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Deadly swine disease struck twice in China

A dangerous infection that pigs can pass to people took an unusually fatal form last year and killed 38 people, Chinese scientists reported Monday.
/ Source: Reuters

A dangerous infection that pigs can pass to people took an unusually fatal form last year and killed 38 people, Chinese scientists reported Monday.

All but one of the people killed by Streptococcus suis in July and August 2005 in China died of streptococcal toxic shock syndrome, they said. This severe type of immune reaction had never been seen in S. suis infections.

Anyone who is diagnosed with toxic shock syndrome and who has been around pigs should be checked for S. suis infections, other experts said.

The researchers, led by George Gao of the Chinese Academy of Sciences in Beijing, said last year’s outbreak, which affected 204 people, mostly in Sichuan province, was not unique.

“Retrospectively, we found that this outbreak was very similar to an earlier outbreak in Jiangsu Province, China, in 1998,” they wrote in their report, published in the open-access Public Library of Science Medicine journal.

In the 1998 outbreak, 14 of the 25 infected died.

It is not clear if the Streptococci bacteria that causes the disease in pigs and in people has mutated into a form that causes new symptoms, the researchers said. Only 198 people had been known to have been infected before last year’s outbreak and usually only about 10 percent of them died.

Their symptoms included meningitis and septicemia — a bacterial infection carried in the blood.

First details of outbreak
Gao’s report was the first to share details of the 2005 outbreak.

“In the fatal human cases, the disease started with acute illness, malaise, fever, headache, diarrhea, rapidly developing hyperpyrexia (very high fever), hypotension (low blood pressure), and a decline of pulse pressure,” they wrote.

Rash was common and the sickest patients fell into a coma.

“Ultimately, some cases progressed to multisystem dysfunction, such as acute respiratory distress syndrome, liver failure, heart failure, disseminated intravascular coagulation (a type of internal bleeding), and acute renal (kidney) failure,” they wrote.

They said genetic examination showed the bacteria have evolved slightly, but it is not clear if the mutations are responsible for the severe new symptoms. Usually, toxic shock syndrome is caused by different bacteria such as Group A Streptococci and Staphylococcus aureus.

It also does not appear the bacteria can be passed from human to human, meaning there is little likelihood of an epidemic. But S. suis is common in pigs worldwide, the researchers noted.

“S.suis infection is of major economic and veterinary importance in the farming world, and should now be on the list of differential diagnoses when clinicians encounter patients with unexplained sepsis who have a history of exposure to pigs,” Dr. Shiranee Sriskandan and Dr. Joshua Slater of the Imperial College Faculty of Medicine and Hammersmith Hospital in London wrote in a commentary.

Sriskandan and Slater said eradication of S. suis in the pig population is not feasible because antibiotics do not work well in pigs.