Diphtheria

Revised May 2007

Dr. Sarma R V S NConsultant Physician

Diphtheria

Greek diphthera (leather hide)Caused by Aerobic Gram +ve rods Cornyebacterium diphtheriaeExotoxin production only if

infected by virus phage infected carrying toxin gene

Gram +ve Bacilli and Colonies

Diphtheria Epidemiology

Reservoir Human carriers Usually asymptomatic

Transmission Respiratory Skin and fomites rarely

Temporal pattern Winter and spring

Communicability Up to several weekswithout antibiotics

Diphtheria Clinical Features

Incubation period 2-5 days (range, 1-10 days)

May involve any mucous membraneClassified based on site of infection

anterior nasalpharyngeal and tonsillar laryngealcutaneousoculargenital

Pharyngeal and Tonsillar Diphtheria

Insidious onset of exudative pharyngitisExudate spreads within 2-3 days and may

form adherent pseudo membraneMembrane may cause respiratory

obstructionFever usually not high but patient appears

toxic

Thick Membrane

Pseudo membrane

‘Bull Neck’

Skin Lesions

Diphtheria Complications

Mostly attributable to toxinSeverity generally related to extent of local

diseaseMost common complications are myocarditis

and toxic neuritis with palsyDeath occurs in 5%-10% for respiratory

disease

Diphtheria Antitoxin (DAT)

Produced in horsesFirst used in the U.S. in 1891Used only for treatment of diphtheriaNeutralizes only unbound toxin

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

1940 1950 1960 1970 1980 1990 2000

Cas

esDiphtheria – in USA, 1940-

2005*

Year*2005 provisional total

DTaP, DT, and Td

DTaP, DT

Td, Tdap (adult)

Diphtheria7-8 Lf units

2-2.5 Lf units

Tetanus5-12.5 Lf units

5 Lf units