When waste becomes a carrier of disease: Finding solutions to protect Sweden's pigs and food production

Waste disposal facilities and wild boar food 

Garbage bags can appear slightly different across Sweden; brown paper bags, black sacks, or multicolored varieties. However, their function is the same: to separate food waste from other household waste. 

How it works: The journey from when the bin is emptied outside our homes to the final destination of the waste varies slightly depending on where you live in Sweden. However, what they all have in common is that in many parts of Sweden, the waste makes a stopover at various types of waste facilities. 

So what happens when we dispose of waste incorrectly, and food waste ends up in nature or in the residual waste bag? Well, it risks attracting wild animals, including wild boars.

Which has proven to be far from risk-free.

When wild boars find our garbage – and the infection finds them

There are a number of diseases that can affect pigs, both domestic pigs and wild boars, but which are not dangerous to humans. One such example is African swine fever (ASF), which can be found in meat products imported from countries where the disease is present. For example, via illegally imported meat from pigs or wild boars. 

This marked the start of the first ever outbreak of ASF in Sweden. A case that the SVA (Swedish National Veterinary Institute) has repeatedly analyzed. The conclusion? That it most likely occurred when wild boars found meat that was already infected, and ate it. Whether the initial spread of infection occurred at or outside a waste disposal site is impossible to determine with certainty, but it is known that many wild boars gathered there and spread the infection further. 

This time, Sweden managed to stop the outbreak through rapid intervention, cordoning off affected areas, and culling all animals that could potentially carry the infection. Fortunately, the infection never reached our domestic pigs, . But the outbreak also shows how quickly a contagious disease can spread once it gains momentum, and how serious the consequences can be. 

How infected wild boars become a danger to our domestic pigs 

But how can  an infection such as ASF reach our domestic pigs, just because wild boars gets exposed? 

Well, pigs in food production are currently kept either indoors (conventional farming) or outdoors (organic farming). Since diseases such as ASF are transmitted both through direct contact between animals (e.g., wild boars and pigs through fences for outdoor animals) and indirectly via other objects/people that have come into contact with the infection and bring it in, it is important to ensure that the infection does not exist in our country at all. 

Joining forces for safer waste management 

Shortly after the outbreak, research leader Elisabeth Rajala and her colleagues at SLU, in collaboration with Swedish pig farmers, submitted an application to contribute to greater knowledge about waste management in Sweden and, in the long term, to prevent further outbreaks in Sweden. Then, doctoral student Astrid Bornfeldt Persson was hired. 

The research team now has an important mission: To investigate how we can prevent our waste management from providing opportunities for the spread of infection in the future. To People from several disciplines, including veterinarians, sociologists, and the chair person from the Swedish Pig Farmers' Association, are now working together. Efforts includes risk analyses to identify more places in Sweden where future outbreaks could occur, based on both the presence of wild boar and how waste is managed locally. 

Since the infection most likely reached wild boars via food waste when Sweden was affected in 2023, the project's goal is to look at Sweden's waste management: From the bin outside your home to its final destination. The aim is to identify critical points/routes of infection where wild animals can access food waste and potentially be exposed to diseases such as ASF.  

Because believe it or not, this has not been mapped before. 

Doctoral student Astrid Bornfeldt Persson adds: 

More specific information about how the project will be carried out can be found at the bottom of the page. 

Right on time: Knowledge to bring home to your waste management 

You, me, and all of us as individuals can contribute to solving this problem by sorting food waste into the right bags, and avoiding throwing meat away in nature. Also, remember that it is illegal for private citizens to bring meat from countries outside Europe into Sweden. 

She believes that this project is right on time, now that we have seen evidence that infectious diseases such as ASF can spread here in Sweden – fast and with deadly efficiency.