# Diphtheria

> The content on this page is for informational and educational purposes only. It does not constitute medical advice, diagnosis, or treatment recommendations. If you have health concerns, consult a qualified healthcare professional. Medova is not a medical service provider.

Source: https://medova.health/en/knowledge/diseases/diphtheria · Language: en

## Overview

Serious bacterial infection of the throat and nose causing a characteristic membrane. Can be fatal due to airway obstruction or toxin-mediated heart and nerve damage. Preventable by DTP vaccination.

## Medical Information

- ICD-10: A36
- ICD-11: 1C17
- Causative Agent: bacteria
- Severity: Critical
- Incubation Period: 2–5 days
- Mortality Rate: 0.1%
- Vaccine available: Yes

## Symptoms

- Dysphagia (75%)
- Edema (25%)
- Fatigue (80%)
- Fever (70%)
- Hypotension (10%)
- Malaise (85%)
- Paralysis (5%)
- Shortness of breath (25%)
- Skin ulcer (20%)
- Sore throat (90%)
- Swollen lymph nodes (70%)
- Tachycardia (20%)
- Blurred vision (8%)
- Cough (40%)
- Headache (50%)
- Loss of appetite (65%)
- Paresthesia (10%)
- Nausea (30%)
- Vomiting (15%)
- Nasal congestion (8%)

## Transmission

- Droplet transmission (Primary route)
- Direct Contact

## Overview

Serious bacterial infection affecting the mucous membranes of the throat and nose.

## Overview

Diphtheria is caused by toxigenic strains of Corynebacterium diphtheriae transmitted via respiratory droplets. It produces a potent exotoxin causing local pseudomembrane formation and systemic cardiotoxic and neurotoxic effects. Once a leading cause of childhood death, it is now rare where vaccination coverage is high. Resurgence has been documented in Yemen (2017–2020), Southeast Asia, and among unvaccinated populations.

## Emergency Signs

Seek emergency care immediately if:

- Severe throat pain with visible grayish membrane

- Difficulty breathing, stridor (high-pitched breathing), or drooling

- Neck swelling ("bull neck") with difficulty swallowing

- Rapid heart rate with chest pain (myocarditis)

- Any neurological symptoms: double vision, difficulty swallowing, facial weakness

## Detailed Symptoms

**Pharyngeal/tonsillar diphtheria (most common):**

- Sore throat, low-grade fever, malaise

- **Characteristic grayish-white pseudomembrane** on tonsils/pharynx — bleeds when removed

- "Bull neck" appearance from cervical lymphadenopathy and soft tissue edema

- Nasal voice and dysphagia

**Laryngeal diphtheria:**

- Hoarseness, croup-like cough

- Stridor — risk of complete airway obstruction and suffocation

**Cutaneous diphtheria:**

- Chronic, non-healing skin ulcers with gray membrane; more common in tropical regions

**Toxic complications (from exotoxin):**

- Myocarditis (usually onset 1–2 weeks after infection)

- Neuropathy (bulbar palsy, respiratory paralysis, peripheral neuropathy)

## Course of Disease

**Typical disease course (pharyngeal/tonsillar):**

1. **Incubation period:** 2–5 days.
2. **Onset:** Sore throat, low-grade fever, malaise. Cervical lymphadenopathy ("bull neck" in severe cases).
3. **Pseudomembrane formation (days 2–3):** Tough, gray-white pseudomembrane on tonsils/pharynx. Bleeds on attempted removal. May extend to larynx causing stridor and airway compromise.
4. **Toxin-mediated complications (weeks 1–6):**
   - Myocarditis: conduction abnormalities, heart failure (week 1–2).
   - Neuropathy: palatal weakness, nasal voice, difficulty swallowing (week 3–5). Peripheral motor neuropathy (week 5–7).
5. **Recovery:** Gradual with antibiotics + antitoxin. Pseudomembrane sloughs within days of treatment.

**Note:** Cutaneous diphtheria (skin ulcers) is generally milder with less systemic toxicity but serves as a reservoir.

## Diagnosis

- **Clinical diagnosis:** characteristic pseudomembrane in throat in a febrile patient with toxicity signs

- **Culture:** C. diphtheriae from membrane or throat swab — confirmatory; takes 24–48 hours

- **PCR:** rapid detection of tox gene (confirms toxigenicity)

- **Elek test or ELISA:** confirms toxin production from isolate

- Notify public health authorities immediately — diphtheria is a quarantinable disease in many countries

- Screen close contacts; culture all household contacts

## Treatment

Treatment is urgent and should not await laboratory confirmation:

- **Diphtheria Antitoxin (DAT):** equine antitoxin — administered as early as possible (20,000–100,000 IU depending on severity)

- neutralizes circulating toxin. Premedicate with antihistamines

- desensitization may be required.

- **Antibiotics:** erythromycin or penicillin G for 14 days — eliminate the organism and reduce toxin production

- **Airway management:** early intubation or tracheotomy may be necessary for laryngeal diphtheria

- **Cardiac monitoring:** ECG monitoring for myocarditis

- beta-blockers/pacemaker for arrhythmias

- **Strict isolation:** until two negative cultures ≥24 hours apart after antibiotics completion

- **Active immunization:** during convalescence (natural infection may not confer immunity)

## Prevention Details

Diphtheria toxoid vaccination is highly effective:

- **Primary series:** DTP at 2, 4, 6 months; booster at 15–18 months and 4–6 years

- **Adult boosters:** Td or Tdap every 10 years

- **Outbreak control:** ring vaccination and chemoprophylaxis (erythromycin/penicillin) for close contacts

- **Travelers to endemic areas** should ensure vaccination is current
Endemic regions include Yemen, Pakistan, India, Indonesia, Philippines, and parts of Sub-Saharan Africa

## Travel Advice

- Ensure DTP/Td/Tdap vaccination is current; receive booster if last dose >10 years ago.

- **High-risk destinations:** Yemen, parts of Southeast Asia (Philippines, Indonesia, India), Papua New Guinea, Sub-Saharan Africa

- Travelers to refugee camps or crowded, low-vaccination settings face elevated risk.

- Close contact with local populations in endemic areas increases transmission risk.

## How common is it?

Global diphtheria cases decreased dramatically with vaccination: from >100,000/year in 1980s to ~8,000 in 2020. However, recent resurgence in Yemen (>30,000 cases, 2017–2020 due to civil war-related vaccine collapse), India, Indonesia, and among European migrants. Most countries maintain <5% of cases. Waning adult immunity is a growing concern — antibody levels decline below protective threshold in ~50% of adults >40 years.

## Risk Factors

The risk of diphtheria is primarily determined by **vaccination status** and **proximity to endemic or outbreak settings**. The following factors increase the likelihood of infection and/or severe disease:

**Risk factors for infection:**

- **Incomplete or absent vaccination:** The dominant risk factor globally. In the 1990s outbreak in the former Soviet Union (>150,000 cases, >5,000 deaths), the majority of cases occurred in adults whose childhood vaccine-induced immunity had waned without booster doses.

- **Living in or traveling to endemic areas:** Regions with DTP3 coverage <80%, particularly sub-Saharan Africa, South Asia, and Southeast Asia

- **Crowded living conditions:** Military barracks, refugee camps, prisons, homeless shelters — outbreaks propagate rapidly in overcrowded settings with poor hygiene

- **Close contact with a case or carrier:** Household contacts of a diphtheria case have a secondary attack rate of 2–5% even in partially immunized populations

- **Low socioeconomic status and poor hygiene:** Both respiratory and cutaneous diphtheria are diseases of poverty

**Risk factors for severe disease and death:**

- **Age:** CFR is highest in children <5 years (up to 20%) and adults >40 years (up to 20–30%). The relatively lower CFR in older children and young adults (3–5%) reflects both immune maturity and lower membrane burden.

- **Delayed antitoxin administration:** Every day of delay after day 2 of illness increases mortality. Antitoxin given on day 1 is associated with ~1% CFR; by day 4+, CFR exceeds 15%.

- **Extensive membrane:** Membrane involving the larynx, trachea, or extending across the entire pharynx carries higher risk of airway obstruction and systemic toxicity.

- **Bull-neck (severe cervical edema):** Indicates massive toxin production and correlates with higher rates of myocarditis and neuropathy.

- **Biotype:** C. diphtheriae biotype *gravis* has historically been associated with more severe disease, though this correlation is not absolute.

**Populations at increased risk in high-income countries:**

- Adults aged >50 years (waning immunity, inadequate booster uptake — serological studies show 30–60% are below protective antibody levels)

- Immigrants and refugees from low-coverage countries

- Homeless populations (cutaneous diphtheria)

- Healthcare workers in contact with cases

## Complications Details

- **Myocarditis:** 10–25% of cases; onset 1–2 weeks after infection; can cause heart failure, heart block, ventricular arrhythmias — most common cause of death

- **Neuropathy:** bulbar palsy (difficulty swallowing/speaking), peripheral neuritis, respiratory muscle paralysis (weeks to months after infection) — can be fatal

- **Airway obstruction:** from membrane extension into larynx/trachea — can cause asphyxiation

- **Renal failure:** tubular necrosis from toxin

- **Thrombocytopenia:** from toxin-mediated platelet destruction

## Recovery & Outlook

**With antitoxin + antibiotics:** CFR 5–10%.

**Without treatment:** CFR 30–50%.

**Complications determining prognosis:**

- Myocarditis: 10–25% of cases, may be fatal. Can occur 1–2 weeks after onset.

- Neuropathy: cranial nerve palsies (palatal, oculomotor), peripheral polyneuropathy (3–7 weeks post-onset). Usually reversible over weeks to months.

- Airway obstruction: from pseudomembrane extension. May require tracheostomy.

- Renal tubular necrosis (rare).

**Recovery:** With treatment, most patients recover fully within 4–6 weeks. Myocarditis carries the worst prognosis.

## Available Vaccines

- [Diphtheria](https://medova.health/en/knowledge/vaccines/diphtheria)
- [Td (Tetanus, Diphtheria)](https://medova.health/en/knowledge/vaccines/td-%28tetanus,-diphtheria%29)
- [Tdap Vaccine](https://medova.health/en/knowledge/vaccines/tdap-vaccine)

## Sources & content verification

- Data sources: WHO/ICD-11, CDC, ECDC (SafeTripVax QMR-003, 2026-02-25), WHO Disease Factsheets 2024 + CDC Travelers' Health 2024 + Heymann CDD 21st ed., WHO Disease Factsheets 2024 + CDC Yellow Book 2024 + Heymann CDD 21st ed.
- Generated by: AI + Human review
- Review status: Awaiting medical review
- Last updated: 2026-02-25
- [www.who.int](https://www.who.int/emergencies/disease-outbreak-news)
- [www.who.int](https://www.who.int/news-room/fact-sheets)

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The content on this page is for informational and educational purposes only. It does not constitute medical advice, diagnosis, or treatment recommendations. If you have health concerns, consult a qualified healthcare professional. Medova is not a medical service provider.

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