Any attempt to explain African swine fever must include a clarification to differentiate it from classical swine fever, also known as “hog cholera,” and swine influenza. Although there are similarities among them, ASF is an entirely different disease.

How does it spread?

The OIE states that the disease can be spread by domestic and wild pigs, even after death, and can be transmitted through the following.

1. Direct contact with infected pigs
2. Indirect contact, through ingestion of contaminated materials, such as food waste, feed, or garbage
3. Contaminated fomites, such as shoes, clothes, knives, and equipment, or biological vectors (through infected soft ticks of the genus Ornithodoros)

To determine the enigmatic progression of the disease in our country, we need not only to trace back the causes, modes of transmission, clinical signs, postmortem lesions, treatment, and prevention, but also to carefully look at the bigger picture and study its global spread – that is, which countries were declared positive.

The virus itself is not a human threat, but one that poses a huge economic catastrophe. Whether it has indeed produced huge incalculable losses or just a minor dent is attributable to and considered a matter of human misbehavior.

Do you know Ringo?

African swine fever (ASF) is a viral disease caused by a DNA virus of the Asfaviridae family. It is listed by the World Organization for Animal Health (Office International des Epizooties, or OIE), World Health Organization (WHO), and Centers for Disease Control and Prevention (CDC) as a reportable disease in the advent of the One Health Concept. It is a highly contagious viral disease causing approximately 100% mortality in domestic pigs and wild boars, and arguably the most dangerous swine disease worldwide.

According to the information found on OIE’s website, ASF outbreaks originated in Africa and parts of Europe, South America, and the Caribbean. For the past 13 years, ASF has been documented in countries across Africa, Asia, and Europe. Unfortunately, there is no effective vaccine available to eradicate the deadly disease.

Pigs vs People

As early as 2018, the Bureau of Animal Industry has declared that there was an outbreak of ASF in many countries in Europe, and the ASEAN made necessary precautions to temporarily ban the entry of any product made from pig body parts as listed on a per-country basis. However, the advisory from the government fell on deaf ears as the disease continued to spread.

Only lately were concerted efforts with cooperation from pig breeders was the message communicated more thoroughly. The Department of Agriculture strongly reiterated the advisory, which states the following measures, as published on their website.

1. For small backyard raisers – “Report to your City, Municipal or Provincial veterinarian any sign of disease or deaths of pigs in their area. Refrain from swill feeding, particularly those from airlines, hotels and restaurants. Do not slaughter sick or dead pigs and sell the meat to traders.”
2. For traders – “[Do not] buy and slaughter sick pigs. Any backyard or illegal slaughtering, or use of meat from infected pigs will contribute to the spread of the disease, and will only result to further deaths, and losses to the P260-billion swine industry that supports millions of Filipinos.”
3. For the public – “Pork is safe to eat. When buying pork in the market or meat shops, always look for the seal and certificate issued by the DA-NMIS.”

A matter of misinterpretation?

During a conference in October of the previous year, The Department of Health assured the public that those who have accidentally consumed ASF-positive pork have nothing to worry about as it is safe for human consumption and will not affect human health.

Some consumers mistook this information as a go signal to keep eating ASF-positive pig flesh while a few producers continued to sell their products despite knowing it was illegal.

Safe for human consumption?

All disease-injured carcasses release histamines. Histamine is a chemical found in our body and is involved in local immune responses, and by itself cannot be degraded by heating. Though histamine cannot cause clinical disease assuming that the pathogen has been killed by heating (for the same reason that we don’t get distemper, parvo, or feline panleukopenia), the consumer is not free from hypersensitivity or allergic reactions following its consumption.

As it stands, the cytokines – which are cell-signaling molecules that aid immune responses – and histamines released from injured tissues cannot be removed by boiling or high-temperature cooking. This is the hidden truth as to why it is not right to consume flesh that comes from diseased animals whose deaths are caused by any disease!

This is why I disagree with the “safe for human consumption” line. Moreover, humans will eventually spread the virus, presumably by fomites and excreta.

Not a matter of argument

Any conclusions and press releases of the spreading of the disease that are not borne out of scientific, laboratory verification by the Department of Agriculture are suspect to be laced with political overtones that do not reflect official findings.

It is unfair to blame regulatory authorities here in the Philippines of the spread of ASF since Eastern and Western Europe, and even the Baltic states, are witnesses to the spread of the disease.

Therefore, restriction – if not a total ban – of products made from pigs in Hong Kong North Korea, Laos, Germany, China, Hungary, Latvia, Poland, Romania, Russia, Ukraine, Vietnam, Zambia, South Africa, Czech Republic, Bulgaria, Cambodia, Mongolia, and Belgium as per FDA order 2018-133; 2019-229 is no longer debatable.

Our responsibility

Again, while it is true that the virus might not be a threat to human health and safety, laymen and authority figures alike must be educated that animal health affects human health in general – and, of course, it also affects agricultural endeavors, such as the swine industry.

This is the practical ramification of the One Health Concept. The health of one species, I daresay, will disastrously affect an estimated 200-billion peso industry here in the Philippines alone, and they may go bankrupt if efforts to control the spread of ASF are all for naught!

We can only hope that the virus will be stopped by euthanizing its end hosts, but doing so may inflict grave incalculable losses to the economy of any sovereign state. Our best solution to eradicate the disease is for the government, the agriculture industries, and the public to be fully cooperative in the fight against it; and we, who are in the field of veterinary medicine, must actively participate in educating the masses and must not espouse half-baked conclusions.

Disclaimer:

The conclusions I make are not definitive statements of a scientist, but are a proximate medical inference to convey accurate, fair, and just surmising based on the best literature available. Any statement I make is not meant to usurp government mandates as well as regulations and recommendations from qualified authorities and are not supposed to be inflammatory, but are primarily opinions from a board-certified veterinarian researching on the disease and its known mechanisms of causation, modes of transmission, clinical signs, postmortem evaluations, control and prevention, and history in terms of epidemics and experiences of other countries.

This appeared in Animal Scene magazine’s February 2020 issue.

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– Hong Kong to cull 6,000 pigs as first swine fever case found
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