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Pig survival rates in the ASFV infection (red line) and negative control (blue line) groups.
Individual rectal temperatures in pigs from the ASFV infection and negative control groups. Red and blue circles and horizontal lines indicate individual and mean temperatures of the ASFV and negative control groups, respectively. Red and blue short lines represent the average temperature of ASFV infection and negative control group, respectively, at each time point. * P<0.05
Chinese pig farmers see livelihoods washed away by devastating floods
The pigs died five to eight days post-inocula- tion, and the incubation period was 3.7 ± 0.5 dpi.
Pathogenicity of ASFV strain in Vietnam
AFRICAN swine fever is a highly contagious haemorrhagic viral dis- ease that affects do- mestic and wild pigs in all age groups, causing substantial economic and production losses.
detected in the ASFV iso- lates from China.
based in Hanoi Vietnam, and the National Insti- tute of Animal Science based in Wanju Republic of Korea, published re- cently on Porcine Health Management.
Furthermore, ear tissue samples might be a simple alternative spec- imen for diagnosing ASF infection in dead pigs.
ASF has been included in the list of notifiable diseases by the World Organisation for Animal Health.
The pig farm was situ- ated about 50km south of Hanoi and 250km from the China border.
ASF is caused by ASF virus, a double-stranded DNA virus of the family asfaviridae and the genus asfivirus, having a diam- eter of 175–215nm.
Since then, the virus has rapidly spread across the country, leading to the culling of approximately six million pigs – 20 percent of Vietnam’s pig production.
In addition, herd and environmental samples were collected daily.
The spread of ASF can only be controlled by early detection, meticu- lous surveillance, strict biosecurity measures and animal movement con- trol.
The virus contains 151–167 genes in its 170– 192kbp long genome and a total of 24 genotypes have been identified worldwide.
As of November 2020, ASF outbreaks have been reported in more than 20 of the country’s 63 prov- inces.
ASFV genome was first detected in the blood 2.2 ± 0.8 and then in rectal 3.1 ± 0.7, nasal 3.2±0.4andoral3.6±0.7 dpi swab samples.
To perform successful ASF surveillance in farms, it is necessary to obtain relevant blood specimens from pigs with suspected ASFV infec- tion.
The virulence of dif- ferent ASFV isolates in the same host may vary, and the ASF outbreaks in Asia have been caused by highly virulent strains.
Several molecular and pathological studies on ASFV-infected pigs from ASF outbreak farms were conducted to evaluate the characteristic lesions and examine the genetic prop- erties of ASFV strains from Vietnam.
ASFV was detected in oral fluid samples col- lected using a chewed rope from three days post-inoculation.
However, the identifica- tion of such pigs is dif- ficult because of the short incubationperiod.
These highly virulent ASFV strains caused mortality in 90–100 per- cent of cases.
Because no virus inocu- lation studies have been conducted to evaluate the virulence and patho- genicity of ASFV isolates from Vietnam, the patho- genicity of these strains is not fully understood.
The liver showed the highest viral loads, and ear tissue also exhibited high viral loads among 11 tissues obtained from dead pigs.
The appropriate surveil- lance might not succeed, especially in developing countries, due to the lim- ited availability of veteri- nary services.
A previous study re- ported that the Chinese ASFV isolates are highly lethal to domestic pigs even at low doses of the virus and that the clinical signs start showing very early in the period of in- fection.
To address these knowl- edge gaps, collaborative research was undertaken by contributors from the International Livestock Research Institute and the National Institute of Vet- erinary Research, both
Overall, ASFV from Vietnam was classified as peracute to acute form.
The time lag to ini- tiate sampling enabled ASF outbreaks to rapidly spread across these coun- tries.
Wangfan village farmer 47-year-old Cheng waded through knee-deep water, pulling dead pigs behind him one-by-one by a rope tied around their ankles to line up the bloated car- casses for disposal.
“I don't think even one pig will be left."
is as if the sky has fallen.” Across the village, where most of the 3000 other residents also raise pigs or chickens or grow grain, people were clearing de- bris left by the receding
Across Henan, rains have deluged 1678 larger scale farms, killing more than a million animals.
The swine fever virus lives for about 10 days in pig faeces and water, and can survive for up to 100 days in manure pits.
More than 100 of Cheng's pigs drowned in floods that paralysed China's cen- tral Henan province last week, and the outlook for those left alive is bleak.
Cheng's farm is one of thousands in Henan, fa- mous for agriculture, and pork production in par- ticular.
floodwaters.
Some carted out wheel-
Though Chinese pig production has become increasingly intensive in recent years, millions of small farmers still play a major role in producing the country's favourite meat.
Beijing-based Enable Ag-Tech Consulting con- sultant and veterinarian Wayne Johnson said: “Whatever's in the manure pits will be washed out and spread around.”
“They've been in the water for a few days now and can't eat at all.
money to raise pigs again.” Cheng, who has raised pigs all his life, said, “This
At least 200,000 chickens and up to 6000 pigs were lost in the flood, half of the village's herd.
The province was struck by heavy rains last week that sparked the worst flash flooding in centuries, catching many by surprise.
barrows and crates of life- less chickens.
“In an instant, we now
Dead pigs lay bloated in the water, tied to trees to stop them floating away.
Even after a devastating epidemic of the deadly pig disease African swine fever swept the country during 2018 and 2019, many farmers returned to pig raising and expanded their herds to capitalise on high prices.
Last week, the Ministry of Agriculture and Rural Affairs issued guidelines to local governments on how to prevent animal disease after flooding, including measures on disposal of carcasses and disinfection of farms.
A recent study revealed that a 10-nucleotide in- sertion was detected in all Vietnamese ASFV isolates, similar to that
The rope-based oral fluid collection method could be useful for early ASFV detection and al- lows successful ASF surveillance in large pig farms.
More information on this research can be found at porcinehealth management.biomedcen tral.com/articles/10.1186/ s40813-021-00215-0
In Vietnam, the first ASF outbreak was de- tected in February 2019 at a family-owned back- yard farm in Hun Yen province.
Ten pigs were intramus- cularly inoculated with an ASFV strain from Vietnam – titer, 103.5 HAD50/mL – and their temperature, clinical signs and virus excretion patterns were recorded.
The research data pro- vided valuable insights into the characteristics of a typical ASFV strain isolated in Vietnam and suggested an alternative, non-invasive specimen collection strategy for early detection.
China’s use of wheat in feed is expected to stay high as the grain retains a price advantage over corn.
China confirms 11 ASF outbreaks
OFFICIALS from China’s agriculture ministry have re- ported that China’s use of wheat in pig feed is expected to remain high and that the country has had 11 African swine fever outbreaks this year.
of African swine fever this year prompted it to cull 2216 pigs and there was a risk of the virus spreading from overseas.
China’s use of wheat in feed is expected to stay high as the grain retains a price advan- tage over corn.
“The control and prevention situation is still severe and com- plicated,” Mr Xin said of the disease that reached China in Au- gust 2018, and warned that the risk of its re- bound persisted.
Wheat prices in the central province of Henan, a top producer of the grain, were $A527.73 per tonne on July 19, outstripping the price of corn at $A609.40.
China’s herd of 439 million pigs at the end of June 2021 was 99.4 percent of the level at the end of 2017, as the country rebuilds the herd decimated by the African swine fever.
Ministry of Agricul- ture and Rural Affairs Husbandry Bureau’s Xin Guochang said China’s 11 outbreaks
The sow herd of 456.4 million at the end of June 2021 was up 102 percent on the end-2017 figure.
ON top of the ongoing “I'm waiting for the
have no way of surviving,” Parts of the village
fever, a disease that usu- ally kills pigs though is not harmful to people.
issues with African swine fever, Chinese pig farmers must deal with devastating floods that have destroyed their herds.
water levels to go down to see what to do with the remaining pigs,” Cheng said.
Cheng said.
“We have no other skills. “We have no more
smelled strongly of mud and rotting carcasses.
Rabobank senior analyst Pan Chenjun said: “The disease issue is a much more severe issue than the direct losses.”
Cheng said he's facing losses and worries he won't receive any govern- ment compensation. Concerns over disease outbreaks
For now though, Wangfan farmers are not even sure they'll return to farming.
The flooding also has many worried about fresh disease outbreaks.
Zhang Guangsi, who lost about half his herd, said, “After doing this for so many years, in a flash, eve- rything is gone.”
Last summer, heavy rain and flooding across southern China was blamed for dozens of out- breaks of African swine
“I don't feel like raising pigs anymore.”
Farmers were forced to think of creative ways to rescue pigs caught in the floods in China’s Henan province. Photo: Simon Song
First appeared in Global Ag Media
Page 14 – Australian Pork Newspaper, August 2021
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