ZIKA: Climate Change Threat?

Guest Essay by Kip Hansen


featured_image_zikaZIKA!  A frightening new disease that burst onto the front pages in 2016 as “linked to thousands of babies being born with underdeveloped brains.”  Over the next two years, current outbreaks of Zika had spread from Brazil through South America, Mexico, the Caribbean, and even a few cases in southern Florida.


As of May 2019, the U.S. Centers for Disease Control and Prevention gives this brief:

Q: What is Zika?

  • A: Zika virus disease is caused by the Zika virus, which is spread to people primarily through the bite of an infected mosquito (Aedes aegypti and Aedes albopictus). The illness is usually mild with symptoms lasting up to a week, and many people do not have symptoms or will have only mild symptoms. However, Zika virus infection during pregnancy can cause a serious birth defect called microcephaly and other severe brain defects.

What we know:

Zika is spread mostly by the bite of an infected Aedes species mosquito (Ae. aegypti and Ae. albopictus). These mosquitoes bite during the day and night.

Zika can be passed from a pregnant woman to her fetus. Infection during pregnancy can cause certain birth defects.

There is no vaccine or medicine for Zika.

The New York Times brings Zika back onto the news scene with an article written by  Andrew Jacobs titled:   ”The Zika Virus Is Still a Threat. Here’s What the Experts Know”.   The news item was prompted by “the World Health Organization issued a report on Zika that listed 61 such countries, among them densely populated behemoths like China, Egypt and Pakistan as well as much of Africa.”

Zika is a tricky viral disease; the NY Times quotes Dr. Karin Nielson of UCLA:

“Zika has completely fallen off the radar, but the lack of media attention doesn’t mean it’s disappeared,” said Dr. Karin Nielson, a pediatric infectious disease specialist at U.C.L.A. who studies Zika’s impact in Brazil. “In some ways, the situation is a bit more dangerous because people aren’t aware of it.”

“The virus, which is mostly spread by mosquitoes but also through sex with an infected person, is still circulating in Brazil and other countries that were at the center of the epidemic, and two years ago the same strain from the Americas arrived in continental Africa for the first time. That strain, researchers recently discovered, had been causing birth defects in Asia long before the Zika epidemic of 2016.”

It is this  risk to pregnant women of subsequent birth defects in their unborn children, primarily microcephaly (and other severe brain defects), that is so worrying, particularly for those who have the least access to health care and long-term assistance for the affected children.

The primary defense against mosquito-transmitted diseases is a three pronged attack, as I explained in an earlier essay on dengue:

  1. Rapid knock-down of mosquito populations in and around the area of an outbreak through spraying.
  1. Identifying and isolating infected persons where they can receive treatment and not be bitten by mosquitoes, further passing on the disease.
  1. Public education of eliminate mosquito-breeding sites — rain barrels, trash piles, old tires, etc.

Here’s how dengue, yellow fever and Zika are primarily spread:


We see on the left the most usual case: uninfected mosquito bites an infected person (symptomatic – showing the symptoms of the disease) — mosquito becomes infected — mosquito bites uninfected human — human becomes infected — back around again to — uninfected mosquito bites infected human.

On the right we find the trickier case in which all members of a family become infected, but only one (in this case) shows symptoms.  Isolating only the obviously sick member of the family (the symptomatic member) doesn’t stop the chain of infection because mosquitoes can bite the asymptomatic (showing no symptoms) members of the family, thus becoming infected and spread the disease to other families.   This is often the case with Zika:

“Q: What are the symptoms of Zika virus disease?

A: The most common symptoms of Zika virus disease are fever, rash, headache, joint pain, red eyes, and muscle pain. Many people infected with Zika won’t have symptoms or will have mild symptoms, which can last for several days to a week.” (CDC)

These mild Zika infections are easily misdiagnosed even if reported to a doctor where they can be mistaken for a cold or the flu, thus making isolation of Zika infected individuals less likely.

What is the Threat of Zika in the United States?

 Andrew Jacobs of the NY Times, following his editor’s narrative for climate change, includes this in his article:

“Warming temperatures associated with climate change are expected to expand the range of Aedes, according to a recent study, putting tens of millions more people at risk for Zika and other mosquito-borne diseases.”

The link leads to the NY Times’ earlier piece on the possible threat of the spread of dengue, which features a map grossly misrepresenting “the risk” of dengue in the continental United States — based on a study with some complex modelling of the possible expansion of the range of Aedes aegypti.  As with dengue, this “increased risk” is a fallacious claim.  The area of “increased risk” in the quoted study is smaller than the current (as of 2017) range of Ae aegypti.  There is no endemic dengue in the continental United States now, and there is no biological plausibility of dengue becoming endemic here.


Here Mr. Jacobs of the Times does a better job of journalism than his colleagues who write for the Times’ Climate section — he does real journalism and fact checks the subject.  Thus he reassures us:

“In the United States, the Aedes mosquito can be found across significant swaths of the country during summer, though epidemiologists say the potential for large-scale American outbreaks is limited by the near ubiquity of air conditioning, window screens and local mosquito control efforts.

“It also helps that people in the U.S. tend to live fairly far apart in single-family homes,” said Dr. Lyle R. Petersen, who oversees vector-borne diseases at the Centers for Disease Control and Prevention. “This is a mosquito that doesn’t fly very far.””

Quoting myself in the earlier dengue essay;

“Note that Aedes mosquitos can only fly about 100 meters in the wild, so suitable breeding sites have to be ubiquitous in the environment and many infected human hosts have to be present and live close together.  This is why dengue has such prevalence in the tropical third world.”

Of course, the same applies to Zika.  However,  “Zika can be spread by a person infected with Zika to his or her sex partners.” (CDC)

What is our risk in the United States now? 

The CDC reports: “In 2018 and 2019, no local mosquito-borne Zika virus transmission has been reported in the continental United States.”

Here’s the map: (lack of counties in green indicate zero cases of Zika)


Zika_Puerto_Rico_2019Things are not so good in Puerto Rico, where the climate is more tropical and living standards can be a bit more like other Caribbean nations.  However, the US Virgin Islands, comprising St. Thomas, St. John, and St. Croix, have no Zika recorded.


On the international scene, the situation is also better, though it may be skewed by lack of reporting from some areas, with the current CDC travel risk map:


So, that’s the good news, despite (or, possibly, as a result of) increased attention from the World Health Organization, there are no current Zika outbreaks.

So what happened?

 Quoting the Times again:

“Arboviruses like dengue, chikungunya and yellow fever provide something of a template for the future of Zika. During the 1940s and 50s, successful eradication campaigns aimed at quelling deadly yellow fever outbreaks vanquished Aedes from Brazil and much of the region. But by the 1970s, as those efforts were abandoned, the mosquito quickly re-established itself, leading to increasingly intense outbreaks of dengue and yellow fever, and more recently the emergence of new arboviral pathogens like chikungunya and Zika. These days, dengue infects over 100 million people globally a year, killing 10,000.”

It was not only Brazil that ended or cut back on vector control (mosquito spraying) — many parts of the US did as  well.

As in so many other things, we humans have trouble learning things and once having learned, when the immediate threat has passed, we let that hard-earned knowledge slip away, dropping our guard and letting known threats return to plague us.

Climate, changing or not, will not increase the risk of Zika (or any other tropical diseases) — only the spread of poverty and lowered living standards will do that.

There will be outbreaks as the people from areas with endemic tropical diseases continue to move into Europe and the United States — bringing with them their sick — but these outbreaks will be quickly quelled by the higher levels of public health access and  generally higher living and housing standards.  Increased spending by the U.S. federal government in Puerto Rico, in conjunction with rebuilding in the aftermath of Hurricane Maria, which must include restored vector control (neighborhood spraying for mosquitoes) and improved public health access, will eliminate Zika there.

The Bottom Line:

As with malaria, yellow fever and dengue defeating Zika and keeping it at bay requires:

  1. Constant public health vigilance to identify and isolate infected individuals
  2. Increased and continuous vector (mosquito) control
  3. Public Health education on tropical diseases, their symptoms, their relationship to travel and educational campaigns on how to eliminate mosquito-breeding sites in potentially-affected neighborhoods.

All of the above require caring governments with adequate resources to carry out the necessary work.

# # # # #

Author’s Comment Policy:

As with so many other alleged climate change threats, the spread of Zika “because of climate change”  is a fairy-tale hobgoblin.  It just isn’t so.  The spread of Zika, though, is a real problem, mostly because it is not a serious disease for the majority of people infected — only causing serious harm for babies born of infected mothers.  For that reason, work on a vaccine must be accelerated.  It may be possible, as past infection seems to provide immunity.

The Times’ Andrew Jacobs gets credit for avoiding the worst of the climate change fear mongering and writing in some reassuring reality regarding the lack of any real threat to those of us living in the continental United States (and, I assume, that the same applies for most of Europe as well).

My personal experience includes humanitarian work in Puerto Rico and the Virgin Islands (US and British) in the 2000s.    Puerto Rico had endemic dengue and HIV  at the time but no Zika.   Many of the poorer homes we visited lacked effective window and door screens and most homes had to have mosquito bed nets.  Hurricane Maria was very hard on Puerto Rico and surely made matters of public health worse.  Readers in Puerto Rico might let us know the current situation for the average rural citizen.

Those spreading fear of the future are enemies of the public mind and need to be countered wherever and whenever they find a public voice.  There are enough real things to concern  modern man without the continuous injection of bogus threats into the daily news-stream.

# # # # #

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Mark Broderick
July 9, 2019 4:23 pm

Kip Hansen

“Public education of (to?) eliminate mosquito-breeding sites — rain barrels, trash piles, old tires, etc.”

Great post..

[I deleted the duplicate comment. Mod]

July 9, 2019 4:27 pm

Worried about ZIKA? Kill the mosquitoes. Problem solved.

Reply to  Kip Hansen
July 10, 2019 10:40 am

We’ve had these skeeters forever in Florida .. we spray, and we control them accordingly, just like the others.

During the great Zika scare of 2016, we were breathlessly told that the Ae aegypti were going to spread Zika virus all over Florida, where we have both a subtropical climate lacking cold winters, and we have lots and lots of moisture during our “wet season”.

Yet, as it turned out, virtually ALL of the Zika cases discovered in Florida were people who were exposed while on travel to Brazil and Latin America. We have a very large segment of our population here in Florida who came from and still have family and business connections to Latin America, so travel there routinely.

Zika turned out to be a huge nothing burger. Our mosquito controls obviously are pretty effective though they can never be 100% effective.

In any case, “global warming” had nothing to do with the extent of either the Zika virus or of the Ae aegyptia skeeters.

Tombstone Gabby
Reply to  Kip Hansen
July 10, 2019 6:12 pm

Maricopa County, Arizona – has reported 27 cases of West Nile so far this year. ( on July 9, 2019)

“Wear repellent and don’t leave any places for mosquitoes to breed” is the official advice.

July 9, 2019 4:42 pm

Almost certainly pesticide related; nothing to do with a virus IMO.

Reply to  icisil
July 9, 2019 5:11 pm

icisil ==> Well, Zika Virus Disease is — definitionally — a virus-caused disease. What do you think is
“Almost certainly pesticide related”?

Reply to  Kip Hansen
July 9, 2019 6:12 pm

Apologies, I wasn’t clear enough. The microcephaly was almost certainly caused by the larvicide that was added to drinking water in Brazil. Without the birth defects, Zika appears to be just a boring virus.

Massive New Study Suggests Pesticide the Cause of Microcephaly — NOT Zika Virus


Referenced study

“Pyriproxyfen acts as a larvicide by interfering with the development of mosquito larvae. It may unintentionally do the same in humans. Its structure mimics the role of juvenile hormone, which has been shown to correspond in mammals to a number of molecules including retinoic acid, a metabolite of vitamin A, with which it has cross-reactivity. The application of retinoic acid during development has been shown to cause microcephaly. ”

Rod Evans
Reply to  icisil
July 9, 2019 11:13 pm

An interesting article that gives strong cause for thought. It may well be a case of the supposed cure, being more dangerous than the problem.
How is it even possible for scientists/health officials to add lavacides to drinking water?

Samuel C Cogar
Reply to  Rod Evans
July 10, 2019 4:03 am

How is it even possible for scientists/health officials to add lavacides to drinking water?

Probably the same way that chlorine is added to drinking water here in the US.

Or, the larvicide was “sprayed” over large areas and leached/landed in water supplies.

Anyway, it was sure a wonderful blessing that they were not ”spraying” DDT.

Reply to  icisil
July 10, 2019 6:46 am

Problem is that Dade County, Florida had a Zika outbreak and they do not use pesticides in their drinking water. Don’t remember how many cases of microencephaly we had but there was a couple and we tracked all infected women.

Two problems with Zika and other Flavivirus. Flavivirus infections are sometimes asymptomatic. Enough so that with rapid modern transportation an infected person, whether it is Zika, dengue, yellow fever, etc, can take such viruses around the world in less that 24 hours. The two primary vectors A. aegypti and A. albopictus have been pressured by pesticides a long time. We saw resistance in Dade County. While aegypti may be more “tropical,” albopictus is a more temperate species, though their ranges significantly overlap.

One of the problems mosquito control faces is the lack of new control products in the pipeline. The market is not huge and development cost to get through US-EPA labeling procedures is significant. Baytex (fenthion) was lost in the USA. It is a pesticide designed to help fight resistance. Due to screw up by US EPA and the testing labs when Baytex was first labeled the original label was thrown out requiring it to be relabeled. Even though a lot of money had been spent on none target effects since it was first labeled, EPA was demanding 20+ million in additional research. With a market of only a couple of million per year nationwide, the manufacturer could not longer support relabeling.

Today Florida, after two recent dengue outbreaks and a Zika outbreak, is looking into several sterile male control systems. We should have a good understanding whether the techniques work in a year or two. Bottomline is that Flaviviruses are not on the rise due to global warming but to modern immigration and shipping.

Michael Jankowski
Reply to  icisil
July 9, 2019 5:22 pm

What a ridiculously ignorant and stupid thing to say.

Reply to  icisil
July 9, 2019 5:30 pm

SOUNDS like you’re ‘on the money.’

Joel O'Bryan
Reply to  Kip Hansen
July 9, 2019 9:34 pm

The ZIKV – microencephaly link is on solid clinical evidence and experimental evidence grounds. The pesticides link is garbage (not supported) IMO.


and the virus crosses endothelial barriers similar to placenta to reach in utero fetus.

and the mouse model appears to replicate much of what is seen in humans:

…and ZIKV infection during periods of rapid brain growth and development demonstrates neural development periods are vulnerable to the effects of ZIKV infection:

It is pretty much a “beyond a reasonable doubt” level of evidence that ZIKV during the 2nd trimester is strongly linked to subsequent microencephaly in humans, and the ability to manipulate mouse models of infection are showing us how it happens.

Dave Fair
July 9, 2019 4:43 pm

“Those spreading fear of the future are enemies of the public mind and need to be countered wherever and whenever they find a public voice.”

That will become my personal credo.

Reply to  Dave Fair
July 9, 2019 4:54 pm

I still support killing the mosquitoes, it was working for malaria.

Reply to  2hotel9
July 9, 2019 6:54 pm

Nobody these days has heard of Western Equine Encephalitis (WEE) but it was epidemic on the Great Plains even into the 1960s. One of my high school teachers had been infected, but not fatally thank goodness. I do not mess with mosquitoes and never go outside without a protective spray of DEET. link

WEE isn’t a problem any more but West Nile Virus is.

I don’t know if people are being alarmist about Zika but I treat mosquitoes as dangerous anyway.

John Minich
Reply to  commieBob
July 9, 2019 8:15 pm

commieBob: I beg to differ about “nobody these days has heard of …(WEE)”. I definitely have as well as eastern and Venezuelan strains.

Edith Wenzel
Reply to  Dave Fair
July 9, 2019 5:59 pm

Another reason to have controlled immigration. You can’t have hoards of people living in masses coming in without them carrying some diseases with them. If the virus can be passed via sex partners how is that different than a STD. Also they bring things with them which can carry the larvae into the country. Good grief.

Earl Smith
July 9, 2019 5:21 pm

When the papers were blaring the crisis I noted one very glaring fact. The US (with zero Zika) had a far higher incidence of microencephaly than Brazil with the rampaging Zika problem. Something just did not add up. We know that the problem was caused by chemicals that the peasants were being drenched with. But for some reason we were introducing a new cause and ignoring the obvious effects of the agricultural agents.

Reply to  Kip Hansen
July 9, 2019 9:43 pm

It might be worth researching the reason that Europe banned Naled insecticide in 2012. I hear that it’s regularly still used in Florida,for instance.

Earl Smith
Reply to  Kip Hansen
July 10, 2019 1:52 am

Yes we do!
Not that this episode is solely the result of the chemicals, but the agri chemicals that were in use are definitely known to cause microencephaly . There was no need to gin up a new cause except to protect the use of known deform causing chemicals . And once again, why is the US suffering from a significantly larger incidence of microencephaly than Brazil with no known cases of Zika.

Reply to  Earl Smith
July 9, 2019 11:49 pm

I am perfectly willing to believe that Zika causes microcephaly because, seemingly, almost anything causes microcephaly. list of causes Holy Moses, that’s a long list.

July 9, 2019 5:56 pm

Kip Hansen, an excellent article, thankyou.

Kevin McNeill
July 9, 2019 6:39 pm

I see the mosquitoes respect borders as it appears from the graphics that none cross the Canadian border. If the little effers are not mosquitoes what are they??

July 9, 2019 6:46 pm

One of the biggest misunderstanding is the belief that mosquitoes are a tropical insect.
Some of the biggest swarms can be found above the Arctic Circle, where there are no predators.

Walter Sobchak
Reply to  Kip Hansen
July 9, 2019 8:17 pm

Malaria was endemic in Russia in the 19th Century.

It is not a tropical disease. it is a disease of bad drainage.

In Italy in Roman Times, Malaria was not a problem because the Romans were good hydraulic engineers. Rome is farther north than New York City. After the collapse of the Roman Empire Malaria was endemic in Italy until the 20th Century.

Don K
Reply to  Walter Sobchak
July 10, 2019 6:13 am

Kip. Given that humanity is, albeit painfully slowly, becoming more affluent and more mobile, do you have any problem with the notion that ALL diseases will eventually become worldwide? Potentially found in any region that supports suitable vectors. That would include not only “tropical” diseases but also diseases like plague which is carried by fleas, not mosquitoes, and doesn’t seem to be especially tropical. Also rabies which seems already to be everywhere.

A bottomless supply of alarming news reports for future reporters it would appear.

Don K
Reply to  Don K
July 10, 2019 11:41 am

“Unless the developed World regresses into poverty and standards of living drop to 3rd World levels …”

I wasn’t suggesting that exactly. Just that unless/until we develop tools that actually eradicate harmful viruses, bacteria, and fungi and/or the disease vectors, there will be likely be occasional cases of all the ancient diseases anyplace that the vectors can survive. Those that have insect or animal vectors.

Reply to  Neo
July 10, 2019 9:07 am

There are lots of predators – most birds up there eat mosquitoes – but still not enough to make much difference in those huge northern swamps.

I use to say that if it wasn’t for the diseases they spread, mosquitoes in tropical areas would be completely insignificant compared to the taiga. The only places in the tropics where mosquitoes can be a problem is mangrove swamps.

July 9, 2019 6:46 pm

Here is an interesting link. I just don’t trust any government agency any more including WHO. I don’t think its just CAGW that is being used to usher in Agenda 21/30. Check out the world of Dr John Ionnidis who researches the researchers, he says that probably 60% of medical research is unreproducible.


Walter Sobchak
July 9, 2019 7:40 pm

Bring back DDT.

Problem solved.

Walter Sobchak
Reply to  Kip Hansen
July 9, 2019 8:22 pm

Dominican is not that hardscrabble. Haiti maybe yes. But, there is nothing wrong with using pesticides. Yes you need drainage. Drainage is key. The Romans didn’t have pesticides, but they had drainage, and they didn’t have a malaria problem.

But, in a pinch pesticides are are wonderful, and DDT was one of the best.

Reply to  Walter Sobchak
July 10, 2019 2:04 am

Walter Sobchak,

DDT never went away in most of the world, it has been in almost continuous use outside of the USA, Europe, Australia etc., and there are populations of Aedes aegypti in the Caribbean that are resistant to DDT. DDT was once a panacea, but we abused it and now it is just another not very useful chemical. There is no simple solution to this problem, but there is a weak spot in the mosquito vector’s life cycle – it breeds in small accumulations of water around people and it prefers human blood to all others. We have had the knowledge and ability to eradicate Aedes aegypti for more than a century through eliminating its breeding sites, and we did pretty well from the 1920’s until the 1960’s, but then it all went down the drain. Bring back public health organisations that are free from politics and free to concentrate on vector control and these diseases would be gone.

Samuel C Cogar
Reply to  DaveW
July 10, 2019 4:24 am

…… and we did pretty well from the 1920’s until the 1960’s, but then it all went down the drain.

Yup, the EPA gave up on their namesake duties of ‘protecting the environment’ in order to aid and abet the Democrat liberals and Rhinos in their quest to control all facets of public activities.

Pamela Gray
July 9, 2019 9:01 pm

By far, the biggest mosquito threat in nearly all countries now is West Nile. In 10 years, it not only swept across the US and Europe, it mutated into 4 lines and 12 strains with possible increased virulence. There is no vaccine and no cure, with little hope of any soon. My suggestion? Wear mosquito repellant and sleep under a net no matter where you live. I contracted West Nile and now must contend with life long brain injury. Get this, so far the CDC has recorded 10 cases in the US already and 6 of them were neuroinvasive, a very serious form of the virus. By snow fall, we will see a repeat of 2018, with multiple cases in every state.

The world is seriously lacking a proper response to this disease and we will rue the day that we did not marshal enough resources from the beginning of what I consider to now be a world emergency.

Pamela Gray
Reply to  Kip Hansen
July 10, 2019 8:00 am

Yes there is. Of the 10 infections so far, one was detected in a blood donation before she started to have symptoms. According to the CDC, the live virus was in the blood sample. She experienced fever just a few days following giving a blood donation.

Pamela Gray
Reply to  Kip Hansen
July 11, 2019 10:24 am

Thank you Kip. I will work on a draft. One of the major effects I am contending with is a disconnect from brain to fingers when I type. I was a speed typer before West Nile and now function more like a person who has had a mild stroke in multiple language areas. Even this short message took 5 minutes of deleting, typing, deleting. Correcting spelling errors actually causes more errors than the original one on the first attempt to edit. Bizarre.

Pamela Gray
Reply to  Kip Hansen
July 11, 2019 5:27 pm

This should ring alarm bells. The delay in reporting, and inaccuracies in reporting could easily delay immediate action when West Nile is active in a particular area. I predict 2019 will see many more deaths than previous years, and the idea that 80% of infections produce no symptoms comes from a single suspect study from 1999! The % was an extrapolation of a very small study. I think the risk is WAY higher and that symptoms occur in many more cases but symptoms are not severe. However, new studies are demonstrating that even mild symptoms are leaving evidence of brain damage in synaptic junctions, in the hippocampus especially.


Kip, I will need some help getting 80% study. I can’t find a pdf:



CDC still has not recorded my case in Baker County from last August!

Pamela Gray
Reply to  Kip Hansen
July 11, 2019 6:27 pm

Nope. This 80% number comes from the 1999 study. All others since then either refer back to an older study that when you read it, refers to the 1999 study, or refer directly to the 1999 study. I have not found a large study that surveys positive serum subjects and reported symptoms.

Pamela Gray
Reply to  Kip Hansen
July 11, 2019 6:38 pm

“By extrapolation from the 59 diagnosed meningoencephalitis cases, we conservatively estimated that the New York outbreak consisted of 8200 (range 3500–13 000) West Nile viral infections, including about 1700 febrile infections.”

Using their extrapolated numbers, 20% of infected people would be febrile, 80% would be asymptomatic but that is an extrapolation of just 19 seropositive subjects, of which 6 reported symptoms. So I apologize for my potty mouth but WTF?


Pamela Gray
Reply to  Kip Hansen
July 11, 2019 7:37 pm

And one more thing, you would think that in this day and age, emergency room doctors would be up to speed on what to test for when a confused 62 yo, with a 104 F temperature, arrives at their door. Nope. Wasn’t on their minds. They thought I was coming down with the flu.

We are no where near prepared for this thing and more people will die. At this point in time, we should be spraying. Period. No need to test for this virus in mosquitoes. They have it. All across the world except polar regions.

Pamela Gray
Reply to  Kip Hansen
July 11, 2019 7:45 pm

If a serologic study is to be done again, it needs to be in every state, every county, and with random selection of subjects to determine infection rate in the general population, and asymptom versus symptomatic rates.

But that is not the worst of it. It is not known whether or not I lose immune status to the strain I was infected with, or if that inoculates me against the other 11 strains. It is also not known how fast mutations will produce a new strain. Think influenza strains as a virus comparison.

July 9, 2019 10:01 pm

Hi Kip,
Another interesting post. As a personal aside, it was early hyping of Global Warming causing the spread of arthropod-borne diseases to ‘new’ areas that first caused me to suspect something was amiss with AGW. The lack of historical knowledge or understanding of the epidemiology I thought incredible for papers published in ‘reputable’ journals, but that was before I realised the people promoting these myths were charlatans and not just ignorant.

I would expand on with a couple of your points though, probably at too much length, but it is an area of interest (I’m only an hour’s drive from a population of Aedes aegypti and dengue is endemic in Queensland).

True, epidemics of Zika and the other arboviruses are unlikely in the US for the points you note, especially small, dispersed reservoir (infected people) populations and moderately effective mosquito deterrents (window screens, air-conditioning, etc.) and usually some mosquito abatement ongoing (mostly because of annoyance mosquitoes rather than vector control). All bets are off, though, during a natural disaster like another Katrina or a massive earthquake.

Also, local outbreaks where viremic migrants or travellers are present as a reservoir seem likely to me, even in the US. We have local outbreaks of dengue in northern Australia (Townsville, Cairns, Mareeba even) most years in spite of moderate efforts at mosquito control and public education. Aedes aegypti readily enters homes and bites day and night. Screens and airconditioning reduces biting, but don’t eliminate it and people are susceptible when they are having a drink on their deck, mowing the lawn, etc.

So, I seem to be less sanguine than you about the chance for an epidemic in the US. West Nile certainly swept through the US causing quite a bit of disease, morbidity and mortality. This isn’t directly comparable to Aedes aegypti transmitted viruses because WN is a zoonosis (mostly in wild birds) and there are many mosquito vectors, but it does indicate that a lot of Americans get bitten by mosquitoes. Anyway, I suppose we will see, but if there is an epidemic in the US, then global warming will have nothing to do with it.

Some minor points too. I’ve read that ‘breeding in a bottle cap’ a few times and while it may be literally true, it has not much to do with disease transmission unless your yard is full of bottle caps. The handful of wrigglers that might mature in a bottle cap is unlikely to add much to the population. Larval control through sanitation and some of the modern larvicides is much more effective than spraying adults. One of the jobs I had to pay my way through undergraduate uni was mosquito control including efficacy tests of insecticides (organophosphates and synthetic pyrethroids) and although adult spraying is useful for reducing numbers of annoyance mosquitoes and hence complaints from the public, the actual kill rate tends to be low. Adulticides tend to be contact insecticides, so a droplet has to actually hit a mozzie or, if it has a residual effect, coat an area where the mozzie is likely to rest. In an outbreak situation you don’t really have much choice and it probably helps, but Aedes aegypti and albopictus are uniquely susceptible to sanitation – and they can’t evolve resistance to eliminated breeding areas. If Bill Gates or Jimmy Carter really wanted to do something to relieve the suffering of humanity then eradication of Aedes aegypti and albopictus would be a major boon.

July 9, 2019 11:19 pm

We should be more concerned about the major risk posed by multiple drug resistant staph, TB and other bacteria. They are the ones with potential for taking out significant numbers of our population.

July 10, 2019 12:16 am

Kip Hansen, a briallent article, thank you.

July 10, 2019 1:52 am

“ZIKA! A frightening new disease that burst onto the front pages in 2016 as “linked to thousands of babies being born with underdeveloped brains” and leading to a population explosion of climate scientists


Smart Rock
Reply to  chaamjamal
July 10, 2019 6:01 am

Beat me to it!

Paul Hull
July 10, 2019 8:36 am


Great article and followup comments. One of the best books I have read on disease control was David McCollough’s The Path Between the Seas. While it was not the main thrust, considerable space was given to the conquering of both Yellow Fever and Malaria. As was mentioned above, we will rue the days and years ahead because we have forgotten the lessons of control in the glow of conquering the disease.


tom in texas
July 10, 2019 1:06 pm

I you would like a background on Zika. The virus patent belongs to the Rockefeller Foundation and was discovered in south America in the 50’s while doing experiments on male mosquitos. David Rockefeller believed the human race should be at 500 million. simple research will show this to you.

July 10, 2019 2:10 pm

Zika is the cause, not the effect.
People’s brains are shrinking, therefore they believe in impending doom from climate change.

July 11, 2019 7:26 am


Zika Virus Disease is a bit of a scary thing for women living in Zika affected areas — like “German measles” with the accompanying threat fetal damage leading to of birth defects.

It is not, and will not, be a problem for those living in Europe or the United States except for those that travel to those parts of the world affect by Zika.

There are other mosquito-borne diseases in the United States that are of more concern — West Nile, which is zoonotic (transmitted from animals, birds in the case of West Nile) among them.

Readers are encouraged to investigate their local situation regarding vector-borne diseases and vector control. Be careful about mosquitoes and use common sense to avoid being bitten.

Thanks for reading.

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