Evolution of Infectious Diseases 2018

One hundred years ago, the deadly Spanish influenza pandemic of 1918 swept through the world and killed an estimated 50 million people. Globally, infections still account for 13-15 million deaths annually. Dr Wong Sin Yew was invited to give lectures in July and August 2018 at the following places – Department of Infectious Diseases, Tan Tock Seng Hospital (July 11th, 2018), Gleneagles Hospital (August 8th, 2018) and Department of Laboratory Medicine, National University Hospital (August 28th, 2018). He shared his thoughts on the evolution and the megatrends of infectious diseases. Some highlights of these 3 lectures are listed below

Megatrend One: “There will always be another infection”

It is estimated that there are more than 1400 microbial pathogens that infect humans. More than half of these (58%) are zoonotic infections, that is, they have originated from infections that first occurred in animals. Every year, new pathogens infecting humans are identified. The majority are zoonotic and more than 70% of emerging and re-emerging infections in the past 2 decades have been due to RNA viruses.

Outbreaks of infections are ongoing problems in developed and developing countries. Even in a developed and urbanized society like Singapore, we have had our fair share of outbreaks and some notable ones include Nipah virus, SARS-CoV, Zika virus and Group B Streptococcal infections. We remain concerned about the ongoing “imported” risk for MERS CoV and avian influenza. Some of the factors associated with these emerging and re-emerging infections include global travel, changes in land use, agricultural practices, the centralised production of food and human factors such as migration, increased antibiotic use etc.

Somewhere out there, there are emerging or re-emerging microbial threats lurking. When the “right” conditions coalesce, it will unleash itself onto the global population who will have no immunity to this “new” pathogen and present as a “black swan” event. Knowing this, it is imperative for us to start preparations to improve infrastructure and capacity to deal with such threats of infection. The focus of preparations to manage outbreaks include rapid identification, containment and medical interventions such as antimicrobial treatment and vaccinations.

Megatrend Two: “There will always be antimicrobial resistance”

All the antimicrobial agents that have been developed for treatment of infections in humans have inherent weaknesses. Microbes adapt readily and will attempt to develop resistance to the antimicrobial agents to survive. With the steady rise in antibiotic consumption, antimicrobial resistance (AMR) follows rapidly. At the 68th World Health Assembly in May 2015, WHO declared antimicrobial resistance as a global health threat and proposed a multi-year action plan to reduce antimicrobial resistance. The “global action plan on antimicrobial resistance” has 5 strategic objectives:

• To improve awareness and understanding of antimicrobial resistance
• To strengthen surveillance and research
• To reduce the incidence of infection
• To optimize the use of antimicrobial medicines
• To ensure sustainable investment in countering antimicrobial resistance

On November 1st 2017, the Ministry of Health announced the launch of the National Strategic Action Plan on Antimicrobial Resistance. The plan provides a framework to strengthen and enhance activities to combat AMR. It utilises a OneHealth approach and also involves the Agri-food and Veterinary Authority (AVA), National Environment Agency (NEA) and Public Utilities Board (PUB), Singapore’s national water agency.

Megatrend Three: “There are important demographic changes to consider”

The global population is projected to increase steadily to 7.5 billion in 2025 and 8.1 billion in 2050.

Demographic changes in the next 10-20 years will have a major impact on infectious diseases. The 3 global demographic trends that are particularly important in infectious diseases are:

• Increase in the elderly population
• Increase in the number of immunocompromised patients
• Increase in the migrant population, especially refugees and asylum seekers

Globally, the elderly population, defined as more than 65 years of age is expected to reach 2.1 billion in 2050. In Singapore, this is keenly felt with the elderly expected to constitute more than 25% of Singapore’s population by 2030. The major health concerns in the elderly are the increased medical conditions and the higher risk of infections in this subgroup of the population.

Many developed countries including Singapore are taking pro-active steps to manage the projected increase elderly population and the associated health issues that accompany this trend.

Medical advances have allowed improved survival of patients whose immunity is impaired. This includes HIV infected patients, cancer patients on chemotherapy, organ transplant recipients and the increasing number of patients on immunosuppressive agents. With reduced immunity, these patients have a higher risk of infections and often, the manifestations of infections are “atypical”.

The issue of refugees and asylum seekers entering Europe has dominated the news headlines in 2017 and 2018. Besides cultural concerns about “assimilation” into their new country, there may be health issues such as tuberculosis, chronic hepatitis B infection etc that need to be considered. Many of these refugees are first housed in transit centres which are often overcrowded and may not have safe water and sanitation. Outbreaks of infections such as measles, meningococcal infections, diarrhoeal diseases have been reported in these transit centres.

Megatrend Four: ”There will always be technological advances”

Technological advances in the past 10 years has made a huge impact in the way we work, live and interact with each other. Similarly, technology has been a major driving force in the evolution of healthcare in the areas of diagnosis, monitoring and treatment. In the context of infectious diseases, we highlight the following:

• The revolution in microbiological diagnosis, especially in “hard to culture” infections
• Advances in therapeutics
• Development of novel vaccines
• Increased use of mathematical modelling and prediction models

This is a brief outline of Dr Wong’s recent talks. Some of these themes will be elaborated on in the coming months in separate articles on this website.