Diphtheria

Diphtheria
An adherent, dense, grey pseudomembrane covering the tonsils is classically seen in diphtheria.
Specialty	Infectious disease
Symptoms	Sore throat, fever, barking cough[1]
Complications	Myocarditis, Peripheral neuropathy, Proteinuria
Usual onset	2–5 days post-exposure[2]
Causes	Corynebacterium diphtheriae (spread by direct contact and through the air)[2]
Diagnostic method	Examination of throat, culture[1]
Prevention	Diphtheria vaccine[2]
Treatment	Antibiotics, tracheostomy[2]
Prognosis	5–10% risk of death
Frequency	4,500 (reported 2015)[3]
Deaths	2,100 (2015)[4]

Diphtheria is an infection caused by the bacterium Corynebacterium diphtheriae.^[2] Most infections are asymptomatic or have a mild clinical course, but in some outbreaks, the mortality rate approaches 10%.^[1] Signs and symptoms may vary from mild to severe,^[1] and usually start two to five days after exposure.^[2] Symptoms often develop gradually, beginning with a sore throat and fever.^[1] In severe cases, a grey or white patch develops in the throat,^[2][1] which can block the airway, and create a barking cough similar to what is observed in croup.^[1] The neck may also swell, in part due to the enlargement of the facial lymph nodes.^[2] Diphtheria can also involve the skin, eyes, or genitals, and can cause^[2][1] complications, including myocarditis (which in itself can result in an abnormal heart rate), inflammation of nerves (which can result in paralysis), kidney problems, and bleeding problems due to low levels of platelets.^[2]

Diphtheria is usually spread between people by direct contact, through the air, or through contact with contaminated objects.^[2][5] Asymptomatic transmission and chronic infection are also possible.^[2] Different strains of C. diphtheriae are the main cause in the variability of lethality,^[2] as the lethality and symptoms themselves are caused by the exotoxin produced by the bacteria.^[1] Diagnosis can often be made based on the appearance of the throat with confirmation by microbiological culture.^[1] Previous infection may not protect against reinfection.^[1]

A diphtheria vaccine is effective for prevention, and is available in a number of formulations.^[2] Three or four doses, given along with tetanus vaccine and pertussis vaccine, are recommended during childhood.^[2] Further doses of the diphtheria–tetanus vaccine are recommended every ten years.^[2] Protection can be verified by measuring the antitoxin level in the blood.^[2] Diphtheria can be prevented in those exposed, as well as treated with the antibiotics erythromycin or benzylpenicillin.^[2]In severe cases a tracheotomy is sometimes needed to open the airway.^[1]

In 2015, 4,500 cases were officially reported worldwide, down from nearly 100,000 in 1980.^[3] About a million cases a year are believed to have occurred before the 1980s.^[1] Diphtheria currently occurs most often in sub-Saharan Africa, South Asia, and Indonesia.^[1][6] In 2015, it resulted in 2,100 deaths, down from 8,000 deaths in 1990.^[4][7] In areas where it is still common, children are most affected.^[1] It is rare in the developed world due to widespread vaccination, but can re-emerge if vaccination rates decrease.^[1][8] In the United States, 57 cases were reported between 1980 and 2004.^[2] Death occurs in 5–10% of those diagnosed.^[2] The disease was first described in the 5th century BC by Hippocrates.^[2] The bacterium was identified in 1882 by Edwin Klebs.^[2]