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WHERE AFRICAN SWINE FEVER, COVID-19 AND AVIAN INFLUENZA MEET

In July 2019, the first case of African Swine Fever (ASF) in the Philippines has been reported. It originated from backyard farms in Rizal as a result of imported pork waste and by-products from Manila being fed to hogs in said farms (FAO, 2020a). To date, this hemorrhagic disease of pigs has continuously spread to different regions of the country, from Luzon (all regions except IV-B), all the way to Mindanao (particularly in Region XI) (BAI, 2020). In December 2019, while frazzled hog raisers and feed millers in Luzon were uncompromisingly exhausting efforts in controlling the rapid spread of ASF infection, a novel Coronavirus was also causing mild to severe human respiratory problems in Wuhan, China. Unfortunately, this new Coronavirus disease, known as COVID-19, found its way to the Philippines on January 30, 2020 (DOH, 2020). After the Department of Health (DOH) confirmed the first local transmission of COVID-19 on March 7, cases drastically increased and became widespread all over the country. As of March 30, 2020, confirmed cases nationwide have ballooned to 1,546. Although there were already 42 patients who were reported to have recovered from the disease, death toll, which has reached 78, has come unpreventable especially to the elderly, those with pre-existing conditions, and even health professionals exposed to the disease in medical facilities (DOH, 2020). The mishap of the country did not end there, as a highly pathogenic avian influenza (HPAI) subtype H5N6 struck a quail farm in Jaen, Nueva Ecija on March 9, 2020 (Dar, 2020). Fortunately, this has been the only reported case of bird flu in the country this year, so far.

Even before these diseases stormed the Philippines, numerous cases of infection and transmission outside the country that went far and wide have already been reported. Back in August 2018, China was the first Asian country smacked hard by ASF, followed by its neighboring countries (FAO, 2020a). It was in the same year when HPAI subtype H5N6 hit China’s swans in January, as well as Vietnam’s chickens and ducks in February (FAO, 2020b). China, particularly Wuhan City, now is also indisputably recognized as the origin of outbreak of the worldwide pandemic, COVID-19 (WHO, 2020). 

Aside from the obvious fact that ASF occurs only in pigs, avian influenza mainly in birds, and COVID-19 in humans, these three viral diseases differ in several other ways. The technical profile of ASF, COVID-19 and HPAI, as shown in Table 1, provides another way of comparing these diseases. 

Table 1. Technical profile of ASF (OIE, 2019), COVID-19 (CDC, 2020) and AI (Swayne, 2019) 


Causative
Agent
TransmissionIncubation Period1Signs/SymptomsZoonosis2
African
Swine Fever 
(ASF)
African 
Swine Fever 
virus (ASFv)
Direct contact with infected; indirect contact via fomites3; tick bite;
"swill feeding"
4-19 days

100% mortality, red or bluish- purple skin discoloration esp. on extremities, hemorrhages 

None; Only infects pigs 

Coronavirus 
Disease 2019
(COVID-19)

SARS-CoV-2; nCoV 

Direct contact with infected (via respiratory droplets from coughing and sneezing) 

2-14 days 

Fever, cough, shortness of breath 

Yes; Bats as reservoir 

Avian Influenza (AI) 

Influenza virus A (recent: HPAI H5N6) 

Direct contact with infected; feco-oral4; indirect contact via fomites 

Up to 14 days 

Depression, swollen & congested comb & wattle, swelling under the eye, coughing, sneezing, diarrhea, red shanks, nervous signs, death 

Yes 

1Incubation period – between exposure to an infection and the appearance of the first sign; 2Zoonosis – disease transmissible from animals to humans 3Fomites – objects that carry a disease (vehicle, equipment, clothes, feeds); 4Feco-oral – transmission of disease through ingestion of contaminated feces 

Prevention and Control

The causative agent of COVID-19 belongs to the family of Coronaviruses, as are Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS) in humans, Porcine Epidemic Diarrhea (PED) and Transmissible Gastroenteritis (TGE) in pigs, and Infectious Bronchitis (IB) in chickens. Coronaviruses are highly contagious, yet can be easily inactivated by alcohol and common disinfectants like bleach in water. The World Health Organization (2020) recommends the use of 70% alcohol and 0.1% sodium hypochlorite (bleach), as effective and sufficient disinfection procedures against Coronaviruses. Soap and detergent for cleaning also effectively decrease viral load before disinfection. Table 2 lists down the recommended disinfectants for the three viral diseases. As shown, Influenza viruses, responsible for bird flu and common flu in humans, are susceptible to all compounds used against ASF and COVID-19. Influenza viruses are relatively unstable in the environment, thus, can be readily killed (Swayne, 2019). On the other hand, ASF virus tends to be more resistant to common disinfectants as it is large and can withstand fairly extensive changes in pH (Juszkiewicz et al., 2019). Thus, it requires stronger compounds such as aldehydes and potassium monopersulfate (PMPS) for effective disinfection. 

In all disease-free regions, a quick response is vital for containing outbreaks whether it be a human or animal disease. The Bureau of Animal Industry (BAI) requires veterinarians who encounter or suspect ASF and AI to follow the national and/or local guidelines for disease reporting. The same is true for COVID-19 under the order of the Department of Health (DOH). Upon confirmation of any disease, control strategies are readily implemented. Detailed investigation, with tracing of possible sources and possible spread of infection, is performed (OIE, 2013). Infected zones are identified and are paired with movement control. For animal diseases like ASF and AI, a quarantine area is designated within the 1 km radius from the infected premise (AIPP, 2016; DA, 2019). Transportation of live animals, products and by-products out of the infected premises and quarantine areas is prohibited. Movement is only permitted in non-infected zones provided that there is a shipping permit. As for COVID-19, an enhanced community quarantine was implemented by the DOH to control human traffic (Medialdea, 2020). For all these diseases, checkpoints along the borders of quarantine areas should be in place to ensure compliance (AIPP, 2016; DA, 2016; Medialdea, 2020). 

Table 2.

Similarly, movement or importation of live pigs, pork products, and by-products from ASF-positive countries have been banned by BAI. Undocumented shipments are confiscated and condemned. This is also true for bird flu (AIPP, 2016). In a similar manner, the Office of the President imposed an international travel ban to all countries affected with COVID-19. An exception would be Filipino citizens, their foreign spouse and children, permanent residents and holders of diplomatic visas (CNN Philippines, 2020a). Upon arrival, monitoring of body temperature is a must. Suspected individuals and their immediate co-passengers are then directed to quarantine and isolation. 

Should outbreaks occur, the fastest and most efficient response enacted by the government against ASF and AI is “stamping out” or depopulation of positive herds and flocks by the most humane manner possible (DA, 2019). For HPAI outbreaks, special protocol is observed during depopulation given the zoonotic potential of the disease. Persons involved must wear personal protective equipment such as coveralls, masks, headgears, rubber boots and waterproof gloves (AIPP, 2016). As for COVID- 19, stamping-out is absolutely unacceptable. Instead, wearing of face mask and/or avoiding close contact about 1 meter away from another person or “social distancing” is enforced to prevent spread of the disease in a community (CDC, 2020). 

Proper disposal and adequate cleaning and disinfection must follow immediately. Using the recommended disinfectant, as discussed earlier (Table 2), will enable complete and effective disinfection. In the case of ASF, disinfection is done daily for 30 days. Before repopulation, farm downtime should not be less than 90 days (DA, 2019). As for AI, a final disinfection is performed 14 days after the first disinfection. This is followed by a 21- day resting period, and only then can the farm be restocked (AIPP, 2016). During disinfection, ASF- and AI- infected farms should be closed and remain unloaded. On the other hand, the Centers for Disease Control and Prevention (2020) recommends cleaning and disinfection of frequently touched surfaces (e.g. door knobs, handles, desks, etc.) to address COVID-19. Washing of hands for 20 seconds with soap and water or alcohol-based hand rub is also part of the disinfection protocol. 

As of today, no practical, specific treatment for AI, ASF, or COVID-19 exists. Supportive care and antibiotic treatment have been employed to reduce the effects of concurrent bacterial infections. There are no known effective vaccines for these diseases except for AI. In the country, vaccination is considered as a last resort in case stamping out is not successful or cannot be implemented for whatever reason (i.e. successive infections) (AIPP, 2016). 

Economic impact

The emergence of threatening diseases in the country has mutated from a health problem to an economic one. During the peak of ASF late last year, the industry is under pressure from consumer avoidance of pork and sudden panic to dispose growers and fatteners before the farm gets hit by the disease (Galang, 2019). This caused hog raisers to market them at a very low price. The incidence of ASF has also made the dynamics of supply and demand in the local pork industry pretty strange. While infected areas are limiting the movement of pigs, non- infected areas are enacting pork and pork products ban as a preventive measure. This has resulted in an undersupply in the latter and an oversupply in the former (Mirasol, 2020). 

On a similar note, sudden panic from COVID-19 outbreak has caused people to buy and even hoard face masks and alcohols reaching to a point of shortage. There were unscrupulous traders reported to be hoarding these supplies and selling them beyond their regular prices (Geducos, 2020). But a more significant economic impact of this disease includes sharp decline in trade and tourism (CNN Philippines, 2020b) 

Meanwhile, the case of bird flu this year was emphasized by the Department of Agriculture to be an isolated case which affected a quail farm (Reuters, 2020). Given this, there was no evident effect in the supply, demand and price of poultry products particularly chicken. 

What the industry can learn

As we know, a disease can successfully enter a farm with breach in its biosecurity. Being a farm’s first line of defense, biosecurity should always be given importance. As the saying goes, “Prevention is better than cure”, there is no better and more efficient mode of prevention than strict biosecurity practices and proper human hygiene especially in cases of diseases without primary treatment like ASF, AI and COVID-19.

During a disease, fear and panic seems to be the first response. Fake news is becoming more and more rampant as people are not well-informed. Industry personnel and the general public alike must be educated on how a disease is introduced, how it spreads, and how it can be prevented. They must also know its zoonotic potential in the case of an animal disease to avoid fear among consumers.

Most importantly, sick or affected individuals or population, whether animals or humans, must be reported. This is becoming a problem in the country as disease reporting is largely withheld to avoid panic. The current trend of disease detection and reporting in the country still relies on the presence of a large population of affected flocks, herds, or people. It must be realized that diseases are easiest to control when the affected are minimal in number.

References are available upon request. 


Editor-in-Chief: Emily Angeles

Assistant Editor-in-Chief: Francis Carlo Reyes

Research Team: Harrah Grace Magsino, Lawrence Patrick Amistoso, Kristiana Jil Meg De Castro, Medallaine Dimaiwat

Dixie Grace Mendoza