Swine flu versus swine fever

Dear Prof McCrindle,

Why is there no vaccine for swine flu? Our villagers are losing pigs every year! Kind regards,

Anonymous

Dear Anonymous,

There is often confusion between two different pig diseases called swine fever and swine flu. Swine fever is a controlled disease. It is highly contagious in pigs and many die during an outbreak. If you have many deaths, it is extremely important to contact the State Veterinary Services to make sure of the diagnosis. There is no vaccine and affected pigs are slaughtered out.

Swine flu, on the other hand, is a variant of human influenza and avian influenza; which is often carried into a pig production unit by infected people, roaming hens or wild birds. The best way of controlling swine flu (also known as swine influenza) is to use the human influenza vaccine annually for all workers and to keep your pigs away from poultry and wild birds. Although pigs can become sick, the main symptoms are coughing and sneezing, and mortalities are very low, except in piglets.

The signs of swine fever are high fever and bleeding. It is known as a haemorrhagic disease, with a very high level of mortalities. Previously, a distinction was drawn between African swine fever, which was endemic in warthogs, and European swine fever, which was present globally and transmitted by contact. However, the latest global outbreak was caused by a global variant of swine fever genetically related to both strains. It spread globally from Europe through pork exports.

In South Africa, the highest level of mortality was seen in small-scale pig production systems, where biosecurity was not well in place. Large-scale, commercial piggeries, where pigs were kept in isolation facilities, were less affected. There is no vaccine and many pigs died or were slaughtered out. This outbreak seemed to slow down in 2022, but sporadic outbreaks are still being seen.

Control measures include slaughter of all pigs in contact, and a focus on health certification by a registered veterinarian, which is still obligatory for any pigs taken to abattoirs or auctions.

The State Veterinary Services suggest that pig farmers, especially small-scale producers who breed and fatten pigs in peri-urban areas, should take routine precautions.

Pig farmers should always buy their pigs from herds that are known to be healthy. Those pigs purchased on auction should rather be used for slaughter and not be introduced into a breeding herd. It is also important to prevent contact with wild pigs and warthogs. Birds can also be carriers, and it is suggested that pigs are kept in runs protected with chicken wire to keep out wild birds.

Workers should use hygienic precautions such as washing hands and showering, as well as wearing clean overalls and gumboots that are not used for other activities.

Kind regards,

Prof Cheryl McCrindle

ȊȲSource: Mushagalusa CA, Etter E, Penrith ML. ‘Review of African swine fever outbreaks history in South Africa: From 1926 to 2018’. Onderstepoort Journal of Veterinary Research. 29 Sep 2021; 88.