Veterinarian Charlie Bahnson gives students the skinny on bird viruses

The North Dakota State department of biological sciences hosted its first seminar of the spring semester Jan. 11. Charlie Bahnson, a North Dakota Game and Fish Department wildlife veterinarian, spoke about his experience with experimental infections and serology with white ibis, a type of semi-aquatic bird, in Florida. 

Bahnson, who just recently received his Ph.D., knows the effect that influenza-carrying birds have on humans. Throughout his presentation, Bahnson gave insight on how the influenza is spread from birds through the water in reservoirs. The flu virus is then spread to other animals and even humans.

Bahnson explained that there have been three transmissions of viruses over the past one hundred years and seasonal influenza is a descendent of viruses originated in birds from long ago.   

His project for his Ph.D. took place in Georgia where he explored the influenza A virus in birds. The main focus was on the white ibis in particular. Though there are many flu viruses, the influenza A virus is found in birds and some mammals. It is linked to natural reservoirs, which causes the spread of the virus from wild bird species to other animals. Though sometimes the virus will die, it can remain within those species and end up spreading over large areas. Some of the main carriers are ducks. Mallards are what Bahnson called “the poster children of these viruses.”

Around August and September, when ducks are preparing to migrate south, there is typically a large outbreak of viruses. According to Bahnson, “30 to 40 percent of those birds will be shedding the viruses around that time.” As the ducks migrate south, the viruses will clear, meaning that the infectious rates drop drastically. 

Ducks are typically studied when scientists look at the influenza A virus. So, as new questions are being asked about influenza in bird species, scientists need to study different birds. Bahnson explained: “In order to find questions to these answers, we need to broaden our scope.” Because birds need a life history with the virus that is understood, as well as have contact with other animals that will probably have the virus, it makes selection harder. This is where the white ibis comes into the study.

The white ibis is found in southeast America where they usually nest in dense areas of mixed species. Because of habitat degradation in the Everglades, a lot have become urbanized, making cities the birds’ new home. They surround themselves with other bird species that are found in these areas. And now that they are used to large cities, they like living around humans as well, according to Bahnson.

Bahnson showed the area that one white ibis has traveled over a course of the year in Palm City, Florida. The bird traveled all over the city, going to various settings like a zoo/wildlife rehab center, a golf course and ranches, showing how much contact this single bird had with others and how it can spread viruses. 

The study that Bahnson discussed included ibis chicks that were raised over seven months and split up into three groups with different viruses. The first group had a waterfowl virus, typically found in ducks; the next had a host range virus found in a range of species and the last group had a virus typically found in pelicans.

In each group there were a few birds that weren’t given the virus dose. However, they ended up contracting the virus as well. The only group the virus didn’t spread to was the first one. Birds typically shed the virus through oral and fecal routes, which is why many ducks can obtain the virus through the water. As the study went on, the viruses started to die down after 10 days and the birds stopped shedding the viruses on day 14. Throughout the study, none of the birds felt sick and thus continued to live their lives normally. This is why the virus can spread so quickly over a vast amount of space and time.

Though these particular white ibises were used in the experiment on the influenza virus, Bahnson explained how they are not usually carriers of the influenza A virus. White ibises that were experimented on random dates did not carry the virus. However, when tested for antibodies to influenza, about 60 percent were positive, meaning they had been exposed to other viruses.

Bahnson expressed that understanding viruses in the natural reservoirs gives us an understanding of the issues it causes for other animals.