Strep zoo spread by humans: a rare but emerging global biosecurity concern

The respiratory disease Strep zoo, brought on by S. zooepidemicus, has been found in the US and Canada in recent years. It caused thousands of pig deaths for major Canadian pork producer Maple Leaf. It was recently found on a pig farm in Germany. Researchers warn that the disease should be taken very seriously.

This bacteria can be carried in humans without any symptoms. It is a major pathogen in horses and is associated with abortion, foal arthritis, pneumonia, septicaemia and meningitis. It also causes serious or fatal respiratory infection in dogs. In pigs, symptoms can be similar to reportable diseases such as African Swine Fever, Classical Swine Fever or Pseudorabies.

Canadian mystery

For Maple Leaf, the disease started causing major problems since 2019 at 2 sites, but it took a long time to diagnose. Local media reported that an infection first broke out at a multiplication barn. Staff treated the illness and then sent what they thought were healthy gilts to 4 of the firm’s sow barns. A month later, about 10,500 sows were infected. On some days, dozens of pigs died.

“This went on for 4 years, causing millions of dollars in damage, thousands of pig deaths and employees pushed to the brink,” reported Ed White in the Manitoba Cooperator. “One barn was taken out of production and Maple Leaf almost despaired of safely repopulating it after having to depopulate it 3 times from 2020 to 2023.”

It was only last year when the Maple Leaf investigation team heard news from another pig production firm about a possible cause. Indeed, that cause was S. zooepidemicus, brought into the Maple Leaf multiplication facility and then another barn by an asymptomatic worker carrying the bacteria. As mentioned, this is rare, “but like many barn staff, he had the habit of spitting and sneezing inside the pens.”

Germany

In 2023, a farm in northwest Germany close to the Dutch border “experienced a high morbidity and mortality in their sow herd,” note the scientists. “Sows showed fever, lethargy, oedema, mucosal discharge and dyspnoea.” The farm is a farrow-to-finishing operation with 320 sows in ten groups.

Biosecurity threat

Researchers such as Dr. Matheus Costa, an Assistant Professor with the Western College of Veterinary Medicine in Canada and an Adjunct Professor at Utrecht University in the Netherlands, warn that this bacteria should be taken seriously. Biosecurity must be kept at very high levels at all pig farms worldwide to prevent herd infections and death.