Only Four Studies Linked Aedes to the Zika Virus
Early On, Culex Mosquitoes Were Not Even Investigated
Thank goodness for people with common sense. I chuckled at the comments (shown next) on Chelsea Harvey's article in the Washington Post called El Niño on a warming planet may have sparked the Zika epidemic, scientists report.
And a post by Dennis Thompson included the opinion of Dr. Michael Osterholm who also doubted El Niño had as strong an effect as the researchers argue. Key points:
Aedes aegypti [suspected as the main vector of Zika], doesn’t travel far in its life and most often breeds in small backyard puddles of water ... planters, toys and other water-holding containers in people’s yards had a stronger effect than a global weather phenomenon in promoting Zika.
"What really moves these mosquitoes over time has been all of the additional breeding sites from the nonbiodegradable aspect of the world," added Osterholm.
Comments Left in The Washington Post Article
Aedes and Culex are Zika Vectors
Even though three independent teams of researchers from Brazil, China, and Canada have proven that Culex mosquitoes can also be vectors of the Zika virus, our public health authorities have gone to enormous lengths to dismiss, downplay, or remove this information.
And they have been warned since February 2016.
The WHO Acknowledged Culex
But Soon Removed This Information
Culex Mosquitoes Travel Further
But a Likely Reason: Migratory Birds
I agree with Dr. Constância Ayres that both Aedes and Culex mosquitoes (which require radically different mosquito eradication strategies) are vectors of the Zika virus.
And even though Culex are hardier, are found almost everywhere, and can over-winter in subway tunnels, garages, and homes, birds are able to carry the Zika virus thousands of miles.
If a mosquito makes its way into a garage, culvert, or an attic to hide out for the winter, it has a chance of lasting for up to 6 months.
Most mosquito species can fly up three miles while other large pool breeders in the Midwest have been known to fly up to seven miles from their breeding areas. Salt marsh mosquito species fly the furthest; up to 100 miles in certain circumstances.
The mightiest mosquito and El Niño are no match for migratory birds, like the Arctic tern.
What's more, 15 percent of birds studied in Uganda were found to harbor the Zika virus. However, this was decades ago. Since then, the percentage is probably much higher (as with West Nile virus).
But, for some reason, the WHO, CDC, and some doctors are downplaying, dismissing, or outright lying about the similarities between the Zika virus and West Nile virus.
And I was gobsmacked by the responses from Dr. Aileen M. Marty, a member of WHO's Advisory Group on Mass Gatherings, Risk Assessments, Command & Control, EID (Emerging Infectious Diseases).
A Least Tern Parent Feeding a Chick in Florida
What Caused Zika to Spread: Another Vector
Dr. Ayres completely debunks the few earlier studies that only pointed to Aedes mosquitoes.
In 2007, when 70 percent of Yap Island’s population of 7,300 was infected with the Zika virus, there was no evidence of Aedes aegypti as a culprit.
Dr. Ayres confirmed in a report published July 27th, 2016 by Elton Alisson, in Porto Seguro (Bahia) | Agência FAPESP:
"Aedes aegypti is very rare on most of the islands and is completely absent from the islands where the vast majority of cases of Zika occurred."
So, Dr. Ayres contacted researchers in the region to identify which mosquito species was most abundant there. Their answer was Culex quinquefasciatus (which had not been investigated as a Zika vector).
On February 4th, 2016, Dr. Constância F. J. Ayres published Identification of Zika virus vectors and implications for control in The Lancet Infectious Diseases. And she wrote letters to alert the scientific community and the World Health Organization (WHO):
"This issue deserves urgent attention. Vector control strategies must be directed at all potential vectors. To assume that the main vector is Aedes aegypti in areas in which other mosquito species coexist is naive, and could be catastrophic if other species are found to have important roles in Zika virus transmission."
Listen to Drs. Ayres and Hunter at the 2016 International Congress of Entomology's Zika Symposium. Scroll to 30:12 for Dr. Ayres and 58:54 for Dr. Hunter:
2016 International Congress of Entomology
Culex Mosquitoes Prefer to Bite Birds
When Birds are Scarce, They Feed on Humans
In a fascinating Smithsonian Insider Q & A, ornithologist Peter Marra answered a few questions about mosquitoes and West Nile virus. Remember, the Zika virus is supported 99 percent within the clade shared by West Nile virus and Saint Louis encephalitis virus.
"What is critical for the transmission of West Nile is how good a host is at amplifying the virus particles in their blood stream so the virus can be passed on to another animal ... American robins are one of the best hosts for West Nile Virus ... robins maintain a high ratio of virus particles versus blood particles in their blood — although they sometimes show no symptoms of the disease."
Photo Credit: Jitze Couperus on flickr (CC-by-2.0)
Credit: By Aaron C. Brault (http://www.ncbi.nlm.nih.gov/pubmed/19406093) [CC0], via Wikimedia Commons"What is interesting is that when robins disperse at the end of the breeding season in July, they aren’t as available to the mosquitoes. So, if you continue to look at the blood meals in mosquitoes, as we did in our research, you start seeing more human blood meals."
"With robins scarce, the mosquitoes do a diet switch and start feeding on humans and other mammals. So, it is at this time, just after the robins have dispersed, that you start seeing peaks of West Nile virus in humans, depending upon where you live."
Diagram by Aaron C. Brault [Public Domain], via Wikimedia Commons
When West Nile Virus Appeared in New York
The CDC Misdiagnosed it as St. Louis Encephalitis Virus
As J.A. Ginsburg reminds us in a March 23rd, 2016 post called Zika: How to fight back:
"When West Nile Virus (WNV) first appeared in New York City in the summer of 1999, the Centers for Disease Control and Prevention (CDC) blew the diagnosis, chalking it up to a related virus, St. Louis Encephalitis. It took a veterinary pathologist with a freezer full of dead birds at the Bronx Zoo to connect the dots and prod the CDC to keep looking."
Birds may become infected with WNV in multiple ways. The most common occurrence is through a mosquito. However, studies have shown that they may contract the infection through ingestion of infected organisms or direct contact with infected materials.
Notably, after ingesting infected organisms, viremia in birds usually occurs identically to that of mosquito-borne transmission.
Over 40 species of mosquitoes have been found to carry West Nile virus. The most important for spread is the genus Culex, which feed mainly on birds.
Over 300 species of birds have been found infected with WNV and many do not die from it. Yet, up to 100% mortality was observed in American crows (Corvus brachyrhynchos) and blue jays (Cyanocitta cristata) experimentally inoculated with the virus.
Some dead bird species (such as corvids and American crows), are able to transmit viral particles to vector hosts that feed on their remains up to five days after death. And Wolbachia is tough enough to survive for at least a week after its host's death, allowing it to spread to new organisms.
Therefore, when seabird colonies vanished in 2014 with "massive" chick deaths, it is plausible that both Zika and Wolbachia – and however Zika is enhanced by Wolbachia – could be passed along to other species (including mosquitoes, other birds, larger animals, and aquatic life) for at least five days.
Dead American Crow (Corvus brachyrhynchos)
Nine Real Reasons the Zika Virus is Spreading
1) The WHO and CDC ignored early warnings and evidence that Culex mosquitoes are also a vector of the Zika virus.
2) The WHO, CDC, and Health Canada never enacted level 3 travel warnings even though they were (and are) clearly warranted.
3) The WHO and CDC failed to postpone or move the 2016 Summer Olympic Games held in Rio de Janeiro, Brazil (where about 500,000 foreign tourists attended) ignoring the advice of 240 scientists and public health experts.
4) The CDC downplayed the sexual spread of Zika and did not even recognize it as an STD until August 2016.
"Officials have not said which states they are working with or where these women live because the risk applies to all women in the United States, according to Dr. Jennifer McQuiston, deputy incident manager for Zika virus at the CDC."
"We have been a little surprised by the number of suspected cases we've received, " she told CNN in February 2016.
5) From April until August 2016, the CDC promoted their highly flawed Zika test (Trioplex assay), which failed to detect 40 percent of Zika infections and all four strains of dengue.
6) Over 1/2 million blood donations have tested positive for the Zika virus. Yet, the WHO and CDC ignored early evidence in Eurosurveillance that Zika virus RNA was detected in whole blood up to two months (December 2015 to April 2016).
7) The CDC has not recommended prophylactic spraying of aircraft cabins and shipping containers (even though this is done in malaria-endemic regions).
8) The CDC has not mandated Zika testing for the hundreds of Puerto Rican prisoners that frequent the mainland U.S. every month.
9) Is anyone looking for the Zika virus in birds?
Well, I've written countless letters to get that moving along. And as I've detailed in my previous post, Birds as Reservoir Hosts of Zika: What You Are Not Being Told, it certainly looks like a strong possibility.
Addendum: December 25th, 2016
More Proof Sexual Transmission Has Been Downplayed
In a ScienceDaily post titled Case for sexual transmission of Zika virus strengthened I learned:
- The stage of the reproductive cycle during which a female mouse is exposed to virus determines vulnerability to infection.
- Mice infected in the diestrus (or in between phase) became progressively sick, lost weight, and died in 2 - 3 weeks. Remarkably, the same strain of immunocompromised AG129 mice infected in estrus phase [when female mice are in heat] showed no sign of disease.
- Virus persistence in vaginal fluids may account for why diestrus-infected mice become sick, regardless of mouse strain, yet the molecular or cellular basis for susceptibility remains unclear.
- "Hormones changed the mouse female reproductive tract in ways that either enhanced or protected against sexual transmission," said William Weihao Tang, the study's first author.
- Recent CDC case counts claim few Zika cases were likely transmitted sexually ... but sexual transmission of the Zika virus is taken extremely seriously in other regions, such as South America. In fact, one study of Baranquilla, Colombia, estimated that as many as 47% of Zika cases reported there emerged from sexual contact.
I Wonder if Wolbachia is the Molecular or Cellular Basis of Susceptibility?
When I looked up "does wolbachia in vertebrates infect uterus" a study by Kerstin Fischer, Wandy L. Beatty, Daojun Jiang, Gary J. Weil, and Peter U. Fischer called Tissue and Stage-Specific Distribution of Wolbachia in Brugia malayi caught my eye. It states:
"In young adult worms (5 weeks p.i.), a massive expansion of Wolbachia was observed in the lateral chords adjacent to ovaries or testis, but no endobacteria were detected in the growth zone of the ovaries, uterus, the growth zone of the testis or the vas deferens."
Granted, these are worms.
The study by Fernando Simón et al. called Human and Animal Dirofilariasis: the Emergence of a Zoonotic Mosaic states:
"Initial studies reported that tetracycline blocked the intrauterine development of Brugia pahangi and D. immitis microfilariae dramatically depleting the Wolbachia population in filariae when applied for 2 weeks prior to the L4-to-L5 molting of B. pahangi in the Mongolian gerbil (Meriones unguiculatus)."
A gerbil is a vertebrate, at least.
That supports the finding (mentioned in my article Wolbachia-Infected Mosquitoes Might Reduce Dengue, Enhance Zika, and Cause a Million Souls to Become Sterile) that azithromycin, a common antibiotic regarded as safe for use during pregnancy, can prevent the Zika virus from infecting fetal brain cells.
A Cute Little Least Tern Chick
(Sternula antillarum, formerly Sterna antillarum)
How We Can All Fight the Zika Virus
Press your local politicians and public health departments to test Culex mosquitoes and birds for the Zika virus (they probably do already for West Nile virus). Share this article.
Every week, I spread used coffee grounds around my yard. I share more helpful tips in my article Safe Mosquito Eradication That Works: Using Coffee, Bti, Rubbing Alcohol, and a Cat.
I designed fun and serious products on Zazzle to help raise funds for Zika research and/or bird conservation efforts. My Zazzle collection and my devoted Facebook page are both called: Zika: Let's Stop a Global Pandemic.
Author's note: All of my citations have a clickable link to their source. The list is found in the bibliography at the end of this page.