PRO/AH/EDR> African swine fever – Asia (12): Indonesia (RI) control, Singapore, prevention


A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases

Date: Sun 21 May 2023
Source: CNA [abridged, edited]

Indonesia is developing a blood serum that can provide temporary
immunity among pigs against the African swine fever virus [ASFV] after
containing an outbreak of the disease in the country’s biggest pig
farm. The farm, located on Pulau Bulan [Bulan Island; a 100 sq km
(38.61 sq mi) island belonging to Indonesia’s Riau Islands Province,
situated nearly 30 km (18.64 mi) south of Singapore; map at – Mod.AS] is capable of exporting
around 240 000 pigs a year to Singapore, according to data from the
Riau Islands Agriculture Agency.

Exports from the island constitute about 15% of the Republic’s total
pork supply.

The Singapore Food Agency (SFA) said on [20 Apr 2023] that pig
carcasses originating from the farm were found to be infected with
ASFV, prompting Singapore to stop importing live pigs from Pulau Bulan
[see post – Mod.AS].

Dr. Honismandri, head of the Riau Islands veterinary authority, which
monitors animal health in the province, said Indonesian officials were
subsequently deployed and confirmed that the virus had spread to much
of the farm. “The situation right now is under control. There are no
more deaths. Only survivors,” he told CNA on [Wed 17 May 2023].

ASF does not infect humans. However, it is highly contagious among
boars and pigs and has a high mortality rate. Studies have shown that
the virus can survive in pork for long periods after pigs were
slaughtered. There is currently no vaccine against the disease.

Dr. Honismandri, who like many Indonesians goes by one name, said that
of the more than 200 000 pigs that were on Pulau Bulan, 35 000 died
from the disease. Workers also culled 119 000 pigs that shared the
same compartments – or living quarters – as the symptomatic pigs. Of
the remaining 50 000 pigs, 2 thirds showed signs of contracting the
virus but have since recovered.

Dr. Honismandri said officials are trying to produce convalescent
serums from the blood of the surviving pigs. Convalescent serums are
blood serums containing antibodies that can provide short-term
immunity against infection. The serum is being developed at a
government facility in Surabaya, Indonesia’s second-biggest city and
the capital of East Java province. “This is an important step to
prevent and contain the spread of ASF because there is currently no
vaccine,” he said.

Dr. Honismandri added that the same facility has already developed
serums from infected pigs in other parts of Indonesia. However, the
virus infecting the pigs on Pulau Bulan appeared to have a specific
genetic strain not found in previous cases of ASF in the country.

Developing a serum from the blood of surviving pigs on Pulau Bulan
will ensure the serum’s effectiveness against this particular strain
of the ASF virus, Dr. Honismandri noted. “It will take 2 to 3 months
until a product is ready. That is the estimate. After that we can
begin inoculating (the pigs),” he said.

“We are also exploring potential vaccines. Some countries are
developing potential vaccines for ASF. If one is proven to be
effective we will be working to get our hands on some to be used on
Pulau Bulan.”

No one lives on Pulau Bulan which since the 1980s has been dedicated
exclusively to animal breeding. There are also shrimp and crocodile
farms in Pulau Bulan and at one time there was a chicken farm.

Mr. Aris Hadiyono, chief of the local agricultural quarantine office,
said PT Indotirta Suaka, which manages the pig farm on Pulau Bulan,
has been imposing tight biosecurity measures. The island only has one
access point via a seaport where workers and visitors are told to
change clothes and spray disinfectant before entering or leaving the

Pulau Bulan is off-limits to the general public with dozens of watch
towers constantly monitoring the dense mangrove forests surrounding
the island on the lookout for intruders. With such limited access and
workers’ movements on the island carefully monitored, Mr. Hadiyono
said government officials are still struggling to identify how the
pigs were infected.

“There can be many possible sources (of infection). Pulau Bulan has no
population but the company said there are still many fishermen who
fish there, (or) look for wood. There are still many wild animals:
birds and boars which can become vectors for the virus. It needs to be
investigated how the virus got there,” Mr. Hadiyono told CNA.

The farm divides its 200 000 pig population into different zones which
are spread out to prevent the spread of diseases.

However, ASF can also be transmitted by ticks and insects and the
island also has a native population of wild boars. “We can keep wild
boars away using electric fences, which (the farm) uses, but small
insects can be quite difficult (to contain),” Mr. Purwanto, one of the
quarantine officials leading the investigation on the African swine
fever outbreak on Pulau Bulan told CNA. He added that animals such as
birds could also be carriers of the virus, particularly from the
nearby islands of Rempang, which had a case of ASF in 2021.

CNA tried to reach the company PT Indotirta Suaka and visited its
office in Batam City on [15 May 2023] but representatives did not want
to be interviewed. With no more pigs showing signs of contracting ASF,
the quarantine office this month [May 2023] allowed PT Indotirta Suaka
to ship pork carcasses to the rest of Riau Islands province.

But it will be some time before the firm resumes its export of live
pigs to Singapore. The SFA said the resumption of livestock production
and exports from Pulau Bulan “could take up to a year”, adding that
Singapore authorities will continue to assess the situation.

Dr. Honismandri, the veterinary office chief, said the 50 000 pigs
remaining in Pulau Bulan may not be enough to fulfill demands from
Singapore until stocks of the animals are replenished. It is, however,
enough to repopulate the island with pigs.

But to err on the side of caution, Dr. Honismandri said PT Indotirta
Suaka has agreed to delay the repopulation of Pulau Bulan with more
pigs until the serum – which is currently being developed in East Java
– is ready.

Mr. Hadiyono, the quarantine office chief, said his office is ready to
reissue export permits to PT Indotirta Suaka. The certification was
retracted when the ASF outbreak happened, but Mr. Hadiyono stressed
that he wants to see some measures implemented.

One recommendation is for each farming zone to have its own jetty
which can be utilised should another outbreak occur. The current
arrangement means that the single access point can easily become
contaminated and become a location for a disease to spread.

Mdm. Rika Azmi, chief of the province’s food security, agriculture,
and animal health agency said another recommendation is for the
company to set up its own internationally-certified slaughterhouse.
“This way, if it is not possible to export live pigs, the farm has the
option to export pig carcasses,” she told CNA.

The farm currently has a locally-certified slaughterhouse used to
supply meat to vendors and butcher shops in Batam City, a 10-minute
boat ride away, and other parts of the province.

The quarantine office said the farm currently ships around 2000 pig
carcasses a month to Batam and other places but the recent outbreak
may have eroded consumer confidence. “Some customers are still
cautious about the safety of pork meat coming from Pulau Bulan,”
butcher shop owner Erson Nadeak told CNA. Mr. Nadeak owns a shop in

But there is virtually no alternative. According to data from the
local government, more than 90% of pork meat in Batam is supplied from
Pulau Bulan with the rest coming from small farmers and individuals.

When the outbreak occurred, Mr. Nadeak had to close his shop for days
until shipments from Pulau Bulan to Batam were resumed this month [May

Meanwhile, residents living near Pulau Bulan are anxious about the
possibility of the virus mutating and infecting humans as happened
with avian influenza and the coronavirus. “We are very worried about
what this virus might do to us, especially because we live very close
to Pulau Bulan,” Mr. Laurensius, a resident of Pulau Teluk Sepaku,
told CNA.

The island and Pulau Bulan are only separated by a 200m channel. “When
the outbreak occurred, we could hear the sound of heavy equipment
working day and night to bury the infected pigs. But it was the smell
that was unbearable. “It was so nauseating that people vomited and had
trouble sleeping at night,” he said, adding that the situation has
gradually improved.

Mdm Azmi of the agriculture agency said her office will continue to
educate the public about the virus. “This virus only affects pigs,
not humans or even other animals. We urge people to remain calm,” she

[Byline: Nivell Rayda]

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