The increasing frequency of disease outbreaks is linked to climate change and biodiversity loss. The past 20 years of contained outbreaks may have led to complacency. New technologies offer hope in the search for countermeasures – but protecting the natural world must play a part, too.
The frequency of disease outbreaks has been increasing steadily, according to recent World Economic Forum article.
Between 1980 and 2013 there were 12,012 recorded outbreaks, comprising 44 million individual cases and affecting every country in the world.
A number of trends have contributed to this rise, including high levels of global travel, trade and connectivity, and high-density living – but the links to climate change and biodiversity are the most striking.
Deforestation has increased steadily over the past two decades and is linked to 31% of outbreaks such as Ebola, and the Zika and Nipah viruses.
Deforestation drives wild animals out of their natural habitats and closer to human populations, creating a greater opportunity for zoonotic diseases – that is, diseases that spread from animals to humans.
More broadly, climate change has altered and accelerated the transmission patterns of infectious diseases such as Zika, malaria and dengue fever, and has caused human displacement. Movements of large groups to new locations, often under poor conditions, increases displaced populations’ vulnerability to biological threats such as measles, malaria, diarrheal diseases and acute respiratory infections.
Against this bleak outlook on the frequency of disease outbreaks, the good news is that the impacts of those outbreaks on human health seem to be declining thanks to medical breakthroughs and advances in public health systems.
So far, these have contained the effects on morbidity and mortality through the success of countermeasures such as vaccines, antivirals and antibiotics, which greatly reduce the risk of massive loss of life.
The reality, however, might be much less rosy. The past 20 years of disease outbreaks could be viewed as a series of near-miss catastrophes, which have led to complacency rather than the increased vigilance necessary to control outbreaks.
One of the keys to pandemic preparedness is highlighting where increased research and development is most needed. In 2015 the WHO introduced a “priority diseases” list, reviewed annually to identify “Disease X” in the list as a way to focus researchers’ attention on pandemic risks posed by diseases that cannot currently be transmitted to humans, or which are transmitted only inefficiently. Similarly, in 2019 CEPI offered more funding to companies and academic groups with promising ideas for vaccine platforms and novel manufacturing processes that can produce, at scale, vaccines, or “vaccine-like” immunoprophylactics, which aren’t traditional vaccines, in a matter of weeks or months rather than years.
Innovative technologies are critical in the search for new vaccines. One promising area of research is gene-encoded antibodies that create “factories” in our bodies to make antibodies against specific pathogens. Another is monoclonal antibodies (mAbs), typically used to treat existing disease, but which can also prevent infection. Successful drug development is not always about advanced synthetic biology – there is also a link to nature-based solutions and biodiversity as researchers are increasingly “reverting to nature” to look for new therapeutic options. An estimated 50,000 to 70,000 plant species are harvested for traditional or modern medicine, while around 50% of modern drugs have been developed from natural products that are threatened by biodiversity loss.
The weakness of basic preparedness in individual countries is an important obstacle to pandemic responses. Progress has been made, particularly since the 2014–16 Ebola epidemic, but most countries have not yet reached minimum international standards in their capacity to detect, assess, report and respond to acute public health threats as set out in international health regulations that took effect in 2007. This is a focus of the WHO’s efforts to combat the COVID-19 outbreak with support for countries whose healthcare systems are unprepared to respond properly. Since the beginning of 2020, the WHO has helped set up 40 labs in 35 African countries (from zero before the outbreak) to carry out testing that will improve early detection and control.