CDC Yellow Book
- Saba
- safaris, East African
- SAFETI (Center for Global Education Safety Abroad First-Educational Travel Information) [table]
- safety supplies, for adventure travel
- Saint Barthelemy
- Saint Helena (UK)
- Saint Kitts (Saint Christopher) and Nevis (UK)
- Saint Louis encephalitis virus
- Saint Lucia
- Saint Martin
- Saint Pierre and Miquelon (France)
- Saint Vincent and the Grenadines
- Saipan
- saline irrigation
- salt (sodium chloride) electrolysis
- Samoa
- sand, as hazard
- sandfly fever viruses
- San Marino
- São Paulo exanthematic typhus [table]
- sarcocystosis
- sarilumab (Kevzara) [table]
- savannah (intermediate) cycle, yellow fever
- SCCs (squamous cell carcinomas)
- scombroid
- scopolamine
- scorpions
- seasonal influenza
- seat belts [table]
- secukinumab (Cosentyx) [table]
- seizures
- self-treatable conditions
- Semliki Forest virus
- septicemic plague
- Serbia
- Serengeti National Park
- service animals
- severe dengue
- severe fever with thrombocytopenia syndrome virus
- severe tetanus
- sexual abuse
- Seychelles
- shellfish poisoning
- shigellosis
- Siberian tick typhus [table]
- sildenafil [table]
- silver, water disinfection with
- Simponi (golimumab) [table]
- Simulect (basiliximab) [table]
- simultaneous administration, of vaccines
- Sindbis virus
- single-dose vaccines
- Sint Eustatius
- Sint Maarten
- sinus barotrauma
- skin lesions [table]
- skin ulcers
- sleep apnea
- sleeping sickness
- sleep problems
- Slovakia
- Slovenia
- Society Islands
- sodium chloride electrolysis
- soft tissue infections
- solar irradiation
- Solomon Islands
- soroche
- South-central Asia [table]
- Southeast Asia [table]
- South Georgia and the South Sandwich Islands
- spatial repellents
- spider bites
- sporotrichoid spread
- Sprycel (dasatinib) [table]
- squamous cell carcinomas (SCCs)
- SSPE (subacute sclerosing panencephalitis)
- Stelara (ustekinumab) [table]
- STI 571 (imatinib mesylate, Gleevec) [table]
- stings, animal
- Street Parade (Zurich, Switzerland) [table]
- Strongyloides stercoralis
- subacute sclerosing panencephalitis (SSPE)
- subcutaneous lesions
- Sub-Saharan Africa [table]
- substandard medical products
- Summer Olympics [table]
- sun avoidance
- sunburn
- sun damage to skin
- sunitinib malate (Sutent) [table]
- support groups for travelers with mental health issues
- suspected human rabies
- Sutent (sunitinib malate) [table]
- Swaziland (Eswatini)
- Sweden
- swine influenza viruses
- sylvatic (jungle) cycle, yellow fever
- Syria