Diphtheria Risk Groups: Unvaccinated, Immunocompromised, Travelers

Populations at Highest Risk for Diphtheria

Diphtheria, caused by toxigenic Corynebacterium diphtheriae, remains endemic in regions with low vaccination coverage.

High-Risk Groups

1. Unvaccinated/Under-vaccinated: Incomplete primary series (DTaP/DTP) or missed boosters (Tdap/Td). Immunity wanes ~10 years.
2. Infants & Young Children: Before completing primary series (2,4,6,15-18 mo, 4-6 yr). Highest mortality <5 years.
3. Immunocompromised: HIV/AIDS, malignancy, transplant, immunosuppressive therapy → impaired antibody response.
4. Close-Quarter Settings: Dormitories, barracks, refugee camps, prisons – facilitate droplet spread.
5. Travelers to Endemic Areas: South Asia, Southeast Asia, Africa, Eastern Europe, Haiti, Venezuela, Yemen. Booster if >10 years since last dose.
6. Healthcare Workers: Exposure risk; require up-to-date Tdap.

Transmission & Clinical Forms

• Respiratory droplets, skin lesions (cutaneous diphtheria).
• Respiratory: pseudomembrane in pharynx/tonsils → airway obstruction, myocarditis, neuropathy.
• Cutaneous: chronic ulcers, less systemic toxicity.

Prevention

• Childhood: DTaP at 2,4,6,15-18 mo, 4-6 yr.
• Adolescent/Adult: Tdap once, then Td/Tdap q10yr.
• Pregnancy: Tdap 27-36 weeks each pregnancy.
• Post-exposure: Antibiotics (erythromycin/penicillin) + booster if indicated.

Global eradication requires sustained high vaccination coverage and surveillance.