Fellow's pre-read · Infectious Diseases
The travel clinic
CDC Yellow Book 2024 + ACIP · pre-read 2026-07-07
Pre-read for tomorrow's travel-medicine didactic. Drug and vaccine specifics are drawn from the CDC Yellow Book (2024) and ACIP. Country-specific malaria/yellow-fever requirements change — always check the live Yellow Book destination pages. Not a substitute for the full source.
In one line
Pre-travel care = match the itinerary to the risk: update routine vaccines, add destination vaccines, prevent malaria (bite avoidance + chemoprophylaxis), arm the traveler for diarrhea, and counsel altitude/rabies. Post-travel fever = rule out malaria first.◆The pre-travel visit — the framework
- Assess the traveler AND the trip: destinations, rural vs urban, season, activities (safari, freshwater, high altitude, health care), duration, and host factors (age, pregnancy, immunocompromise).
- Update routine vaccines first — measles (MMR) given global resurgence, Tdap, influenza, COVID-19, and polio boosters for certain destinations.
- Then layer destination-specific vaccines, malaria prevention, and a self-treatment plan for diarrhea.
◆Malaria prevention
Two pillars: bite avoidance (DEET/picaridin, permethrin-treated clothing, bed nets, dusk-to-dawn precautions) + chemoprophylaxis matched to the destination's resistance.
| Drug | Schedule | Notes |
|---|---|---|
| Atovaquone-proguanil | Daily; 1–2 d before → 7 d after | Well-tolerated; good for last-minute trips (short tail); avoid in severe renal impairment |
| Doxycycline | Daily; 1–2 d before → 4 wk after | Cheap; photosensitivity, GI; not in pregnancy or <8 y |
| Mefloquine | Weekly; ≥2 wk before → 4 wk after | Only weekly option; neuropsychiatric precautions; OK in pregnancy |
| Tafenoquine | Weekly (after loading); long half-life | Requires quantitative G6PD testing first |
| Chloroquine | Weekly | Only chloroquine-sensitive areas (limited — parts of Central America, Caribbean) |
- Get a quantitative G6PD level before primaquine OR tafenoquine — both cause hemolysis in G6PD deficiency.
- P. vivax/ovale hypnozoites → radical cure / terminal prophylaxis with primaquine (or tafenoquine).
◆Travelers' diarrhea
- Mostly self-limited; the mainstay is hydration. Give a stand-by self-treatment antibiotic for moderate-to-severe illness.
- Azithromycin is first-line, especially in South/Southeast Asia (fluoroquinolone-resistant Campylobacter): 1 g once, or 500 mg daily ×3 d.
- Fluoroquinolones (cipro/levo) work elsewhere but resistance is rising; rifaximin covers noninvasive E. coli only (not for febrile/bloody diarrhea).
- Loperamide as an adjunct: 4 mg, then 2 mg per loose stool (max 16 mg/24 h) — avoid if fever or bloody stools.
◆Travel vaccines
| Vaccine | Who | Notes |
|---|---|---|
| Hepatitis A | Most travelers to endemic areas | Highly effective; can give up to day of departure |
| Typhoid | South Asia & other endemic regions | Oral Ty21a (live; boost ~5 y; hold with antibiotics/immunocompromise) or Vi polysaccharide IM (boost ~2 y) |
| Yellow fever | Sub-Saharan Africa, tropical S. America; often an entry requirement | Live; single lifelong dose; ICVP valid from day 10. Contraindicated if immunosuppressed, <6 mo, or egg/gelatin allergy; precaution if ≥60 y or 6–8 mo |
| Rabies (pre-exposure) | Remote travel, animal contact, long stays | 2-dose IM series [days 0, 7] (2022 ACIP — shortened from 3) |
| Japanese encephalitis | Rural Asia, prolonged or rural/agricultural stay | 2-dose series |
| Cholera | High-risk (aid/relief work, active outbreak) | Single oral dose (live, CVD 103-HgR) |
| Meningococcal ACWY | Required for Hajj/Umrah; African meningitis belt | Saudi Arabia mandates proof of vaccination |
◆Altitude illness
- Prevent with gradual ascent; acetazolamide 125 mg every 12 h, starting the day before ascent and continuing the first ~2 days at altitude (a sulfonamide — caution in sulfa allergy).
- AMS (headache, nausea) → stop ascending; acetazolamide ± dexamethasone. HACE → dexamethasone + descend. HAPE → nifedipine + descend + oxygen. Descent is the definitive treatment.
◆Post-travel fever
- Malaria until proven otherwise — thick & thin smears (± rapid antigen); repeat if negative and suspicion remains. P. falciparum usually presents within 1–3 months.
- Anchor the differential on incubation + exposure: dengue/chikungunya/other arboviruses (<2 wk), typhoid, rickettsioses (eschar), leptospirosis, acute HIV, viral hepatitis, amebic liver abscess (later).
What's changed / worth knowing
Reviewer synthesis — not the source text.
- Rabies pre-exposure is now 2 doses [days 0, 7] for immunocompetent adults (2022 ACIP), down from 3. MMWR 2022;71(18)
- Yellow fever is a single lifelong dose with a lifetime-valid ICVP (2016 IHR amendment) — no routine 10-year booster. CDC Yellow Book
- Azithromycin, not a fluoroquinolone, is first-line TD therapy in South/Southeast Asia because of resistant Campylobacter. CDC Yellow Book
◆Likely pimp questions
- Which malaria drug has the shortest post-travel tail? Atovaquone-proguanil — only 7 days after (vs 4 weeks for doxycycline/mefloquine).
- Which malaria prophylaxis is weekly? Mefloquine (and chloroquine, in sensitive areas).
- What must you check before primaquine or tafenoquine? Quantitative G6PD level (hemolysis risk).
- First-line antibiotic for travelers' diarrhea in SE Asia — and why? Azithromycin — fluoroquinolone-resistant Campylobacter.
- Yellow fever vaccine: how many doses and how long is the certificate valid? One lifelong dose; ICVP valid for life, starting day 10.
- Contraindications to yellow fever vaccine? Immunosuppression, age <6 months, egg/gelatin allergy (precaution ≥60 y and 6–8 mo).
- Current rabies pre-exposure schedule? 2 doses IM, days 0 and 7 (2022 ACIP).
- Vaccine required for the Hajj? Meningococcal ACWY.
- Acetazolamide prophylaxis dose for altitude? 125 mg every 12 h, starting the day before ascent.
- Treatment of HACE vs HAPE? HACE → dexamethasone + descend; HAPE → nifedipine + descend + O₂.
- Post-travel fever — first thing to rule out? Malaria (blood smears).
Sources: CDC Yellow Book 2024 (Health Information for International Travelers) — Malaria, Travelers' Diarrhea, Yellow Fever, Rabies, Typhoid, Japanese Encephalitis, High-Altitude Travel & Altitude Illness chapters (wwwnc.cdc.gov/travel/yellowbook). · Rao AK, et al. Use of a Modified Preexposure Prophylaxis Vaccination Schedule to Prevent Human Rabies — ACIP, United States, 2022. MMWR 2022;71(18). · ACIP adult immunization schedule.