Understanding the Flu

smith and Dhanasekaran

Flu fighters: Vijay Dhanasekaran and Assoc. Prof. Gavin Smith

Published April 9, 2014, last updated on April 9, 2018 under Research News

From Vital Science, a publication of Duke-NUS

Influenza, or the “flu” for short, remains one of the most common infectious diseases in the world. The diversity of the different viral strains and their ability to adapt and evolve and even jump the species barrier makes the disease one of the most challenging infections to study, prevent and treat.

Many types of influenza, such as Influenza A, originate from birds and other animals such as pigs. There are many types of influenza because the virus mutates readily when it comes into contact with other influenza viruses or the human immune systems. This helps influenza virus adapt to become more resistant or to gain the ability to transmit more effectively between hosts, be it between animals, from animal to humans or from human to human. Associate Professor Gavin Smith, also associate research professor of global health at the Duke Global Health Institute, pointed out that increased air travel and intensification of farming and urbanization that brings human environments closer to natural ones, have also led to the increased spread of the disease.

At Duke-NUS, the Emerging Infectious Diseases (EID) Program collates and analyzes data on influenza and other infectious diseases to gain better insights into understanding their ecology. Disease ecology, explains Assistant Professor Vijaykrishna Dhanasekaran, is the study of how pathogens interact with their human or animal hosts and the impact of this on the transmission of diseases. “Every now and then, viruses that circulate in animals jump from animals to humans. This inter-species transmission can cause a major epidemic or in some cases, a global pandemic because we don’t have any immune protection against these viruses. This is one reason we need to understand the ecology of infectious diseases not just in humans, but in animals as well.”

Dr. Gavin Smith, who runs the Laboratory of Virus Evolution elaborated, “Understanding where those contact points (between animals and humans) exist is important to stop any transmission; because if you understand where transmission happens, why it happens and the probability of transmission, then you can remove the source.”

These factors make influenza a challenging pathogen to study, he explained, but it also presents an opportunity for researchers. “Because of its properties, influenza spreads easily, has a relative high mortality, and a high level of interest, a lot of information is being collected globally all the time. This makes it a good model virus to study.” The high mutation rate also means there is a lot of information to work with.

Areas of research

Making sense of this wealth of information plays an important role in understanding the fundamental behavior of influenza. “When a new pathogen emerges, the response is necessarily reactive because we don’t know what it is, where it comes from and how it will spread. The general idea is to gain a better understanding,” said Dr. Smith. The work is akin to doing the “homework” beforehand. Surveillance in the absence of disease, the study of at animal populations and analyzing data on influenza patterns all help researchers make better predictions. “What we are trying to do is to learn from past events and currently circulating viruses to then try and understand what the possible scenarios are if something new emerges,” he explained. That information also helps develop mathematical modeling about different control scenarios for pandemic preparedness plans. “In the event of a pandemic, it sets out what to do and whether there are enough antivirals, how effective an antiviral is or how long it will take to develop a vaccine.”

For instance, the Laboratory of Virus Evolution at Duke-NUS helps to fill in the existing gaps in global influenza data. “While surveillance in North America and parts of Europe are highly-represented, surveillance in South East Asia, South Asia and Africa are not so established. One of the things we want to do is to fill these gaps,” explained Dr. Dhanasekaran. Thus far, the lab has established surveillance in three different countries and works with four of the six WHO centers that compile influenza data.

Other areas of research include studying the global movements of the virus (called epidemiology), analyzing adaptations in the inter-species transmission to try and understand why some viruses are more successful than others, risk assessment and tracing the origins of pathogens. This involves collaborative research with different teams around the world. Recently, Dr. Dhanasekaran was part of a team that discovered that certain populations, namely indigenous Australian and Alaskan people, are more vulnerable to H7N9 than others due to an absence of preexisting antibodies. All this, explains Dr. Smith, goes into enabling better pandemic preparedness plans.

The lab also contributes to the development of the biannual influenza vaccine by working with collaborating centers and training people in disease ecology analysis. “We help these centers to analyze big data sets on flu surveillance,” said Dr. Smith, “The information plays a role in the global vaccine strategy”. (See box story: Creating the flu vaccine). 

Creating the flu vaccine

The constant mutations in influenza viruses means vaccine formulas too have to be adjusted every six months to ensure they remain effective. The WHO's Global Influenza Surveillance and Response System works with a wide network of National Influenza Centres who monitor and compile information on the types of influenza viruses circulating in humans. Every six months, the WHO meets to review the data and uses the information to develop a vaccine that targets the most virulent strains in circulation. 

 

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