Travel Medicine

1 Make sure travelers get up to date, timely, itinerary-specific advice from a reliable source (e.g., travel clinic, travel website).

Travellers are encouraged to plan their travel consult four to six weeks prior to their anticipated departure date. The reason for this timing is that your immune system needs time to generate antibodies to vaccines. You need to be immune when you arrive at your destination.

Infections to consider:

  1. Vector borne: malaria, dengue fever, cihkungunya fever, yellow fever, Rickettsia, West Nile virus, trypanosomiasis, Japanese encephalitis, tick-borne encephalitis, spotted fever, leishmaniasis
  2. Sexually transmitted: HIV, HBV, syphilis, usual STIs
  3. Zoonotic: rabies, hantavirus, tularemia, Q fever, anthrax, brucellosis
  4. Airborne: TB
  5. food/water: HAV, HEV, brucellosis, typhoid, paratyphoid, amoebiasis, dysentery, traveller’s diarrhea, cholera, campylobactor spp.
  6. soil/water: schistosomiasis, strongyloidiasis, leptospirosis, cutaneous larva migrans, histoplasmosis, paracoccidiodomycosis

2 When seeing patients planning travel, discuss the common, non-infectious perils of travel (e.g., accidents, safer sex, alcohol, safe travel for women).

General Travel Precautions

  1. Vector-borne: long-sleeves, long pants, hats, repellents (containing permethrin) applied to clothes, belongings nd bed nets, repellents applied to skin containing DEET
  2. food/water: avoid eating raw meats/seafood, uncooked vegetables, and milk/dairy products;
    1. drink only carbonated beverages, chlorinated water, boiled water, beer, wine
  3. Recreation: Caution when swimming in schistosomiasis-endemic regions, fresh water rafting/kayaking, beaches that may contain human/animal waste products, near storm drains, after heavy rainfalls
  4. Prophylaxis:
    1. Malaria: chloroquine, mefloquine, atovaquone + proguanil, coxycycline
    2. Traveller’s diarrhea: bismuthh salicylate
  5. Vaccines: Hep A/B, Japanese encephalitis, typhoid fever, yellow fever, rabies, ETEC, cholera
  6. All travelers should have standard vaccines UTD:
    • Hep B, MMR, tetanus/diptheria/pertussis (DTaP), varicella, polio
  7. STI/blood-borne infections: safe sex practices, avoidance of percutaneous injury through razors, tattoos, piercings

6 Use patient visits for travel advice as an opportunity to update routine vaccinations.

Routine immunizations: 

  • influenza, Tdap [tetanus, diphtheria, and pertussis], MMR [measles, mumps, and rubella], poliovirus, and varicella vaccinations are current.
  • Travelers to destinations in the developing world are at increased risk for infection due to these pathogens and in some cases additional doses are indicated.

Available travel immunizations: 

  • Travelers to the less developed world should have adequate immunity against measles, mumps, rubella, tetanus, diphtheria, pertussis, varicella, and haemophilus influenza B.
  • Travelers to Asia and Africa should have adequate immunity against poliovirus
  • Long-term travelers should be immunized against Hep B
  • Hep A is the most frequent vaccine-preventable, travel-realted illness
Risk factors of Typhoid:
  • Traveling beyond the usual tourist itineraries
  • Long-term travelers, travelers staying with family and friends in less developed nations
  • Immunocompromised person and pt with chronic medical conditions

 3 In patients presenting with symptoms of infection without an obvious cause, especially those with a fever, enquire about recent travel history to identify potential sources (especially, but not exclusively, malaria).

Fever in the Returned Traveller

Etiology:

  1. Common etiology:
    • Parasitic: Malaria (20-30%)
    • Viral: non-specific mononucleosis-like syndrome, dengue, viral hepatitis
    • bacterial: typhoid from salmonella, rickettsioses
    • Diverse group of causative pathogens: traveller’s diarrhea (10-20%), RTI(10-15%), UTI/STI (2-3%)
  2. Routine infections that are common in nontravellers: URTI / UTI
  3. Non-infectious causes: DVT / PE

Hx:

  1. Pre-travel preparation: Immunizations, malaria prophylaxis, personal protective measures (clothing covering skin, insect repellent, bednets)
  2. Travel itinerary: When, where, why, what, who, how
    • Dates of travel (determine incubation period)
    • Season of travel: wet/dry
    • Destination: country, region (urban/rural), environment (jungle, desert,etc)
    • Purpose of trip
  3. Persons visiting friends / family more likely to be exposed to local population & pathogens
    • Style of travel: lodgings, camping, adventure travelling
    • local population: sick contacts
    • Transportation: use of animals
  4. Exposure Hx
    • Street foods, untreated water: ↑risk of traveller’s diarrhea, enteric fever
    • uncooked meat/unpasteurized dairy:  ↑risk of parasitic infection
    • body fluids: sexual contacts, tattoos, piercings, IVDU, other injecitons
    • increased risk of HBV, HCV, HIV, GC, C. trachomatis, syphilis
    • animal/insect bites:  ↑risk of malaria, dengue, rickettsioses, rabies
  5. Fever pattern
  6. Incubation period: Use the earliest & latest possible dates of exposure to narrow the ddx & excludes serious infections
    • <21d: consider malaria, typhoid fever, dengue fever, rickettsioses;
      • exclude HBV, TB
    • >21d: consider malaria, TB;
      • exclcude dengue fever, traveller’s diarrhea, rickettsioses
  7. body systems affected: GI, resp, CNS, skin

Ix:

  1. All travelers with fever should undergo the following tests:
    • b/w: CBCD, LFT, electrolytes, Cr/GFR, thick & thin blood smears (for malaria), blood C&S
    • urine: U/A, U Cx
  2.  Special tests based on Hx / S/Sx, geography:
    • Stool C&X, O&P
    • CXR
    • dengue serology for IgM

Fever In the Returned Travellers

  1. Malaria – see malaria post
  2. Dengue
  3. Typhoid (enteric fever)
  4. Tick typhus
  5. TB
  6. Mononucleosis

4 Provide prevention and treatment advice and prescribe medications for common conditions associated with travel (e.g., traveler’s diarrhea, altitude sickness).

  • Air travel is associated with risks including venous thrombosis, diminished oxygen tension, changes in cabin pressure affecting ears or sinuses, and jet lag.
  • Cruise ship travel has been associated with gastrointestinal disease outbreaks.
  • Environmental exposures warranting additional counseling include diving and high-altitude travel

High altitude illness:

Acute mountain sickness (AMS) and high altitude cerebral edema (HACE) are considered to represent two points along a single spectrum of disease, with the same underlying pathophysiology. Increased cerebral vascular permeability is a central feature that occurs through a number of mechanisms

Dx – clinically

  • In a person who lives at low altitude but has recently ascended to high altitude (generally over 2000 m).
  • Symptoms resemble those of an alcohol hangover:
    • primarily headache often associated with fatigue, lightheadedness, anorexia, nausea and vomiting, disturbed sleep, and mild shortness of breath with exertion.
  • Onset of AMS is usually delayed for 6 to 12 hours following arrival at high altitude, but can occur as rapidly as one to two hours or as late as 24 hours.

Risk Factors

  • Past history of HAI (strongly predictive if conditions are similar)
  • Rate of ascent
  • Altitude attained, especially sleeping altitude
  • Vigorous exertion prior to acclimatization
  • Substances (eg, alcohol) or conditions that interfere with acclimatization
  • Comorbidities that interfere with respiration (eg, neuromuscular disease) or circulation (eg, pulmonary hypertension)

Preventions

  • Gradual ascent is the surest and safest method of preventing or ameliorating HAI.
    • As a general guideline, individuals who normally reside below 1500 m (5000 feet) elevation should avoid an abrupt ascent to sleeping altitudes above 2800 m (9200 feet).
  • Alcohol and sedative-hypnotics should be avoided during acclimatization.
  • Vigorous exertion at altitude contributes to the development of both AMS and HAPE, and should also be avoided during acclimatization.

Tx

  • Mild illness can be managed conservatively (avoid ascent, limit activity) with symptomatic treatment (eg, analgesic, antiemetic)
  • Moderate to severe symptoms may require medication (eg, acetazolamide, dexamethasone), supplemental oxygen, and occasionally descent. In the field, portable hyperbaric therapy may helpful.
  • dexamethasone immediately upon the first suspicion of HACE. The initial dose is 8 to 10 mg given orally, intramuscularly (IM), or intravenously (IV), followed by 4 mg every six hours until complete descent is achieved. Dexamethasone is NOT a substitute for immediate descent.

Prophylaxis

  • Clinicians should reserve prophylactic medications for high-to-moderate risk situations, particularly individuals with a history of altitude intolerance. Even in individuals with a previous history of HAI, gradual ascent should be emphasized over pharmacologic prophylaxis.
  • Prophylactic acetazolamide (carbonic anhydrase (CA) inhibitor) should be given to individuals with a history of HAI who ascend to altitudes above 2500 m. It is also reasonable to give acetazolamide to individuals without such a history who travel directly from low altitude (near sea level) to altitudes above 2800 m.
  • A clinically effective preventive dose that also minimizes side effects is 125 mg every 12 hours (250 mg daily), although most clinical trials have been performed with higher doses

Traveler’s Diarrhea

  • Travelers’ diarrhea is a common entity and can be induced by a variety of bacteria, viruses, and parasites.
  • It is uncommon to have to make an etiologic diagnosis. Stool cultures or examination for ova and parasites should generally be reserved for cases that last beyond 10 to 14 days, except for patients with fever and colitis, those with upper intestinal symptoms in whom giardiasis is more likely, or immunocompromised patients.
    • Routine stool cultures are rarely warranted routine since ETEC and EAEC cannot be distinguished from nonpathogenic E. coli on stool culture and viral agents would not be identified with stool cultures.
  • The mainstay of therapy for travelers’ diarrhea is fluid replacement. Attention to fluids including those with sugar and salt is sufficient for mild diarrhea but severe diarrhea should be treated with oral rehydration solution. Packets, which can be reconstituted in clean drinking water, are available for sale in most countries.
  • Travelers should be given a prescription for antibiotics to fill and take with them in case diarrhea develops. Antibiotics should be taken by the traveler if unformed stools occur more than four times a day or for fever, or blood, pus or mucous in stools
  • Ciprofloxacin 500 mg bid up to three days 20 to 30 mg/kg per day div bid for up to three days; maximum dose 500 mg
  • Medical care should be sought if fevers persist beyond 10 to 14 days or if fevers become higher, or abdominal pain, bloody diarrhea, or vomiting ensue.
  • Antimotility agents are usually not necessary for mild to moderate diarrhea and should not be used in severe diarrhea except in association with antibiotic therapy. These agents should be discontinued promptly if abdominal pain develops, other symptoms worsen, or diarrhea persists.
  • Attention to choices of food and drink, water purification, and antibiotic prophylaxis are all means of attempting to prevent travelers’ diarrhea. Antibiotic prophylaxis is usually reserved for patients in whom dehydration would put them at severe risk.
  • Although enterotoxigenic E. coli (ETEC) predominates as an etiology of travelers’ diarrhea, vaccination strategies that have focused on this pathogen as a target have been suboptimal.
Prevention
  • Avoid uncooked foods (other than peeled fruits / vegetables), unbottled or unpasteurized products
  • Eat only well-cooked hot foods and avoid foot purchased from street vendors
  • Use bottled or treated water for all drinking, teeth brushing, and making ice cubes
  • Wash hands with soap and water before each meal

5 Ensure patients understand how to manage their chronic disease while traveling (e.g., diabetes, asthma, international normalized ratios [INRs]).
7 Advise patients to check insurance coverage issues especially in regard to recent changes in chronic disease and any recent treatment changes.

8 Advise patients traveling with medications to have an adequate supply, documentation of need for use, and to transport them securely (e.g., carry-on bag).

Basic Medical Kit:
  • Thermoeter, tweezers, bandages, tape, arm sling, tensor bandage, sunscreen ± sterile disposable syringes, needles, gloves
  • Topical abx, analgesics, antimotility
  • Trip related and Rx medications
  • Carry a list of medical conditions, allergies, medications, dosages, and contact numbers
  • If cardiac problem, carry a copy of a recent ECG
  • Water purification tablets or purifier
  • Consider medical evacuation insurance in addition to routine travel medical insurance

References

  • TN 2013 ID
  • UTD Travel medicine
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Posted in 93 Travel Medicine, 99 Priority Topics, FM 99 priority topics, ID

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