From nuclear war to mass shootings, we worry about a lot of things that could kill a lot of people. I mostly worry about emerging infectious diseases or EIDs. It could be a vector-borne disease, like ones transmitted by mosquitoes. Dengue fever is an example. It could be a zoonotic disease, or one that jumps from 1 species (in which it doesn’t cause disease) to another, and ultimately causes disease in humans. An example of a zoonotic infection is the Middle East Respiratory Syndrome, MERS.
EIDS can kill a lot of people fast. It doesn’t help that we can’t “see” viruses or bacteria in action, infecting and killing millions of people. Just think: It’s the 100th year anniversary of the 1918 flu pandemic that killed more people than any illness in human history. Forget bombs, EIDS are on a whole other level.
Sadly, scientists and researchers who track EIDs are predicting another epic outbreak that will have the potential to kill millions of people and cost billions to defeat. Perhaps you’ve heard of “Disease X.” Organizations like NYC-based EcoHealth Alliance and the Prokopec Lab at Emory University in Atlanta are using data and statistical and mechanistic models to predict outbreaks and pathogen transmission with the goal of preventing or containing them. A significant driving factor of EIDs is human behavior and how we interact with our environment and fellow species. Things like land use, cultural habits and traditions, climate change, travel, live food markets, illegal wildlife trade and antibiotic use in livestock are all ways we contribute to EIDs. So, if you didn’t give a crap about the environment before, hopefully you’ll start. I believe EIDs should be one of our top international concerns, even in terms of global security, so I’ve decided to feature EID experts on the blog. First up is Dr. Gonzalo M. Vazquez-Prokopec.
Gonzalo M. Vazquez- Prokopec, PhD is a professor at Emory University and heads the Prokopec Lab. Some of his research includes analyzing the spread of West Nile virus, the human impact on the spread of Dengue virus, the eco-epidemiology of Chagas disease and how animal movement contributes to pathogen spillover. He was kind enough to answer a few questions about his latest research on mosquito-borne illnesses, how to predict outbreaks, how to protect ourselves, and why we might see new outbreaks in new locations in the near future.
Can you talk a little about how you track Dengue Fever and then use that information to predict other mosquito-borne diseases?
Gonzalo: Many emerging arboviruses, like Dengue, Chikungunya and Zika, are transmitted by the same mosquito vector: Aedes aegypti. This vector is predominantly urban and inhabits indoors, where it primarily and very frequently feeds on humans. Such conditions favor the transmission of such diseases, which now are termed Aedes-borne viruses. We hypothesized that, because they are transmitted by the same mosquito, there ought to be an important level of overlap in the intensity of transmission of the three viruses in specific areas within cities. For our work we analyzed big data collected by ministries of health, specifically the geocoded distribution of cases of the three viruses by week in the city of Merida.
How accurate are these predictions?
Gonzalo: We found strong statistical overlap in the distribution of the three diseases. Furthermore, if we look at the historical distribution of Dengue hot-spots ( previous Dengue outbreaks) and the occurrence of the first 10 cases of Zika and Chikungunya that invdaded the city, the latter overlapped 75% and 100% with the distribution of Dengue. That is a very strong signal of agreement.
Does spraying make the risk of mosquito-borne diseases worse or better in the long-term?
Gonzalo: In the absence of a vaccine, vector control is the most important tool for preventing disease. Well implemented vector control does work and has an impact on epidemiologic endpoints, as long as it is implemented while taking into consideration the ecology and behavior of Ae aegypti. Fogging from trucks is not effective in situations where Ae aegypti is found resting primarily indoors (it does work if the mosquito rests and feeds outside). There are methods that have effect (fogging indoors, indoor residual spraying), but the issue generally is that they are implemented at scale once an outbreak is declared (this affects their coverage and level of impact). Our results provide a framework to identify areas where control can be done BEFORE the transmission season, increasing efficiency of control and providing time to increase coverage in these areas that experience transmission regularly.
Do you foresee an increase in mosquito-borne diseases due to climate change and/or human behavior? And if so, what sorts of human behavior increase that risk?
Gonzalo: Human mobility and travel have increased the map of vector-borne diseases, primarily because they extend areas of exposure and move viruses into new areas. If those areas have a healthy mosquito population, outbreaks can occur. The fear now is the possibility for Yellow Fever to leave jungle areas in Brazil, where a rural outbreak is in place, and get introduced in areas where vaccination is low and Ae aegypti is present (Yellow Fever is transmitted by Ae aegypti in urban areas).
Are vaccines on the horizon?
Gonzalo: Many vaccines are on the horizon. But it will be many years until a licensed, effective and affordable vaccine will be implemented.
In your opinion, what are the best measures at the population level for preventing the spread of these infectious diseases? And what are the best preventive measures an individual can take?
Gonzalo: Exercise personal protection (use repellent) and limit mosquito breeding in the house (remove containers standing water that are breeding habitats) and advocate for mosquito population control.