Diseases such as dengue fever, Zika Virus, chikungunya, yellow fever and malaria may sound exotic but they’re becoming more common in the places that New Zealanders like to travel - the Pacific Islands and South East Asia. At the least these illnesses cause extremely unpleasant symptoms, and at worst they can be fatal. In 2015 malaria caused an estimated 600,000 deaths worldwide.
While these diseases can be found in different countries, the one thing they have in common is that they are all transmitted by the bite of infected mosquitoes. Unfortunately for travellers, with the exception of malaria there are no vaccines or preventative medicines available so avoiding mosquito bites is your best protection.
If you’re travelling to a country where mosquito-borne diseases are present it’s essential you take protective steps to avoid mosquito bites.
View our interactive map to see what countries have reported cases of the most common mosquito-borne diseases or click on the map above.
Where, when and how do mosquitoes bite?
There are hundreds of different species of mosquitoes around the world and they feed at different times and prefer different habitats. It’s best to assume that mosquitoes can bite at any time of the day or night in urban and rural areas, so you must take appropriate precautions.
Mosquitoes are attracted to carbon dioxide and the heat of our bodies. There is also some evidence that body odour, sweat and other chemicals in the skin can attract mosquitoes and some people are more attractive than others. There is no known evidence that diet makes you more or less attractive to mosquitoes.
Mosquitoes will tend to favour biting exposed skin but are also capable of biting through clothing and other materials. Protection from mosquito bites involves using an effective insect repellent, covering exposed skin and treating clothing and sleeping equipment with permethrin.
What diseases do mosquitoes carry?
|Disease||Species||Main feeding time|
|Chikungunya||Aedes aegypti and Aedes albopictus||Day|
|Japanese Encephalitis / West Nile Virus||Culex||Night|
|Yellow Fever||Aedes and Haemogogus||Day|
Types of insect repellent
Insect repellents are applied to the skin and come in gel, spray, roll-on or aerosol forms. They rely on chemical or natural ingredients to stop mosquitoes from landing on the skin or biting.
When choosing a repellent it pays to follow the recommendations from The World Health Organisation (WHO) and the US-based Centers for Disease Control and Prevention (CDC). These organisations have thoroughly researched the history and effectiveness of insect repellents, especially in high risk areas.
There are 5 main types of insect repellents on the market. These include DEET, Picaridin, IR3535, Oil of Lemon Eucalyptus and natural formulations.
DEET first went on sale in the 1950s, and remains the most effective insect repellent ever invented. It has been used by hundreds of millions of people around the world and is considered safe to use by many health agencies including the WHO and the CDC.
There are many DEET-based insect repellents on the market and they can contain DEET at different concentrations, usually between 10% to 80%. The World Health Organisation recommends between 20-50% DEET for maximum effectiveness on adults. DEET is also safe to use on children over 2 months at lower concentrations (up to 30%).
DEET’s effectiveness cannot be disputed, however it is a plasticiser and should be kept away from plastic, vinyl, rubber, leather and other synthetic products. It does not damage cotton, wool or nylon. You will need to wash your hands after application and wipe it off any equipment.
Picaridin is a colourless and odourless synthetic repellent developed in the 1980s. Picaridin has been recognised by the WHO and CDC to be an effective repellent and a good alternative to DEET and is typically used at concentrations between 10 to 30%.
Compared to DEET it does not have a long history of safe and effective use but it is a good alternative for DEET sensitive individuals and is growing in use. Unlike DEET it will not damage plastics and other man-made materials and some users may prefer its odourless qualities.
Picaridin is not recommended for use on children under 2 years old.
IR 3535 is a synthetic insect repellent that was developed in the 1970s and was widely used in Europe for 20 years prior to its introduction in the United States in 1999. It is less commonly used in New Zealand and Australian products.
IR3535 has been known to cause eye irritation but it poses no other known health risks and is recognised by the CDC as an effective insect repellent alongside DEET and picaridin.
Like DEET it is a plasticiser and may damage plastic, rubber, vinyl and leather.
Oil of Lemon Eucalyptus (OLE)
OLE is a 100% natural extract from the lemon-scented Eucalyptus tree and is the only natural insect repellent recognised by the WHO and CDC. OLE products are most effective at 30% OLE concentration and can provide protection for up to 6 hours. It may be a suitable alternative to people who are sensitive to man-made repellents or those looking for a natural alternative.
There is no evidence that OLE poses any health risks but it should not be used on children under 3 years old.
Natural insect repellents are made from a blend of herbs and essential oils that have insect repelling properties. However, their use is more suitable where there is no risk of exposure to mosquito-borne diseases.
Natural repellents tend to require more regular application than their chemical alternatives but can be a good option for people looking for pleasant smelling natural product to deter insects. Typical ingredients can include citronella, lavender, lemongrass, rosemary, tea tree, eucalyptus and peppermint.
Insect repellent active ingredients
|Ingredient||Recognised by WHO / CDC||Recommended concentration||Protection||Suitable for children|
|DEET||Yes||20% - 50%||Up to 8 hours||Over 2 months at 30%|
|Picaridin||Yes||20% - 25%||Up to 8 hours||Over 2 years|
|IR3535||Yes||20%||4 - 6 hours||Over 2 years|
|Oil of Lemon Eucalyptus||Yes||10% - 40%||Up to 6 hours||Over 3 years|
|Natural||No||No guidelines||2 - 4 hours||Over 2 months|
Clothing and permethrin treatment kits
To help avoid mosquito bites, it is recommended you minimise exposed skin by wearing long sleeves and long pants, enclosed shoes, socks and hats or headnets where possible. Shirts can be tucked in at the waist and pants tucked into socks to close any gaps.
Mosquitoes can bite through clothing so you should also treat clothing and other travel gear with permethrin. Permethrin is a synthetic insecticide that mimics extracts from the chrysanthemum flower.
Permethrin treatment packs are commonly used to treat clothing, sleeping bags, liners and mosquito nets and will provide protection for a limited period of time before reapplication is needed. Make sure you closely follow the instructions of any permethrin treatment kits.
Permethrin should only be used to treat clothing and gear, never use it directly on the skin as it can cause some irritation.
Mosquito nets are are essential if you are sleeping outside or where your accommodation is not adequately screened or air conditioned. The primary carrier of malaria, the Anopheles species, prefers to bite during the night and makes no sound when it flies, making you a perfect target while you sleep.
The best kind of mosquito nets are pre-treated with insecticide which can last for the life of the net. Long Life Insecticidal Nets will kill mosquitoes (and other biting insects including bedbugs, fleas and scabies) on contact and offer better protection than untreated ones. Other nets can be treated after purchase but will require retreating every few months with suitable products. Permethrin treatment kits are commonly used for this.
Nets are only effective if there are no gaps or tears allowing mosquitoes through. To stop even the smallest mosquitoes getting through they should also have no less than 285 holes per square inch.
When using a hanging net, the net doesn’t reach the floor it should be tucked under your mattress. Try and avoid touching the net while you sleep as mosquitoes can bite through the holes. Make sure you regularly check your net for any holes or damage and replace as necessary.