What pops in your mind when you think about “health”? Medical doctors, nurses, hospitals, clinics, med-students, vaccines, pharmacies. All these people and dependencies are related to health management, disease prevention, and treatment. Health, however, is more than that. For example, how did Jenner discover that the milkmaids who had had contact with cowpox did not contract human smallpox? By doing research.
In this blog post, I want to dedicate myself to talk about people involved in health that are generally ignored: researchers. While it is true that many researchers in the health area are medical doctors, there is a branch of health research colonized by veterinarians, biochemists, and biologists. “WHAT? Aren’t biologists supposed to be picking up animals in the forest and photographing them and working in conservation? I get veterinaries related to health, but animal health!”
Let me explain. First of all, let’s remember that as human beings we belong to a big ecosystem and we interact with all types of organisms (animals, plants, virus, fungi, and bacteria). Second, many of the diseases, such as Zika virus or malaria or Chagas, are transmitted by vectors. The vectors are generally arthropods (mosquitoes, bed bugs, fleas, ticks). Each of these animals has its own biological history, a life cycle that can influence the ability to transmit an agent that causes a disease, and someone must study that life cycle. Third, most infectious diseases are not diagnosed and are recorded as “febrile”. Several studies, from several countries, have found that these diseases are zoonotic.
Zoo-what? Zoonotic: that they get passed on to humans from a different vertebrate animal. A well-known example is that of yellow fever: South American monkeys are hosts of the yellow fever virus and, if an Aedes mosquito bites them and then bites a human, it transmits yellow fever. The most common animals involved in zoonotic diseases are bats and mice.
So we’ve seen already that many animals are involved in the cycle of human diseases. But that does not really explain what a biologist and a veterinarian do in health research (although I would hope you have some ideas already). To explain it, I will tell you about my own personal experience. I am a biologist and I work in a line of research dedicated to studying diseases transmitted by vectors, particularly malaria and Zika. We do not study human cases, which are very important, but we study the vectors. Knowing the history of the vector, its ecology and behavior can help us find ways to interrupt the transmission of diseases, make predictions about outbreaks, and find ways to control vector populations.
One of our biggest obstacles is the development of insecticide resistance, which means that mosquitoes are no longer dying when being sprayed with Baygon or Raid, or with the nebulization that the Ministry of Health does. This is a global problem and the conditions in which the resistance emerges are local. Along with this, it turns out that the mechanisms in which the mosquito becomes resistant to the insecticide can be genetic, biochemical, cuticular, or it can be mediated by symbiotic bacteria in its stomach. This poses more obstacles.
As I mentioned before, the goal is to help interrupt the transmission of diseases and that is reflected in the incidence of human cases. However, there are so many variables that can influence the transmission, which will surely have us busy for a long time. Another example in the subject of malaria: the main measure of protection against mosquito bites is to use insecticide-impregnated mosquito nets. However, the behavior of the mosquito can have an influence on this. Will the mosquito prefer to bite on the face, on the abdomen, on the feet? Many of the new mosquito nets are being reinforced with more insecticide in the area in which they are more likely to bite us. But, what if the preferences change? What if my Latin American mosquito does not have the same preferences as an African mosquito? We must continue studying this.
Okay, so we already know that biologists and biochemists can help by studying ecology, vector behavior, and genetic mechanisms. And the vets? We’re getting there.
Let’s explore the case of rabies. One of the most common ways to get rabies is to expose yourself to the bite of an unvaccinated dog. And who vaccinates the dog? Yes, a veterinarian! In some studies, it has been evaluated that the extent of vaccinated dogs is one of the most important factors for the elimination of rabies. Through the “herd effect” the vaccinated dogs “protect” the unvaccinated and the transmission of rabies decreases. It does not sound that hard, does it? Well yes, it is difficult. In many Latin American countries, the estimation of the number of dogs by the ministries involved has been so bad that the transmission of rabies is maintained. The veterinarian is then responsible for making those estimates and helping in the design of a strategy to interrupt transmissions.
These years working in health have taught me that a multidisciplinary approach is necessary to eliminate diseases and to avoid the emergence or re-emergence of others. We all work for the same goal, in an ecosystem that connects all living beings. The diseases are community and ecosystemic-based, they are not isolated affecting only humans. There are many other diseases that have that link between human beings and their ecosystem like influenza, Ebola, hantavirus, Nepah. The work that everyone does in order to control diseases is admirable. The passion and goal to achieve the elimination of diseases motivates us and keeps us going, even when more obstacles are discovered or the people involved in politics do not collaborate. My respect and admiration to all colleagues who spend hours and hours working, even during vacations to take care of the colonies of their vectors (mosquitoes don’t care if it’s Christmas and you have to rest) and that they give their all to have a positive impact.
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As you read this, right at this moment, during one of the most horrible Ebola outbreaks in recent years in the Democratic Republic of Congo, many people struggle to control the transmission. Too many people have died, more than 1,000 have been infected, and above all, they must endure the horror of war. There have been direct attacks at the health station camps, in which people of many nationalities work day and night to care for the sick people…and there, near the outbreak, are biologists and veterinarians also looking for the animal reservoir. The evidence points to fruit bats, but more research must be done.
Book recommendations from the author:
“This is a very extensive and interesting topic. For those who want to learn a bit more, I recommend David Quammen’s Spillover book.”
Yaimie López
#FunFact!
There is a zoonotic species of malaria in which the macaques are the reservoir. By the way, malaria is originally zoonotic from thousands of years ago and seems to come from a parasite of the gorillas that was selected for human infection.
Your blog is interesting. Keep sharing such type of content.