A little miracle of evolution, an ancient arthropod dating back to the age of the dinosaurs, and a flying vector for disease: the humble mosquito may seem to be nothing more than an annoying pest, but this tiny fly is among the deadliest creatures ever to exist on earth, conveying diseases from Zika to Dengue, and the Plasmodium parasites that cause malaria. Take that, Shark Week!
To better understand how diseases spread through mosquitos, we first need to know more about these insects. Eric Westhus, PhD, data scientist and member of RGA’s Global Research and Data Analytics team, specializes in using data to build simulations that reveal how infections rise, advance, and decline. We sat down with Eric to discuss mosquitos and disease – and what insurers need to know; please also see the above video. Warning: What he shared with us might have you reaching for the bug spray!
No creature on earth seems to be as universally hated as the mosquito. Are these insects just misunderstood?
It depends on who you ask. People who have resided in warm, wet climates are very familiar with mosquitos, the diseases they carry, and the dangers they pose. Those of us in the more temperate regions should get to know mosquitos too, and that’s because there is ample evidence that mosquitos are moving – and carrying diseases with them – as the climate changes and the world becomes more interconnected.
Tell us a little more about the mosquito.
Everything in biology or psychology starts with understanding your critter. The mosquito is part of a family of fly: Culicidae. We’re looking at 40-plus genera, 3,500 species – but only three that are important disease vectors:
- Anopheles, responsible for transmitting malaria;
- Aedes/Ochleotatus, once mostly endemic to Africa and Southeast Asia but now found in the Americas and Europe;
- and Culex, responsible for transmitting West Nile.
In many ways, the mosquito is worthy of our admiration. The entire mosquito life cycle can be counted in days, and yet mosquitos were buzzing around on earth long before people came to be. Also, only the female – in search of protein for her eggs – consumes blood. Her saliva contains an anti-coagulant to keep things flowing and often transmits viruses from vector to host. Males, meanwhile, are vegans and only sip flower nectar. Insurers and healthcare providers would be well-served to better understand these bugs in order to grasp the risks they pose.
You mention improving our understanding of risk, yet it seems as though scientists know a lot.
Yes and no. We know, for example, that malaria is a protozoan – a single-celled, animal-like parasite. It’s carried by the mosquito and causes substantial mortality and sickness. It can be prevented through chemoprophylaxis and treated upon infection, but we’ve had real challenges in recent years. Consider a collection of viruses that have made headlines as they’ve turned up in unexpected places: Arboviruses such as Dengue or “breakbone” fever, Zika virus, and Chickungunya. These historically occur in tropics and subtropics but they’ve followed their vectors – Aedes mosquitos – into more temperate climates, where communities were not prepared.
There are no widely effective vaccinations, nor are there very effective antivirals, for these diseases.
Dengue can cause horrific joint and muscle pain and sometimes fatal hemorrhaging. Zika has been linked to severe birth defects. It’s named for a forest in Uganda where it was first described, but it followed the Aedes aegypti mosquito out of Africa and to the Americas. West Nile disease is carried by the Culex mosquito, and can develop into encephalitis or meningitis in humans, as well as wiping out whole populations of birds. I can remember the West Nile invasion that devastated the crow population in North America around the turn of the century. The challenge is partly economics: as public interest waxes and wanes with news cycles; so does funding for research into vaccinations and treatments.
We’ve sent a man to the moon, mapped the human genome, and made humankind’s collective knowledge just a mouse-click away – and yet we can’t seem to defeat this tiny little fly?
I would say that much of the problem is again economic. The best defense – and sometimes the only defense – is effective pest control, so it is important to understand where epidemics might turn up next in order to put effective prevention measures in place. The people at highest risk for these diseases primarily live in economically challenged areas that lack the physical and political infrastructure required for effective long-term pest management. I’m talking about basic civil engineering to eliminate breeding sites in densely populated areas, and buildings capable of keeping insects out. Instead, we repeatedly turn to costly stop-gap solutions such as pesticides and bed nets. Our most effective pesticide, DDT, was eventually banned under international treaties because of its side-effects on the wider environment.
Modern biological control measures do give us hope for controlling these diseases. One is the release of sterile male mosquitos. Females are largely responsible for disease transmission, and when they can’t find mates and reproduce, the population crashes. I’m really excited about this Wolbachia bacteria I’ve been reading about because it is potentially a self-sustaining solution. An approach being explored by the World Mosquito Program artificially infects mosquitos with this bacteria (which is widely found in other insects and therefore presumably safe) that is not naturally occurring in mosquitoes. In mosquitoes, the bacteria inhibits Arbovirus transmission, boosts breeding success, and is passed from mother mosquito to offspring, creating a self-sustaining solution. Exciting stuff!
For the insurance industry, the implications are clear. Developing a greater understanding of mosquitos and their potential impacts on human health can help inform risk assessment and inspire innovative product design. By supporting efforts to control the mosquito population, we can help limit the threat to the human population.
RGA’s Global Research and Data Analytics (GRDA) team is dedicated to developing new research data sets and applying them to expand our understanding of risk in order to meet our clients’ data analytics needs and help move the industry forward. To learn how our GRDA experts can help your business, contact us.