Published Date: 2007-07-17 16:00:03
Subject: PRO/AH/EDR> Porcine reproductive & respiratory syndrome - Viet Nam (06)
Archive Number: 20070717.2293
PORCINE REPRODUCTIVE AND RESPIRATORY SYNDROME - VIET NAM (06)
A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases
Date: Mon 16 Jul 2007
Source: Thanh Nien News [edited]
Local authorities in a central province are crying for help as a
rampant disease has wiped out 20 000 pigs in under 2 weeks.
The pigs have reportedly perished due to porcine reproductive and
respiratory syndrome (PRRS), also known as blue ear disease, which
broke out in Quang Nam province early this month [July 2007].
At a meeting Sunday [15 Jul 2007] with the provincial administration,
Health Minister Cao Duc Phat called for the mobilization of all
available resources to curb the outbreak. He instructed agencies
concerned to keep a close eye on epidemic-prone areas and carry out
inoculation campaigns. He also stressed the importance of preventing
the disease from spreading to other provinces.
Some 250 000 doses of blue ear vaccine would be earmarked for Quang
Nam this week [16-22 Jul 2007], said Bui Quang Anh, head of the
ministry's Animal Health Department. Sterilization equipment would
also be beefed up, he added.
Nguyen Thanh Quang, head of Quang Nam's Department of Agriculture and
Rural Development, admitted the province was in desperate need of
around VND 10 billion (around USD 626 000) to help affected breeders
who have lost their pigs to the epidemic.
Quang also admitted that monitoring the illicit slaughter and
transport of infected pigs would be difficult due to the lack of
Insufficient financial aid for a mass cull of infected pigs was also
another hurdle, he said, pointing out that breeders in need of cash
would sell their pigs with or without the disease.
To date, blue ear has gripped 8 districts in Quang Nam and has killed
up to 4000 pigs per day.
The disease is caused by the Lelystad virus [see comment], which
infects all types of pigs, irrespective of health, breeding methods,
[Viet Nam sent to the OIE (World Organization for Animal Health) an
"immediate notification" on the PRRS epizootic on 11 Apr 2007,
indicating that the disease had started on 12 Mar 2007 and was
confirmed on 26 Mar 2007. The notification mentioned "introduction of
new live animals" and "legal movement of animals" as the sources of
infection. The 6 reported outbreaks included 372 susceptible animals,
of which 133 were clinically affected, 87 died, and 105 were
destroyed. (Apparent morbidity rate 35.75 percent, apparent mortality
rate 23.39 percent, and apparent case fatality rate 65.41 percent).
A follow-up report, sent on 20 Apr 2007, provided data on 7
additional outbreaks, including 2452 susceptible animals, of which
1140 were clinically affected, 580 died, and 184 were destroyed.
(Apparent morbidity rate 46.49 percent, apparent mortality rate 23.65
percent, and apparent case fatality rate 50.88 percent). Both
reports, including a map are available at
Since the summer of 2006, a disease with rather similar
characteristics has been devastating China's pig population,
eventually reported from more than 20 provinces with very serious
economic losses. The disease, initially named "pig high fever
disease", was later reported to be caused by a highly pathogenic PRRS
(blue ear disease) virus, though other possible disease agents may
have played their role. A recent paper included a detailed
description of the 2006 Chinese outbreaks and provided the results of
a whole-genome analysis of the isolated viruses, revealing that these
highly pathogenic PRRSV isolates are grouped into type II. (See
ProMED-mail 20070622.2017 and the on-line paper by Tian, Yu, Zhao, et
al: Emergence of fatal PRRSV variants: unparalleled outbreaks of
atypical PRRS in China and molecular dissection of the unique
hallmark", available at
Phylogenetic analysis of PRRSV isolates from different geographical
regions worldwide, indicate the existence of 2 major genotypes: type
I representing the European prototype (Lelystad virus, LV), and type
II with a North American strain as a prototype. It will be surprising
if the Vietnamese PRRS virus is found to be of a different genotype
than the Chinese isolates, as might be concluded from the newswire
above mentioning the Lelystad virus (genotype I) as the causative
disease agent in Viet Nam. Laboratory findings and sequencing results
will be helpful.
PRRS is included in OIE's list of pig diseases; the exceptional
pathogenicity and infectivity of the virus(es) currently circulating
in China and Viet Nam, deserve international alertness.
Diagnostic methods and requirements of PRRS vaccines are available in
chapter 2.6.5. of OIE's Manual of Diagnostic Tests and Vaccines of
Terrestrial Animals at:
<http://oie.int/eng/normes/mmanual/A_00099.htm>. - Mod.AS]