The passengers travelling abroad are under the risk of several infectious diseases. Travel-related infections are seen particularly in the ones traveling to developing countries. Passengers traveling to developing countries may face some major infectious diseases transmitted through fecal and oral routes.
Some examples are diarrhea, hepatitis A, typhoid, cholera, polio; related to mosquito bite, yellow fever, Japanese encephalitis, malaria; whereas meningococcus menengitis, influenza and legionellosis are transmitted through respiratory route; hepatitis B, C and HIV are transmitted through sexual intercourse and being exposed to blood and bodily liquids; tick-borne encephalitis is due to tick bite, rabies occur because of dog bite.
Traveler should be vaccine routinely depending on age and underlying disease before the travel. These vaccines are tetanus, pertussis, diphtheria, Haemophilus influenzae type B, measles, rubella, mumps, chickenpox, pneumococcus and influenza. Moreover, hepatitis A and B, poliomyelitis, typhoid fever, Japanese encephalitis, and tick-borne encephalitis and rabies vaccines are recommended, if there is risk of traveled-related infection.
Before going to the specific areas where some infections are seen endemically, compulsory vaccinations must be done (Yellow fever, Neisseria meningitidis (Table 1).
Vaccines recommended to be shot routinely
Tetanus-diphteria-acellular pertussis (TDaB)
For children, TDaB is administered at 5 doses (single dose at 2, 4, 6 and 18 months of age and at 5 to 6 years of age).
For adults, one booster dose is given at 19 years of age; Td is repeated once every 10 years.
Haemophilus influenzae type B
For children, 4 doses are administered (2, 4, 6 and 18 months of age). For people undergoing splenectomy after 19 age, 1 dose is administered 15 days before surgery, while for bone marrow transplantation, 3 doses are administered at one-month interval in postoperative course. For other *risk groups, 1 or 3 doses are administered.
Measles- Rubella - Mumps
Single dose is administered at ages of 1 and 5 for children and after the age of 19 for adults. Vaccine is administered in 2 doses at one-month interval for people who plan an international trip, students and healthcare professionals (vaccine is not recommended for people aged <57, since they are deemed immunized).
1 dose per ages of 1 and 5 for children, and at the age of 19, 2 doses in case of a break of a month are recommended
Conjugate Pneumoccocal (PCV13)
1 dose is administered for children in 2, 4, 6 and 12-15 months of age, one dose for the *risk groups at age over 2 and 19.
Pneumoccocal Polysaccharide (PPSV23)
One dose of PCV13 is administered for the *risk groups of age >2, age > 19, and for the ones age >65 followed by one dose of PPSV23 two months after. A further dose of PPSV23 is administered 5 years after.
It is recommended to immunize children aged >6 months and adults every year. In the northern hemisphere, administration time is prior the influenza season (September-October-November) and in the southern hemisphere, it is administered on January-February-March.
Vaccines administered due to risk and recommendations
Contaminated water and foods carries risk of transmitting Hepatitis A, for the passenger traveling to developing countries, 2 doses of vaccination (6-month intervals) are recommended.
If there is a possibility of a medical operation, tattoo, piercing or a sexual intercourse with a new partner, 3 doses of vaccination are recommended (one dose in Month 0, Month 1 and Month 6).
Polio /Inactive Polio Virus (IPV)
For children, three doses are administered in month 2, 4 and 6-18 of age and fourh dose is administered at 4 to 6 years of age. IPV vaccine is dose in single dose to people who will travel to areas where polio could not be eradicated (Ethiopia, Kenya, Somalia, Syria, Afghanistan, Pakistan etc.) and was immunized before.
For those who will travel to developing countries with rabies risk (field work, camp, cycling or backpack travelers), 3 doses of vaccine (one dose on Day 0, 7 and 21) are administered prior to the travel.
The risk is higher in North and West Africa, south Asia, the Middle and South America and the Middle East. Single dose of vaccine is recommended for those aged ≥2 years, who will stay longer than a month, in areas where risk of exposure to contaminated food and water is high and the disease is endemic.
It is recommended for ones who will stay in East and Middle Europe and forestry areas and rural part of Siberia between April to October, since risk of contact with tick increases at those areas in this period. This vaccine is not available in our country. Those going to camp or work in plantation and forestry areas should wear long sleeved shirts and put the shirt into the pants and the pants into the socks and wear covered shoes and a hat; also, they should do a daily tick control on their bodies.
The vaccination is recommended for those who will go and stay in Russia, China, Japan, and KoreanPeninsula’s rural parts in the endemic season. (Figure 1) This vaccine is not marketed in our country. Those who stay in the rural part must wear clothes covering the body, such as long sleeved shirts, long pants and hats, and use fly-repellent sprays.
The vaccine is given as a single dose 10 days prior to travelling to risky areas. The vaccine provides protection for 10 years. For yellow fever, some countries in the South America (Peru, Ecuador, Brazil, Bolivia and Columbia) and in the equator area of Africa pose high risk. (Figure 2 and 3)
In the Sub-saharan Africa, the disease is prevalent from December to June. Meningococcus vaccine is a prerequisite, mandated by Saudi Arabia, for the ones going to visit Mecca and Madinah in the period of Hajj and Umrah.
*Risk groups: people with HIV, kidney disease, splenectomy, chronic heart, lung or liver diseases, diabetes, cancer patients, people who are on immunosuppressive therapy, people with cochlear implant, hemoglobinopathy, multiple myeloma, transplant patients and over 65 years.
Table 1. Vaccinations and suggestions before travelling
Personal hygiene and nutrition precautions: Most travel-related infections occur secondary to ingestion of contaminated food and water. Food sold in the open-unpacked foods-, raw nutrients and uncooked or undercooked meals are not safe. Ice should not be added to water and drinks. Canned or bottled water or drinks with no evidence of damage on package should be ingested. Well cooked and hot served food or canned foods must be preferred; uncooked-raw, undercooked meat and meat products, cream, salads with mayonnaise must be avoided. The best method to avoid travel-related tourist diarrhea is to “boil, cook, peel and wash”, and if we cannot do any of them, just do not eat or drink.
The most common disease seen among travelers is a tourist diarrhea. Diarrhea is seen in 50% of people traveling from developed countries to developing countries for 2-3 weeks period. The causative agents are Enterotoxigenic and Enterohemorrhagic Escherichia coli, Campylobacter, Salmonella and Shigella species. Viruses such as Noroviruses and protozoa such as Entamoeba histolytica can be also the causative agent, albeit in lesser rates.
Generally, antibiotics are not suggested for protection. The treatment must be arranged as per the stool analysis and culture result; however, since those analyses can be hardly done during travel, people going to risky regions can carry antibiotics, which are prescribed by physicians.
According to the report issued by World Tourism Organization, the first ten countries with highest tourist visits in the year 2013 are France, USA, Spain, China, Italy, Turkey, Germany, England, Russia and Thailand in descending order (according to number of tourists visited) (Table 2). Turkey is at 6th rank among countries which attract most tourists.
Incoming international tourists 2013 (million)
Incoming international tourists 2012 (million)
Table 2: The 10 most visited countries in the year 2013 in terms of international travel according to the World Tourism Organization report.
Malaria is a disease that causes the most frequent death among travel-related infections. The most risky regions in the world are Sub-Saharan Africa, Oceania (Solomon Islands and Papua New Guinea) and Vanuatu. The risk is intermediate in India and Haiti, whereas in Southeast Asia and Latin America it is low. Chloroquine-resistant malaria cases are increasing in Central South America, South East Asia and Sub-Saharan Africa. (Figure 4)
Chloroquine-sensitive P. Falciparum is common in Mexico, Caribbean, and Central America in the west and north of Panama Canal, North Africa, Middle East and China. Chloroquine-resistant P. vivax is common in Indonesia and Papua New Guinea.
In order to protect against malaria, Chloroquine tablet is started at the dose of 300 mg 1 week prior to visiting Chloroquine sensitive regions and it is maintained at dose of 1 tablet a week throughout the stay; next, it is taken at dose of one tablet a week for 4 weeks after return to home country. Visiting one week prior to Chloroquine-resistant malaria regions, mefloquine tablet (1 tablet a week) is started at the dose of 250 mg and it is taken at a dose of 1 tablet per week during stay and for 4 weeks after return. As an alternative, Atovaquone-progunail (250-100 mg) or Doxycycline 100 mg should be started 1 day before leaving, maintained at dose of one tablet per day during the stay and at dose of one tablet per day for 4 weeks on return. Also, in order to avoid mosquito bites, you may have lesser outdoor activities, wear long sleeved clothes and pants that are soaked with permethrin, sleep in indoor environment; and if those precautions are not available, a mosquito net that is soaked with permethrin (safe for the pregnant and children) is recommended; in addition, bug repellent solutions can be sprayed on the skin at nighttime. The most effective one is diethyl methyl benzamide (DEET). However, there is not enough data about safety of this product in pregnant woman.
In order to protect against sexually transmitted diseases such as HIV and other microorganisms, it is best not to have any sexual intercourse or to use condom though it is not 100% protective. In order to be protected from HIV, Hepatitis B and Hepatitis C, which are transmitted through contact with blood and body fluids as well as sexual intercourse, it is necessary to refrain from sexual contact and risky processes such as injection, tattooing, beard and hair shaving, and transfusion.
- Recommended Adult Immunization Schedule United States 2015, Mortality Weekly Report (MMWR) on February 5, 2015.
- Recommended Immunization Schedule for Persons Aged 0 Through 18 Years, United States 2015.
- The practices of Travel Medicine: Guidelines by the Infectious Diseases of Society of America. CID 2006;43: 1499-539.