OAHN-swine project: erysipelas in Ontario swine

Josepha DeLay, Durda Slavic, Tim Pasma, Jim Fairles

Erysipelothrix rhusiopathiae septicemia (‘erysipelas’) remains a concern in swine despite continued routine sow vaccination in many herds. In clinical impression surveys carried out by the Ontario Animal Health Network (OAHN), Ontario swine veterinarians have indicated an increased frequency of erysipelas over the past 3 years. Cases of suspected erysipelas are often diagnosed clinically based on distinctive, nearly pathognomonic, rhomboid skin lesions and typically successful response to antibiotic therapy. As a result, these cases are infrequently submitted to the Animal Health Laboratory (AHL) for diagnostic confirmation.

Swine erysipelas may affect all age groups. Typical skin lesions may not be seen in all acute cases, and sudden death may be the primary complaint. Chronic arthritis and lameness, and vegetative valvular endocarditis may be sequelae in surviving pigs. Asymptomatic carrier pigs shed the organism in oronasal secretions and feces; in acutely infected animals, the organism may also be shed in urine.

The multiple known strains of E. rhusiopathiae vary in virulence, and this variation could potentially explain recent clinical reports of an increase in swine erysipelas. Isolation of E. rhusiopathiae is usually straightforward in samples from filtering organs (spleen, liver, lung, kidney, lymph node; also affected skin) of acutely affected, untreated animals. As with most infectious diseases, selection of appropriate individual animal and tissues for sampling is the key to reaching an accurate, successful diagnosis.

Since 2015, 5 cases of E. rhusiopathiae septicemia have been submitted to the AHL. The cases involved nursing piglets (2 herds, including 1 organic herd), sows (1 herd), and grow-finish (GF) pigs (2 herds). Typical skin lesions were described in 1 of the GF herds, but not in other cases. A sudden increase in mortality was described in the nursing piglet cases, with a concurrent increase in stillborn and weak neonates in 1 herd. In all cases, E. rhusiopathiae was isolated in large numbers from various filtering organs (spleen, liver, lung, kidney, lymph node), as well as from skin and meninges in some animals.

E. rhusiopathiae is a zoonotic pathogen, and education of producers and barn staff in this regard is important. Localized cutaneous lesions (‘erysipeloid’ or ‘pork finger’) are most common, although systemic illness and endocarditis occur in some people, with potentially fatal outcome. Notably, the disease known as ‘erysipelas’ in humans is a separate and distinct condition, and is caused by Streptococcus spp.

In response to swine practitioners’ identification of increased erysipelas cases in the Ontario herd, the OAHN Swine Network is supporting a project to further investigate and characterize E. rhusiopathiae isolates from clinical cases and from abattoir samples.

Veterinarians with suspected erysipelas cases are encouraged to contact Dr. Tim Pasma, Ontario Ministry of Agriculture, Food, and Rural Affairs (OMAFRA) to enroll in the project (tim.pasma@ontario.ca).

For enrolled herds, fresh or frozen samples from spleen and lung of affected pigs should be submitted to the AHL for bacterial culture.   AHL

Chlamydia spp. and reproductive issues in swine

Josepha DeLay, Jim Fairles, Hugh Cai

Recent reports in peer-reviewed publications and in the lay press have suggested an association between sow infection with Chlamydia spp. (primarily C. suis) and poor reproductive performance. A definitive, causal relationship between Chlamydia spp. and poor conception or pregnancy loss remains to be proven. The Animal Health Laboratory (AHL) is developing a PCR assay for C. suis, in order to evaluate the presence of the organism in the Ontario herd, and to investigate a potential link between infection and reproductive failure. The test is currently available as an external (send-out) test. Stay tuned for updates on this topic in future editions of the AHL Newsletter.   AHL