Multiple Potential Causes for Avian Flu Outbreak

By ThinkReliability Staff

An outbreak of avian influenza (flu) H5N2 centered around Iowa in the United States has resulted in nearly 47 million birds being killed in 21 states. There is a low risk that this outbreak could spread to humans as the 1996 avian flu did. The impacts on the poultry industry have been significant: the number of birds being killed has led to an increase in poultry prices. Says Phil Lempert, “We’ve lost 10 to 13 percent of the laying hens in this country, so we’re going to have this period of time where we have less birds and less eggs. That means higher prices.”

The financial impact isn’t limited to consumers. The United States Department of Agriculture (USDA) estimates it will spend more than $500 million fighting the outbreak. The impact on poultry producers is expected to be even higher. The USDA Animal and Plant Health Inspection Service (APHIS) is studying the outbreak and attempting to put into place measures that will reduce the spread of the outbreak. Finding the causes leading to the outbreak has proven to be challenging.

We can capture the information that is known in cause-and-effect relationships using a Cause Map to better understand what caused this outbreak. The first step in the Cause Mapping process is to fill in an Outline with basic background information, which includes listing how the overall goals are impacted by the issue. The Cause Map is than built by asking “why” questions to lay out the cause-and-effect relationships. In this example, the animal safety goal is impacted due to the deaths of nearly 47 million birds. These birds were killed because of an outbreak of avian flu. An outbreak results from an initial infection (believed to have been transmitted in this case to domestic flocks by wild birds) and the spread of the disease. Based on genetic analyses from APHIS, this outbreak appears to have multiple independent introductions within the outbreak area (i.e. the transmission from wild birds to domestic flocks happened in multiple locations).

According to their Epidemiologic and Other Analysis of HPAI-Affected Poultry Flocks: June 15, 2015 Report: “APHIS concludes that at present, there is not substantial or significant enough evidence to point to a specific pathway or pathways for the current spread of the virus. We have collected data on the characteristics and biosecurity measures of infected farms and studied wind and airborne viruses as possible causes of viral spread, and conducted a genetic analysis of the viruses detected in the United States.” This means that the cause or causes of the spread of the avian flu cannot be definitively determined due to lack of evidence. When an investigation has a lack of evidence, potential causes are included in the analysis with a question mark, indicating insufficient evidence.

In this case, avian flu was potentially spread by air, by wild birds, and by human movement. Data from APHIS research indicates that the virus has been able to spread on windy days up to a half mile. A solution under consideration is more advanced ventilation systems for poultry farms that would prevent transmission of disease from farm to farm. Previous outbreaks have indicated that wild birds can not only cause an initial infection, but can continue to spread the disease from flock to flock. This evidence supports this cause, but is not strong enough to rule out other causes so all should still be included on the Cause Map. Lastly, APHIS found inadequate biosecurity (primarily cleaning and disinfecting) measures on equipment and personnel that traveled from farm to farm, which could also potentially spread the disease.

The issues found with biosecurity are a particular concern. Says Michael T. Osterholm, the director of the Center for Infectious Disease Research and Policy at the University of Minnesota, “We used to think we had outstanding biosecurity in poultry. But, except for the outbreak in 1983, which was stopped quickly, we have never been tested before.”

Osterholm and other researchers say more research is needed to screen for viruses, and develop drugs and vaccines to ensure public safety. Although the virus has not yet been shown to infect humans, the Centers for Disease Control and Prevention has developed interim guidelines on testing and treatment. APHIS continues research on how to limit the spread and the USDA, in order to offer some relief on prices, has recently allowed poultry imports from the Netherlands.

To view a Cause Map, or root cause analysis presented in a visual cause-and-effect diagram, of the ongoing outbreak, please click “Download PDF” above.