China: Pigs Dying of `Blue Ear Disease'

 

# 747

 

The mystery swine deaths in China have been attributed to `Blue Ear Disease', or PRRS (Porcine Reproductive-Respiratory-Syndrome), according to media reports.

There is just one problem.  The symptoms don't really match the diagnosis.

 

First, the Chinese report from Xinhua news.

 

Mysterious pig disease in south China identified

GUANGZHOU, May 9 (Xinhua) -- Chinese epidemiologists have discovered that a mysterious pig epidemic spreading throughout south China's Guangdong province is an outbreak of an infectious disease commonly known as "blue ear disease".

 

    The disease was first found in Silao town of Yunfu city at the end of April, after pigs stopped eating, developed fevers and started hemorrhaging. More than 300 pigs died.

 

    The "blue ear disease" spread to China in the middle 1990s and the recent outbreak in Guangdong was caused by a deadly mutation of the virus. China has already developed effective vaccines for the disease and they will be used in Guangdong soon, said the provincial agriculture department.

 

    According to Yunfu government, the infected pigs were raised by individual rural households rather than industrialized pig farms and were not exported to Hong Kong or overseas markets.

 

    Major roads in and out of the town have been sterilized and the sale of pigs in the infected area has been banned.

 

Blue Ear Disease, which emerged in the 1980's, normally results in increased stillbirths, and some respiratory symptoms.  Mortality rates are generally low in adult sows and boars, and I find no indication that hemorrhaging is a common symptom.

 

This analysis from ProMED.

 

 

UNDIAGNOSED DISEASE, PORCINE - CHINA (04)

Date: Tue 8 May 2007
From: Richard Knox

Stefane DeLaRocque of the Food and Agriculture Organization's Animal Health Division tells me that Chinese authorities have told the FAO (United Nations Food and Agriculture Organisation) they have isolated a virus from pigs involved in a mysterious disease outbreak in Gaoyao and Yunfu in Guangdong, 140 miles (225 km) north west of Hong Kong. According to media  reports, about 3000 pigs have been affected so far, but FAO has no report more reliable on the extent of the outbreak.

 

Chinese scientists tell the FAO it is PRRS virus (porcine respiratory and reproductive syndrome). If that is correct, FAO thinks it may be a new, more pathogenic mutant. PRRS, which emerged 18 years ago and was initially called "mystery swine disease," is not usually described as a prominently hemorrhagic disease. Gross hemorrhage is said to be a main feature of the  current outbreak.

 

According to DeLaRocque, FAO is currently leaving open the possibility of other causes. It has not ruled out an avian flu mutant, but the picture as it is currently known to FAO, does not look consistent with avian flu, and there have been no recent reported poultry outbreaks of H5N1 in the region.

 

As of Tuesday [8 May 2007] afternoon, China had not invited FAO investigators in.

 

So, for now the story is PRRS, but it isn't entirely clear if that is indeed the case.  If it is, they are brewing a new and improved version of the disease, which should be an even better reason to be inviting the FAO in to investigate.