Veterinarians at Cornell, along with physicians at the Mary Imogene Bassett Hospital in Cooperstown, N.Y., have identified what they believe is the first U.S. case of meningitis resulting from contact with pigs.
The discovery was made after a farmer was admitted to the Bassett Hospital last summer. After several tests were done, the hospital’s lab confirmed the presence of Streptococcus suis, a bacteria found in pigs.
Dr. Ruth Zadoks, a research associate and veterinarian at Quality Milk Production Services (QMPS), a part of the Animal Health Diagnostic Center at Cornell University’s College of Veterinary Medicine, used a DNA-level analysis to help provide the link between the farmer’s sickness and the bacteria found in the pigs.
The discovery, however, was the result of a combined effort.
“There are two ways the connection was made,” Zadoks said. “Samples from the patient were sent to the lab, and a preliminary identification of the bacteria was made there. Secondly, the physician that took care of the patient grew up on a hog farm and was aware of the presence of Streptococcus suis in pigs.”
Dr. Zadoks further identified three other strains of pig strep within the 13 pig samples. Despite none of the strains in the pigs matching those found in the farmer, Zadoks explained that not all of the pigs could be tested.
“Even though we did not match the human strain with those of the pigs, the strain from the farmer matches superficially a strain found in both pigs and humans in Denmark and the Netherlands,” said Zadoks. “Some strains are more likely to cause disease in humans.”
Although this marks the first case in the U.S., cases of the disease are regular throughout Southeast Asia. In China last year, over 200 people contracted the disease, which resulted in 38 deaths. Over 600 pigs had to be slaughtered. Though rare, the disease has been reported in Europe in recent decades.
“It could be that the disease is spreading,” said Zadoks. “But also we may be just better at recognizing it.”
While pig meningitis is similar to the bird flu in that all human cases have originated with an animal infecting a human, scientists don’t think the bacteria will spread from human to human.
Still, scientists are encouraging farmers handling pigs to take extra precautions.
Frank Welcome, a senior extension associate and veterinarian at QMPS, said the infection is “certainly an occupational hazard for those in the pork industry.”
Kara Willenburg, M.D., the lead author of the letter about the disease published in the New England Journal of Medicine, added that the disease “should not impact the general public.”
Zadoks urged anyone coming in contact with pigs to use “common sense.”
“Those working in slaughterhouses need to wear protective gear, e.g. gloves or body protectors, if they work with knives, to prevent cuts,” she said. In the food processing industry and at home, adequate cooking of pork is important, as it will kill these bacteria.”
Cornell’s veterinary school and Department of Food Science, in conjunction with the New York State Department of Health, are also researching bacteria in animals and how they spread to humans.
Zadoks underscored the importance of studying bacteria in animals.
“Bacteria grow and spread more slowly than viruses,” she said. “That is why bacterial diseases don’t get as much attention as viral diseases such as avian influenza, SARS or Ebola. But bacteria are widespread in animals, in pets as well as farm animals, and some bacteria can have a big impact on human health.”
The farmer infected with meningitis was treated and made a full recovery.