Swine Pox
Age affected: Piglets pre-weaning, weaners, (all ages).
Causes: Swine pox virus.
Effects: Red spots, brown or black scabs, conjunctivitis, stunting.
Mode of transmission
Transmission is usually from pig to pig directly, but rubbing or scratching on contaminated pen furniture is an important route of infection, especially if there are protrusions which can break the skin. Bites by insects (lice and flies), cuts and scratches can also allow the entry of infection. Occasionally swine pox may occur in neonates as it can pass the placenta when the sow becomes viraemic. The resistance of the virus to cleaning and disinfection when dried means that it may recur even after extensive cleaning. Both carrier pigs and contaminated items such as implements and clothing can transmit the disease to a clean farm.
Clinical signs
The incubation period is 3-6 days but may be up to 14 days and the lesions persist for 1-3 weeks. Slight fever (104°F) may accompany the appearance of the lesions. Red 1 cm papules (spots) appear on the ventral abdomen and rapidly form circular red brown scabs, which soon blacken. In young piglets the bursting of the vesicular (blister) stage on the face may lead to wetting, scab formation and conjunctivitis.
Slight inappetence may accompany the development of the lesions. Affected pigs appear hairy and growth may be depressed. A large percentage of successive litters of sucking and recently-weaned pigs may be affected but the disease is rare in adults. Mortality is rare although transplacental infection in newborn pigs can cause deaths. Lesions may be seen on the edge of the tongue, lips and all over the body. Badly affected newborn piglets may have to be killed, but all other age groups normally recover.
The size and colour and especially the uniformity and circular shape of the lesions is characteristic. Flank biting, ‘spirochaetal granuloma’ and local infections with Staphylococcus hyicus may also resemble pig pox but the agents of these are usually demonstrable.
Treatment and prevention
Treatment or control are rarely attempted because of the mildness of the disease, but the use of insecticide to eliminate lice and flies which transmit the disease on a farm and the thorough cleaning and disinfection of pens in which outbreaks of the disease have occurred help to reduce the incidence.
Cleaning and disinfection is necessary because the virus may persist in a farm for years between outbreaks in dust and dried secretions in unused pens and fittings. The residual virus infects progeny of newly purchased pigs and weaned pigs from non-immune farms when mixed with carriers or placed in infected pens.
Dr.Parvinder kaur Lubana, Punjab,
