El Niño may be helping spread Zika virus, here's how
Friday, February 5, 2016, 3:53 PM - In a year dominated by El Niño headlines, it now appears that the famed warming weather pattern could be helping to spread the deadly Zika virus, an emerging mosquito-borne disease the World Health Organization (WHO) declared a global emergency earlier this week.
The origins of Zika
Zika was first discovered in the 1940s and it occurs in tropical areas with large mosquito populations. It is known to circulate in Africa, the Americas, Southern Asia and Western Pacific. However, since 2013 the number of cases have multiplied, spreading to 14 different Latin American countries. Mexico and southern United States have been added to the mix with cases confirmed in Florida and Texas.
In Canada there have been four confirmed cases of Zika virus – two people in British Columbia, one in Alberta and a newly diagnosed case in Quebec, according to Canada’s chief public health officer.
The virus is transmitted by mosquitos, specifically two species: Aedes albopictus and Aedes aegypti which are both responsible for spreading dengue, chikungunya and yellow fever.
Albopictus has been found in the southern U.S., including Texas and Florida and have been moving forward, according to Mark Ardis, scientific advisor with G.D.G. Canada. The organization conducts biological control of biting insects and also performs actions to prevent the spread of mosquito-borne diseases such as the West Nile virus.
“The mosquitoes are not in Canada yet. There hasn’t been anything found in any trappings in Ontario and Quebec that I know of,” Ardis told The Weather Network. “There is a sense of relief knowing that we don’t have the mosquitoes that are vectors for the disease.”
One major concern is that the virus can be transmitted sexually as well.
The first known case of Zika transmission was recently identified in the continental U.S., with it being reported in Dallas where local health officials say it was likely contracted through sexual intercourse and not a mosquito bite.
In some cases the virus has been linked to babies born with abnormally small heads and birth defects, including developmental delays, hearing loss and intellectual disabilities.
Scientists are still studying the possibility the virus could be sexually transmitted as there are many unanswered questions including, how long the virus persists in semen or whether it's possible for women to spread Zika sexually.
Why hasn’t both species of mosquitoes been found in Canada? Simply because they cannot survive Canadian winters. In addition, the average mosquito does not fly long distances, usually only between 2 and 5 km, according to Ardis.
In the past, different species of mosquitoes migrated to new locations through cargo ships or aircraft. However, the insects often don’t have enough time to colonize as the average lifespan of mosquito is about 14 days.
With Canada experiencing a mild winter thus far, it is possible Aedes albopictus could thrive in ideal conditions. The species has been found in places like New Jersey, according to Ardis, where winters are similar to Canada.
“It is a possibility and we discover new species every other year with our laboratory and know that new species are moving northward.”
Nonetheless, Ardis says the risk for Canadians based on mosquito transmission is “very low.” Especially, with the recent assumption that the virus can be transmitted sexually.
“It makes it a completely different virus.”
Can El Niño have an effect on Zika?
El Niño which is characterized by a warming of the central and eastern Pacific Ocean near the equator is known to shift precipitation patterns around the globe, including South America. Therefore, some have speculated that El Niño has played a role in the spread of Zika as the phenomenon could help create ideal conditions for mosquitoes to thrive.
While there has been speculation of a link, it has yet to be proven scientifically.
El Niño which is characterized by a warming of the central and eastern Pacific Ocean near the equator is known to shift precipitation patterns around the globe, including South America. Therefore, some have speculated that El Niño played a role in the spread of Zika by enhancing the conditions in which mosquitoes thrive. However, the link between the spread of Zika and El Niño has not been scientifically proven.
What is the connection?
The end of 2015 came with substantial flooding that impacted parts of Uruguay, southern Brazil and Paraguay, displacing some 150,000 people. Large amounts of rain causes standing water which mosquitoes need to lay eggs and for the larvae to develop. The rains created the ideal breeding grounds for the infected mosquitoes in the area, according to reports.
The United Nations mentions, “The majority of deaths and disease associated with El Niño are attributable to extreme weather events, including droughts, cyclones, typhoons and floods…There may also be an increase in vector-borne diseases including dengue, chikungunya and Zika virus due to increase mosquito vectors and increased temperatures that can enhance reproduction and transmission of these viruses.”
Both albopictus and aegypti species are difficult to control as they can lay their eggs where there is very little water, Ardis explained.
“You could have an open bottle of water that has been sitting in your house for a couple of days and all of a sudden there will be mosquito larvae in there. They are extremely opportunist when it comes to where they will lay their eggs and that’s one of the reasons why they are a difficult species to control.”
Programs are in place for mosquito control in areas across South America which involve the process of fogging. Fogging is a technique used for killing insects that involves using a fine pesticide spay that kills adult mosquitoes. Larviciding is also taking place in bodies of water, whereby an insecticide is used to interrupt the development of larvae.
“This is the most effective way to control mosquitoes but it’s difficult because they can breed anywhere,” said Ardis.
While scientists are not testing for Zika in Canada, G.D.G. continues to monitor mosquito populations for species that are known vectors of the virus.
Currently, there is no vaccine to prevent infection or medicine to treat Zika.
The following information was taken from Centers for Disease Control and Prevention.
What are the symptoms of Zika?
About one in five people infected with Zika will get sick. For people who get sick, the illness is usually mild. For this reason, many people might not realize they have been infected.
The most common symptoms of Zika virus disease are fever, rash, joint pain, or conjunctivitis (red eyes). Symptoms typically begin two to seven days after being bitten by an infected mosquito.
Who is at risk of being infected?
Anyone who lives in or travels to an area where Zika virus is found and has not already been infected with Zika virus can get it from mosquito bites.
What can people do to prevent becoming infected with Zika?
- There is no vaccine to prevent Zika. The best way to prevent diseases spread by mosquitoes is to protect yourself and your family from mosquito bites. Here’s how:
- Wear long-sleeved shirts and long pants.
- Stay in places with air conditioning or that use window and door screens to keep mosquitoes outside.
- Use Environmental Protection Agency (EPA)-registered insect repellents. All EPA-registered insect repellents are evaluated for safety and effectiveness.
- Always follow the product label instructions.
- Reapply insect repellent as directed.
- Do not spray repellent on the skin under clothing.
- If you are also using sunscreen, apply sunscreen before applying insect repellent.
- If you have a baby or child:
- Do not use insect repellent on babies younger than 2 months of age.
- Dress your child in clothing that covers arms and legs, or
- Cover crib, stroller, and baby carrier with mosquito netting.
- Do not apply insect repellent onto a child’s hands, eyes, mouth, and cut or irritated skin.
- Adults: Spray insect repellent onto your hands and then apply to a child’s face.
- Treat clothing and gear with permethrin or buy permethrin-treated items.
- Treated clothing remains protective after multiple washings. See product information to learn how long the protection will last.
- If treating items yourself, follow the product instructions carefully.
- Do NOT use permethrin products directly on skin. They are intended to treat clothing.
- Sleep under a mosquito bed net if you are overseas or outside and are not able to protect yourself from mosquito bites.