1. Center for Communicable Diseases Control
Diphtheria
Dr. S.M.Zahraei
Center for Communicable Diseases Control
Revised May 2009

2. Diphtheria Greek diphthera (leather hide)
Caused by Aerobic Gram +ve rods
Cornyebacterium diphtheriae
Exotoxin production only if infected by virus phage infected carrying toxin gene

3. Gram +ve Bacilli and Colonies

4. Diphtheria Epidemiology
Reservoir Human carriers Usually asymptomatic
Transmission Respiratory Skin and fomites rarely
Temporal pattern Winter and spring
Communicability Up to several weeks without antibiotics

5. Corynebacterium diphtheriae
Aerobic gram-positive bacillus
Toxin production occurs only when C. diphtheriae infected by virus (phage) carrying tox gene
If isolated, must be distinguished from normal diphtheroid
Toxoid developed in 1920s

6. Pharyngeal and Tonsillar Diphtheria
Insidious onset
Exudate spreads within 2-3 days and may form adherent membrane
Membrane may cause respiratory obstruction
Pseudomembrane: fibrin, bacteria, and inflammatory cells, no lipid
Fever usually not high but patient appears toxic

7. Diphtheria Clinical Features
Incubation period 2-5 days (range, 1-10 days)
May involve any mucous membrane
Classified based on site of infection
anterior nasal
pharyngeal and tonsillar
laryngeal
cutaneous
ocular
genital

8. Thick Membrane

9. Pseudo membrane

10. ‘Bull Neck’

11. Skin Lesions

12. Diphtheria Complications
Mostly attributable to toxin
Severity generally related to extent of local disease
Most common complications are myocarditis and toxic neuritis with palsy
Death occurs in 5%-10% for respiratory disease

13. Diphtheria Antitoxin (DAT)
Produced in horses
First used in the U.S. in 1891
Used only for treatment of diphtheria
Neutralizes only unbound toxin