African Swine Fever Information and Resources

African swine fever (ASF) is a highly harmful infectious disease in the global pig breeding industry. There is no specific drug, no commercial vaccine, and the mortality rate is extremely high.Once ASF epidemic breaks out in pig farms, it will not only lead to large-scale elimination of pig herds and huge breeding losses, but also lead to production stoppage of pig farms, obstruction of regional pig industry chain, restriction of pig trade, fluctuation of pork price and other chain problems, which is the core epidemic risk of normal prevention and control of all pig farmers and breeding enterprises.

The core reason for the risk of frequent epidemic diseases in most pig farms is not the lack of hardware facilities, but the insufficient cognition of the virus characteristics, transmission path, symptoms and prevention and control process of African swine fever, weak awareness of epidemic prevention and the formalization of the process.This paper focuses on the pain points of first-line breeding practice, systematically explains ASF core knowledge, diagnostic methods, prevention and control schemes, emergency response and industry impact, and matches the needs of novice entry and optimization of epidemic prevention in large-scale pig farms with high-frequency answering questions.

What Is African Swine Fever?

What causes ASF?

African swine fever (ASF) is a highly pathogenic and highly contagious animal infectious disease, caused by ASFV double-stranded DNA virus with stable structure and strong resistance. It only infects domestic pigs and wild boars, and will not spread across species.The virus has strong environmental survival ability, hidden transmission and difficult eradication. At present, there is no specific drug and commercial vaccine. The core of pig farm prevention and control can only rely on standardized biosafety system and early accurate screening.

Why ASF is so dangerous

African swine fever is called a terminal disease in pig farming, with four fatal characteristics at its core.The death rate of acute cases of the disease is nearly 100% and the onset speed is fast, and there is almost no possibility of self-healing.At the same time, the virus resistance is extremely strong, can survive for weeks or even months in feed, instruments, feces and pork products, and survive longer in low temperature environment. Conventional disinfection and sterilization methods are difficult to completely remove, and epidemic prevention is extremely difficult.

ASF has a wide and hidden transmission route, which can be transmitted through direct contact with pigs, personnel and vehicles, feed, wild boars and ticks, and recessive infection is easy to cause silent outbreak in pig farms.At present, there is no specific therapeutic drug for African swine fever, and there is no commercial protective vaccine. Infected pigs can only be treated innocuously.The outbreak of the epidemic will also trigger a regional trade ban, causing a huge economic impact on the entire pig industry chain.

Where ASF has spread worldwide

Since the virus was discovered, African swine fever has gradually spread from the birthplace of Africa to Europe, Asia, America and other major pig breeding regions in the world, becoming a major epidemic risk in the global pig industry.Over the past ten years, ASF has been spreading in Eurasia, with outbreaks in several large pig breeding countries, resulting in a large-scale decline in pig stocks, shrinking production capacity and fluctuation in pork market.

At present, the ASF epidemic situation presents the characteristics of normalization, dot distribution and cross-regional transmission, and there is no absolute non-epidemic area.Wild boar carrying poison, cross-border transportation, circulation of live pig products and omission of breeding and epidemic prevention are the core causes of repeated outbreaks of global epidemic diseases.For domestic pig farms, there is no absolutely safe breeding area. No matter large-scale large factories or small and medium-sized retail investors, a normalized and standardized ASF prevention and control system must be established to eliminate lax epidemic prevention.

How Does African Swine Fever Spread?

The core misunderstanding of epidemic prevention failure in many pig farms is to only pay attention to direct contact transmission of pigs and ignore hidden paths such as indirect transmission and media transmission.In combination with the characteristics of ASFV virus and the actual practice of first-line breeding, all transmission channels of African swine fever can be summarized into four core categories, covering all scenarios of virus entering from outside and spreading in the field, which is also the core target for biosafety prevention and control of pig farms.

Direct contact

This is the primary and most efficient way of propagating ASF.Healthy pigs and infected pigs, pigs with recessive virus, pigs in the recovery period of disease direct contact, through the mouth and nose mucosa, respiratory tract, digestive tract infection virus.All body fluids and excreta such as blood, saliva, nasal discharge, feces, urine and milk of sick pigs contain high concentration of virus, and the probability of infection is extremely high after contact with pigs in the same pen and house.

At the same time, the cross-border and cross-field transfer of virus-carrying pigs and recessive infected pigs with no obvious symptoms in appearance are the primary risks of external introduction and infection of pig farms.The outbreak of epidemic situation in many pig farms is due to blind introduction and failure of isolation and detection, which leads to rapid spread of virus to the whole population after entering the site.

Contaminated feed, equipment and vehicles

This is the most easily overlooked indirect core transmission path in small and medium-sized pig farms, and is also the main reason for the silent transmission of non-plague.The first is feed and drinking water pollution, kitchen residues contaminated by ASF virus, deteriorated feed, contaminated water, pigs will be directly infected after eating and drinking, which is also a high-frequency cause of outbreak of rural free-range households and small pig farms.

The second is the pollution of breeding equipment, trough, drinking fountain, scraper, syringe, disinfection equipment, transfer tools, etc. If they have contacted with poisoned pigs and contaminated dirt, they will be reused without thorough disinfection, which will cause cross infection in the field.Finally, the virus carried by transportation vehicles, pig dispatching vehicles, feed transport vehicles, material distribution vehicles, excrement transfer vehicles, vehicle bodies, tires and chassis can enter the site with the vehicles, pollute the pig farm area and roads, and then infect the pigs.Vehicle circulation is strong, wide range of activities, is the key carrier of cross-regional transmission of non plague.

Wild boars and ticks

Wild pigs and insect vectors are the core vectors of natural circulation transmission of ASF, and also the key to the complete elimination of ASF in the wild.Wild boars are the natural hosts of ASFV. A large number of wild boars carry the virus but have no obvious symptoms. They can spread the virus to surrounding pig farms through migration, foraging and contact with domestic pigs, causing the virus to penetrate into the farm area. The risk of this kind is extremely high in mountainous and suburban pig farms.

At the same time, soft ticks are the exclusive transmission vector and storage host of ASF virus, which can not only directly transmit the virus by biting pigs, but also realize vertical passage of virus. Tick eggs can carry virus and continuously spread epidemic diseases.The soft tick has strong survival ability and high concealment. It inhabits the corner, gap and corner of the piggery. It is difficult to completely remove it by routine disinfection and sterilization, which will cause repeated epidemic diseases on the pig farm and risk all the year round.

Human activities

Personnel are the most mobile and difficult media in pig farm epidemic prevention.Pig farm breeding personnel, technicians, maintenance personnel, foreign visitors, slaughtering and purchasing personnel, if they have come into contact with other pig farms, pig markets, slaughterhouses, poisonous pork products, clothes, soles and hands, will carry viruses, which will indirectly pollute pens, feeds and pigs after entering the site, causing infection.

In addition, fresh pork products brought in illegally, foreign materials that have not been thoroughly disinfected, and breeding utensils carried by personnel are all important inducements for man-made transmission.Many large-scale pig farms have perfect hardware epidemic prevention facilities, but due to weak epidemic prevention awareness of personnel and lax admission control, epidemic losses finally occur.

African Swine Fever Symptoms

The incubation period of ASF is 3-19 days. During the incubation period, pigs have no obvious symptoms but carry virus and are infectious, which is also the core difficulty that the epidemic situation is difficult to be detected early.According to the pathogenesis process and severity, it can be divided into early mild symptoms, acute severe symptoms and chronic persistent symptoms. Meanwhile, it is easy to be confused with classical swine fever. Farmers need to distinguish them accurately to avoid misdiagnosis and misjudgment and delay disposal opportunity.

Early signs

Early symptoms are the key to stop loss in pig farms. There is no specific fatal symptom at the beginning of the disease, which is easily mistaken for common cold, fever and stress reaction.The core warning signals include sudden high fever, body temperature rising to 40-42℃, persistent non-return, sharp decrease in feed intake, refusal to eat, listlessness, drowsiness, mild respiratory symptoms, occasional cough and panting, mild constipation or diarrhea in some pigs, unexplained abortion, stillbirth and abnormal return to estrus in sows.

At this stage, the mortality rate of pigs is relatively low, but if timely isolation, screening and detection and cutting off the transmission chain can effectively avoid the outbreak of the whole herd, it is the golden disposal stage of ASF prevention and control, and also the key observation index of daily patrol of pig farms.

Acute symptoms

Acute ASF is the most common type of disease, with a short course, rapid deterioration, and near 100% mortality, with mass mortality occurring within 6-13 days of onset.The typical symptoms are very recognizable, with persistent high fever, ineffective drug cooling, purplish red blood stasis plaques and cyanosis on the skin of ear tip, abdomen, inner side of limbs and buttocks, which do not fade when pressed, purulent and serous secretions flow out of eyes and nose, severe vomiting, hematochezia, diarrhea, mucus and blood streak in feces, dyspnea, rapid heartbeat, unstable standing, shaking walking, and some pigs. Neurological symptoms, convulsions and rigidity on the ground.

Chronic symptoms

Infection with low virulent strains can cause chronic ASF, with hidden symptoms, long course of disease and relatively low mortality, which is the most easily ignored risk type in pig farms.Sick pigs with long-term low fever, appetite sometimes good or bad, slow growth, emaciated and stiff pigs, repeated mild respiratory and digestive tract symptoms, which cannot be cured for a long time, sporadic skin congestion spots, occasional appearance, joint swelling, walking lameness.

Chronic ASF pigs can carry virus for a long time and expel toxin intermittently, which becomes a mobile source of infection in the pig farm, continuously pollutes the environment of the site and infects healthy pigs, resulting in repeated epidemic diseases in the pig farm and long-term treatment, and long-term loss of breeding benefits.

How ASF differs from Classical Swine Fever

The symptoms of the two epidemic diseases are highly similar, and ordinary farmers are easy to confuse, but the prevention, control and disposal methods are completely different, so accurate differentiation is very important.

How to Prevent African Swine Fever

Combined with the global breeding experience and the epidemic prevention standards of the Ministry of Agriculture and Rural Affairs of China, there is no treatment for African swine fever, and prevention and control are more important than everything else.The core epidemic prevention logic of all pig farms is to build an all-round and dead-angle biosafety system to block the virus from entering and spreading in the farm from the source. The following are a complete set of prevention and control measures that can be directly implemented.

ASF ViroShield Solution

ASF ViroShield is Lima Biotech's functional feed additive for pigs designed specifically for modern, large-scale pig farms.The product is formulated with Bacillus subtilis and plant-derived active ingredients, which can help maintain intestinal microecological balance, support digestive health and immune function, provide stable nutritional support for pigs at different growth stages, and help improve overall health level.

In the process of African swine fever prevention and control, ASF ViroShield can be used as an auxiliary product of comprehensive biosafety management system, combined with strict biosafety measures, standardized disinfection, scientific breeding and health management, to help improve the resistance of pig herds to environmental stress and disease risks, and to provide support for pig farms to establish a more stable health management system.

Farm biosecurity

Biosafety is the core foundation of ASF prevention and control, and the core logic is zoning control, closed-loop management and source blocking.First of all, the site area shall be divided into living area, isolation area, production area and sewage treatment area strictly. Each area shall be physically isolated, personnel and materials shall not cross flow, and cross pollution shall be eliminated.Secondly, implement closed-loop control of introduction, adhere to the principle of "self-breeding and self-cultivation, less introduction and careful introduction". If introduction is needed, the qualification of introduction source must be checked in advance, isolated and observed for more than 30 days before entering the site, nucleic acid detection shall be completed synchronously, and mixed breeding can be carried out only after passing the test.

At the same time, establish a one-way flow system for personnel, materials and pigs on the site, prohibit reverse flow, regularly carry out biosafety self-inspection in the site area, rectify epidemic prevention loopholes, eliminate fluke psychology, and form a normal epidemic prevention mechanism.Small and medium-sized pig farms can simplify the process, but must retain isolation, zoning, screening three core links.

Feed and water safety

Eliminating feed and water pollution is the key to cut off ASF indirect transmission.First, it is strictly prohibited to use kitchen residues and swill to feed pigs, which is the primary cause of ASF outbreak in rural pig farms in China and must be completely prohibited.Second, select regular manufacturers of feed, strictly control feed procurement, transportation, storage links, feed warehouse to maintain dry ventilation, regular disinfection and sterilization, prevent mildew, pollution, eliminate foreign virus attachment.

Third, ensure the safety of drinking water, give priority to the use of deep well water and tap water, and prohibit the use of wild ditches and open water as aquaculture water.Regularly clean and disinfect drinking water pipes, water towers and drinking fountains, regularly detect water quality, and prevent water sources from carrying viruses and breeding bacteria.Fourth, feed transportation vehicles and loading and unloading personnel shall be strictly controlled, fully disinfected before entering the site, materials shall be handed over outside the site, and vehicle personnel shall be prohibited from entering the production area.

Cleaning and disinfection

Normalized cleaning and disinfection is the core means to kill environmental viruses and reduce virus load in the field.Daily implementation of daily cleaning system, timely cleaning of feces, dirt, debris, keep the house dry and ventilated, reduce virus breeding and survival environment.Formulate standardized disinfection and sterilization plan, regularly kill roads, isolation areas and excrement areas in production areas, site areas every day, and fully cover and kill the periphery of the site every week.

Disinfectants effective against ASF virus shall be preferentially selected. Sodium hydroxide, peracetic acid and glutaraldehyde are all high-efficiency disinfectants and disinfectants. They shall be used strictly according to the proportion concentration to prevent disinfection failure caused by random dilution.The breeding equipment and appliances shall be used for one pig and eliminated immediately after use. The infected pigsty and contaminated area shall strictly implement the system of empty pen disinfection, sterilization and standing to thoroughly kill residual virus.At the same time, regularly replace disinfection and sterilization agents to avoid virus resistance and ensure disinfection effect.

Visitor and vehicle control

As high-frequency mobile carriers, personnel and vehicles are the main channels for external viruses to enter, and the strictest control standards must be implemented.In terms of vehicle control, all foreign vehicles are strictly prohibited from entering the production area. Disinfection and sterilization, standing, handover, all-round spray disinfection of vehicle body, tire and chassis shall be completed in the designated area outside the site. Operation shall be conducted only after standing meets the standard.Special use for on-site transfer vehicles, regular thorough disinfection and sterilization, no external circulation.

In terms of personnel control, the system that outsiders are prohibited from entering the production area is strictly implemented, and visitors, technicians and procurement personnel communicate and operate in the office area and off-site area.Before entering the site, the breeding personnel must change their work clothes, shoes and hats, wash their hands for disinfection and atomization disinfection. It is prohibited to bring in fresh pork products and exotic breeding equipment without permission.After personnel go out and return to the site, they must be re-sterilized and allowed to stand before entering the production area, so as to cut off the artificial transmission path to the maximum extent.

What to Do If ASF Is Suspected

Once suspected ASF symptoms are found in pig farms, panic disposal, concealment and random transfer are the most taboo. Correct standardized disposal process can control the spread of epidemic situation to the maximum extent and reduce breeding losses. All pig farms must be familiar with and strictly implemented.

Isolate affected animals

In case of high fever, cyanosis of skin, hematochezia, batch death and other abnormalities of pigs, all transportation, breeding and delivery operations in the field shall be suspended as soon as possible, and the suspected sick pigs and pigs in contact with the same column shall be transferred to independent isolation area immediately. Contact with healthy pigs is strictly prohibited.At the same time, mark the risk area, block the infected house, prohibit the cross-regional flow of personnel, materials and pigs, cut off the transmission chain in the field from the source, and avoid the rapid spread of the epidemic situation to the whole group.

Cleaning and disposal procedures

Under the guidance of the official, carry out full-field intensive disinfection and sterilization, increase the frequency of disinfection, carry out all-round and dead-corner thorough disinfection on the infected houses, isolation areas, roads in the field area, excrement pollution areas and all breeding equipment, so as to eliminate residual viruses in the environment.For dead pigs and suspected sick pigs, harmless treatment, deep burial, incineration and other compliance disposal shall be carried out in strict accordance with animal epidemic prevention standards. It is strictly prohibited to discard, sell or transfer dead pigs at will, so as to prevent secondary transmission of virus.

At the same time, the excrement, residue and contaminated sundries in the site shall be comprehensively cleaned up, and centralized disinfection shall be carried out. During the epidemic control period, closed-loop disinfection and sterilization shall be continued, so as to continuously reduce the virus load in the site and eliminate the recurrence of epidemic situation.

Farm Recovery and Restocking

The pig farm can enter the recovery period only after the epidemic situation is put out, the disinfection and sterilization of the whole field reaches the standard, the official inspection is qualified, and the control is released.First of all, implement the empty column rest system, house, field empty standing, repeated disinfection and sterilization, thoroughly eliminate residual virus.Secondly, carry out full-field environmental sampling test. After confirming that there is no virus residue, a small number of test pens can be supplemented to observe the health status of pigs. After there is no abnormality, the normal breeding scale can be gradually restored.

After the restoration of breeding, it is necessary to comprehensively recover the original epidemic prevention loopholes, upgrade the biosafety system, optimize the personnel, vehicles and feed control process, prevent the recurrence of similar epidemic diseases, and steadily restore the production capacity of pig farms.

Conclusion

African swine fever is still the most severe and stubborn severe disease in the global pig breeding industry. There is no specific drug, no commercial vaccine, hidden transmission and high mortality rate, which determines that prevention in advance is always better than disposal afterwards.For all pig breeding practitioners, fluke psychology is the biggest breeding risk, systematic, normalized and landing biosafety prevention and control system is the only core grasp to resist ASF risk, stabilize breeding capacity and guarantee breeding income.

In addition to strict biosafety management, scientific nutritional support also helps to improve the overall health of pigs.Lima Biotech's ASF ViroShield is formulated with probiotics and active ingredients of plant origin and is an important complement to integrated pig health management programs to help maintain gut health, support immune function, and work with biosafety measures to support a more robust African swine fever control system for modern pig farms.