IF THE United States were suddenly facing a potential avian influenza pandemic, just one U.S. manufacturer could be counted on to make human pandemic flu vaccine here. And although the chickens that lay the eggs used in the process are themselves susceptible to the virus, until an emergency arises only voluntary and often inadequate measures by poultry producers are in place to protect flocks, according to a new Government Accountability Office report.

The report, scheduled for release next week, comes at a time of heightened public health worries about bird flu. One of the deadliest strains, H7N9, is causing a surge in human infections in China this season. Of the nearly 200 people who have died, most had direct contact with poultry or poultry markets.

Health officials worldwide are closely monitoring the disease's spread because of the big increase in cases and worrisome changes in the virus. Of all emerging influenza viruses, this strain of H7N9 has the greatest potential to cause a pandemic if it evolves to spread easily from human to human. It also poses the greatest risk to cause serious disease.

Controlling the virus in poultry is the main way to reduce human infection and prevent a pandemic, the GAO report says. It focuses primarily on Agriculture Department actions after bird flu outbreaks in 2014 and 2016, which resulted in the deaths of millions of domesticated poultry in 15 states and $2 billion in costs to the federal government and U.S. economy. Despite the lessons learned, the report concludes that federal agencies face "ongoing challenges and associated issues" in mitigating the potential harm of avian influenza.

Bird flu outbreaks this spring in Tennessee, Alabama and Kentucky have led officials to euthanize more than 200,000 animals. They are different from the strain of the H7N9 virus currently spreading in Asia, according to Agriculture officials.

Among the report's findings:

-- Unless the agency is responding to an emergency, the Agriculture Department doesn't have the authority to require poultry producers to take preventive biosecurity measures to keep avian influenza from spreading from farm to farm. When the agency asked 850 poultry producers to turn in self-assessments on such measures, less than 60 percent said they had key practices in place to reduce contamination - such as having workers shower or change into clean clothes immediately after arriving at a poultry site to reduce the risk of introducing a bird flu virus.

The report noted that commercial flocks raised outdoors and backyard flocks are at greater risk of contact with wild birds infected with avian influenza. These include poultry certified by the USDA as organically raised, which means turkeys and chickens that had access to outdoor space.

-- Pandemic influenza vaccines for humans can be made using several technologies, but the most common approach relies on growing virus cultures in fertilized chicken eggs. The Department of Health and Human Services has a stockpile of influenza vaccines supplied by four companies, the report notes, but only one company has an egg-based vaccine manufacturing facility in the United States.

In the event of an influenza pandemic, the government may not be able to rely on foreign countries to allow exports of pandemic vaccine, the report warns. "Therefore, the U.S. government considers the one U.S.-based company as the only dependable manufacturer for producing egg-based vaccine for rapid pandemic mitigation," it says.

HHS has had a three-year, $42 million contract with that company to protect the egg-supply chain and ensure a supply of vaccine-quality fertilized eggs. The contract expires in September, according to the report, which does not identify the company or its location.

HHS officials and company representatives told the GAO that the company controls the risk of bird flu by limiting the density of birds on each farm that provides it with eggs and by periodically testing the flocks for avian influenza. While the 2014 and 2016 outbreaks did not affect this egg supply, a previous outbreak of highly dangerous avian influenza caused the deaths of laying hens and reduced the company's supply of eggs by about 50 percent, the report says.

-- One way to track the potential for the spread of avian influenza is to look for the virus in pigs, which act as an intermediate host or "mixing vessel" in which flu viruses can recombine to pose new threats to humans. In 2009, H1N1 swine flu caused a global pandemic. But funding for a voluntary surveillance program that gathers data on the types of influenza viruses circulating in pigs will run out of money by Sept. 30, the report says.

The Agriculture program, which is the only federal source of data for influenza surveillance in pigs, relies on $25 million transferred from HHS. But the Trump administration's preliminary budget proposal for fiscal 2018 cuts Agriculture's budget by 21 percent and that of HHS by 18 percent.

-- The Agriculture Department, which is responsible for preventing, controlling and eradicating diseases from poultry and livestock, has taken hundreds of corrective actions since the 2014 and 2016 bird flu outbreaks but has not evaluated their impact. In those outbreaks, for example, states and poultry producers encountered barriers to transporting bird carcasses to landfills. Federal officials provided guidance and training to help producers and states develop disposal plans but never assessed whether either was effective.

The department, which reviewed a draft of the report, said it agreed with the GAO's recommendation for it to develop a plan for evaluating completed corrective actions.

The GAO report was requested by the House Energy and Commerce Committee. In a statement, its investigations subcommittee chairman, Tim Murphy, R-Pa., and ranking Democrat, Diana DeGette, Colo., said: "We know the devastating impacts of a global pandemic. Now it's up to the Department of Agriculture to make sure we are prepared and have a plan to combat this threat. Further, ensuring the effectiveness of their plans and procedures ... is just as important as the plans and procedures themselves."