Official advice for New Zealanders living and travelling overseas

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Mosquito-borne Illnesses

Outbreaks of mosquito-borne illnesses are common in the tropical and sub-tropical climates in many Pacific Islands, in North Queensland (Australia), Asia (including India), tropical Africa and Latin/South America. West Nile virus is commonly found in Africa, Europe, the Middle East, North America and West Asia.

Dengue fever, chikungunya virus and Zika virus are spread by the bite of an infected Aedes mosquito and cannot be spread directly from person to person. Malaria is caused by a parasite spread by the bite on an infected Anopheles mosquito. The mosquitoes that are able to spread these viruses are not normally found in New Zealand. West Nile virus is most commonly spread to people by the bite of an infected mosquito.

Since 2014, there has been an increase in confirmed cases of dengue, chikungunya and Zika virus infection in many Pacific Islands including the Cook Islands, Federated States of Micronesia, French Polynesia, Fiji, New Caledonia, Niue, Tuvalu, Samoa, Tonga and Vanuatu. In November 2015, cases of Dengue fever were reported by the Hawaii Department of Health on Hawaii Island (also known as the Big Island). The Zika virus is spreading to many tropical and sub-tropical countries. The Ministry of Health website provides further information on the Zika virus, including affected Pacific Island states.

The highest rates of transmission of malaria occurs in Africa South of the Sahara and in parts of Oceania such as Papua New Guinea, the Solomon Islands and Vanuatu. For further information about Malaria transmission refer to the CDC website.

Travellers to countries where mosquito borne illnesses are able to spread are advised to use insect repellent, wear protective clothing, and stay in lodgings where there are mosquito screens on windows and doors. Because Zika, dengue and chikungunya viruses are transmitted by mosquitoes mostly active during daytime, it is important that all travellers visiting affected areas continue to take protective measures to prevent mosquito bites throughout the day. The Ministry of Health website contains more advice on avoiding mosquito bites while travelling, including information about mosquitoes and how to fight mosquito borne diseases

Dengue fever is a viral disease that can be serious. Symptoms of dengue fever include high fever, headache, pain behind the eyes, joint pain, muscle and bone pain, rash and mild bleeding (e.g nose bleeds). A small proportion of dengue fever cases have a severe disease which can lead to shock or death. 

Chikungunya virus is a febrile viral illness. Symptoms of chikungunya virus infection include fever, severe joint and muscle pain, headache and a rash. More severe illness may occur in the elderly or newborns.

Zika virus infection is in most cases a mild febrile illness. Zika virus was only detected in Africa and Asia until 2007, but is spreading across Oceania and the Americas. Most people who get infected with the Zika virus do not show any symptoms. Only one in five people who get it will feel sick. Symptoms of Zika virus include mild fever, joint and muscle pain, headache, pain behind the eyes and a rash. There are growing concerns that Zika virus infection during pregnancy could have a negative impact on foetal development. Women who are pregnant or may soon become pregnant should defer travel to Zika-affected countries.

Most people infected with West Nile virus do not experience any symptoms. About 1 in 5 people will develop a fever, headache, and joint and muscle aches. About 1 in 150 people develop a serious, sometimes fatal illness. The more serious illness can occur in people of any age, however people over the age of 50 and some immunocompromised people have the highest risk of falling severely ill when infected with West Nile.

Malaria can be a serious and sometimes fatal disease caused by a parasite. Infection with malaria parasites may result in a wide variety of symptoms, ranging from absent or very mild symptoms to severe disease. Symptoms include high fevers, chills, headaches, nausea and vomiting and body aches. In general malaria is a curable disease provided it is diagnosed and treated promptly.

If you feel unwell during your trip or in the first three weeks after your return, you are advised to seek immediate medical advice and tell the doctor about your travel.

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