Why disease is named African Swine Fever

African swine fever normally affects domestic pig populations when wild members of the pig family or their products get into contact with the domesticated animals.

What you need to know:

  • The disease was first discovered in Kenya in 1921.
  • Later, it was found in other parts of sub-Saharan Africa before spreading to Portugal in 1957. 

The human mind is wired to see things through a multiplicity of prisms, that is why I was not surprised by the kind of responses my articles on Morgan’s pig farm elicited.

Majority of readers wondered how the country has not been able to control African swine fever (ASF) or even develop a vaccine to protect pigs from the disease and farmers from the ensuing economic losses.

These concerns are valid because ASF has been with us in Kenya and Africa for over 100 years. The disease often emerges in sporadic outbreaks and then disappears for long periods before reappearing without notice. It happens that way because it is maintained in the wild by wild boars, warthogs and bush pigs.

ASF normally affects domestic pig populations when wild members of the pig family or their products get into contact with the domesticated animals. The virus may also be inadvertently transmitted to domestic pigs by humans or other animals.

Once the first domestic pig is infected, it takes about five to 19 days to show signs of the disease depending on how infectious the infecting virus type is. This long incubation period for some virus types explains why sometimes the disease may have a slow onset.

However, once a sufficiently large number of pigs are infected, the disease moves fast in the herd, particularly when it infects the young and growing stock.

The disease has no treatment but since 2021, research in the UK and the US has shown promising signs of possible development of protective vaccines. The UK version proved fully effective in protecting pigs in the laboratory and is to undergo field trials in countries with large pig populations.

Commercial production of such a vaccine would be the best news for pig farmers.

I must admit ASF is the disease I dread diagnosing to a farmer. The suffering seen in the pigs and the economic loss that follows death and depopulation of the farm are always difficult to communicate. In addition, the farmer must close the farm for about six months to exterminate the virus.

Now, some farmers surprised me with their responses on the ASF article. They said they thought the naming of the disease as African was malicious. They wondered why scientists associate Africa with bad things. They also wondered whether it was because most discoveries were not made by Africans.

I agree there are some biases sometimes in associating Africa with the bad. But in the naming of diseases, there is a very clear scientific protocol that is followed globally. It has nothing to do with the biases of the scientist discovering a disease or a disease – causing agent, process, gene or the observable effect such as yellowness in yellow fever.

The naming protocol for diseases and pathogens has evolved over time as scientific methods of disease diagnosis have kept improving. In the early days when scientific diagnosis was rudimentary, diseases and pathogens were named after places where they were discovered or after people and scientists who first described them.

In some cases, diseases and pathogens were also named after scientists who had contributed highly in researching the problem. For instance, the human brain degenerative problem called Creuzfeldt-Jakob disease was named by the German scientist Walther Spielmeyer in 1922 after the two German neuroscientists Creuzfeldt and Jakob for their work in neuroscience research.

There are others like Nairobi sheep disease, East Coast Fever and Rift Valley Fever that are associated with Kenya and East Africa because it is where they were first described. 

Marburg fever, on the other hand, is named after a city in Germany where it first broke out and was described in humans in a research laboratory. It was traced to Mt Elgon in Kenya where monkeys used in the German laboratory had been obtained from.

Nowadays, with the advent of sophisticated and accurate scientific diagnostic methods, diseases are named after the pathogen, the disease process or the gene responsible for the observed changes. The naming has, therefore, remained objective.

ASF was first discovered by Montgomery in Kenya in 1921. Later it was found in other parts of sub-Saharan Africa before spreading to Portugal in 1957. Montgomery observed the disease was killing pigs imported from Europe in high numbers when they mixed with local ones. Today, we know that it meant the local pigs were carriers of the virus and hence did not show active disease.

From Portugal, the disease spread to other parts of the world including the Americas through the movement of meat and meat products. Some countries initially infected have been able to eradicate the disease through strict control measures but it remains persistent in African countries and recently in South East Asia.

ASF is currently the biggest challenge in pig production and disease problem in animal health. In 2019, the World Organization for Animal Health reported the death or destruction of about 5.9 million pigs globally due to the disease. 


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