After finding infection in one of the farm's huge chicken stables, they also started testing in nearby stables.
The Swedish Board of Agriculture then discovered infection in different stages in each stable on the farm.
Then the decision was made that all chickens must be killed, not least to keep the amount of virus down to reduce the risk of spreading.
- It was only a matter of time before we had seen an enormous mortality rate, says Håkan Henrikson, chief veterinarian at the Swedish Board of Agriculture.
"Certainly not over yet"
The outbreak means a great tragedy for the farm owners who have lost their entire bird population, but there is compensation to be had.
The Epizootics Act, for example, allows full compensation for loss of production in the event of a bird flu outbreak, and the costs of decontamination also accrue to the state.
That compensation does not cover the entire cost, but may be supplemented with any insurance.
2021 has so far had many outbreaks of extremely aggressive bird flu, not only in Sweden, but also in many parts of Europe.
The fact that the entire farm in Mönsterås will now be decontaminated significantly reduces the risk of infection, but the risk of wild birds spreading the infection is still imminent.
- Unfortunately, it has not looked so good and it is certainly not over yet, says Håkan Henrikson.