Re: Mystery disease kills pigs in Southern China: press
PORCINE REPRODUCTIVE AND RESPIRATORY SYNDROME - CHINA (02)
**********************************************************
A ProMED-mail post
<
http://www.promedmail.org>
ProMED-mail is a program of the
International Society for Infectious Diseases
<
http://www.isid.org>
Date: Sat 12 May 2007
Source: Guangxi News - Modern Life Daily [in Chinese, trans. Dan
Silver, edited]
<
http://www.gxnews.com.cn/staticpages/20070512/newgx46450bf3-1072301.shtml>
On the morning of 11 May 2007, personnel from the Nanning Municipal
Agricultural Bureau spread out to major pig-farming counties to
[organize] comprehensive pig "high fever disease" prevention and
control measures among veterinary departments at all levels,
[including] strengthening immunization supervision. [The same day],
sources in relevant departments said that pig "high fever disease"
has occurred in the past several months in Anhui, Hunan, Guangdong,
Shandong, Liaoning, Jilin, and other provinces, and has caused the
deaths of more than 20 million pigs, with extremely heavy economic losses.
Pig "high fever disease" has already been discovered in 8 counties
(districts) in the [Guangxi Autonomous] Region. Among these, pig
"high fever disease" is suspected to have occurred in 92
administrative villages of 10 townships in Cenxi City. The disease
has been found in 4875 pigs, with 287 deaths. Although there are no
reports of disease within Nanning Municipality at this time, earlier
this year [2007] pig deaths occurred for unknown reasons in 2 or 3
counties (districts) in Nanning. Some medium and small pig farms and
pig-raising households had not implemented pig "high fever disease"
vaccination. The circumstances of prevention and control activities are grim.
On 10 May 2007, the [Guangxi] Autonomous Region People's Government
conducted thorough deployment for prevention and control work across
the Region. While demanding thorough pig "high fever disease"
immunization within about a month, it also demanded that all relevant
departments carry out supervision of pig markets and private
slaughterhouses and sternly strike against illegal sale of diseased
pork and pork products. [The same day], Nanning Municipal Government
held a citywide pig "high fever disease" prevention and control
conference, stipulating that all relevant departments at all levels
make every effort toward implementing prevention and control work for
pig "high fever disease" and other serious diseases, to guarantee
personal health and public hygiene safety for the population.
Veterinary departments at all levels are to strengthen disease
inspection work on production sites and slaughterhouses, allowing
[healthy] pigs to market while resolutely stopping diseased pigs from
entering distribution. Those responsible for illegal purchase, sale,
or processing of diseased pigs will be severely punished according to the law.
Porcine "high fever disease", an OIE (World Animal Health
Organization) notifiable disease, also called pig blue ear disease,
is a pig reproductive and respiratory viral syndrome (PRRS). It is an
infectious illness characterized by reproductive disorder, premature
delivery, miscarriage, and stillbirth, as well as abnormal breathing
in piglets. When pigs contract this disease, it not only spreads
extremely fast, but morbidity and mortality are also very high.
"We are reminding residents that for their own health, they should
not eat diseased pork or pork of uncertain origin!", a staff member
of the Nanning Municipal Agricultural Bureau's Animal Husbandry
Section told reporters. A reporter observed that in Nanning's Xinzhu
Road, Gucheng Road, Minzhu Road, and other produce markets, pig "high
fever disease" had not significantly affected consumption. Many pork
retailers were nearly sold out within an hour.
[Byline: Yuan Lu]
--
Communicated by:
Dan Silver
<
dgsilver@yahoo.com>
[According to the information above, "high fever disease", apparently
caused by PRRS virus (PRRSV), has been observed during the past
several months in more than 7 provinces of China; the official OIE
notification of 9 May 2007, referred to one of them (Guandong).
Nanning, referred to in the newswire above, is the capital of the
Guangxi autonomous Region, situated in southern China, approx.160 km
(100 miles) from the border with Vietnam [see map at
<
http://sedac.ciesin.org/china/admin/bnd90/bnd90data.html>]
PRRSV (currently classified as a member of the newly established
order of _Nidovirales_, family _Arteriviridae_, genus _Arterivirus_)
is now ubiquitous throughout most of the pig-rearing areas of the
world and is believed to exist in 2 main forms -- the type 1
genotype, which predominates in Europe and the type 2, which
predominates in the USA. A complicating factor in PRRS epidemiology
has been the use of live vaccines, some of which have caused clinical
disease and become established in the local pig population. Such
vaccines have allegedly been applied throughout the world, including Asia.
Increasing data indicate that PRRSV is antigenically, genetically,
and pathologically very heterogenic. Since the mid 1990s, a more
virulent form of PRRSV has been causing high abortion and mortality
rates in vaccinated swine populations in the US. These severe
outbreaks of PRRS have been referred to as acute PRRS, atypical PRRS,
hot PRRS, abortion storm, or sow abortion and mortality syndrome.
Zimmerman et al (1997) described the criteria for the diagnosis of
acute PRRS, which include acute onset, clinical signs occurring over
a 2-4 week period, high mortality (greater than 5 percent) in sows
and boars, and a high rate of abortions (greater than 10 percent).
Many of the herds affected by acute PRRS were on a PRRS vaccination
program with the available modified live-vaccines, suggesting that
the vaccine-induced antibodies failed to neutralize the acute PRRS virus.
As discussed by Kijona et al (2001), several recent Danish isolates,
2 Taiwanese isolates (MD001 and FI), 2 Chinese isolates (S1 and
CH1a), a Japanese isolate (Kitasato 931), and an isolate from
Guatemala (249010), are all clustered within the North American
genotype. The North American genotype of the Danish isolates has been
confirmed to be derived from the RespPRRS vaccine that was used in
Danish swine herds. The origins of the Asian isolates with a North
American genotype are not known.
The disease, which in China is called "high fever disease", was
initially attributed to a mix infection of PRRS, classical swine
fever, (CSF) and porcine circovirus (PCV-2), and probably additional
agents. According to China's last notification to the OIE, dated 9
May 2007, the causal agent of an outbreak in Guandong is PRRSV. The
report indicates that the reason for notification is "change in
epidemiology" and that the manifestation of the disease is
"sub-clinical infection". However, the apparent case fatality rate
(20 percent) does not fit the description "sub-clinical".
Clearly, more details on the PRRS virus, currently circulating in
vast areas of China and Viet Nam, are urgently needed. This should
include the exclusion of other disease agents (
including avian
influenza and CSF), studies into the pathogenicity of the Chinese
PRRSV and its genotyping. Such data might indeed be anticipated soon,
since the Chinese notification (under "epidemiological comments")
indicates that the case is "probably caused by highly pathogenic PRRS
virus" and that "laboratory diagnosis is ongoing".
Subscribers are referred to Mod.PC's commentary in ProMED-mail
posting "Porcine reprod & resp syndr - China (Guangdong): OIE
20070512.1517". - Mod. AS]
References:
1. Zimmerman et al (1997): Results of the recent survey of the
membership of the AASP for outbreaks of sow abortion and mortality.
Swine Health Prod. 5, pp 74-5.
2. Kijona et al (2001): Genetic variation and phylogenetic analyses
of the ORF5 gene of acute porcine reproductive and respiratory
syndrome virus isolates. Veterinary Microbiology, Vol 83 (3), pp 249-263.
[see also:
Porcine reprod & resp syndr - China (Guangdong): OIE 20070512.1517
Porcine reproductive & respiratory syndrome - USA (NC) 20070407.1171
Porcine reproductive & respiratory syndrome - Viet Nam: RFI 20070412.1225
Porcine reproductive & respiratory syndrome - Viet Nam (02): OIE 20070414.
Porcine reproductive & respiratory syndrome - Viet Nam (03) 20070418.1281
Porcine reproductive & respiratory syndrome - Viet Nam (04): OIE 20070422.
Porcine reproductive & respiratory syndrome - Viet Nam (05) 20070512.1516
Undiagnosed disease, porcine - China: update (02) 20070406.1155
Undiagnosed disease, porcine - China: update 20070114.0185
2006
----
Undiagnosed disease, porcine - China (04) 20061129.3387
Undiagnosed disease, porcine - China (03): OIE 20060924.2732]
.............................................arn/mj/jw
*##########################################################*
************************************************************
ProMED-mail makes every effort to verify the reports that
are posted, but the accuracy and completeness of the
information, and of any statements or opinions based
thereon, are not guaranteed. The reader assumes all risks in
using information posted or archived by ProMED-mail. ISID
and its associated service providers shall not be held
responsible for errors or omissions or held liable for any
damages incurred as a result of use or reliance upon posted
or archived material.
************************************************************
Become a ProMED-mail Premium Subscriber at
<
http://www.isid.org/ProMEDMail_Premium.shtml>
************************************************************
Visit ProMED-mail's web site at <
http://www.promedmail.org>.
Send all items for posting to:
promed@promedmail.org
(NOT to an individual moderator). If you do not give your
full name and affiliation, it may not be posted. Send
commands to subscribe/unsubscribe,
</td><td colspan="2">
></O
