Classical Swine Fever - Symptoms, Causes, Prevention, Immunization [UPSC]

Classical Swine Fever: It is also known as Hog Virus and is among the most infectious viral diseases of domestic pigs and wild boars. It is caused by the Classical Swine Fever Virus, which belongs to the Pestivirus genus in the Flaviviridae family. It is highly contagious and has severe consequences on porcine health and production. Furthermore, it differs from Swine Flu as it does not affect human beings and their health. However, it creates significant health implications for the swine population. It is a highly  Contagious disease in pigs and sheep.

It is related to the bovine viral diarrhoea virus (BVDV) of cattle and border disease virus (BDV) of sheep.

Refer to this article on Classical Swine Fever for UPSC 2023 – GS Paper – 2.

What is Flaviviridae?

It is a group of viral pathogens responsible for severe diseases and death among animals and humans.

It consists of three genera:

• Flavivirus
• Pestivirus
• Hepacivirus

Pestivirus or border disease virus mostly infects mammals, including cattle, pigs, sheep and goats. There are 11 species in this genus.

Read the article from the following link to understand zoonotic diseases.

Classical Swine Fever – Symptoms and Spread

• The incubation period for the disease varies from 3 to 10 days and causes bovine diarrhoea in pigs and border disease in sheep. 
• The symptoms of the virus include high fever, diarrhoea or constipation, the purple colouration of the skin, lethargy, difficulty in movement, and an unsteady gait in animals.
• Pregnant sows getting infected results in abortions, malformations, and stillbirths. Offspring born to infected ones can release the virus for a long period. Some act as carriers with no signs of infection but keep spreading the virus.
•  An important feature of Classical Swine Fever is immunity suppression by reducing B-lymphocytes and T-lymphocytes. It differs from Swine Flu and simultaneously affects both domestic and wild swine populations.
• The virus is transferred through saliva, faecal matter, urine, and other body secretions. 
• It spreads through contact between an infected and non-infected pig, contaminated food, water, farm equipment, vehicles, and people.
• Classical Swine Flu can survive in processed pork meat when it is refrigerated for years and frozen. Pigs consuming CSF-infected pork meat or products are also susceptible to the virus.
• Classical Swine Fever can cause mortalities and malaise in the pig population. Thereby inflicting severe economic losses and worsened socio-economic conditions on pig farmers.

Hog Virus/Classical Swine Fever – Control and Prevention

• CSF has been detected in parts of Africa, Asia, Europe, South America, and Central America.
• In India, the total population of pigs accounts for 9.06 million or 1.7 % of the total livestock population.
• Understand the important facts related to livestock census from the linked article.
• The pig industry flourished in North and North-Eastern states like Assam, U.P, Meghalaya and Jharkhand. Hence, CSF outbreaks have been reported in this part of the country. However, there are constant outbreaks of CSF at regular intervals in these geographical areas. The severe crisis faced by the piggery sector has negatively affected the breeding and national and international trade of pigs in developed and developing countries.
• There aren’t any specific treatment methods for Classical Swine Flu. The infected pigs must be slaughtered, and the carcasses should be disposed of with utmost care and caution to prevent transmission. Many countries have adopted methods like vaccination to curtail the spread of disease to non-endemic countries. Trading and exporting pork meat from infected to disease-free regions should be banned. Systematic implementation of vaccination can be the best strategy to combat and control the spread of the virus to healthy pig herds. Effective seclusion of the healthy population and a ‘stamping out’ policy through ensured surveillance can be done in areas that are endemic to viruses.
• CSF is listed by OEF or the World Organization for Animal Health as it has a major impact on the piggery industry of countries worldwide.
• Classical Swine Fever causes a loss worth 400 crores yearly in the livestock industry. There has been a considerable reduction in the number of pigs in India since 2019. This situation puts forward a requirement of 22 million vaccine doses every year. Vaccines are highly efficacious in preventing the expansion of CSF. A vaccine under the brand ‘Raksha Class’ has been released by the Indian Immunologists Ltd and Indian Veterinary Research Institute with a unique cell culture technology. It is a live accentuated vaccine with assured safety, sterility, and potency standards.

Examples of Zoonotic Diseases    

1. West Nile Fever –  It is a mosquito-borne disease caused by a virus called West Nile Virus from the family, Flaviviridae. The virus is similar to viruses that cause Japanese Encephalitis, Yellow fever, and St. Louis Encephalitis. It infects human beings through mosquito bites. No history of direct human-to-human transmission has been documented till now. Infections with West Nile Virus are either asymptomatic in around 80% of people or can lead to West Nile disease or West Nile Fever.

2. Bird Flu – It is also known as Avian Influenza, caused by Type A viruses from birds. There are generic symptoms like cough, fever, muscle ache, and shortness of breath, and in a few cases, a mild eye infection or conjunctivitis is the only indication. Generally, Avian Influenza does not affect humans. But some of them, like H5N1 and H7N9, have caused severe infections in human beings. Avian Influenza type A virus is classified based on two proteins on their surfaces.

• • Haemagglutinin (HA)
  • Neuraminidase (NA)

HA has about 18 subtypes, and NA has about 11 subtypes.

3. Zika Virus –  It is transmitted by mosquitoes from the Aedes genus, Aedes aegypti. They also spread chikungunya, yellow fever and dengue. Apart from the human-to-human transmission, the virus can also be transmitted through sexual contact, pregnant women through fetus, blood transfer and organ transplant.

Symptoms of Zika virus include muscle and joint pain, fever, headache etc. WHO has declared the Zika virus a Public Health Emergency.

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