JUN 18, 2020 7:03 PM PDT

How Climate Change Worsened Zika Virus Defects

WRITTEN BY: Amanda Mikyska

Image: Pixabay

 

In 2015 a massive outbreak of the Zika virus started in Brazil and spread across 33 countries. The outbreak was especially frightening because mosquitos easily transmit the virus, and risk for pregnant women who contract it is the underdevelopment of their child's skull and brain (microcephaly). Depending on the severity of underdevelopment, microcephaly can cause seizures and developmental delays, among other disabilities.  

 

You may not remember that at the same time, the epicenter of microcephaly cases related to the Zika virus was gripped in an ongoing drought.

 

In 2012, the northeastern state of Bahia, Brazil, entered a severe drought caused by the El Niño. Freshwater reservoirs evaporated quickly with the exceptional heat, and lack of replenishment. To ease the strain on drinking water resources, residents set up containers to catch the rain. Typically these rain-catchers are poorly covered, making them breeding grounds for Aedes aegypti, the mosquito that carries the Zika virus, and Dengue fever. Freshwater becomes saltier as water evaporates from reservoirs, prompting a bloom of Raphidiopsis raciborskii, bacteria that secrete the neurotoxin saxitoxin. These factors made the perfect storm for two separate, but simultaneous, public health threats.  

 

Saxitoxin is a well-known concern of Brazil's freshwater resources, so R. raciborskii is closely monitored. During droughts, though, higher exposure to saxitoxin is unavoidable. Researchers at the University of Adelaide showed in mice that even in low doses, saxitoxin causes nerve cells to be underdeveloped, stifling communication from the body to the brain and within the brain itself. This finding was later confirmed in an investigation in French Polynesia, linking saxitoxin exposure to Guillian-Barre syndrome.   

 

By 2015, Brazilians in the northeast of the country had been exposed to a higher concentration of saxitoxin for three years, while mosquito populations thrived in the abundance of warm, sedentary rainwater. It was under these conditions that the infamous Zika virus outbreak occurred and terrified expecting mothers everywhere.  

 

Dr. Stevens Rehen, a neuroscientist at the Federal University of Rio de Janeiro, recognized the significance of increased exposure to the neurotoxin combined with Zika virus consequences that also stunt neural development, and began a series of experiments.

 

In March, Dr. Rehen'sRehen's team published a study showing that congenital disabilities caused by the Zika virus piggyback off the weakened state of the nervous system due to saxitoxin exposure. On its own, a long-term, low dosage of saxitoxin does not damage neurons, while the Zika virus can still cause abnormal brain development without the neurotoxin.  

 

Dr. Rehen's research points to three alarming conclusions that foreshadow the worst ways climate change and pathogens can tangle. The researchers found that a combination of a sustained, low dosage of saxitoxin, and prenatal Zika virus exposure, results in an accumulation of dead cells, more than twice the abundance caused by Zika alone. Cells infected with both also showed a threefold increase in the amount of viral DNA in an infected individual. Worst of all, experiments with mice showed that while prenatal exposure to the Zika virus resulted in some neural-development issues (mostly minor), exposure to the Zika virus and contaminated water caused a severe reduction in brain and skull development, with the cortex reduced by about 30%.

 

As climate change intensifies weather events, the severity and number of occurrences of climate change and pathogens piggybacking off one another will increase too. Dr. Amy Vittor, who studies mosquito-transmitted diseases at the University of Florida, tells Climate Central, "If you have an increase in temperatures, you may see an increase in range of mosquitoes and the spread of virus." Citing examples of an extended West Nile season in North America, and increasing cases of Dengue Fever in recent years, Dr. Vittor draws a clear pattern of entangled risks that shows no sign of waning.  

 

Sources: Climate CentralInternation Federation of the Red Cross (IFRC)Pedrosa et al.The ScientistWorld Health Organization (WHO)

About the Author
  • Amanda graduated from the University of Massachusetts Boston with a degree in Biology. After working in research on creating biochemicals from genetically engineered yeast, she started freelance science writing while traveling the world. Now, Amanda is a Lab Manager and Research Assistant at the the University of Central Florida, studying the molecular phylogeny of parasitic wasps. She writes about the latest research in Neuroscience, Genetics & Genomics, and Immunology. Interested in working on solutions for food/water security, sustainable fuel, and sustainable farming. Amanda is an avid skier, podcast listener, and has run two triathlons.
You May Also Like
MAY 15, 2020
Neuroscience
Can You Hear Body Language?
MAY 15, 2020
Can You Hear Body Language?
Most people use body language while talking. Often giving subconscious cues about their feelings and ulterior motives, u ...
JUN 15, 2020
Cell & Molecular Biology
Revealing the Network of Neurons in the Heart
JUN 15, 2020
Revealing the Network of Neurons in the Heart
The autonomic nervous system is linked to the intrinsic cardiac nervous system (ICN), which is thought to help regulate ...
JUN 14, 2020
Chemistry & Physics
Why Are There So Few Black People in STEM?
JUN 14, 2020
Why Are There So Few Black People in STEM?
On June 10th, 2020, thousands of STEM scientists and organizations around the world went on strike to protest systemic r ...
JUN 10, 2020
Neuroscience
Monkeys More Responsive to Hyper-Realistic Animations of Monkeys
JUN 10, 2020
Monkeys More Responsive to Hyper-Realistic Animations of Monkeys
Video:  More about Uncanny Valley Syndrome from MOCH it.   Rhesus macaques are a species of monkey often used ...
JUL 30, 2020
Neuroscience
Brain Thickness and Connectivity Influences Negative Behavior
JUL 30, 2020
Brain Thickness and Connectivity Influences Negative Behavior
When looking at the brain, many think that different areas are individually responsible for different functions- like me ...
AUG 06, 2020
Cell & Molecular Biology
Fragile X Model Has a Very Specific Brain Abnormality
AUG 06, 2020
Fragile X Model Has a Very Specific Brain Abnormality
Cilia are like little antennae on cells, and most cells have one. If they're dysfunctional, it can cause serious problem ...
Loading Comments...