Travellers' Diseases



Last Review Date: August 14, 2017


What are travellers' diseases?

"Travellers' diseases" is a broad term for bacterial, viral, fungal, and parasitic infections that may be acquired when someone travels away from home, especially when traveling from a developed or industrialised area to a less developed area. Every travel destination and every geographical location has its hazards, including home.

Travellers should educate themselves and discuss with their doctors their destinations, expected lengths of stay, and planned activities. With the proper care, many traveller’s diseases are preventable – through avoidance of the carrier's (vector's) environment, avoidance of risky behaviours, vigilant care with food and water, chemoprophylaxis (medicines taken before and during travel to prevent a specific illness), and vaccines.

Some diseases are global in nature - they are found throughout the world and, unless prevented through vaccination, frequently cause childhood illnesses. In some cases, these illnesses can lead to lifelong complications. Many nations have vaccination programs to decrease the number of people who contract conditions such as measles, rubella (German measles), mumps, and polio. In areas that are unable to uniformly vaccinate their populations, these conditions can be endemic and/or there may be epidemics of the disease. Travellers who are not protected through previous vaccinations, young children who have not been fully immunised, and patients who are immunocompromised may be at an increased risk of contracting one of these infections. Adopted children from foreign countries and immigrants to Australia may bring these and other travellers' diseases with them to Australia and should be evaluated for them.


Common Symptoms

The most frequently encountered travellers' illnesses are diarrhoea, nausea, vomiting, fever, and skin manifestations (rashes, sores, swelling, etc). Also seen are hepatitis (liver inflammation) and its accompanying jaundice, headaches, and meningitis and/or encephalitis. Some diseases will also cause respiratory symptoms – coughing and/or difficulty breathing.

The symptoms of some diseases may be so mild and self-limited that they go unnoticed; many may be a miserable annoyance for a few days, and a few may cause an acute medical emergency. There are diseases that may not emerge until the traveller has returned home, with symptoms that may resolve, cycle, grow progressively worse, or linger. Left untreated, a few of the diseases can have serious consequences including death.
 


How are travellers' diseases acquired?

Travellers' diseases can be acquired in a wide variety of ways. Common routes of acquisition include:

  • contact with respratory secretions, carried through the air, on hands, or objects
  • ingestion, or contact with contaminated food or water
  • sexual contact, especially unprotected by condoms
  • exposure to insects that carry disease, especially msoquitos
  • close exposure to infected animals and physical contact with animal hides
  • contact with contaminated soil or sand
  • needle sharing

For a list of common travellers' diseases, visit this CDC web site.


Tests

Laboratory Testing

In many cases it is important to identify the cause of the disease in travellers, not only to treat the individual but also to prevent transmission and to document the prevalence of the specific disease, both in returning travellers and in the countries they visited.

The specific tests that should be ordered depends entirely on the symptoms that the returned traveller exhibits. Testing for some of the more common travel related infections seen in Australians returning from abroad are discussed below. 

Causes of bacterial diarrhoea may be identified with a stool culture, or PCR test. Parasitic causes of diarrhoea can be identified through the microscopy of the faeces, to identify the mature parasite or their ova (eggs), or cyst (dormant) forms. Microscopy is performed on a fresh or specially preserved stool sample. For some parasites, such as Giardia intestinalis (lamblia), cryptosporidium and Entamoeba histolytica PCR tests have been developed, which are more rapid and have superior diagnostic performance characteristics compared with traditional microscopy. For some centres where microscopy or PCR are not readily available, antigen (proteins associated with the parasite) tests may be used. 

PCR tests are now routinely available for a range of common causes of viral diarrhoea. These tests are rapid and accurate, and can help to indentify the cause of an individuals symptoms which may be useful in a returned traveller where there are many potential causes. 

The most common travel related infection is a viral respiratory tract infection, such as influenza (the flu) or the common cold. Investigation of a returned traveller, with a fever, should in most cases include PCR testing of a nasopharyngeal swab (taken from the back of the nose/throat) for the more common respiratory viruses. 

Dengue fever is common in Indonesia (including Bali) and Thailand which are common travel destinations for Australian tourists. In individuals with a fever returning from Dengue endemic areas a sample of blood for antigen/PCR testing is performed to detect the presence of this condition. Later in the illness IgG and IgM antibodies may also be detected. Full blood count may also be performed to monitor the severity and progression of the illness utilising the haematocrit

The parasite that causes malaria (Plasmodium spp.) infects red blood cells. It can be identified by collecting a blood sample and examining specially stained "thick and thin" blood smears on slides under the microscope. Many of the other travellers’ diseases can be identified either by culturing the microorganism, observing it under the microscope, and/or testing for antibodies or antigens. Patients who return from travel with an acute or chronic condition should consult with their doctor, who may suggest a consultation with an infectious disease and/or tropical medicine specialist.  

Typhoid fever is a serious, systemic bacterial infection spread through the consumption of contaminated food or drink. In returned travellers with a fever a sample of blood for culture is indicated to attempt to identifiy this condition.
 

Non-Laboratory Tests

Sometimes x-rays or CT scans may be used to evaluate body organs, such as the lungs or liver, for evidence of infection or damage.


Prevention and Treatment

Advance planning can help prevent many travellers' diseases. Check the Australian Smart Traveller website. Prior to a trip, people should consult with their doctor and verify that they have been vaccinated for diseases such as mumps, measles, rubella, polio, and tetanus and if any boosters are needed to maintain a protective level of antibodies. They should discuss their travel plans and get additional vaccinations as recommended for diseases such as hepatitis A, yellow fever, typhoid fever and meningococcal disease. For information from the CDC (Centers for Disease Control & Prevention, USA) on vaccinations, visit their Travelers' Health web site.

If they are going to go to areas where malaria is prevalent, they will usually be given chemoprophylaxis, such as mefloquine, doxycycline or chloroquine, to begin taking prior to their trip. These medications will need to be taken regularly during the trip and for a specified time period after the traveller's return. Some doctors may give their patients antimicrobial agents to take with them along with instructions on how and when they should be taken if symptoms appear during their trip.

Both the U.S. Centers for Disease Control and Prevention and the World Health Organization have current information on traveller’s health and preventative strategies. They also have up-to-date country- and region-specific travellers' disease information (see Related Pages tab).

In spite of taking every precaution, travellers may still become ill, either during their trip or several months after they have returned home. In general, the earlier the travellers' diseases are detected and diagnosed, the easier they are to treat. Travellers should know which symptoms signal the need to seek prompt medical care in the country they are visiting and which may be safely self-medicated. For several months after their return home, they should note any symptoms that occur and bring them to their doctor's attention.


Related Pages

On This Site

Tests: AFB Smear & Culture, FBC, Flu tests, Hepatitis A, Hepatitis B, Hepatitis C, HIV Antibody, O&P, Measles and Mumps, Rubella

Conditions: Diarrhoea, Viral Hepatitis, HIV, Tuberculosis, West Nile Virus, Malaria

Elsewhere On The Web

Smart Traveller (Aust government)
Travel Doctor

Centers for Disease Control and Prevention: Traveler's Health
World Health Organization: International travel and health publication
CDC NCID, Division of Parasitic Diseases: DPDx Laboratory Identification of Parasites of Public Health Concern
CDC: Diseases & Conditions 
MedlinePlus: Traveler's Health