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By Joyce Sakamoto and Shelley Whitehead
Mosquitoes, long spreaders of malaria and yellow fever, have more recently spread dengue, Zika and Chikungunya viruses, and caused epidemic outbreaks, mainly in U.S. territories. The insects are also largely responsible for making West Nile virus endemic in the continental U.S.
Today we face a challenging political climate, but the climate crisis shouldn't be political. It is not only the greatest existential crisis we face: it is also causing a global health emergency, where the stakes are life and death.
A mysterious Zika case in Utah has been solved and it shows we still don't know everything about the virus.
Back in July, a 38-year-old man stumped experts when he was diagnosed with the Zika virus, even though he hadn't traveled to any Zika-infected areas or had sexual contact with someone who did. He also lived in Salt Lake City, an area not considered a hospitable environment for the Aedes Aegypti mosquito that transmits the virus.
So far, the only ways Zika is known to be transmitted is through a bite from an infected mosquito, sexual contact with an infected person, contact with infected blood or a pregnant mother to her baby.
After tracking how this man could have gotten the virus, they discovered that he had visited a 78-year-old friend in a Utah hospital, just seven to 10 days before his symptoms began.
Eight days before the elderly man was admitted to the hospital, he had returned from a 3-week trip to the southwest coast of Mexico where it was learned he contracted Zika from mosquitoes, according to a new paper published in the New England Journal of Medicine.
During the 38-year-old's visit, the paper says he helped the nurse re-position his friend and had wiped the man's eyes. That's it.
The paper concludes:
"Given the very high level of viremia in Patient 1, infectious levels of virus may have been present in sweat or tears, both of which Patient 2 contacted without gloves. Transmission of the infection through a mosquito bite appears to be unlikely, since aedes species that are known to transmit ZIKV have not been detected in the Salt Lake City area. In addition, the second case occurred 7 to 10 days after contact with the index patient in the hospital, which implicates direct contact during hospitalization."
So can Zika be transmitted through someone's sweat or tears, and how easily?
In a study published on Sept. 6, traces of the virus were detected in the tears of mice, but there hasn't been any studies conducted yet on sweat.
"It should not be able to pass through unbroken skin," Sankar Swaminathan, the chief of infections disease at University of Utah Health Care, and first author on the paper, told The Atlantic. Meaning the man probably either had a cut somewhere on his skin, or he inadvertently touched his eyes, nose or mouth, and the virus entered his body.
What scientists are now looking into with this case is the severity of the elderly man's infection. Four days after he was admitted into the hospital he died and, while he was elderly, was reportedly not immunocompromised.
His blood had 200 million copies of the virus per milliliter—with a typical infection you'd expect to see hundreds of thousands, and 1 million would be considered high, Swaminathan said, which lead to progressive respiratory and renal failure, metabolic acidosis and hepatitis just before his death.
A factor being considered is that because he had contracted dengue in his past, it's possible remaining antibodies from that somehow worsened his infection. He also may have had a genetic immune deficiency that just happened to be very specific to this virus, and the fact that he had a very high viral load of the virus in his system is what likely led to it being transmitted in this way, Swaminathan said.
There have been 13 fatal cases in adults—not counting deaths from Zika-related Guillain-Barré—many of which had pre-existing conditions. While this case is definitely scary, mosquitoes and sexual transmission are still the main worries in the spread of the virus.
"For the general public, this doesn't really change very much," Swaminathan said.
Aerial spraying of the pesticide naled in a South Carolina county, done in an attempt to prevent Zika-infected mosquitoes from gaining a foothold in the state, resulted instead in the massacre of millions of honeybees.
On one farm in Summerville, South Carolina, 46 hives were wiped out instantly, killing 2.5 million bees.Flowertown Bee Farm and Supplies Facebook
While 43 Zika cases have been reported in the state, all but one were from travelers who were infected abroad. The other was a sexually transmitted case. No one in South Carolina has been locally infected by a mosquito. Nevertheless, county officials sprayed a 15-square mile area early Sunday morning. Dorchester County officials said they announced the spraying on Friday and via a Facebook post on Saturday, but many residents said they received less than 10 hours notice.
43 cases of Zika reported in South Carolina to date. Credit: South Carolina Department of Health and Environmental Control
The scenario reprises the days of DDT spraying that prompted Rachel Carson's seminal book, Silent Spring. The 1962 book by the former U.S. Fish and Wildlife Service writer detailed the disastrous effects on birds from the widespread use of synthetic pesticides following World War II. The leading culprit, DDT, was shown to cause reproductive failure in bald eagles, ospreys, brown pelicans and peregrine falcons. Indiscriminate aerial spraying laid a film of the pesticide where birds would pick it up.
Naled, the pesticide used in South Carolina, is an organophosphate first registered for use as a pesticide in 1959. Organophosphates were developed in the 1940s as biological warfare agents. The U.S. Environmental Protection Agency (EPA) currently authorizes use of naled for mosquito control. It is currently being applied by aerial spraying to 16 million acres of the mainland U.S., including highly populated areas. The EPA says that the chemical does not pose risks to people, although it recommends staying indoors during aerial spraying.
However, the agency appears to underplay the risks to honeybees. Its website states:
Applications made between dusk and dawn, while bees are not typically foraging, can reduce exposure to honey bees.
Although we do not anticipate significant exposure to bees, beekeepers can reduce exposure to bee colonies even more by covering colonies and preventing bees from exiting colonies during designated treatment periods, or if possible, relocating colonies to an untreated site. Providing clean sources of food (supplemental sugar water and protein diets) and clean drinking water to honey bee colonies during application can further reduce exposure.
Contrary to the EPA's recommendation, however, the spraying in South Carolina took place from 6:30 - 8:30 a.m.
Toxipedia, the online toxicology encyclopedia, is far more circumspect on the potential dangers of naled. They call it a severe skin and eye irritant, and cite a study that showed exposure to the chemical resulted in chronic nervous system damage in dogs and rats. Toxipedia also states that naled is "highly toxic to many bird species especially Canadian geese" and affects reproduction in Mallard ducks. They also note that its use "puts many endangered species at risk." With respect to honeybees, they couldn't be more clear:
It is toxic to bees and stoneflies (#EXTOXNET, 1996).
In April, EcoWatch reported that the U.S. Department of Agriculture (USDA) was silencing its own bee scientists. A Feb. 7, 2014 story documented the EPA's approval of two other pesticides known to be highly toxic to bees. The EPA's action came despite the concerns of beekeepers facing colony collapse.
On one farm in Summerville, South Carolina, 46 hives were wiped out instantly, killing 2.5 million bees. Compounding the problem was the weather: hot, 90 degree temperatures caused bees to leave their hives in order to cool down. That meant the bees were active during the widespread spraying.
As many residents became aware of the insecticide spraying, they tried to contact Dorchester County Mosquito Abatement by phone, as the notices had stated. No one answered. A resident who has started a petition on change.org wrote, "To our knowledge not one phone call was returned and no answers were given." The petition asks for the spraying to be stopped, for more information on the chemicals used and for a public forum to discuss their concerns. By Tuesday, Dorchester County had issued an apology, but there is no word to date on whether they will compensate beekeepers for the destruction of their hives.
The honeybee genocide in South Carolina came as a study published on Monday by the National Academy of Sciences links high demand and federal subsidies for corn and soybean crops to the loss of grassland in the Great Plains that bees need to survive. The study says that expansion of these crops in the Northern Great Plains is "altering the landscape in ways that are seemingly less conducive to beekeeping." The area in the study is home to more than 40 percent of the U.S. bee colonies.
Honeybees are nature's best pollinators. Without them, important crops including almonds, blueberries, apples, asparagus and broccoli would be threatened. It is estimated that bees are responsible for some $19 billion of U.S. crop production. The agricultural impact of the South Carolina disaster is not yet known.
This warning comes just days after the Center for Disease Control expanded on its first ever domestic travel warning by advising pregnant women not to travel to Miami Beach due to the spread of Zika. Fauci highlighted the increased risk of Zika in Louisiana because of recent flooding, as standing water provides an ideal breeding ground for mosquitos.
For a deeper dive:
Amid news of a Zika outbreak in the Miami area, the U.S. Food and Drug Administration's Center for Veterinary Medicine (FDA-CVM) has cleared the experimental release of genetically modified (GMO) mosquitoes in the Florida Keys to help combat the virus.
Four Florida residents have been infected with Zika in the first known case of local transmission of the virus in the continental U.S., according to health officials.
female Aedes aegypti mosquitoJames Gathany/CDC, 2006
A new study shows that climate change is increasing the length of mosquito season in the U.S. thus increasing the risk of Zika. However, Tom Frieden, director of the Centers for Disease Control and Prevention, said widespread transmission of Zika in the U.S. is unlikely.
What can be done to prevent the Zika virus? Here's some advice from a Natural Resources Defense Council blog post:
Drenching our homes and communities with harmful pesticides will not address Zika. Pesticides may seem like an attractive solution, but these chemicals must be used judiciously and strategically to avoid harming the very people we seek to protect (Duprey et al 2008). Aerial or even backpack spraying of ultra-low volume pesticides has had a very hard time achieving effective control of these particular mosquitoes, which have proven almost impossible to get rid of. Instead, we need a range of tactics to help prevent mosquito bites and disease transmission (CDC 2016 prevention):
- Wear protective clothing such as long sleeves and long pants.
- Apply personal mosquito repellant, such as EPA recommended formulations in the morning and early evening (CDC 2016 prevention; EWG 2016 on Zika). Try to pick products using minimal risk ingredients, if appropriate.
- Use window and door screens to keep mosquitoes out of homes.
- Every week, inspect the inside and outside of your home for standing water and eliminate it. This includes flowerpots, tires, buckets, planters, toys, birdbaths, empty garbage cans and lids, etc.
- Stop infected people from getting further mosquito bites to prevent spreading the disease to more mosquitoes.
For a deeper dive:
Background: Climate Signals