Limitations of current avian influenza compensation

Culling diseased birds and contact farms has substantial financial consequences. Photo: ANP

Stamping out avian influenza is the go-to method of many governments around the world. However, as the outbreaks get bigger and occur more frequently, current disease compensation schemes are reaching their limits. How long is society willing to pay for damage that could potentially be mitigated in new ways?

Over the past 10 years, the US poultry industry has been affected by 3 devastating outbreaks of the avian influenza virus. Between April 2015 and March 2024, the highly pathogenic virus was diagnosed on 683 poultry farms. A total of 128.8 million birds died as a result of the infections and preventive culling of flocks. Of these, 100.3 million were laying hens and 20.7 million turkeys (Table 1).

While there were about 7 years between the first 2 outbreaks, the third massive epidemic followed only 2 years after the second. After the devastating economic effects of 2022, it had been hoped that a similar outbreak would not follow so soon. The new wave of outbreaks hit the poultry industry shortly after recovery from the Covid-19 pandemic. This reignited a number of issues that had already been the subject of much controversy in 2022. One of these was the idea of preventive vaccination and the other was if and how farms should be compensated for animal losses due to infection or culling using funding from the US Department of Agriculture. This article looks at the timeline and impacts of the 2023-2024 epidemic.

Outbreak dynamics

There is a clear correlation between the infection of migrating wild birds with the avian influenza virus and outbreaks on poultry farms. The 3 major flyways of wild birds (Pacific, Mississippi and Atlantic) have had a decisive impact on the spatial pattern of outbreaks. While in 2015 it was primarily bird migration on the Mississippi route that led to a concentration of cases in the northern Midwest (Minnesota, South Dakota), the pattern in 2022 was very different. It could be shown that, strictly speaking, these were 2 separate epidemics caused by bird migration on all 3 routes.

The first cases occurred in turkey farms in Minnesota and South Dakota and 4 weeks later in parent stock farms for broiler chicks in Arkansas and Alabama in early October 2023. The fact that outbreaks were recorded in the southern part of the Mississippi route was surprising, but showed that the wild birds were travelling far south. The spatial pattern changed in November, which showed a peaked with 61 outbreaks, as farms in Iowa, California, Oregon and Montana became infected, in addition to the initially affected states.

The number of outbreaks in turkey flocks decreased significantly in December, but the number of infected flocks of other poultry species increased sharply, especially in California. A total of 16 farms were infected there, with duck and broiler flocks also affected, deviating from the pattern in 2015 and 2022. The Pacific flyway was obviously more frequented by wild birds than in previous outbreaks. On the Atlantic route, there were infections in New York, Pennsylvania and Ohio.

The number of outbreaks fell significantly in January 2024, with only 2 infections in turkey farms in Wisconsin and Indiana and in 2 laying hen and broiler flocks in California. Remarkably, 6 game bird farms in Kansas and South Dakota were also affected. In December, 2 cases had already occurred in South Dakota. Although the number of outbreaks continued to decline in February, there were again 6 infections in turkey flocks in Missouri and South Dakota, as well as a parent stock farm for broiler chicks in Colorado and a broiler growing farm in Nebraska. Only 1 outbreak was documented in March 2024, on a turkey farm in South Dakota. With higher temperatures, the end of the epidemic seemed to be in sight.

An analysis of the timeline and spatial pattern of the main outbreaks can be summarised as follows: The outbreak in October 2023 began similar to those 2015 and 2022, with a large number of infections in turkey flocks in the northern Midwest. In the following months, however, outbreaks became more frequent in western US, especially in California, as well as Oregon and Montana. States on the Atlantic flyway were less affected than in 2022.

Animal losses

It might be expected that the highest number of infections would also result in the greatest number of animal losses. However, this was not the case as can be seen from Table 2 and Figure 1. Although turkey flocks accounted for 59.3% of the outbreaks, they only shared 15.2% in animal losses. The picture was completely different for laying hen farms. They only shared 16.9% in the total number of infected farms but, at 68.7%, they accounted for over two-thirds of animal losses. Of the 26 infected laying hen farms, 4 had more than 1 million places and 1 had more than 2 million. By contrast, the average number of animals kept on a turkey farm was only 38,000. The broiler flocks affected were also much larger, with an average of 232,000 places. The epidemics in 2015 and 2022 showed a similar size pattern.

Major regional differences

A comparison of the avian influenza outbreaks that occurred in a state in the period under review with the resulting animal losses also reveals characteristic differences. Figure 2 shows that South Dakota, Minnesota and California accounted for 60% of infected poultry farms, but shared only 38.5% in the animal losses. The difference was obvious in South Dakota. Although the state shared 22.1% in the number of affected flocks, it only accounted for 6% of animal losses. The average size of the farms was 41,000 places. By contrast, the situation in Ohio was completely different. With 6 outbreaks, the state only shared 3.9% of the total number of infected farms but accounted for over a quarter of animal losses with 25.5%. Here, the average flock size was 983,000 places, 24 times larger than in South Dakota.

In Iowa, Kansas and California, the proportion of outbreaks was also smaller than the proportion of animal losses. With 290,000 (Iowa), 230,000 (Kansas) and 200,000 (California), respectively, large average flock sizes were also seen here. It is clear that animal losses were particularly high in states with large layer farms. Although a similar situation had already occurred in 2015 and 2022, in the meantime, the large laying hen farms had apparently not been able to improve biosecurity measures to prevent the entry and spread of the avian influenza virus.

Weather conditions also played a role, as the prolonged winter meant that wild birds migrated from the northern states of the Midwest and California to the northern breeding areas weeks later than usual. This may partly explain the numerous outbreaks in Kansas, Nebraska and California in January 2024.

Outlook

Since 2015 and 2022, over 150 outbreaks of the avian influenza virus occurred again in the US in the winter months of 2023-2024. Commercial turkey meat and laying hen flocks were again primarily affected, but duck and broiler farms were also infected. Unlike the first 2 outbreak waves noted above, states in the west of the US were affected to a much greater extent in 2023-2024, as were states in the central south.

While there had been almost 7 years without any major outbreaks or animal losses between the outbreaks of 2015 and 2022, the time gap between the last 2 outbreaks was less than 2 years. Because of the short time period, this reignited the debate about preventive vaccination of poultry and how to provide financial compensation to the affected farms for the animal losses suffered from tax revenues. There are indications that a new legislation is impending which expands the compensation available to poultry producers affected by highly pathogenic avian influenza.