(Hog Cholera) Highly contagious disease of pigs characterised by rapid spread, high mortality associated with septicaemia and haemorrhage. It can affect pigs of all ages and has a worldwide distribution. Disease is caused by a RNA virus belong to Toga viridae. This virus is closely related to Bovine Viral Diarrhoea virus. Virus will be there in all secretions and excretions of the affected. Virus is destroyed by heat at 60 – 70˚C. It will be destroyed by 5% cresol, Lysol and 3% Sodium hydroxide. Only suckling white mice and rabbits are artificially infected. Transmission: Direct and indirect contact can transmit the disease. Main mode is through uncooked garbage. Virus can be recovered in urine even after 2 – 3 weeks of clinical recovery. Recovered ones act as carriers. In pregnant the virus can cross placental barrier and infect foetus leading to still birth or piglets with abnormalities. After entry viraemia occurs about seven days of time and incubation period is only 5 – 6 days. Pathogenesis: Degeneration and necrosis of the infected cells mainly on the endothelial cells of capillaries, small blood vessels and reticulo-endothelial cells. After gaining entry through nasopharynx; the virus localises in tonsil. Then enters blood stream and a period of viraemia occurs and subsequently invade the endothelial cells and various clinical manifestations occur. Lesions: Petichae and echymotic haemorrhages throughout serous membranes and also on the mucus membrane lining the digestive and respiratory tract. Presence of button ulcers on mucosa of caecum and colon can be observed. Pinpoint haemorrhages in kidney are readily visible on capsule giving Turkey egg appearance to kidney. Spleen, skin and lungs show infarcts of varying sizes. Nervous tissue will show non-suppurative encephalitis. Clinical findings: a. Per acute: Course may extend from hours to days. Majority will die within hours in per acute. Erythematous patches on the non-hairy parts of the skin and high rise in temperature (106-107˚ F) are main symptoms. Young piglets mostly suffer with this type. b. Acute: Period may extend to 19-20 days. Temperature rise up to 107˚ F, anorexia, depression, dullness, vomition, constipation, offensive diarrhoea, development of petichae on skin at base of ears and ventral side of abdomen. Extension of petichael lesions also can be seen. Purplish discolouration of snout, blotching effect on ears, necrotic lesions on tip of ears, tail, lips and vulva. If CNS is affected, then wobbling gait, ataxia, tremor, convulsion, paralysis, circling and coma can be seen. Mummified foetus or still birth or birth of piglets with abnormality also recorded. c. Chronic: Period will be around 3 months. Chronic diarrhoea, pneumonia, emaciation and alopecia noted. Trembling of piglets at the time of birth, cerebellar hypoplacia, reduction in litter size, less survivability of piglets born, deformity of joints and reduced size of head also observed. Diagnosis: History, symptoms and post-mortem lesions of dead ones. Confirmative diagnosis is with the help of laboratory tests viz. GDT, CCFT, HA, NT, FAT. It should be differentially diagnosed from 1. Salmonellosis (mostly affects between the ages of 2 to 4 months), 2. Swine erysipelas (diamond markings on skin) 3. Collibacillosis (laboratory confirmation using faecal smear has to be done) 4. Pupura haemorrhagica (self limiting disease) 5. Mulberry heart disease (no temperature) 6. Aujesky’s disease (mostly nervous lesions) Treatment: No specific. Hyper immune serum @ 50 – 150 mL in very early stages can be tried if value of the animal justifies treatment. Control: Slaughter of the affected and in contact animals. Farm premises should be properly disinfected restriction of movements, personal hygiene and proper cooking of garbage before offering to pigs. Vaccination can be practiced in endemic areas. 1. Lapinised vaccine: By serial passage in rabbits. Dose: 1 Ml, SC, immunity for 1-2 years. 2. Crystal violet vaccine: 0.5% Crystal violet is added. Dose 1 mL 3. Tissue vaccine: Spleen and reticulo-endothelial tissues of pigs after 6 days of infection are used. Dose: 5 mL SC, immunity for 10 months.
