Other risks
There are some risks that are relevant to all travellers regardless of destination. These may for example include road traffic and other accidents, diseases transmitted by insects or ticks, diseases transmitted by contaminated food and water, sexually transmitted infections, or health issues related to the heat or cold. Some additional risks (which may be present in all or part of this country) are mentioned below and are presented alphabetically.
Altitude
There is a risk of altitude illness when travelling to destinations of 2,500 metres (8,200 feet) or higher. Important risk factors are the altitude gained, rate of ascent and sleeping altitude. Rapid ascent without a period of acclimatisation puts a traveller at higher risk.
There are three syndromes; acute mountain sickness (AMS), high-altitude cerebral oedema (HACE) and high-altitude pulmonary oedema (HAPE). HACE and HAPE require immediate descent and medical treatment.
Altitude illness in USA
There is a point of elevation in this country higher than 2,500 metres. Example places of interest: Mt McKinley 6,194m, Mt Rainier 4,392m, Pikes Peak 4,301m, Leadville 3,100m and Mt Kea (Hawaii) 4,205m.
Prevention
- Travellers should spend a few days at an altitude below 3,000m.
- Where possible travellers should avoid travel from altitudes less than 1,200m to altitudes greater than 3,500m in a single day.
- Ascent above 3,000m should be gradual. Travellers should avoid increasing sleeping elevation by more than 500m per day and ensure a rest day (at the same altitude) every three or four days.
- Acetazolamide can be used to assist with acclimatisation, but should not replace gradual ascent.
- Travellers who develop symptoms of AMS (headache, fatigue, loss of appetite, nausea and sleep disturbance) should avoid further ascent. In the absence of improvement or with progression of symptoms the first response should be to descend.
- Development of HACE or HAPE symptoms requires immediate descent and emergency medical treatment.
Altitude illness in brief
Biting insects or ticks
Insect or tick bites can cause irritation and infections of the skin at the site of a bite. They can also spread certain diseases.
Diseases in North America
There is a risk of insect or tick-borne diseases in some areas of North America. This includes diseases such as West Nile virus.
Prevention
- All travellers should avoid insect and tick bites day and night.
- There are no vaccinations (or medications) to prevent these diseases.
Further information about specific insect or tick-borne diseases for this country can be found, if appropriate on this page, in other sections of the country information pages and the insect and tick bite avoidance factsheet.
Dengue
Dengue is a viral infection transmitted by mosquitoes which predominantly feed between dawn and dusk. It causes a flu-like illness, which can occasionally develop into a more serious life-threatening form of the disease. Severe dengue is rare in travellers.
The mosquitoes that transmit dengue are most abundant in towns, cities and surrounding areas. All travellers to dengue areas are at risk.
Dengue in United States
Dengue outbreaks are reported from time to time in United States. Affected states include Florida, Hawaii, and Texas.
Prevention
- All travellers should avoid mosquito bites particularly between dawn and dusk.
- There is currently no medication or vaccination available for travellers to prevent dengue.
Dengue in brief
Zika Virus
Zika virus (ZIKV) is a viral infection transmitted by mosquitoes which predominantly feed between dawn and dusk. A small number of cases of sexual transmission of ZIKV have also been reported. Most people infected with ZIKV have no symptoms. When symptoms do occur they are usually mild and short-lived. Serious complications and deaths are not common. However, there is now scientific consensus that Zika virus is a cause of congenital Zika syndrome (microcephaly and other congenital anomalies) and Guillain-Barré syndrome.
Zika virus in Florida and Hidalgo and Cameron Counties in Texas, United States
The risk in Florida and in Hidalgo and Cameron Counties, Texas is considered low. For information on the previous locally aquired cases see Florida Health and Texas Department of States Health Services websites.
Prevention
- All travellers should avoid mosquito bites particularly between dawn and dusk.
- There is no vaccination or medication to prevent ZIKV infection.
Pregnant women should seek medical advice if they develop ZIKV symptoms, and contact their GP on return.
Zika virus in brief
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