Infectious Disease: “The Human Problem”

Infectious Disease: “The Human Problem”

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Kevin C Kain, MD, FRCP
Senior Scientist, Toronto General Research Institute
Director, SAR Laboratories, Sandra Rotman Centre for Global Health
Science Director, Tropical Disease Unit, UHN-Toronto General Hospital
Canada Research Chair, Molecular Parasitology

By Brittany Campbell

Another part of the human problem that Dr. Kain pointed out is our tendency to shift blame away from ourselves when it comes to a number of emerging infectious disease threats, including antimicrobial resistance.  We focus squarely on the microbe or virus itself, a squiggly illustration of the molecular structure plastered on magazine covers all over newsstands. Except, contrary to your average Economist headline, the bugs are not out to get us. “The microbe, once inside, is usually trying to adapt to you, at least over time. There is no evolutionary pressure for a bug to kill its host, because then it can no longer propagate its gene pool.” Moreover, focusing on the bug detracts from the responsibility we have as humans to reduce our activities that cause them to emerge in the first place and to establish living conditions and health systems that reduce the chances of transmission and spread. “We tend to demonize microbes, when in reality, many of these outbreaks have human fingerprints all over them,” he says. This phenomenon is all over our news outlets, instilling fear in the general public and even going so far as to create hostility towards West Africans.1

Dr. Kain is quick to point out that it’s not just low resource countries that struggle with the ‘human problem’. Here in Canada, the three biggest negative economic impacts have been infectious: Severe Acute Respiratory Syndrome (SARS) took billions of tax-payer dollars out of the economy, the highly infectious avian flu virus led to the culling of millions of poultry, and mad cow disease was a huge hit to Alberta’s beef industry. Infectious outbreaks are a societal eye-opener to the vulnerabilities of our health care system, showing us that even Canada’s famed publicly funded system has its limits. The importance of properly allocating every public health dollar becomes increasingly clear.

Dr. Kain is both unique and widely known for his ability to translate scientific findings into dollars and cents. His research focuses on “trying to get the biggest bang out of your public health dollar.” This experience comes from working in resource-constrained communities where they just don’t have resources to waste and want to see “impact” (i.e. preventing disabilities, premature deaths, and dollars wasted) for public investments in health care. The ‘sweet spot’ for these investments is clearly in maternal child health.  He contrasts this way of thinking to the health expenditures in the West, where we tend to spend the majority of health resources at the end-of-life. For example, we spend billions of dollars annually on cardiovascular and pulmonary conditions, when the number one cause of preventable death, smoking, is, well, preventable.  Is enough being done to promote smoking cessation and to prevent teenagers from starting to smoke in the first place? Similarly, the United States spent an estimated 265 billion dollars last year on Type 2 diabetes, another lifestyle-related and potentially preventable disease. Even a small proportion of these resources directed to diseases of impact in low resource settings could have a profound influence on global health, security, and productivity.

“If you only have $10 per year per child for health in low income countries, you want to make sure you maximize the impact and circumvent the biggest risks to your next generation, the one that will ultimately result in the most productive and healthy future generation,” he explains. He and other global health researchers refer to this phenomenon as “looking into the future.” The future of the planet is in the hands of the fastest growing populations, where the majority of children are being born, which is, currently, in South Asia and Africa.

A major threat to the health and productivity of future generations in all countries is pre-term birth; it is the leading cause of mortality of children under five. Pregnant mothers who acquire an infectious disease are at higher risk for pre-term births.  While studying how malaria in particular affects the risk for pre-term birth, Dr. Kain is stumbling upon compelling new data that challenges the way we perceive a number of diseases.

In any ‘Intro to Global Health’ class, we learn that there are two main types of disease: communicable and non-communicable, where one has the ability to spread from person to person, and one, presumably, does not. However, in studying how malaria affects pregnancy outcomes, it appears that children born to moms who had malaria during pregnancy may be at increased risk for affective disorders and neurocognitive deficiencies. For the first time ever, evidence is suggesting that infections acquired during pregnancy may increase the risk of mental illness in exposed offspring; linking “communicable” and “non-communicable” illness in novel ways and providing intriguing new avenues to prevent mental illness.2

An interesting series of experiments are being performed in Dr. Kain’s lab to test this in model systems. Pregnant mice that survive infection and carry to term have pups that perform poorly in neurocognitive tests originally designed for Alzheimer’s mouse models. Despite the full-term pregnancy and normal birth weight, the mice are hyperactive with altered neurotransmitter levels. Similarly, another study in humans followed the children of mothers exposed to influenza during pregnancy and found them to be four-fold more likely to develop bipolar disorder.3 Mental illnesses still have a significant genetic component, but “exposure in utero may be a second hit that alters your neurological capacity to handle later life stressors.”

The notion that moms can ‘catch’ an infection that might increase the risk of mental illness creates an urgency to prevent the disease, whether it’s the common flu or malaria. Treating mental illnesses is notoriously difficult and creates an enormous financial stress on Ontario’s health care system.

Dr. Kain and his lab are working on finding simple, safe, and inexpensive interventions that protect the unborn in nations where malaria and other infections run rampant. He believes that focusing resources to that critical 9-month period could have a huge payoff for global health and contribute to a lifetime of healthier, more productive people and populations. He also believes that the affordable solutions that work in low resource settings will also impact the west, since these advances may well get retrofitted into our health care systems, so we can invest more wisely in our own population’s health.  Dr. Kain’s work shows health researchers that examining and circumventing risk in early life should be a priority all over the world.

 

References:

  1. Sack K, Fink S, Belluck P, et al. How Ebola Roared Back. New York Times. 30 Dec 2014. Available from: http://www.nytimes.com/2014/12/30/health/how-ebola-roared-back.html
  1. McDonald CR, Elphinstone RE, Kain KC. The impact of placental malaria on neurodevelopment of exposed infants: a role for the complement system? Trends Parasitol. 2013;29(5):213-19.
  1. Parboosing R, Bao Y, Shen L, et al. Gestational influenza and bipolar disorder in adult offspring. JAMA Psychiatry. 2013;70(7):677-85.