Monday, April 25, 2016

Zika virus infection 2015-16 Epidemic - Update #4

Zika virus infection 2015-16 Epidemic
April 12, 2016 Update
Paul Herscu ND, MPH
Herscu Laboratory

The Time is NOW for Some Mosquitoes to Go

This article deals with only one aspect of prevention of Zika virus caused disease, and is the fourth of a series. For previous writings on the subject and to contextualize this writing, see:

When my older son was entering middle school, he and I attended several Bioblitz events, which are 24-hour inventories of all species in a certain area. We got into the concept, after he read a book written by E.O. Wilson, Consilience. He later met Dr. Wilson, exchanged correspondence, joined the Explorer's Club and eventually gave lectures on the concept of the bioblitz. He also had the idea of connecting the E.O. Wilson's Encyclopedia of Life ( project with the Bioblitz events that occur in the National Parks of the USA. If you want to read about how the Bioblitz concept began, please see this link: 

The reason I highlight this concept is to say that my family is and has always been very environmentally friendly. We have worked for and continue to work towards a stable, robust biodiversity, not only for trophy, keystone, or umbrella species, but for all species. Diversity is essential for our own species to survive and thrive.

That said, and as an environmentalist, I believe the time has arrived for us, as a species, to drive into functional extinction a few mosquito species or species groups. The reasons are compelling, rational, ethical, and scientific. I would like to place this topic in context.

First, I am not suggesting we attempt to get rid of all or even most mosquito species, only a few which act as vectors of diseases that haunt humanity, and represent less than 1% of mosquito species. The best, or most troubling example of this is the Anopheles gambiae group, which is a collection of several very similar mosquitoes that are the primary vectors of malaria. There are perhaps 40 subspecies of Anopheles that carry the Plasmodium falciparum parasite, which is primarily responsible for malaria. In other words, more than half a million men, women, and children die annually of malaria in sub-Saharan Africa because of bites from these mosquitoes. It is often said that half of all people who have ever lived died due to the mosquito being the vector of disease. That is a huge impact! This may seem abstract for people, but if you come from or travel to an area impacted by malaria, it becomes very clear, very quickly the price our species pays because of malaria.

For a closer example of another mosquito, we have the Aedes aegypti species that likely carries Yellow fever, Dengue fever, Chikungunya, and Zika virus, leading to many thousands of human deaths per year, let alone all the many millions of infections and hospitalizations.

A single species of mosquito makes many individuals ill and is more dangerous to our species than most things we worry about like seat belts, food additives, non-organic foods, gun violence, or any other threatening species. Yes, these are all important, but nothing comes close to the misery that a few species of mosquitoes cause humanity. It may be that the reader has felt immune from these issues, because of where they live, but the problem is very real.

There are well over 3,000 mosquito species, with only a small handful being vectors for human disease or diseases of animals important to us. I am suggesting leaving over 99% of those species alone and only addressing the main species that harm us.

Here is an ethical argument. By not acting, we let many millions of people die of malaria. In fact from the time I finish writing this short essay until the time it is published, thousands of people will die from malaria. Which is not to say that a great many other interventions are not occurring or working.  But even with these effective interventions, we still have so much preventable morbidity & mortality; half a million people will still die this year.

Here is another ethical argument, for the mosquito's sake. People kill mosquitoes in most cultures around the world. We swat at those that land on our bodies, realizing that they are going to bite us; action and reaction. However, in many cultures, we also fumigate areas to kill all surrounding mosquitoes, even ones that do not interact with humans. This is done inside the house, but also a great deal outside the home, with high, low, or ultra-low volume (ULV) applications (spraying) of neighborhoods, from trucks, cars, and planes. Given that we do this, currently, around the world, we are killing many, many millions of mosquitoes belonging to species that are not vectors of human disease, killing ones that do not even bite us. I have an ethical problem with this, as we are killing living beings that are not a problem for us. This means that there is an ethical argument to change the current status quo. Help me save 99% of the mosquitoes out there.

In every calculation, these few species of mosquitoes are not modeled to be missed from the web of life. In other words, since we are not getting rid of all mosquitoes, there will be no large crash of a food web. Bats will continue to eat; pollination will continue to take place. I began this writing by saying functional extinction. By which I mean we can keep remaining mosquitoes of those species in closed quarters. This means that for the rest of the world, the species is missing, yet it is still in a lab, much as smallpox exists in a lab but not in the outside world. Then if and when we ever want to release them again, we can.

I have a hypothesis about time sensitivity. Early on, the viruses are carried by one vector. If we let the viruses spread without specifically addressing their life cycle, an ever-increasing number of species will act as vectors carrying these viruses. This seems to have been a pattern of spread through the web of life. This is my way of saying that the very best time to stop the spread of these illnesses is now! Time works against us in this instance. We have seen this already in the migration of Zika virus from one mosquito in Asia to another one in the Americas.

Also relevant is the vaccine challenge. Sooner or later we will have to address a simple reality around the current vaccine concept, so let's do it now. When we thought that there was just one infectious agent that we had to vaccinate against, things theoretically worked out well enough. Then the one infectious agent and one vaccine became 2, 5, 10 different agents requiring ten different vaccines. Consider the following trajectory. We are very early on in our ability to identify which viruses and bacteria exist and how they impact us. In other words, there is an ever-increasing list of viruses and bacteria that we are discovering that cause disease, and potentially, epidemics. If we continue at the current rate of infector discovery followed by the creation of a vaccine, and adding that vaccine to our vaccine programs, we are going to end up with hundreds of vaccines for each of us. Sooner or later this approach is unsustainable, both practically and economically. While it may not seem obvious now, soon we are going to have to rethink the vaccine concept. I am not even addressing here efficacy failures, such as the annual influenza vaccine that often fails, or other issues associated with vaccines. Simply put the general population, including the medical profession is going to have to develop a different method of protecting the general population, different from species-specific vaccines we have now. More on this exciting topic another time.

The point I am making here is a simple one: there is one mosquito species, the Aedes aegypti species, that may well be carrying Yellow fever, Dengue fever, Chikungunya, or Zika virus. It is conceivable that removing one mosquito species may mean that we may have to give 4 less vaccines (once they are fully developed). An added benefit is that we would not have to contend with issues of efficacy or adverse events of any one vaccine. The public relation mess of the Lyme Disease Vaccine LYMERix is a case in point. And whether it caused adverse effects in reality, and whether it protected a greater number than 78% of those vaccinated is not the issue, as much as a complete mess that this caused and had to be withdrawn from the marketplace. We could skip all these headaches if the vector carrying these bugs did not exist, and thereby making it less likely for humans to be exposed to these viruses.

The how to. Sadly, or fortunately, our species has gotten increasingly more efficient at driving other species to extinction. We now have a mechanism that can do this fairly well, relatively cheaply, and without harming the environment, in a targeted fashion against a species that is harming us, as conceived by Raymond Bushland and Edward Knipling ( One main problem is that it is really misunderstood and conflagrated with other similar sounding mechanisms that are truly toxic to the environment and for our species. And here, before understanding the full enormity of human suffering, I think people are going to raise incredible objections to, confusing this with very real issues of GM food. Here I speak of Sterile Insect Technique (SIT). The concept is a pretty simple one. Release many, many sterile male mosquitoes such that there is no next generation after mating. A related method RIDL (Release of Insects Carrying Dominant Lethal) where the males have been genetically modified such that when they mate with a female, the next generation does not survive ( These groups of males outcompete the wild type counterparts, making there be a smaller next generation and thereby the population diminishes. Repeating this process several times, you can imagine how the population would decline. The strength of this sort of program is that it is species specific, not harming food or other species, sidestepping fumigation and the toxicity it brings, halting larvicidal sprays and applications and the potential harm they bring to all mosquitoes, even the ones that do not harm us.

To most of us this seems both inhuman behavior and not likely to work. However, a closer look at our history shows that we have already used these approaches. Medfly in Chile, Screwworm fly in the USA, or the Tsetse fly in Zanzibar have all been dealt with using one of these techniques. We have saved lives, limited disease, and gotten rid of a fly that was decimating the livestock in the southern USA and Mexico. I highlight only a few examples of this approach, even malaria being a work in progress.

And I know these biological strategies seem complex and confusing. In fact, we are at the point that some people actually think that Zika virus has spread in Brazil because of this strategy being used this past year. They may not fully understand the biological strategy fully, or the life cycle of mosquitoes, as for example thinking that these modified males are biting people and spreading the disease, not realizing that males do not bite people.

In summation, every single year there are hundreds of thousands of people dying and many millions of others becoming gravely ill from illnesses that are preventable by getting rid of a few species of mosquitoes. It does not seem that these few species add much to the web of life, yet cause us a great deal of misery, in morbidity and mortality as well as national economic hardships depriving survivors of a stable future.

Back to my introduction. What might be surprising, or enlightening, is that many of the most prominent entomologists, biologists, and environmentalists, have taken the same position. Here I would give as an example E.O. Wilson, who helped coin the term biodiversity, who's love of insects is not just infectious but has raised to our awareness the full import that insects play within the web of life. He would like to see these particular species of mosquitoes gone. All you have to do is take a proper appraisal of the human misery such illnesses produce to arrive at this conclusion.

If you have concerns about biodiversity, pick a species that we already know provides benefits to the environment and to people. I am sure there is a species near you that needs help. But if you would like to pick mammals nearing extinction you can pick a project such as the one attempting to double the number of wild tigers, for the benefit of the species, of people, and as an umbrella species for the region.

For equal time and full disclosure. Zika virus is coming to the USA. One of the main ways to contend with this Zika virus is to contend with the mosquitoes. The FDA is currently evaluating safety and efficacy of one such process. If allowed, at least one company will be releasing these types of mosquitoes in the USA as a way to reduce the population of the species. If you have any comments or concerns about the technology, pro or con, consider writing the FDA by following the link: