porcine epidemic diarrhea virus (PEDV). The authors found 32.7% (35/107) small intestinal samples from 87 pig herds diagnosed with PEDV-infection positive for PCV2 nucleic acids by PCR and 29.9% (32/107) PCV2 positive by ISH. Since most of the pigs in this study were less than 3 days old, it was concluded that prenatal in utero PCV2 infection may be common (Jung et al., 2006).
Carrasco L, Segalés J, Bautista MJ, Gómez-Villamandos JC, Rosell C, Ruiz-Villamor E, Sierra MA: Intestinal chlamydial infection concurrent with postweaning multisystemic wasting syndrome in pigs. Vet Rec. 146:21-23, 2000
Halbur PG, Opriessnig T: Update on porcine circovirus type 2 (PCV2)-associated diseases. In: Proc Swine Disease Conf Swine Pract, Ames, Iowa. 12:12-23, 2004
Jung K, Ha Y, Ha SK, Kim J, Choi C, Park HK, Kim SH, Chae C: Identification of porcine circovirus type 2 in retrospective cases of pigs naturally infected with porcine epidemic diarrhoea virus. Vet J. 171:166-168, 2006
Kim J, Chae C: A comparison of virus isolation, polymerase chain reaction, immunohistochemistry, and in situ hybridization for the detection of porcine circovirus 2 and porcine parvovirus in experimentally and naturally coinfected pigs. J Vet Diagn Invest. 16:45-50, 2004a
Núňez A, McNeilly F, Perea A, Sánchez-Cordón PJ, Huerta B, Allan G, Carrasco L: Coinfection by Cryptosporidium parvum and porcine circovirus type 2 in weaned pigs. J Vet Med B Infect Dis Vet Public Health. 50:255-258, 2003
Segalés J, Fernandez-Salguero JM, Fructuoso G, Quintana J, Rosell C, Pozo J, De Arriba ML, Rubio P, Domingo M: Granulomatous enteritis and lymphadenitis in Iberian pigs naturally infected with Lawsonia intracellularis. Vet Pathol. 38:343-346, 2001b