Insight @ McGill: McGill microbiology expert Brian Ward on avian flu
Brian Ward, a McGill professor of microbiology and researcher at the McGill University Health Centre, was the first lecturer in the University's new learning series for media: Insight @ McGill.
Dr. Ward is an expert in immunology, vaccines and infectious diseases. As director of the McGill University Division of Infectious Diseases, he studies how vaccination can affect measles, anthrax, smallpox and influenza.
Ward's laboratory studies the immunologic evaluation of vaccines and vaccine safety, the evaluation of micronutrient-microbial interactions, and the development of novel therapeutic strategies for microbial pathogens. His laboratory focuses on the discovery and implementation of practical solutions to microbial challenges.
Although a good deal of Ward's work is performed in Montreal, he's collaborated with researchers in the U.S., Peru, Zimbabwe, Haiti, Sudan and Brazil. He is currently exploring novel therapeutic agents for protozoal, fungal and bacterial infections.
What is avian influenza? (courtesy of the Centers for Disease Control and Prevention)
Type A influenza viruses can infect several animal species, including birds, pigs, horses, seals and whales. Influenza viruses that infect birds are called "avian influenza viruses." All known subtypes of influenza A viruses circulate among wild birds, which are considered the natural hosts for influenza A viruses.
Avian influenza viruses do not usually directly infect humans or circulate among humans.
Avian influenza usually doesn't make wild birds sick either, yet can make domesticated birds very sick or kill them. Avian influenza A viruses do not usually infect humans; however, several instances of human infections and outbreaks have been reported since 1997.
Characteristics of avian influenza in birds
Certain water birds act as hosts of influenza viruses by carrying the virus in their intestines and shedding it. Infected birds shed virus in saliva, nasal secretions and feces. Avian influenza viruses spread among susceptible birds when they have contact with contaminated nasal, respiratory and fecal material from infected birds; however, fecal-to-oral transmission is the most common mode of spread.
Most influenza viruses cause no symptoms, or only mild ones, in wild birds; however, the range of symptoms in birds varies greatly depending on the strain of virus and the type of bird. Infection with certain avian influenza A viruses can cause widespread disease and death among some wild species and especially domesticated birds such as chickens and turkeys.
Symptoms of avian influenza in humans
The reported symptoms of avian influenza in humans have ranged from typical influenza-like symptoms (e.g., fever, cough, sore throat and muscle aches) to eye infections, pneumonia, acute respiratory distress, viral pneumonia, and other severe and life-threatening complications.
Antiviral agents for influenza
Studies to date suggest that the prescription medications approved for human influenza strains would be effective in preventing avian influenza infection in humans; however, sometimes flu strains can become resistant to these drugs and so they may not always be effective.
Potential for an influenza pandemic
All influenza viruses can change. It is possible that an avian influenza virus could change so that it could infect humans and could spread easily from person to person. Because these viruses do not commonly infect humans, there is little or no immune protection against them in the human population. If an avian virus were able to infect people and gain the ability to spread easily from person to person, an "influenza pandemic" could begin.
Background on pandemics
Once a new pandemic influenza virus emerges and spreads, it typically becomes established among people and circulates for many years. The U.S. Centers for Disease Control and Prevention and the World Health Organization conduct extensive surveillance programs to monitor the occurrence of influenza activity worldwide, including the emergence of potential pandemic strains of influenza virus.
An influenza pandemic is a global outbreak of influenza and occurs when a new influenza virus emerges, spreads and causes disease worldwide. Past influenza pandemics have led to high levels of illness, death, social disruption and economic loss.
There were three pandemics in the 20th century. All of them spread worldwide within one year of being detected. They are:
1918-19, Spanish flu, caused the highest number of known flu deaths: more than 500,000 people died in the United States, and 20 million to 50 million people may have died worldwide. Many people died within the first few days after infection and others died of complications soon after. Nearly half of those who died were young, healthy adults.
1957-58, Asian flu, caused about 70,000 deaths in the United States. First identified in China in late February 1957, the Asian flu spread to the United States by June 1957.
1968-69, Hong Kong flu, caused approximately 34,000 deaths in the United States. This virus was first detected in Hong Kong in early 1968 and spread to the United States later that year. Type A (H3N2) viruses still circulate today.
