Multisystem Processes & Disorders

Travel medicine: pre-travel counseling and prophylaxis

Clinical Overview and When to Suspect Travel-Related Risk

— Travel to low/middle-income regions (sub-Saharan Africa, South/Southeast Asia, Latin America)

— Long stays (>4 weeks), rural/remote itineraries, VFR travelers ("visiting friends and relatives")

— Immunocompromised hosts (HIV, transplant, biologics, asplenia), pregnant patients, infants

— Travelers with chronic conditions (DM, CKD, CAD, COPD, sickle cell) or planned high-altitude/diving/adventure activity

— Itinerary-specific risk map (CDC Yellow Book, Travax)

— Routine + required + recommended vaccines

— Malaria, traveler's diarrhea (TD), altitude, DVT, STI, rabies, and arbovirus counseling

— Insurance, evacuation coverage, and access to care abroad

— Self-treatment kit and personal protection measures

Step 3 management: When a patient presents <2 weeks before departure, do not defer the visit — prioritize malaria chemoprophylaxis, yellow fever (if required for entry, single dose gives lifelong immunity within 10 days), accelerated hepatitis A/B if needed, and TD self-treatment. Partial protection now beats perfect protection too late.

Board pearl: Always ask about purpose of travel (tourism vs. VFR vs. medical mission vs. business) — it changes risk profile more than destination alone.

Definition and scope: Pre-travel medicine is the structured risk assessment and prophylaxis planning for international travelers, ideally 4–6 weeks before departure to allow time for vaccine series, antimalarial titration, and chronic disease optimization.

Who needs a pre-travel visit:

Core deliverables of the visit:

Risk hierarchy: The most common travel-related illnesses are TD and respiratory infections; the highest-mortality preventable causes are road traffic injuries, drowning, and cardiovascular events — not infections. Malaria, however, is the leading infectious cause of death in returned travelers.

VFR travelers carry disproportionate risk: they underestimate exposure, less often seek pre-travel care, and have higher rates of malaria, typhoid, TB, and hepatitis A.

Presentation Patterns and Key History

— Who: age, comorbidities, immune status, pregnancy, medications, allergies, prior vaccines, prior travel illness

— Where: every country and region within country (urban vs. rural, altitude, season)

— When: dates, duration, time until departure

— What: activities (safari, freshwater swim, caving, sex, tattoos, medical care, food sources)

— Why: tourism, business, VFR, humanitarian, study abroad, adventure

— Chronic disease control (HbA1c, BP, INR stability, seizure control)

— Mental health (travel disrupts sleep, medications, support systems; SSRIs + tramadol/mefloquine interactions)

— Reproductive: pregnancy plans, contraception, menstrual suppression on trip

— Allergies: eggs (yellow fever, influenza), neomycin/gelatin (MMR), latex

— Adequate supply + extra; carry in original labeled bottles with copy of prescription

— Time-zone adjustment for insulin, OCPs, anticoagulants, antiepileptics, immunosuppressants

— Controlled substances: check destination legality (e.g., pseudoephedrine banned in Japan, ADHD stimulants in UAE)

— Sexual activity abroad → STI/HIV PrEP, condoms, emergency contraception

— Alcohol, recreational drugs, tattoos/piercings (HBV, HCV, HIV)

— Animal contact (rabies pre-exposure consideration)

— Freshwater exposure (schistosomiasis, leptospirosis)

Key distinction: Routine vaccines (MMR, Tdap, varicella, polio booster, influenza, COVID-19) are reviewed for every traveler regardless of destination; required vaccines (yellow fever, meningococcal for Hajj, polio for certain countries) are for entry/exit; recommended vaccines (typhoid, hepatitis A/B, rabies, JE, cholera) are destination- and activity-specific.

Board pearl: A measles outbreak in a U.S.-born adult traveler is a classic stem — confirm 2 documented MMR doses or immunity titers before any international travel, especially to Europe, Africa, or Asia.

Pre-travel history checklist (the "5 Ws"):

Targeted medical history:

Medication review:

Behavioral risk screen:

Physical Exam Findings and Pre-Travel Functional Assessment

— Vitals, BMI, baseline BP/HR for comparison if illness develops abroad

— Functional/fitness assessment for trekking, diving, altitude, or remote itineraries

— Murmurs, arrhythmias → consider stress test if planned strenuous activity or altitude >2500 m in patients with CAD risk

— Lung exam in COPD/asthma: FEV1, oxygen needs at altitude (predicted PaO2 falls ~30% at 3000 m)

— DVT risk assessment: prior VTE, malignancy, OCP, pregnancy, recent surgery, obesity — flights >4–6 hours

— Open wounds, eczema, tinea → may worsen in tropical climates; counsel on wound care kit

— Venous insufficiency → graduated compression stockings for long-haul flights

— Seizure history → mefloquine contraindicated; chloroquine lowers threshold

— Psychiatric history → mefloquine contraindicated in active depression, anxiety, psychosis, schizophrenia

— Confirm pregnancy status before live vaccines (MMR, varicella, yellow fever) and before doxycycline/primaquine

— Counsel on Zika: avoid travel to active transmission areas if pregnant or trying to conceive

— Recommend pre-travel dental check for long trips; carry spare glasses/prescription

Step 3 management: For a patient with stable CAD planning travel to >2500 m (Cusco, Lhasa, Addis Ababa), counsel gradual ascent, avoid alcohol, continue beta-blocker and antiplatelet, and consider supplemental O2 the first 24–48 hours. Recent MI (<4–6 weeks), unstable angina, decompensated HF, or recent stroke are relative contraindications to commercial flight and high-altitude travel.

Board pearl: Commercial cabins are pressurized to ~6000–8000 ft — patients with resting SpO2 <92% at sea level usually need in-flight supplemental O2 (arrange ≥48 hours pre-flight with airline).

General assessment:

Cardiopulmonary:

Skin and extremities:

Neurologic:

Pregnancy/GU:

Dental and vision:

Diagnostic Workup — Initial Labs, Titers, and Risk Tools

— CBC, CMP: baseline for travelers starting chemoprophylaxis with hepatic/renal metabolism (atovaquone-proguanil → renal; mefloquine → hepatic)

— G6PD level: mandatory before primaquine or tafenoquine (P. vivax/ovale radical cure or tafenoquine prophylaxis) — hemolysis risk in G6PD-deficient patients

— Pregnancy test (β-hCG): before live vaccines, doxycycline, primaquine, tafenoquine

— HIV test: if risk factors or planned sexual activity abroad; affects live vaccine eligibility

— Measles, mumps, rubella, varicella IgG

— Hepatitis A and B serologies (anti-HAV total, HBsAg/anti-HBs/anti-HBc) — particularly for healthcare workers, VFR, long-stay travelers

— Tetanus history (booster every 10 years; Tdap once in adulthood)

— Baseline IGRA or PPD before prolonged stay (>1 month) in high-prevalence area, healthcare/refugee work; repeat 8–10 weeks after return

— CDC Travelers' Health, WHO International Travel and Health, ISTM, Shoreland Travax

— Country-specific malaria maps (urban vs. rural, altitude cutoffs, drug resistance)

Key distinction: Yellow fever vaccine is the only travel vaccine that often requires written documentation (International Certificate of Vaccination — "yellow card") for entry; certificate valid for life starting 10 days after vaccination.

Board pearl: Always document G6PD status before primaquine — a stem describing a returned traveler with P. vivax who develops dark urine and anemia after primaquine = G6PD-mediated hemolysis. Stop the drug, supportive care, transfuse if severe.

Routine labs are not required for most healthy travelers. Targeted testing:

Immunity titers (when records unavailable):

TB screening:

Itinerary risk tools:

ECG: Consider baseline ECG if starting mefloquine (QT prolongation) or chloroquine/hydroxychloroquine in patients with cardiac disease or on other QT-prolonging drugs.

Diagnostic Workup — Advanced and Confirmatory Pre-Travel Studies

— High-altitude simulation test (HAST) with FiO2 15% for COPD, ILD, pulmonary HTN, or borderline resting SpO2; if PaO2 <50–55 mmHg, in-flight O2 indicated

— Stress testing for symptomatic or high-risk CAD planning strenuous travel

— Echocardiogram if suspected pulmonary HTN or significant valvular disease before altitude

— Required for recreational SCUBA: assess pneumothorax history, asthma control, ear disease, seizures, pregnancy (absolute contraindication)

— Fitness-to-dive forms (PADI, DAN) — pulmonary function testing if asthma

— Yellow fever: contraindicated in age <6 months, severe egg allergy, thymic disease, symptomatic HIV with CD4 <200, immunosuppression; precaution in age >60 (first dose), pregnancy, breastfeeding, asymptomatic HIV with CD4 200–499

— Live vaccines (MMR, varicella, YF, oral typhoid, LAIV): avoid in pregnancy and significant immunosuppression

— Mefloquine + antiarrhythmics, beta-blockers, antiepileptics

— Doxycycline + warfarin (↑ INR), retinoids, OCPs (minimal effect, but counsel)

— Atovaquone-proguanil + rifampin, metoclopramide, tetracycline (↓ levels)

Step 3 management: A 65-year-old planning safari to Kenya needs yellow fever — discuss age >60 risk of YEL-AVD (viscerotropic disease, ~1 in 50,000 first doses) and YEL-AND (neurologic). Shared decision-making: if itinerary mandates entry, vaccinate; if optional, weigh against actual transmission risk.

Board pearl: Asymptomatic HIV with CD4 ≥200 and undetectable VL is a precaution (not contraindication) for yellow fever — vaccinate if travel is necessary.

Cardiopulmonary clearance:

Diving medicine evaluation:

Special vaccine pre-checks:

Drug-drug interaction screening:

Mental health screening before mefloquine (PHQ-9, GAD-7 if any prior symptoms)

Risk Stratification and First-Line Management Logic

— Tier 1 — Routine: update all age-appropriate vaccines per ACIP regardless of destination

— Tier 2 — Required: yellow fever (entry to/from endemic countries), meningococcal ACWY (Hajj/Umrah, sub-Saharan meningitis belt Dec–Jun), polio booster (specific countries per IHR)

— Tier 3 — Recommended: hepatitis A (nearly all developing-country travel), typhoid (South Asia especially), hepatitis B (long stay, sexual activity, healthcare, tattoos), rabies (long stay, rural, children, animal workers), Japanese encephalitis (rural Asia >1 month or high-risk activity), cholera (humanitarian workers in active outbreak areas)

— High-risk (sub-Saharan Africa, Papua New Guinea): chemoprophylaxis mandatory

— Moderate (parts of South/Southeast Asia, Amazon basin): chemoprophylaxis based on itinerary

— Low/no-risk areas: counsel mosquito avoidance, no chemoprophylaxis

— High: South Asia, parts of Africa and Latin America

— Moderate: Eastern Europe, Caribbean

— Low: Western Europe, Canada, Australia, NZ, Japan

— Itinerary (rural/urban, altitude, season)

— Duration and remoteness

— Host factors (age, pregnancy, immune status, comorbidities)

— Behavioral exposures

— Local drug resistance patterns

Key distinction: Required vaccines protect populations (entry regulations under International Health Regulations); recommended vaccines protect the individual traveler. Both matter, but only required vaccines can bar entry.

Step 3 management: For a healthy adult on a 10-day urban trip to Costa Rica: update routine vaccines, give hepatitis A, prescribe TD self-treatment (azithromycin), counsel mosquito avoidance for dengue/Zika. No malaria chemoprophylaxis needed (low risk in most tourist areas); no yellow fever required for entry from US.

Tiered approach to the pre-travel visit:

Malaria risk stratification:

Traveler's diarrhea risk:

Decision drivers:

Pharmacotherapy — Malaria Chemoprophylaxis and Vaccine Schedules

— Atovaquone-proguanil (Malarone): 1 tab daily, start 1–2 days before, continue 7 days after leaving. Well-tolerated, good for short trips. Avoid CrCl <30, pregnancy.

— Doxycycline 100 mg daily: start 1–2 days before, continue 4 weeks after. Cheap. SE: photosensitivity, esophagitis, vaginal candidiasis. Avoid pregnancy, children <8.

— Mefloquine 250 mg weekly: start ≥2 weeks before (assess tolerance), continue 4 weeks after. Avoid in seizure, psychiatric disease, cardiac conduction abnormalities. Resistance in Southeast Asia border regions.

— Chloroquine: only for chloroquine-sensitive areas (limited — parts of Central America west of Panama Canal, Caribbean, Middle East). Weekly dosing.

— Tafenoquine (Arakoda): single weekly dose; loading 3 days; requires G6PD testing. Also for P. vivax radical cure (Krintafel).

— Primaquine: primary prophylaxis for P. vivax–predominant areas; G6PD testing required.

— Hepatitis A: 2 doses 6 months apart; single dose protective for travel

— Typhoid: oral Ty21a (4 doses, live, age ≥6) or IM Vi polysaccharide (single dose, age ≥2, q2 years)

— Yellow fever: single dose, 10 days for protection, lifelong (booster only for high-risk specific scenarios)

— Rabies pre-exposure: 2-dose IM series days 0 and 7 (updated 2022 ACIP)

— Japanese encephalitis (Ixiaro): 2 doses 28 days apart (accelerated 7-day schedule available age 18–65)

— Meningococcal ACWY: required for Hajj; valid certificate ≥10 days before arrival

— Cholera (Vaxchora): single oral dose for adults to active outbreak areas

Board pearl: Doxycycline must continue 4 weeks post-travel; atovaquone-proguanil only 7 days — because atovaquone-proguanil is a causal prophylactic (kills liver-stage parasites), while doxycycline and mefloquine are suppressive (blood-stage only).

Step 3 management: Patient flying to rural Tanzania in 5 days → atovaquone-proguanil (fastest onset, short post-travel course); mefloquine inappropriate (requires 2-week lead-in).

Malaria chemoprophylaxis (start before, continue during, continue after exposure):

Key travel vaccines:

Traveler's Diarrhea, Altitude, DVT, and Other Prophylaxis

— Prevention: safe food/water ("boil it, cook it, peel it, or forget it"); bismuth subsalicylate 2 tabs QID can reduce risk ~50% (avoid in pregnancy, ASA allergy, renal disease)

— Antibiotic prophylaxis NOT routinely recommended — reserve for high-risk hosts (IBD, immunocompromised, short critical trips)

— Self-treatment (preferred strategy):

– Mild: loperamide alone or bismuth

– Moderate: loperamide + single-dose antibiotic

– Severe/dysenteric/febrile: antibiotic, avoid loperamide monotherapy

— First-line antibiotic: azithromycin 1 g single dose (or 500 mg × 3 days) — preferred for South/Southeast Asia (fluoroquinolone-resistant Campylobacter)

— Alternative: ciprofloxacin 500 mg BID × 1–3 days (avoid Asia)

— Rifaximin: noninvasive E. coli only; not for dysentery

— Oral rehydration salts always

— Indicated for rapid ascent >2800 m, prior AMS, or sleeping altitude gain >500 m/day above 3000 m

— Acetazolamide 125 mg PO BID, start 24 h before ascent, continue 2 days at altitude

— Sulfa allergy: dexamethasone alternative

— Treatment of HACE: dexamethasone + descent + O2; HAPE: nifedipine + descent + O2

— All travelers: hydration, ambulation, calf exercises, avoid alcohol/sedatives

— Moderate risk: graduated compression stockings

— High risk (prior VTE, active cancer, recent surgery): consider single prophylactic LMWH dose; aspirin not recommended

CCS pearl: For a returned traveler with fever, always order thick and thin smears ×3, rapid malaria antigen test, CBC, LFTs, blood cultures, UA, and CXR — malaria is the rule-out until proven otherwise.

Traveler's diarrhea (TD):

Altitude illness prophylaxis (acetazolamide):

DVT prophylaxis on long flights:

Rabies post-exposure: counsel that pre-exposure vaccination simplifies but does NOT eliminate need for post-exposure boosters (2 doses on days 0, 3, no immunoglobulin needed).

Special Populations — Elderly and Renal/Hepatic Impairment

— Higher baseline cardiovascular and thromboembolic risk; counsel on hydration, mobility, DVT prophylaxis

— Yellow fever: increased risk of YEL-AVD (~1 in 50,000) and YEL-AND with first dose at age ≥60 — shared decision-making, avoid if not truly required

— Verify pneumococcal (PCV15/PCV20 ± PPSV23), zoster (Shingrix 2 doses), influenza, COVID, RSV (age ≥60 per shared decision) vaccines

— Medication review for polypharmacy and QT interactions (mefloquine, fluoroquinolones, azithromycin)

— Travel insurance with medical evacuation strongly advised

— Atovaquone-proguanil contraindicated if CrCl <30 → use mefloquine or doxycycline

— Adjust ciprofloxacin, acetazolamide doses

— Avoid NSAIDs for altitude headache

— Counsel on dehydration risk (TD, heat) precipitating AKI

— Mefloquine metabolized hepatically — caution in severe disease

— Hepatitis A vaccination especially important (fulminant hepatitis risk in chronic liver disease)

— Avoid hepatotoxic combinations; review acetaminophen dosing for travel kit

— Time-zone insulin adjustments; carry glucagon, extra supplies, sharps container

— Letter for syringes/insulin at customs

— Foot care in tropical climates (cellulitis risk)

— Hepatitis B vaccination indicated in all adults with DM <60 (and shared decision ≥60)

— Continue antiplatelets, statins, beta-blockers; carry copy of ECG and med list

— Counsel on altitude, DVT, and air travel timing post-MI/PCI

Step 3 management: A 72-year-old on warfarin traveling to India needs: confirm INR stability, avoid doxycycline (↑ INR) → use atovaquone-proguanil if renal function permits; bring INR self-monitoring or arrange testing abroad; carry medical alert documentation.

Board pearl: Atovaquone-proguanil = renally cleared; mefloquine = hepatically metabolized — match the drug to the organ.

Older adults (≥60):

Chronic kidney disease:

Hepatic impairment:

Diabetes:

Cardiovascular disease:

Special Populations — Pregnancy, Pediatrics, and Immunocompromised

— Avoid travel to Zika-active areas at any gestation (CDC); if unavoidable, strict mosquito precautions, condoms throughout pregnancy

— Malaria during pregnancy is severe (placental sequestration, stillbirth, maternal death) — defer non-essential travel to malarious regions

— Chemoprophylaxis: chloroquine and mefloquine (all trimesters per CDC) acceptable; doxycycline and primaquine/tafenoquine contraindicated; atovaquone-proguanil not recommended (limited data) but may be used if alternatives unsuitable

— Live vaccines contraindicated: MMR, varicella, yellow fever (precaution — give only if travel unavoidable), LAIV, oral typhoid

— Safe: inactivated influenza, Tdap (every pregnancy 27–36 wk), hepatitis A/B, IM typhoid, rabies, meningococcal

— DVT risk elevated — compression stockings, hydration, ambulation

— Accelerate routine vaccines (MMR from 6 months for travel, repeat at 12–15 mo and 4–6 yr)

— Yellow fever: minimum age 9 months (6–8 mo only if unavoidable)

— Malaria: doxycycline contraindicated <8 yr; atovaquone-proguanil from 5 kg; mefloquine any weight

— TD: azithromycin preferred; loperamide avoid in <6 yr

— Rabies pre-exposure strongly considered for children (less likely to report bites)

— HIV with CD4 <200, transplant, biologics, high-dose steroids (≥20 mg prednisone ≥14 days), chemotherapy

— Avoid all live vaccines; inactivated vaccines safe but possibly less immunogenic — check titers

— Higher infection risk → emphasize food/water, mosquito avoidance, malaria prophylaxis

— Coordinate with specialist; defer travel if active immunosuppression intensification

Key distinction: Yellow fever in pregnancy = precaution (not absolute contraindication) — vaccinate if travel to high-risk area unavoidable. Yellow fever in symptomatic HIV or CD4 <200 = contraindication.

Board pearl: Counsel reproductive-age travelers to wait 1 month after MMR or varicella and 3 months after live attenuated vaccines before conception.

Pregnancy:

Pediatrics:

Immunocompromised:

Complications and Adverse Outcomes

— YEL-AVD (yellow fever viscerotropic disease): multiorgan failure mimicking wild-type YF, ~1 in 250,000 (higher in age >60, thymic disease); fatal in ~50%

— YEL-AND (neurologic): encephalitis, GBS, ADEM

— Egg-allergy anaphylaxis (YF, influenza)

— Live vaccine in unrecognized immunosuppression → disseminated disease

— Mefloquine: vivid dreams, anxiety, depression, psychosis, seizures, QT prolongation — discontinue and switch if neuropsychiatric symptoms

— Doxycycline: photosensitivity (sunscreen, hats), pill esophagitis (take with full glass of water, stay upright), Candida vaginitis, GI upset

— Atovaquone-proguanil: GI upset, headache, rare hepatotoxicity

— Primaquine/tafenoquine: hemolysis in G6PD deficiency, methemoglobinemia

— Malaria (esp. P. falciparum) — cerebral malaria, severe anemia, ARDS, AKI

— Dengue — hemorrhagic fever, shock syndrome on second infection

— Typhoid — intestinal perforation, bacteremia

— Hepatitis A — fulminant in older adults/chronic liver disease

— Rabies — universally fatal once symptomatic

— Schistosomiasis — Katayama fever, chronic GU/GI disease

— Leptospirosis — Weil disease (jaundice, AKI, hemorrhage)

— Road traffic accidents — #1 preventable cause of traveler death

— Drowning, altitude illness (HACE, HAPE), heat stroke

— DVT/PE from prolonged immobility

— Acute MI from exertion/altitude/stress

Step 3 management: Returned traveler from West Africa with fever within 3 months → admit, isolate if hemorrhagic features (consider Ebola/Lassa), draw thick/thin smears immediately, empiric antimalarial if smear delayed and high suspicion (artesunate IV for severe falciparum).

Board pearl: Fever in a returned traveler is malaria until proven otherwise — three negative smears 12–24 hours apart are needed to exclude it.

Vaccine-related:

Chemoprophylaxis adverse effects:

Travel-acquired illness:

Non-infectious:

When to Escalate — Specialist Referral and Inpatient Triage

— Complex itinerary (multi-country, prolonged, expedition)

— Significant immunosuppression (transplant, biologics, advanced HIV)

— Pregnancy with unavoidable high-risk travel

— Yellow fever vaccine with precaution/contraindication

— Pediatric travel to malaria-endemic regions

— Returning traveler with undifferentiated fever, eosinophilia, or persistent diarrhea

— Cardiology: recent ACS/PCI, decompensated HF, severe valvular disease, pulmonary HTN before altitude

— Pulmonology: severe COPD/ILD with hypoxemia — HAST, in-flight O2

— Hematology/Oncology: active malignancy, anticoagulation management

— Psychiatry: stable medication adjustments, mefloquine alternatives

— OB: pregnancy travel risk counseling, Zika areas

— Hepatology: chronic liver disease + hepatitis vaccination, drug clearance

— Severe malaria (parasitemia >5%, cerebral, AKI, ARDS, hypoglycemia, shock) → IV artesunate, ICU

— Suspected viral hemorrhagic fever → isolation, public health notification

— Sepsis, typhoid with peritonitis, severe dehydration

— Meningitis, encephalitis (JE, rabies, arboviral)

— Hemolysis from antimalarials

— Yellow fever, malaria, typhoid, cholera, plague, viral hemorrhagic fevers, measles, polio, MERS, novel influenza, TB, rabies exposure

CCS pearl: For returned traveler with falciparum malaria and any severity criterion → IV artesunate is first-line (CDC distributes); admit to ICU; check glucose q4h (hypoglycemia common, especially with quinine); monitor for post-artesunate delayed hemolysis 1–3 weeks later.

Step 3 management: Always notify the local health department for confirmed malaria, typhoid, or any case meeting CDC reportable criteria — this is not optional.

Refer to travel medicine specialist or ID:

Subspecialty co-management before travel:

Post-travel — admit if:

Mandatory public health reporting (varies by state, but commonly):

Key Differentials — Fever in the Returned Traveler (Same Category)

— Malaria (P. falciparum 7–30 days; vivax/ovale can be months) — any tropical exposure

— Dengue (3–14 days) — urban tropics, fever + retroorbital pain + rash + thrombocytopenia + leukopenia

— Chikungunya — fever + severe polyarthralgia

— Zika — mild fever + rash + conjunctivitis; pregnancy concern

— Typhoid/paratyphoid (5–21 days) — fever, relative bradycardia, rose spots, hepatosplenomegaly, S. Asia

— Leptospirosis — freshwater exposure, biphasic illness, conjunctival suffusion, jaundice + AKI (Weil)

— Rickettsial — eschar (African tick bite fever in S. Africa safari travelers)

— Acute HIV, viral hepatitis A/E

— Influenza, COVID-19, respiratory viruses — most common overall

— Acute schistosomiasis (Katayama fever) — freshwater swim + eosinophilia + urticaria

— Amebic liver abscess — RUQ pain, fever, single right lobe lesion

— Viral hepatitis A, E, B

— Q fever, brucellosis

— TB (rare acute presentation)

— Malaria (vivax, ovale, malariae)

— TB

— Visceral leishmaniasis (kala-azar) — fever + massive splenomegaly + pancytopenia

— Chronic schistosomiasis, filariasis

— HIV seroconversion to AIDS-defining illness

Key distinction: Dengue vs. malaria: both cause fever and thrombocytopenia. Dengue → leukopenia, retroorbital pain, rash, tourniquet sign positive, no parasitemia. Malaria → smear positive, hemolysis pattern (↑LDH, ↓haptoglobin, ↑indirect bili).

Board pearl: Eosinophilia in returned traveler = think helminths (schistosomiasis, strongyloides, filariasis, hookworm, ascaris) or drug reaction — not malaria or typhoid.

Approach to febrile returned traveler: incubation period + geography + exposures narrows differential.

Short incubation (<14 days):

Intermediate (2–6 weeks):

Long incubation (>6 weeks):

Key Differentials — Non-Infectious and Cross-Category

— Jet lag — circadian misalignment; melatonin 0.5–5 mg at destination bedtime

— DVT/PE — post long-haul flight; pleuritic chest pain, dyspnea, unilateral leg swelling

— Altitude illness persisting after descent — usually resolves; if not, consider HAPE/HACE residua, pulmonary embolism

— Decompression sickness — after diving + flying within 12–24 h; joint pain, neurologic symptoms

— Heat-related illness — heat exhaustion vs. heat stroke (CNS dysfunction + core >40°C)

— Acute coronary syndrome triggered by exertion, dehydration, altitude

— Acute mountain sickness — headache, nausea, fatigue, insomnia; treat with rest, acetazolamide, descent if worsening

— Mefloquine neuropsychiatric symptoms

— Doxycycline photodermatitis mistaken for sunburn vs. drug rash

— Atovaquone-proguanil hepatitis

— Antimalarial-induced hemolysis (G6PD)

— DRESS or SJS from sulfa, antiepileptics started for travel

— Travel-precipitated mania, psychosis (especially with mefloquine)

— PTSD from travel trauma, MVC, assault

— "Culture shock" depression, adjustment disorder

— STIs acquired abroad (HIV, gonorrhea, syphilis, hepatitis B/C) — offer post-travel screening at 3 months

— TB exposure — repeat IGRA 8–10 weeks post-return

— Pregnancy — confirm/exclude in any fever workup

Step 3 management: A traveler returns from Thailand with fever, headache, and confusion 2 weeks after return. Differential must include cerebral malaria, JE, dengue encephalopathy, typhoid, leptospirosis, rabies, bacterial meningitis. Workup: smears, LP, MRI, blood cultures, JE/dengue serology, public health notification.

Board pearl: Always think non-infectious in the returned traveler stem — pulmonary embolism after a 14-hour flight is a classic distractor for "tropical disease."

Non-infectious causes of post-travel symptoms:

Drug reactions mimicking travel illness:

Psychiatric and stress-related:

Other diagnoses commonly missed:

Secondary Prevention, Discharge, and Long-Term Travel Health Plan

— Written itinerary-specific vaccine + medication list

— Yellow fever certificate (if applicable)

— Malaria chemoprophylaxis prescription with start/stop dates

— TD self-treatment kit prescription (antibiotic, loperamide, ORS)

— Altitude prophylaxis (acetazolamide) if indicated

— Contraception, EC, condoms

— Documentation of chronic medications and ICD-10 codes for customs

— DEET 20–50% repellent, permethrin-treated clothing instructions

— Travel insurance + medical evacuation policy info

— CDC Travelers' Health and embassy contacts

— Insect avoidance: DEET 20–50%, picaridin 20%, IR3535; permethrin on clothing/bednets; long sleeves dusk-to-dawn

— Food/water: bottled or boiled water; avoid ice, raw produce, undercooked meat, unpasteurized dairy

— Sun protection, hydration, foot care

— Sexual health: condoms; consider HIV PrEP if high-risk

— Road safety: helmets, seatbelts, avoid night driving, avoid motorcycles

— Animal avoidance: do not touch dogs, monkeys, bats; rabies post-exposure plan

— Freshwater avoidance in schistosomiasis-endemic regions

— Annual travel medicine review

— Hepatitis A/B series completion

— Periodic TB screening

— Mental health surveillance

— Update routine vaccines on US schedule

Step 3 management: For a Peace Corps volunteer departing for 2 years in Senegal, ensure: full hepatitis A/B series, rabies pre-exposure series, typhoid, meningococcal ACWY, yellow fever, polio adult booster, MMR/varicella confirmed, malaria prophylaxis plan with refills, baseline IGRA, mental health resources, evacuation insurance.

Board pearl: Permethrin-treated clothing + DEET on skin outperforms either alone — this combination is the single most evidence-based mosquito-borne disease prevention.

End-of-visit deliverables (give the patient before departure):

Personal protective measures (always counsel):

Long-term traveler health (expats, frequent travelers):

Follow-Up, Monitoring, and Counseling

— Daily chemoprophylaxis adherence (use phone alarms)

— Recognize TD severity (call/seek care if bloody, febrile, dehydrated)

— Recognize AMS escalation to HACE/HAPE (descend if neurologic or pulmonary symptoms)

— Animal bite → immediate wound wash 15 minutes + soap + iodine, seek post-exposure prophylaxis

— Document any illness, medications taken, contacts

— Asymptomatic short-trip travelers: no mandatory visit

— Long-stay travelers (>3 months), expats, healthcare workers, refugees: post-travel screening visit at 4–8 weeks

– CBC with differential (eosinophilia)

– LFTs, BUN/Cr, UA

– Stool O&P ×3, Giardia antigen, Strongyloides serology

– Schistosoma serology if freshwater exposure

– HIV, syphilis, hepatitis B/C if behavioral risk

– Repeat IGRA at 8–10 weeks post-return (window for conversion)

– Malaria smears if any febrile episode

— Complete vaccine series initiated pre-travel (hepatitis A dose 2, hepatitis B doses 2 and 3, JE dose 2, rabies if exposure occurred)

— Thick + thin smears ×3, rapid malaria antigen, CBC, CMP, UA, blood cultures ×2, CXR, dengue NS1/IgM if <7 days

— Targeted serologies by exposure

— Discuss reverse culture shock and re-entry mental health

— Ongoing safe sex if new partners

— Continue mosquito precautions 3 weeks post-return (mosquito-borne disease transmission can occur from viremic traveler)

CCS pearl: A returned traveler with fever should have malaria smear results within 4 hours — if your hospital can't run them STAT, transfer or treat empirically with high pretest probability.

Board pearl: Persistent post-travel diarrhea >14 days → think Giardia, Cyclospora, Cryptosporidium, post-infectious IBS, tropical sprue, and C. difficile (if recent antibiotic use).

During travel — patient self-monitoring:

Post-travel routine follow-up:

Post-travel fever workup (any fever within 12 months of tropical travel):

Counseling pearls:

Ethical, Legal, and Patient Safety Considerations

— Yellow fever: explicit discussion of YEL-AVD/YEL-AND in older adults; document shared decision-making

— Mefloquine: FDA boxed warning for neuropsychiatric effects — provide medication guide, document discussion, give alternative options

— Live vaccines in borderline immunosuppression: document risk-benefit

— Off-label uses (e.g., tafenoquine, certain pediatric dosing)

— Malaria, yellow fever, typhoid, cholera, measles, polio, viral hemorrhagic fevers, MERS, novel influenza, TB, rabies exposure

— International Health Regulations (IHR) require yellow fever certificate verification for entry from endemic regions

— Returning healthcare workers with potential VHF exposure → active monitoring per CDC

— Provide written summary of vaccines, prophylaxis, allergies in English and destination language when feasible

— Medication reconciliation including time-zone adjustments

— Coordinate chronic disease management (anticoagulation, insulin, immunosuppressants) with destination resources

— Establish point-of-contact for telemedicine follow-up

— Pregnant patient insisting on travel to Zika area: counsel risks, document refusal, do not withhold prenatal care

— Patient requesting prophylaxis without indication (e.g., antibiotics "just in case"): shared decision, antimicrobial stewardship principles, avoid overprescribing

— VFR traveler declining vaccines for cost/cultural reasons: explore barriers, offer lower-cost alternatives, document

— Pediatric travel with parental disagreement on vaccines: follow standard pediatric vaccine consent rules; involve ethics if needed

— Workplace-mandated travel for an employee with contraindications: advocate for accommodation

— Travel medicine often not covered by insurance — disclose costs upfront

— Medical evacuation insurance can cost $50,000–$200,000 out of pocket without coverage

Step 3 management: A patient with active depression on SSRIs requests mefloquine because "it's free at the clinic." Document the contraindication, prescribe atovaquone-proguanil or doxycycline instead, and clearly explain the safety rationale — patient autonomy does not override a clear contraindication.

Board pearl: Yellow fever certificates can be medically waived by an authorized provider for true contraindications — issue a signed waiver letter; some countries still deny entry, so verify with the embassy.

Informed consent for vaccines and prophylaxis:

Mandatory and public health reporting:

Transition-of-care safety:

Ethical edge cases:

Insurance and access:

High-Yield Associations and Rapid-Fire Clinical Facts

— Last-minute trip → atovaquone-proguanil

— Long trip, cost-conscious → doxycycline

— Weekly dosing, no psych history → mefloquine

— Chloroquine-sensitive areas only → chloroquine (Caribbean, Central America west of Panama Canal, parts of Middle East)

Board pearl: "Returned from sub-Saharan Africa with fever" → malaria smear immediately; do not wait for travel history details.

Key distinction: Pre-exposure rabies vaccination eliminates the need for HRIG after a future exposure — huge benefit in countries where HRIG is unavailable.

Step 3 management: Quick rule — if exposure happened in a country with limited rabies immunoglobulin supply, pre-exposure vaccination is cost-effective and life-saving.

Yellow fever: live attenuated, single dose lifelong, age ≥9 months, egg allergy contraindication, valid 10 days post-vaccination, required for entry from endemic areas

Hepatitis A: nearly every developing-country traveler; 2 doses 6 months apart

Typhoid: South Asia highest risk; oral Ty21a (live, q5y) vs. IM Vi (inactivated, q2y)

Rabies pre-exposure: 2-dose IM (days 0, 7) per 2022 ACIP update

Japanese encephalitis: rural Asia >1 month or high-risk activity; 2 doses 28 days apart

Meningococcal ACWY: Hajj requires within 3 years and ≥10 days before arrival; meningitis belt sub-Saharan Africa Dec–Jun

Cholera (Vaxchora): humanitarian workers in active outbreaks; single oral dose

Malaria chemoprophylaxis cheat sheet:

TD first-line: azithromycin 1 g single dose (all regions, especially Asia); cipro elsewhere

Altitude prophylaxis: acetazolamide 125 mg BID, start 24 h before; dexamethasone if sulfa allergy

Zika: avoid pregnancy travel; condoms × pregnancy duration; conception delays — 2 months (female) and 3 months (male) after exposure

Schistosomiasis: never swim in fresh water in endemic Africa/Asia; praziquantel treatment

Rabies post-exposure without pre-vaccination: HRIG + 4-dose vaccine series (days 0, 3, 7, 14); with pre-vaccination: 2 doses (days 0, 3), no HRIG

DVT: hydrate, ambulate, stockings; LMWH only in very high-risk individuals

Top killers: road traffic accidents > cardiovascular > drowning > malaria

Board Question Stem Patterns

— "Healthy 30-year-old leaving for 2-week safari in Kenya in 5 days" → atovaquone-proguanil, yellow fever, hepatitis A, typhoid, routine vaccines, TD self-treatment

— "VFR traveler bringing children to rural India for 6 weeks" → emphasize pediatric malaria prophylaxis (mefloquine or atovaquone-proguanil), typhoid, hepatitis A, MMR catch-up, JE if rural

— "Pregnant patient with mandatory travel to malaria area" → mefloquine or chloroquine (per region), avoid doxy/primaquine, Zika counseling, defer if possible

— "Patient with seizure history wanting cheap malaria prophylaxis" → avoid mefloquine and chloroquine; choose doxycycline or atovaquone-proguanil

— "Patient with G6PD deficiency" → avoid primaquine and tafenoquine; standard options otherwise

— "65-year-old to Brazil for the first time, asking about yellow fever" → counsel YEL-AVD risk, shared decision-making

— "Returned from Thailand with fever and thrombocytopenia" → dengue most likely; rule out malaria

— "Returned from East Africa 3 weeks ago with fever, jaundice, AKI" → severe falciparum malaria; IV artesunate, ICU

— "Returned from freshwater swimming in Lake Malawi with eosinophilia and urticaria" → Katayama fever (acute schistosomiasis); praziquantel

— "Hajj pilgrim returning with fever and neck stiffness" → meningococcal disease; confirm vaccination history

— "Traveler took mefloquine and now has vivid dreams + paranoia" → discontinue, switch to atovaquone-proguanil or doxycycline

— "Bitten by stray dog in Bali" → wound care, rabies post-exposure: HRIG + 4-dose vaccine, report

— Offering chloroquine for chloroquine-resistant regions (Africa, most of Asia)

— Prescribing doxycycline to a child <8 or pregnant patient

— Giving live vaccines in pregnancy or significant immunosuppression

— Treating TD with antibiotics without addressing dehydration

— Forgetting routine vaccines (MMR, Tdap) in the rush of travel-specific ones

— Choosing rifaximin for dysentery (it doesn't work for invasive pathogens)

Board pearl: When the stem mentions "departure in less than 2 weeks," mefloquine is wrong — it needs a 2-week lead-in to assess tolerance.

Step 3 management: Always re-check routine ACIP vaccines first before adding travel-specific ones — the right answer often includes "update Tdap and MMR."

Classic stems and triggers:

Common distractors:

One-Line Recap

The pre-travel visit is a structured 4–6-week-ahead risk assessment that combines itinerary-specific vaccines, malaria chemoprophylaxis, traveler's diarrhea self-treatment, and behavioral counseling — tailored to host factors (age, pregnancy, immunosuppression, comorbidities) and exposure risks — with the highest-yield interventions being routine vaccine updates, malaria prophylaxis matched to drug-resistance maps, hepatitis A vaccination, mosquito avoidance, and counseling on the leading killers of travelers (road traffic injuries and cardiovascular events).

— Malaria prophylaxis selection: atovaquone-proguanil for last-minute/short trips, doxycycline for cost-conscious long trips, mefloquine for weekly dosing if no psych/seizure/cardiac history; never chloroquine in resistant regions (most of Africa and Asia).

— Vaccine tiers: Routine (MMR, Tdap, influenza, COVID, pneumococcal, zoster) for everyone; Required (yellow fever, meningococcal ACWY for Hajj, polio for IHR-listed countries) for entry; Recommended (hepatitis A, typhoid, hepatitis B, rabies, JE, cholera) based on itinerary and behavior.

— TD strategy: prevention through food/water hygiene + self-treatment with azithromycin 1 g single dose (especially Asia) plus loperamide for non-dysenteric illness, ORS for hydration; routine antibiotic prophylaxis is not recommended.

— Returned traveler fever: malaria until proven otherwise — thick/thin smears ×3, rapid antigen, CBC, LFTs, blood cultures; severe falciparum gets IV artesunate + ICU; report to public health.

Board pearl: The single most impactful pre-travel intervention is insect avoidance (DEET + permethrin-treated clothing + bednets) — it prevents malaria, dengue, Zika, chikungunya, JE, yellow fever, and leishmaniasis simultaneously.

Step 3 management: When time is short before departure, prioritize in this order: malaria prophylaxis → yellow fever (if required for entry) → hepatitis A → TD self-treatment kit → routine vaccine catch-up → behavioral counseling.

Top 4 high-yield recaps: