HERD HEALTH
PIH-118
pork industry handbook
PURDUE UNIVERSITY COOPERATIVE EXTENSION SERVICE • WEST LAFAYETTE, INDIANA
Streptococcus suis Disease in Pigs
Authors:
S. Ernest Sanford, Huron Park, Ontario, Canada
Roy Schultz, Avoca, Iowa Barbara Straw, Cornell University
Reviewers:
Martin Bergeland, University of Minnesota
William Ingalls, The Ohio State University
Patricia Tuttle, University of Kentucky
Streptococcus suis infection is an emerging disease in swine operations. Diagnostic laboratories recently have reported Strep suis as the fifth most common disease and the leading cause of meningitis, an inflammation of the brain tissue. In a recent survey of 200 swine practitioners. Strep suis was listed second as a disease that will cause increasing problems in the next 5 years.

Strep suis is a bacterium that lives in the tonsils of some pigs and is capable of causing disease in the brain (meningitis) and other organs (septicemia). While Strep suis is most often associated with meningitis, other manifestations in pigs caused by Strep suis include pneumonia, a “fading piglet syndrome,” polyserositis, arthritis, valvular endocarditis, myocarditis, pericarditis, and abortion.

There are several types of Strep suis. Although in the past, type 2 has been most commonly identified with meningitis outbreaks, types other than 2 may also cause meningitis. In fact, type 7 is more frequently isolated than type 2 from pigs at the Veterinary Diagnostic Laboratory at Iowa State University.

Clinical Signs
Although pigs from birth to adult may be affected. Strep suis disease outbreaks occur most frequently in recently weaned pigs. Typically, meningitis is seen in the post-weaning period. It may involve 1 to 5% of the herd. Meningitis may appear as sudden deaths or pigs with convulsions dying in the first three weeks post-weaning. Previously robust pigs may be found dead without having shown clinical signs. Usually, however, pigs with Strep suis meningitis go through a progression of loss of appetite, reddening of skin, fever, depression, loss of balance, lameness, paralysis, paddling, shaking, and convulsing. Blindness and deafness may also occur. Septicemia and arthritis in the absence of meningitis are less striking and may go unrecognized. The outbreak may be brought on by stress
such as mixing, moving, weighing, vaccinating, and weather changes that affect ventilation and heating in buildings.

Strep suis septicemia in newborn pigs produces a “fading piglet syndrome.” These pigs are born in good health, and initially they suck avidly, but some time over the first day or two of life they stop nursing, become lethargic, and cold to the touch and die usually 12 to 24 hours after birth. The “fading pig” syndrome can be confused with starve-outs, but pure cultures of Strep suis are often cultured from the heart, blood, and joints of these pigs.

In breeding herds. Strep suis infections are less common; however, there have been cases in which the herd experienced a drop in farrowing rate from 85% to about 70% over a 3-month period. Strep suis 2 could be cultured from stillborn fetuses as well as from uteri of infected sows. In one herd, abortions at 60 to 80 days gestation were observed. The sows were obviously sick, running temperatures of 106 to 107° F.

Pneumonias due to Strep suis are most common in 2-to 4-week-old pigs but are seen in the growing-finishing period as well. The Strep suis organism is quite often associated with other organisms such as Pasteurella multocida, Haemophilus pleuropneumoniae, or with Pseudorabies virus. In the finishing period, the condition is commonly observed after treating pneumonias with tetracyclines.

Epidemiology
Strep suis is one more in a series of newly recognized diseases afflicting pigs in our modern pig production systems. Strep suis disease is prevalent in the intensive, high-population-density systems. Poor ventilation, buildup of pit gases, overcrowding, and other stress factors such as mixing, moving, weighing, and vaccinating are all associated with 
Strep suis outbreaks.

Strep suis is introduced into new herds by healthy car-
Cooperative Extension work in Agriculture and Home Economics, state of Indiana, Purdue University and U. S. Department of Agriculture cooperating. H. A. Wadsworth, Director, West Lafayette, IN. Issued in furtherance of the acts of May 8 and June 30, 1914. The Purdue University Cooperative Extension Service is an affirmative action/equal opportunity institution.