10 COMMON INFECTIOUS DISEASES FOR THOSE TRAVELING ABROAD + PRECAUTIONS

While travel is often exciting and enjoyable, contracting an infection abroad can detract significantly from the experience. Many have fallen ill as a result of entering a new environment, particularly those that promote culture shock in the individual.

Fortunately the most common infections to afflict travelers are well-known and over the course of the last century, highly successful prevention measures have been developed to ward them off!

Global infectious diseases to affect travelers mostly consist of mosquito-derived illnesses and food or water-borne infections. The below article reviews these types of infections, as well as a few more diseases that commonly affect travelers. Symptoms, high risk regions, precautions and treatment options are also discussed.

Food and Water Borne Infections

Outbreaks of food and water borne infections typically occur in over-populated, temperate areas that have poor sanitation facilities, adopt unhygienic practices and that are prone to power outages.

The most common ones known to affect travelers are Cholera, Hepatitis A, Traveler’s Diarrhea and Typhoid, as discussed below alongside tips for preventing food and water borne infections abroad.

1. Cholera

Cholera is a bacterial disease spread through water contaminated with infected sewage. It is often found in overcrowded areas where citizens have adopted poor hygiene practices or where optimal sewage infrastructure is lacking.

The organism secretes a toxin that causes the body to release large amounts of stored water into the intestine in order to flush it out. Dehydration is the main consequence of having a cholera infection. Those with poor digestive function are at an increased risk for cholera as the organism is usually unable to survive in stomach acid.

Symptoms

Symptoms of cholera typically take up to 14 days to manifest post infection and can include^[1]:

• Long-lasting diarrhea with a pale, milky appearance
• Nausea
• Vomiting
• Extreme dehydration
• Fatigue
• Cramps

Some individuals with Cholera may not notice any symptoms or only experience very mild symptoms.

Complications can include those associated with severe dehydration, such as muscle wasting, low blood sugar, low electrolyte count, and kidney failure. Those with chronic Cholera or who contract the disease while already severely dehydrated stand a risk of death due to hypovolemic shock.

Countries at Risk

Countries most at risk for cholera include the majority of those in central and southern Africa, South-East Asia and Haiti.^[2]

If traveling to any of these regions, check the risk for the specific country you intend to visit. It’s worth mentioning that the risk is likely to be contained to specific areas within a cholera-endemic country and that a less crowded area may be at a lesser risk than other areas.

Travel Precautions

Travelers going to an area in which Cholera is endemic or where there is an outbreak occurring ought to be careful with regard to hygiene, food and water (see ‘Preventing Contamination of Food and Water Abroad’ below). ^[3]

Keeping hydrated can help to reduce the severity of diarrhea if one happens to get infected. Furthermore, probiotics and zinc have been shown to reduce the risk of infection as well as lower the length and severity of symptoms. Probiotics and bitter foods beneficially enhance the acidity of the stomach and gut, helping to degrade unwanted bacteria before they have a chance to infect the gut.

Cholera vaccines are available, however, they do not offer complete protection^[4] and are only recommended to those who intend to stay for long periods of time in countries with a high risk of infection.^[5]

Treatment

The first prescription for cholera tends to be an oral rehydration solution. Antibiotics are not recommended at first as these can contribute towards microbial resistance, promoting chronic cholera.

Zinc has been shown to reduce the severity and infection time in children under age 5.

For severely dehydrated individuals, a combination of IV rehydration and antibiotics are administered.

2. Hepatitis A

Hepatitis A is a liver virus, commonly contracted through consuming contaminated food or drinks abroad. It may also be passed on through close contact with an infected person.

Viral particles make their way to the liver via the gut, where they replicate. During infection, the liver can become severely damaged. Chronic infection may result in liver disease. The virus is cleared through bile and exits via the feces, which remains to be the number one vector for the virus. Transmission through close contact with the blood of an infected person may also spread the virus.^[6]

Symptoms

Hepatitis A can present with mild to severe symptoms. These include:

• Nausea
• Vomiting
• Bilirubin in stool (orange color)
• Dark urine
• Abdominal discomfort where the liver is situated
• Fever
• Fatigue
• Itchiness
• Muscle wasting
• Jaundice (orange-yellow complexion with yellow-tinted eyes)

The virus takes between 14-28 days on average to incubate. Many who contract the infection are asymptomatic. In symptomatic individuals, symptoms develop roughly 2-7 weeks after infection occurs. They tend to resolve within 2 months, however some may experience symptoms for up to 6 months.^[7] Only 10% of those with hepatitis A develop jaundice.

A subset of those with the virus can experience a relapse, after which recovery is usual.

Countries at Risk

Countries where Hepatitis A is endemic, include parts of South Asia and Sub-Saharan Africa. Outbreaks are rare in these countries as immunity is developed at an early age in children who have contracted the virus. Nonetheless travelers without immunity are still susceptible.^[8]

Travel Precautions

Travelers can protect against contracting Hepatitis A by practicing good hygiene and avoiding potential sources of contamination. Bottled water and properly cooked food can help reduce the risk of contracting Hepatitis A^[9] (see ‘Preventing Contamination of Food and Water Abroad’ below).

If traveling to a high risk country, a vaccine can provide increased immunity that lasts for at least 17 years, if not longer. Two doses are required for optimal immunization, 6 months apart. The second dose may be staggered if one is required to travel swiftly, with one dose offering protection for over a year on average.^[10] Vaccines are only recommended to those below the age of 40, as the efficacy is compromised in those older.

Treatment

There is no treatment for Hepatitis A aside from plenty of rest and rehydration. Once symptoms occur, it is a good idea to consult with a doctor to make sure that there are no complications pertaining to liver disease or failure.

3. Traveler’s Diarrhea

Traveler’s Diarrhea is a generalized term given to any gastric upset a traveler may experience while abroad. It commonly affects 30-70% of those traveling, depending on the destination and time of year.

Pathogenic contamination of food or beverages is the most common cause, typically as a result of poor hygiene practices in restaurants.

Symptoms

Symptoms of traveler’s diarrhea include^[11]:

• Abdominal cramping
• Three or more watery stools a day
• Defecation urgency
• Nausea
• Vomiting
• Fever

The onset of symptoms differs depending on the cause. Generally, incubation takes 6-72 hours and may last 2-7 days on average. If persistent for weeks to months, then it is a sign of protozoal infection and should be treated with appropriate antimicrobials.

Some travelers experience chronic traveler’s diarrhea, which can lead to irritable bowel syndrome, reactive arthritis, or Guillain-Barre syndrome.^[12]

Countries at Risk

All foreign countries convey a risk for traveler’s diarrhea. However, developing nations or regions in which electricity supply is frequently cut, or where there is inadequate sanitation, are prone to a higher risk of food and water contamination. Regions that are hot and humid experience more cases of traveler’s diarrhea on average by comparison to other climates.

Furthermore, some individuals are likely to be more sensitive to foreign cuisine vastly different to that of their home country, making the risk specific to the individual.

Travel Precautions

Travel precautions demand practicing good hygiene, as well as avoiding contaminated food and water (see ‘Preventing Contamination of Food and Water Abroad’ below).

Sensitive individuals may benefit from taking preventative drugs, antimicrobials and/or probiotics. Probiotics and non-antimicrobial drugs appear to have better efficacy than prophylactic antibiotics.

Stress can also contribute towards stomach upsets and ought to be managed when visiting a foreign country.

Treatment

Traveler’s diarrhea usually resolves on its own and it’s rare that treatment is required. If symptoms do not dissipate after a week, then consult with a doctor for an appropriate antimicrobial.

While symptoms are current, antimotility agents may be useful in reducing their severity. Antimotility agents are not recommended in those with fever or bloody stool.

Severe diarrhea ought to be treated with an oral rehydration solution to replace lost electrolytes and treat dehydration.

4. Typhoid

Typhoid is the infectious disease caused by Salmonella typhi and/or Salmonella paratyphi. The disease caused by the latter can also be referred to as Paratyphoid. However, as there is no way to distinguish between the symptoms of both, they are often collectively known as enteric fever. Food and water contamination are the most common routes of transmission. Eggs and poultry are especially prone to carrying Salmonella.^[13]

Once ingested, Salmonella bacteria are most commonly destroyed in the stomach due to the acidity. In those with compromised digestive function, or those who consume large amounts of Salmonella, the organism makes it through to the intestines. Once there, it releases various toxins that erode the lining of the gut and promote its uptake by gut cells into the bloodstream. Immune cells attempt to confine it to the gut’s lymphatic system, however Salmonella toxins have the ability to inhibit the immune system. Symptoms occur once the bacteria has disabled immune function and had a chance to proliferate.

Symptoms

As the name suggests, gastrointestinal distress is a common early symptom of enteric fever, which can spread systemically if left untreated.

Symptoms present within 12-48hours post exposure and include^[14]:

• Nausea
• Vomiting
• Abdominal pain
• Cramping
• Tummy bloating
• Diarrhea, or (rarely) constipation
• Rapid weight loss

After 1-3 days, the bacteria can move into systemic circulation. This leads to different symptoms including fever, lethargy and other flu-like symptoms. Some patients develop pneumonia, respiratory distress and chest pain pertaining to myocarditis or pericarditis. This phase can last for weeks to months, unless proper treatment is sought.

Long-term complications of typhoid can include tissue damage (necrosis) and hemorrhage (internal bleeding).

Countries at Risk

Salmonella infections are common throughout all countries of the world. The risk for contracting typhoid is greater in temperate and tropical countries with poor sanitation, frequent power outages and overcrowded regions.

Travel Precautions

Travel precautions demand practicing good hygiene, as well as avoiding contaminated food and water (see ‘Preventing Contamination of Food and Water Abroad’ below).

Gut flora protect against Salmonella infection, which can be promoted by optimal nutrition, probiotics, and avoiding the use of prophylactic antimicrobials. Antibiotics are known to make the infection more persistent if taken prior to infection.

Typhoid vaccines have been developed that reduce the risk of acquiring typhoid. These are recommended for travelers entering a high-risk area^[15]. A booster shot is required every 5 years for long-lasting immunity.

Treatment

Antibiotics are often administered once typhoid has been confirmed. If contracted in a high risk country, stronger antibiotics are prescribed in order to help protect against resistant strains of Salmonella. It’s important that the right medications be used to treat typhoid, as the bacteria are able to proliferate inside immune cells, which simultaneously protects them from conventional treatment options.

Aside from antibiotics, oral rehydration is important post infection. In severe cases, hospitalization may be required to stabilize the patient’s vitals.

Preventing Contamination of Food and Water Abroad

Food and water borne infections are typically transmitted through the four ‘F’s’: flies, fingers, feces, and fomites (surfaces that are conducive to bacterial breeding). Food and water are included in fomites, as are surfaces in the kitchen, bathroom, at plumbing outlets, and in public places.

When traveling, it’s important to maintain optimal hygiene to avoid contamination from the above four factors. Hand washing, disinfecting surfaces, and keeping flies at bay can go a long way towards preventing an infection of this type.

Only consume bottled water, sealed food, and hygienically-prepared food, especially when traveling to a country with a high risk of any of the below infections. Raw, cooler foods stand a greater risk for spreading infections than cooked, warmer food. Special attention ought to be paid towards seafood, poultry, and eggs, which ought to be cooked thoroughly before consumption. Commercially available ice and sushi may not be safe. If consuming raw fruit, then it's best to opt for those one can peel.

It’s equally important to avoid water that could be contaminated by infected individuals, such as from rivers, lakes, and dams. If bottled water is not an option, then either boiling or disinfecting tap water can help to reduce the risk of infection. Disinfectants may be available at a local pharmacy.

Mosquito-Related Infections

Mosquitoes are some of the most persistent vectors for disease, particularly in tropical regions near bodies of water.

The most common mosquito-borne illnesses to affect travelers include Dengue Fever, Japanese Encephalitis, Malaria, and Yellow Fever. Following on from these, tips for preventing mosquitoes are shared below.

5. Dengue Fever

Dengue fever is a viral infection transmitted by mosquitoes. It is usually confined to tropical and subtropical regions around the world. There are four types of dengue virus. While symptoms are the same for all types, immunity is type-specific.

The virus makes use of proteins on its outer coating to bind to cells. Once bound, it invades the cell and causes the cell to produce more virions. Some of its viral by-products increase inflammation and remain in circulation after the infection subsides. These are suspected to increase the risk for more severe forms of dengue upon reinfection, as they result in higher viral loads.^[16]

Symptoms

Dengue fever typically produces symptoms that mimic the flu, which include:

• High fever
• Fatigue
• Muscle, bone and/or joint pain
• Pain behind the eyes
• Nausea and vomiting
• Abdominal pain
• Loss of appetite
• Headaches
• Rash and itching
• Swollen glands

Symptoms usually resolve within a week of onset. The dengue fever virus can take 4-10 days to incubate before symptoms manifest. Symptoms usually resolve within 4-5 days, but may take as long as 12 days in some individuals.

Severe dengue fever is a potentially-lethal complication of dengue; also known as severe dengue, dengue hemorrhagic fever or dengue shock syndrome. This form usually occurs in those that have had ordinary dengue at least once before. Symptoms of this severe complication begin within 1-2 days after the initial fever resolves, and include:

• Persistent vomiting
• Severe stomach pain
• Bleeding from the gums, nose, under the skin (looks like bruising), in vomit, stools and in urine
• Respiratory distress
• Restlessness
• Severe fatigue

In this condition, blood vessels are damaged and have become leaky. If left untreated, this can result in organ damage, failure and eventual death. Immediate attention is required should this complication arise post dengue fever.

Countries at Risk

Dengue fever is mostly found in tropical and subtropical regions of the world, with the majority of the burden being confined to South-East Asia. Africa, tropical regions of the Americas, the Western pacific and parts of the Mediterranean are also affected by Dengue outbreaks.^[17]

According to the WHO, dengue was most active in 2021 throughout Brazil, the Cook Islands, Columbia, Fiji, Paraguay, Peru, Reunion islands and Kenya.

Travel Precautions

As the virus is transmitted by mosquitoes, it’s very important to reduce exposure to them (see ‘Mosquito Prevention Measures’ below). Pregnant women should take stricter precautions in order to avoid dengue-related birth complications.^[18]

While a vaccine for dengue exists, it is only prescribed to those living in endemic areas where infection rates are high. It is also only administered to those who have already been previously infected in order to avoid complications.

Treatment

There is currently no treatment for dengue. Physicians recommend lots of bed rest, keeping hydrated and making use of medication for pain relief or to break the fever. Acetaminophen (paracetamol) is best. Aspirin or ibuprofen are not recommended for breaking the fever.

If the fever goes over 40˚C (104˚F) or symptoms of severe dengue begin to manifest, it’s important to visit a hospital immediately.^[19]

6. Japanese Encephalitis

Japanese Encephalitis is another mosquito-derived viral illness commonly found in areas with a tropical climate. Mosquitoes acquire new variants of the virus from birds and pigs, wherein intermediate replication takes place.^[20]

Once bitten, the virus propagates from the mosquito bite into the bloodstream and nearby lymph nodes. The virus is infamous for it’s potential to invade the nervous system and promote lifelong neurological disability. In some cases it can be lethal.

Japanese Encephalitis cannot be passed on from one person to another.

Symptoms

The virus incubates for 6-8 days on average. After which the following general symptoms typically occur for several days:

• Fever
• Fatigue
• Headache
• Nausea
• Vomiting
• Diarrhea

Most people recover with mild or no symptoms. ^[21]

Severe cases of Japanese Encephalitis progress to encephalitis, in which the virus infects and damages the nervous system. Neurologic stem cells are some of the prime cells affected, impairing the patient’s capacity for neurogenesis.

Other symptoms of severe Japanese Encephalitis include:

• Reduced cognitive ability
• Psychosis
• Agitation
• Confusion

Seizures (more common in children), mutism, and flaccid paralysis are complications that may develop. Patients may develop dystonia, muscle rigidity, and slight tremors that resemble Parkinson’s Disease.

Countries at Risk

Countries belonging to South-East Asia and the Western Pacific regions are virtually the only areas that are known to have a risk for Japanese Encephalitis.

Travel Precautions

Infection rates in travelers are low. Travel precautions include reducing exposure to mosquitos (see ‘Mosquito Prevention Measures’ below). A Japanese Encephalitis vaccine exists that is recommended for those planning to spend more than one month in an endemic country, or for a shorter stay in a rural area.

Treatment

There is no direct treatment for Japanese Encephalitis. If one contracts symptoms, one ought to seek immediate medical attention. Therapy consists of providing intravenous fluids and administering medications to break the fever if it gets too high.

1% of those who contract Japanese Encephalitis go on to experience neurological manifestations of the disease. Of those that contract severe disease, 30-50% end up with neurologic disability and 20-30% do not survive.^[22] Those with neurologic disability may require rehabilitation in order to learn to live with their condition.

7. Malaria

Malaria is one of the worst types of parasitic infections transmitted by mosquitoes. There are five mosquito species capable of spreading Malaria that are common to tropical regions of the planet.

The parasite usually travels to the liver first, where it remains relatively dormant until it has reached maturity. Mature parasites then leave the liver to carry out the lifecycle in the bloodstream. This is when symptoms typically manifest.^[23] When in the bloodstream, the parasite gives rise to a cyclic pattern of symptoms in which the patient experiences fevers every few hours to days. Malaria can be fatal if left untreated.^[24]

Symptoms

Symptoms of Malaria include:

• Fever
• Fatigue
• Headache
• Muscle weakness and cramps
• Digestive problems
• Cardio-respiratory difficulties

Seizures may develop in severe cases. Adults may additionally experience jaundice, confusion, and dark urine; while children with severe infection can land up in a coma.

An active infection can last anywhere between 2 and 24 weeks. Malaria may relapse in 6 months to 20 years after one had an initial infection, depending on what type of mosquito-transmitted the parasites.

There are three main complications of malaria that are all lethal. They account for the following:

• Cerebral malaria is a condition in which malaria reaches the nervous system, promoting swelling in the brain. Symptoms consist of headache and cognitive decline followed by violent behavior, extremely high fevers, metabolic acidosis, potential coma or seizures, and eventual death. 80% of malaria-related deaths are as a result of this complication of Malaria.
• Severe malarial anemia results from an autoimmune response towards red blood cells, which can develop as a result of long-term Malaria. The parasite makes use of red blood cells to reproduce, with anemia being a common symptom. The body mounts a defense by destroying infected blood cells. When this response becomes faulty, severe malarial anemia can develop in which any blood cells are attacked by the immune system. Eventually, red blood cells stop being produced.
• Nephrotic syndrome can develop as a result of excessive blood protein levels, which results in reduced kidney function, damage,and potential kidney failure.

Countries at Risk

The highest risk of contracting Malaria is found in sub-Saharan African countries, which contain more than 90% of infections globally. These countries also have the highest risk of mortality. South-East Asia, the Western Pacific, and Central America are also Malaria-endemic regions.

Travel Precautions

Travel precautions include reducing exposure to mosquitos (see ‘Mosquito Prevention Measures’ below).

Additionally, before travelling to an area with a high risk for Malaria transmission, it’s a good idea to consult with a healthcare physician about prevention. A doctor is likely to prescribe an antimalarial drug that can help lower the risk of infection in the event of being bitten by suppressing the life cycle of the parasite.

An anti-malaria vaccine is available; however, it is only recommended for children that live in a malaria-endemic area (specifically with P. falciparum mosquitoes).^[25]

Treatment

Malaria is treated with anti-Malarial drugs (e.g. malarone, doxycycline or mefloquine) and supportive care. If symptoms present, one ought to seek hospitalization immediately. Those with severe infection need to remain hospitalized for longer than 24 hours.

8. Yellow Fever

Yellow Fever is a hemorrhagic viral infection, with symptoms similar to that of Dengue Fever. It is most commonly passed on through mosquito bites and can infect both humans and monkeys. The virus is known to have three transmission phases: jungle, intermediate, and urban. Mosquitoes transmit the virus from jungle monkeys to those who work in rural areas near jungles. Eventually, the virus made its way into an urban setting. Through these transmission phases, distinct variants have been created.^[26]

Once bitten, the virus spreads rapidly through the whole body, capable of causing damage to multiple organs and tissues. The liver is the primary site of replication and is often the most damaged post-infection. The kidneys, central nervous system, digestive organs, and immune system^[27] are also heavily affected.

Symptoms

Symptoms of Yellow Fever can range from mild to severe. The virus incubates over the course of 3 to 6 days, in which the following is commonly experienced:

• Fever
• Chills
• Headaches
• Joint and muscle pain

After the initial fever, the patient enters a remission period of 24-48 hours. After this, a relapse of fever occurs in a subset of people, which produces extreme fevers and toxicity. In addition to severe forms of the above, symptoms of the second phase include:

• Jaundice (yellow color to the skin and eyes, hence the name ‘yellow fever’)
• Dark urine
• Vomiting (may present as black due to blood)
• Bleeding from the digestive tract and nose
• Encephalitis or cerebral edema
• Brain hemorrhage

If the patient makes it to the second phase, the risk of mortality is high (roughly 50%)^[28]. Urgent hospitalization is required for those with severe symptoms.

Countries at Risk

Yellow Fever is endemic to tropical regions of Africa and South America.

Travel Precautions

Travel precautions include reducing exposure to mosquitos (see ‘Mosquito Prevention Measures’ below).^[29]

A live-attenuated yellow fever vaccine has been developed for travel to endemic regions. It is usually required for travel from people that have just visited a high-risk area. If considering a yellow fever vaccine for travel, it’s important to consult with a doctor first to make sure it’s not contraindicated in your case.

Treatment

There is no treatment for yellow fever. Patients that come down with severe symptoms require immediate hospitalization in an intensive care unit. Rehydration and supportive care are the first port of call. For those with renal failure, kidney dialysis may be required. Plasma transfusion may be required for those with severe hemorrhage or coagulopathy.

Immune suppression is a well-known phenomenon caused by yellow fever. Patients may experience comorbid bacterial infections, for which antibiotics may be administered.

Mosquito Prevention Measures

Wearing long garments and making use of netting, air-conditioning or repellants can go a long way towards preventing dengue fever infection. Garments and netting can be sprayed with repellants to increase their efficacy.

No water should be left standing for long periods of time without being covered or sprayed.

Common Infections of the Wilderness

For those who dare to travel into uninhabited and rural regions, it’s important to be extra vigilant. Tick-borne illnesses and rabies are two of the main dangers to afflict travelers in the wilderness, as discussed below.

9. Rabies

Rabies is a viral disease caused by the rhabdovirus. It is transmitted through being bitten by wild animals infected with the virus, referred to as rabid animals.^[30]

The virus spreads from the wound in the periphery to the central nervous system, whereupon it enters the brain, promoting severe inflammation and brain swelling. It then travels back towards the periphery into highly innervated areas, leading to the classic symptom portrayed in movies where the patient is frothing at the mouth. Rabies is often fatal if left untreated.

Symptoms

After receiving a rabid bite, the patient often experiences tingling at the site of the wound in the first few days. The virus is capable of asymptomatically incubating for 2 weeks to 6 years after one is bitten. After the incubation phase, there is a prodrome phase, in which fevers, fatigue, headache, and other general viral symptoms are experienced.

Following on from these mild symptoms, the patient then becomes anxious, agitated, and then delirious. While occasionally seeming like frothing at the mouth, hypersalivation is common and often accompanied by muscle spasms in the throat. Less than 20% of patients may become paralyzed. Other complications include psychosis, dysautonomia, and seizures.

The brain and nervous system become severely damaged through the process. Eventual brainstem failure causes a coma, followed by swift death. This phase is reached within 10 days of showing severe symptoms.

Countries at Risk

Every country has a risk of rabies transmission. Wild animals affected are often different from country to country. It’s best to check before travel if you are going to be staying in an area affected by a rabies outbreak and whether you stand the risk of encountering a wild rabid animal while there.

Travel Precautions

Avoid areas where you may encounter a rabid animal, particularly one that carries a risk for the area you are visiting. In most cases, small animals, such as rats and rabbits, are not likely to transmit rabies as they typically do not survive being bitten by other rabid animals.

If traveling specifically to a wild area with a high risk of getting bitten by a rabid animal, it is recommended to vaccinate before departing. Rabies vaccinations have helped to reduce the number of cases, particularly when animals are vaccinated.

Treatment

If one is bitten by a rabid animal, the first port of call is to sterilize the wound vigorously. The wound ought to be thoroughly cleaned with soap and water or a disinfectant solution. If deep punctures are present, these ought to be swabbed and fully disinfected.

Physicians will treat for rabies if the patient has knowingly been bitten by an animal with a high risk of transmission. In this instance, a rabies vaccine and rabies antibodies will be administered to the patient immediately. If the patient is already vaccinated against rabies, a different type of vaccine is administered.

If uncertain, the healthcare practitioner may send off samples for testing to rule rabies out.

10. Tick-Borne Encephalitis

Tick-borne encephalitis is a disease transmitted from the bite of infected ticks. It is caused by a virus, simply known as the tick-borne encephalitis virus. There are three subtypes of the virus, transmitted by different kinds of ticks from different regions (European, Far Eastern, and Siberian). ^[31]

Once bitten, the virus takes time to incubate. The infectious phase is divided into two parts. The first part is systemic, resulting in generalized symptoms of illness. The second phase is localized to the nervous system. While symptoms can be long-lasting, tick-borne encephalitis is rarely fatal.

Symptoms

Up to 60% of infections are asymptomatic. Of those who experience symptoms, incubation can take 7-28 days before symptoms manifest. The first phase often presents with mild signs of viral infection, including a fever, fatigue, joint and muscle pain, stiffness, and headaches.

The second phase is generally more severe, giving rise to neurological symptoms including meningitis, encephalitis, myelitis, radiculitis, or paralysis.

Differences amongst the subtypes are as follows:

• European subtype: The first phase is very mild, with only 20-30% of patients going on to experience the second phase 1-33 days after the first phase is over. Only 10% of patients acquire severe neurological symptoms.
• Far Eastern subtype:  This type only presents with one phase of disease, in which more severe flu-like symptoms progress into neurological complications. This type has a high mortality rate of 35%.
• Siberian subtype: The Siberian type emulates a slightly more virulent version of the European type. Patients often develop chronic infections with little or no neurological symptoms.

Countries at Risk

All countries in Europe and Asia are endemic to tick-borne encephalitis.

The European subtype is present throughout all of Europe. The Far Eastern subtype is endemic to the far East of Russia, China, and Japan. The Siberian subtype is endemic in Siberia, the far East of Russia, the Urals region, and some parts of Northern Europe.

The intermediate seasons (spring and autumn) are when ticks are most active. In the Northern regions of Europe, ticks are active in Summer when the temperature is conducive for breeding. They are mostly found in grasslands and forests, on grasses and other kinds of low-lying vegetation.

Travel Precautions

If traveling to a wild part of Europe or Asia during the warmer months of the year, taking precautions against ticks is highly recommended. Wearing closed shoes, long garments (especially pants), and spraying one’s clothes with a tick repellant are the best-known precautions. Keep contact with wild animals to a minimum.

After arriving back from an outdoor expedition, check your body thoroughly for any ticks. If you find any, remove them with tweezers or forceps. Take special care to remove the teeth, as these are known to contain toxins that can increase the risk of contracting an infection.

Raw dairy products may also be contaminated with tick-borne encephalitis virus. Avoid consuming these and opt for pasteurized versions instead.

Vaccines are available against tick-borne encephalitis. These are only recommended for those living in an endemic country^[32].

Treatment

There is no known cure for tick-borne encephalitis. Symptoms are managed through supportive care. Of those who present with second phase symptoms, hospitalization is often required to prevent mortality.[1] 

Other On-Going Travel Outbreaks

Other outbreaks of the following viruses occur frequently in various parts of the world:

• SARS-COV-2 is a lower respiratory tract infection that is known to cause the disease COVID-19 and is responsible for the current global pandemic. Symptoms vary from mild to severe, with some individuals being asymptomatic. Common symptoms include loss of taste and smell, cough, fever, and fatigue. Some may also experience headaches, aches and pains, a sore throat, rashes or discoloration, eye irritation, or diarrhea. Vaccination is the best known prevention measure, accompanied by mask wearing, social distancing, and disinfecting hands and surfaces. Various travel restrictions have been imposed that are country-specific and it is advisable to stay away from areas with an outbreak of a new variant of concern.
• Avian Flu (also known as bird flu) refers to a family of avian viruses that are contagious amongst birds. Some bird flu viruses have the ability to infect humans as well. When traveling abroad, it is best to check for any known local outbreaks in the country you are headed towards.^[33] Precautions include avoiding poultry or cooking any poultry thoroughly, only consuming poultry products while hot. If traveling to an area with an outbreak, it’s important to keep one’s immune function strong by exercising, maintaining optimal sleep hygiene, and consuming a nutritionally balanced diet.
• Zika Virus is spread through close contact with Aedes Aegypti mosquitoes. Itching, a rash, pain in muscles and joints, a headache, conjunctivitis, and fever are the most common symptoms. While the infection is thought to be mild, lasting only 2-7 days, it can cause severe birth defects (e.g. microcephaly) in those whose mothers were infected while pregnant. Precautions against Zika Virus outbreaks in affected countries are the same as those described above (see Mosquito Prevention Measures).^[34]
• Chikungunya Virus is contracted through mosquito bites. Symptoms include fever and joint pain. There are no vaccines or medication that serves to protect against the virus. When traveling to a country with a Chikungunya virus outbreak, travelers are advised to use mosquito repellant, make use of netting or air conditioning, as well as wear long sleeves and pants.^[35]

Routine Vaccinations

Routine vaccinations are commonly administered to infants and children, often providing lifetime immunity against various infectious diseases.^[36]  Those who have not received the full regimen of routine vaccinations as children will benefit from receiving them prior to travel as they are more vulnerable to contracting the infections overseas.

In addition to unvaccinated individuals, those who have received a full regimen of routine vaccinations in their childhood should consider receiving the following routine vaccinations prior to travel^[37]:

• Measles (MMR) vaccines offer lifetime immunity, with an efficacy of up to 97%. An additional round of MMR is advisable to those traveling to a country with an active measles outbreak. In spite of vaccine efforts, outbreaks frequently occur across all continents^[38].
• Polio vaccination offers lifetime immunity. A booster shot is recommended for anyone traveling to either Pakistan or Afghanistan^[39], as these are the last two countries in the world where Polio wildtype virus is still active (as of 2016, Nigeria has been removed from this listing^[40]). A booster is also recommended if traveling to an area with an active outbreak.
• Tdap (Tetanus-Diphtheria-Pertussis) vaccination immunity lasts for 10 years. It is recommended that adults get booster shots to keep current. Immunity is especially pertinent to travelers entering regions where diphtheria outbreaks are common, including countries in Africa, central Asia and the former Soviet Union^[41].
• Influenza vaccines are routinely administered as part of the developmental immunity suite, however their immunity only lasts for 12 months. Everyone is advised to take annual influenza shots^[42]; particularly those traveling to a region with an active influenza outbreak or during flu season.
• Hepatitis B vaccines are recommended to travelers who have not been vaccinated against Hepatitis B. Immunity lasts for at least 20-30 years, if not longer; with further studies still being required to confirm if the vaccine offers lifelong immunity or not^[43]. A booster is likely not necessary for immune-competent individuals. However is it recommended to get one if one is traveling to a particularly high-risk area and blood levels of antibodies fall below 10mIU/mL^[44].

Travel Medicine Agencies Specialize in Coordinating Precautions

Before traveling abroad, particularly to tropical locations, it’s important to make sure you have everything you need for preventing potential infections. A travel medical specialist can help to organize all the relevant medications and vaccinations prior to travel to streamline the process. This type of agency is able to coordinate with your healthcare provider for prescriptions.

It’s best to consult with your doctor before getting any vaccination or medication as it may be contraindicated in your case. Those who are immune compromised or pregnant ought to take special precautions as many medical prevention measures are unsuitable.^[45]

A healthcare specialist ought to be contacted at least one month prior to travel^[46]. It may take a longer time if you require a vaccination.

Conclusion

Travel has traditionally been associated with infectious outbreaks. The preventive efforts of the last century have made travel safer and easier to enjoy by reducing the risk of contracting an illness while abroad.

It’s crucial to understand the nature of the destination you wish to travel towards and to be prepared in the event of contracting an infection. Emphasizing good hygiene, sealed food, and taking care not to expose oneself to potential vectors of disease are all important considerations to make prior to travel.

Find out beforehand if there are any medications or vaccinations you need in order to protect yourself from an outbreak in a high-risk location. Medical travel agencies are available that can assist with organizing the appropriate precautions. A consultation with a healthcare specialist is advisable in order to get scripts and to discuss which precautions are able to adequately meet your needs.

To search for the best doctors and healthcare providers worldwide, please use the Mya Care search engine.

Source: