Chikungunya and Zika: Let’s talk about mosquitoes

UPDATE: March 31, 2016. This post has been updated with new information about Zika Virus.

Travelling south to escape the winter blues? Travellers planning a sun vacation are contacting us wondering about the risk of Zika and Chikungunya. Currently, countries in the Caribbean, Central America, and South America are reporting cases.

Understanding mosquito behaviour and brushing up on your mosquito bite prevention skills are two ways to reduce your risk so that you can enjoy your holiday.

6 things you should know about Chikungunya and Zika

Both viruses are primarily transmitted by daytime biting Aedes aegypti female mosquitoes.
There are no preventive vaccines or medications; treatment includes supportive care of symptoms.
The illnesses are usually self-limiting – they typically run their course after a few days. Zika symptoms are generally mild. Chikungunya causes joint pain that can last for months or years after the illness, although it’s rarely fatal and anyone who has had the illness becomes immune. See Chikungunya and Zika Virus for more details on symptoms.
If you are bitten by an infected mosquito, you may be asymptomatic (meaning that you don’t have symptoms) and may be unaware that you’re carrying the virus.
Aedes mosquitoes are resilient and mobile. They are rapidly spreading via international travel, moving further north or being reintroduced where they were once eliminated due to climate change and resistance to insecticides.
Chikungunya and Zika outbreaks also overlap with Dengue outbreaks in some areas and the three illnesses are often misdiagnosed. (Keep an eye out for our in-depth blog post about Dengue next month.)

Current outbreaks: What to expect in 2016

The Zika Virus received significant media attention after the Ministry of Health in Brazil noted an increase in babies born with microcephaly in areas reporting Zika cases.

Infectious disease models predict that Zika will continue to spread in the Americas. Chikungunya has spread throughout the region in a similar manner, beginning on the island of St Martin in 2013. Today, Chikungunya remains a risk for travellers in many parts of Central America, South America, and the Caribbean. Some countries, like Brazil, are fighting outbreaks of Chikungunya, Zika, and Dengue.

If you’re planning a trip, find out exactly where outbreaks are occurring. You may discover that there is no outbreak in the area where you’re staying. For example, at the time this blog was published in January 2016, Chiapas and Nuevo León were the only states in Mexico reporting Zika. If you’re unsure about the risks, meet with your health practitioner to discuss your travel plans.

Emerging research: Zika Virus

Although the Zika Virus was first isolated in Uganda in 1947, it did not receive much attention until the current outbreak. Neurological complications related to Zika Virus infections have been reported, mainly microcephaly (decreased brain size) in fetuses of women who contracted Zika while pregnant and Guillain-Barré syndrome (which causes weakness or paralysis).

See our Zika Virus page for a summary of what to do if you’re planning a trip to, or returning from, a country with active Zika Virus transmission.

Preventing mosquito bites

The best way to avoid getting Chikungunya or Zika is to use meticulous anti-mosquito bite measures: Understand the mosquito’s behaviours, practise skin and clothing protection, and know how to use a bed net properly.

Learn about mosquito behaviour

Aedes species are quick to adapt to their environment. Here are 4 things to keep in mind about their preferences. They:

Bite during the daytime; peak biting times are early in the morning and late in the afternoon.
Live inside homes and outdoors.
Are attracted to standing water.
Present in urban and suburban areas.

Skin protection and clothing protection

The following are physical barriers that you can use to prevent any mosquito from coming close to you in the first place.

Wear light-coloured, loose-fitting, long clothing (cotton, linen) as much as possible. This is hard to do in the tropics, but an important prevention method.
Ensure that door and window screens do not have tears or holes, and that they close tightly. Don’t use scented soaps, shampoos, deodorants, perfumes or after-shaves; scents attract mosquitoes.
Remove any standing water in containers or items inside and outside the home.
Cover any food, drinks, compost and garbage.
If you rest during the day, consider using an insecticide-treated bed net.

Use chemical barriers like repellent and insecticide.

Use a spray, lotion, towelette, or liquid repellent containing 20% – 30% DEET (such as Deep Woods Off) or 20% Picaridin/Icaridin (such as Sawyer Picaridin Insect Repellent). Apply according to the manufacturer’s directions to ensure optimal protection. Re-apply more frequently if you start to get bitten.
Apply sunscreen before repellent. Wait about 20 minutes to allow sunscreen to penetrate the skin before using repellent. This could reduce the efficacy of the sunscreen, so it’s best to reapply often or wear long clothing.
In the USA, some repellents can be used on children older than 2 months of age. In Canada, the recommendation is for children over 6 months of age. Talk to your doctor or travel health provider about using a repellent if you’re travelling with an infant to an area with high risk of mosquito-transmitted illnesses. To further protect your child, ensure that they wear long light-coloured, loose-fitting clothing, and cover their carrier with tight-fitting mosquito netting or place them under an insecticide-treated net when playing or resting.
Treat outer-layer clothing and gear with permethrin. Note that permethrin treatment products are not commercially available in Canada, but you can obtain them through US retailers such as Bass Pro Shops, REI, and Amazon.
Consider spraying your accommodations with an insecticide and use according to the manufacturer’s directions.

Myth busting

The best anti-mosquito protection is a combination of the physical and chemical options mentioned above. There is no evidence that the products listed below protect you against illnesses transmitted by mosquitoes.

Combined sunscreen and repellent lotions
Citronella-based plants, coils, or candles
Vitamin B1 or garlic
Ultrasonic products, electrocuting devices, odour-infused mosquito traps
Repellent-containing wristbands, ankle bands or neckbands

Most travellers can safely visit countries affected by these viruses as long as they’re taking meticulous anti-mosquito bite precautions. By taking an active role in your health, you can reduce your risk of getting sick.

More about Chikungunya and Zika

Zika virus: a new global threat for 2016 – The Lancet

Zika virus in the Americas – Yet another arbovirus threat – NEJM

Chikungunya virus-associated encephalitis (abstract only) – Neurology

The virus that ruins Caribbean vacations – Washington Post

Zika Virus Timeline – ESRI

Photo of Aedes aegypti mosquito by James Gathany (PHIL, CDC) [Public domain], via Wikimedia Commons.

Article by Tullia Marcolongo and Daphne Hendsbee.