Hog cholera - Pedigogy

Master Preventive Medicine – Notes, Case Studies and Practical Insights – with Lomash

Hog cholera

Syn: Classical swine fever (CSF), Swine plague

It is highly contagious, acute septicemic and fatal disease of swine affecting all ages
It is characterized by sudden onset, high morbidity and mortality with generalized hemorrhages.
It is widespread almost in tropical world, prevalent among pigs and wild boars.

Etiology:

Epidemiology:

Disease was first reported in Ohio in USA in 1833 and etiology was recognized in England in 1862.
Disease has a world-wide distribution.
Disease was widespread in South African Countries, Europe, China and Japan.
Disease is completely eradicated from Canada, Australia, North Ireland, Denmark, New Zealand and UK.
Disease is prevalent in moderate to severe proportions in India, Burma, Nepal, Pakistan, Bangladesh, Philippines.
In a study conducted in 2018 in Kavrepalanchowk and Bhaktapur; seroprevalence of CSF was found to be 18.40%.
A total of 184 outbreaks of CSF were reported in the country during year 2010-2011.
Case mortality in pigs in two districts; Bhaktapur and Makwanpur during 2011 was 76.5 % and 72.3% respectively.

Transmission:

Disease is very contagious and spreads rapidly among pig populations
Direct contact with infected pig is the principal way of transmission
Disease transmits through ingestion of garbage or contaminated feed and water.
Virus also enters the body through inhalation of aerosol, fomites
Biological vector; soft ticks of genus Ornithodoros can also transmit disease.
Urine, nasal, and ocular discharge are most infective material.
Virus has reported to transmit over a distance of 1 km through fomites, aerosol.
Recovered pigs acts as a carrier.

Pathogenesis:

Virus gains entry through ingestion or inhalation of fomites, aerosol
Virus localizes in tonsil. Through tonsil, it reaches blood circulation
Virus multiply rapidly in blood and invade vascular endothelium which give rise to severe clinico-pathological manifestation
Degenerative changes in endothelial cells and cells undergo swelling, proliferation and dilatation
Infarction and necrosis of kidney, spleen and intestinal mucosa.

Clinical Signs:

Acute form:

Incubation period of 2-6 days
Sharp rise of temperature upto 107°F
Dullness, anorexia, depression, listless
Sticky and tenacious mucopurulent discharge through eye and subcutaneous tissues via nose.
Eyelids completely glued together.
Erythema appear in skin, showing diffused purple discoloration of abdomen.
Skin lesion soon develops into multiple cutaneous hemorrhages.
Severe diarrhea (offensive), vomition, constipation
Death occurs in about 1 week.

Chronic form:

Nervous Signs:

Reproductive disorder:

PM Findings:

Petechial hemorrhages in skin, mucus membrane, SC fat, pulmonary tissue, pericardium, GIT and kidney
Petechial hemorrhage in kidney gives ‘Turkey egg-like’ appearance.
Liver, dark, congested swollen shedded with mottled appearance.
Cecum and colon show circular raised button ulcers.

Diagnosis:

Differential Diagnosis:

Treatment and Control:

No effective treatment. Hyper immune serum @50-150 ml, IV
Slaughter of all infected and susceptible animal.
Access to pig farm should be limited.
Visitor who have a travel history to endemic countries shouldnot be allowed in farm.
Safe disposal of carcass, beddings, etc.
Disinfection of farm premises with appropriate disinfectant.
Vaccination of animals; inactivated vaccine also called crystal violet is administered @5ml, SC. It provides immunity for a year
Lapinised swine fever; live vaccine @1ml, SC. Immunity is 2 years.
Crystal violet is safe for pregnant sows and administered in pig above 3 months of age.