Diphtheria is a potentially fatal, contagious disease that usually involves the nose, throat, and air passages, but may also infect the skin. Its most striking feature is the formation of a grayish membrane covering the tonsils andupper part of the throat.
Like many other upper respiratory diseases, diphtheria is most likely to occur during winter months. At one time it was a major cause of childhood death,but it is now rare in developed countries because of widespread immunization.
People who have not been immunized may get diphtheria at any age. The diseaseis spread most often by the coughing or sneezing of an infected person or carrier. It is vital to seek medical help at once when diphtheria is suspected.
The symptoms of diphtheria are caused by toxins produced by the diphtheria bacillus, Corynebacterium diphtheriae. These toxins destroy healthy tissue in the throat around the tonsils, or in open wounds in the skin, causing the telltale gray or grayish green membrane to form. Inside the membrane, thebacteria produce an exotoxin--a poisonous secretion that causes the life-threatening symptoms of diphtheria. The exotoxin is carried throughout the body in the bloodstream, destroying healthy tissue in other parts of the body.
The most serious complications caused by the exotoxin are inflammations of the heart muscle (myocarditis) and damage to the nervous system. Disturbances in the heart rhythm may culminate in heart failure. Symptoms involving the nervous system can include seeing double, painful or difficult swallowing, and slurred speech or loss of voice. The exotoxin may also cause severe swelling in the neck ("bull neck").
The signs and symptoms of diphtheria vary according to the location of the infection:
- Nasal diphtheria produces few symptoms other than a watery orbloody discharge. Nasal infection rarely causes complications by itself, butis a public health problem because it spreads the disease more rapidly thanother forms of diphtheria.
- Pharyngeal diphtheria gets its name from the pharynx--the part of the upper throat connecting the mouth and nasal passages with the voice box. This is the most common form of diphtheria, causing the characteristic throat membrane. The membrane often bleeds if it is scrapedor cut. It is important not to try to remove the membrane because the traumamay increase the body's absorption of the exotoxin. Other signs and symptomsof pharyngeal diphtheria include mild sore throat, fever of 101-102°F (38.3-38.9°C), a rapid pulse, and general body weakness.
- Laryngealdiphtheria, involving the voice box or larynx, is the form most likely to produce serious complications. The fever is usually higher than in other forms of diphtheria (103-104°F or 39.4-40°C) and the patient is very weak. Patients may have severe cough, difficulty breathing, or lose their voices. The development of a "bull neck" indicates a high level of exotoxin in the bloodstream. Obstruction of the airway may result in respiratory problems and death.
The skin accounts for about 33% of diphtheria cases. It is found chiefly among people with poor hygiene. A diphtheria membrane may form over the wound butis not always present.
Because diphtheria must be treated quickly, doctors usually make the diagnosis based on visible symptoms without waiting for test results. The patient's eyes, ears, nose, and throat are examined to rule out other diseases that maycause fever and sore throat. The most important single symptom suggesting diphtheria is the membrane. When a patient develops skin infections during a diphtheria outbreak, the doctor will consider the possibility of cutaneous diphtheria and take a smear to confirm the diagnosis.
Diphtheria is a serious disease requiring hospital treatment in an intensive-care unit if the patient has developed respiratory symptoms. The most important step is prompt administration of diphtheria antitoxin, without waiting forlaboratory results. The antitoxin is made from horse serum and works by neutralizing any circulating exotoxin. The doctor must first test the patient forsensitivity to animal serum. Patients who are sensitive (about 10%) must first be desensitized with diluted antitoxin.
Antibiotics (penicillin, ampicillin, or erythromycin) are given to wipe out the bacteria, prevent spread of the disease, and to protect the patient from developing pneumonia, but they are not a substitute for treatment with antitoxin.
Cutaneous diphtheria is usually treated by cleaning the wound with soap and water, and giving the patient antibiotics for 10 days.
Diphtheria patients need bed rest with intensive nursing care. Patients withlaryngeal diphtheria are kept in a croup tent or high-humidity environment; they may also need throat suctioning or emergency surgery if their airway is blocked.
Patients recovering from diphtheria should rest at home for a minimum of twoto three weeks, especially if they have heart complications. In addition, patients should be immunized against diphtheria after recovery, because having the disease does not always protect against re-infection.
Diphtheria patients who develop myocarditis may be treated with oxygen and with medications to prevent irregular heart rhythms. An artificial pacemaker may be needed. Patients with difficulty swallowing can be fed through a tube inserted into the stomach through the nose. Patients who cannot breathe are usually put on mechanical respirators.
The prospects for recovery depends on the size and location of the membrane and on early treatment with antitoxin; the longer the delay, the higher the death rate. The most vulnerable patients are children under age 15 and those who develop pneumonia or myocarditis. Nasal and cutaneous diphtheria are rarely fatal.
Universal immunization is the most effective means of preventing diphtheria.The standard course of immunization for healthy children is three doses of DPT (diphtheria-tetanus-pertussis) preparation given between two months and sixmonths of age, with booster doses given at 18 months and at entry into school. Adults should be immunized at 10 year intervals with Td (tetanus-diphtheria) toxoid.
To prevent spread of the disease, diphtheria patients must be isolated for one to seven days or until two successive cultures show that they are no longercontagious. Because diphtheria is highly contagious and has a short incubation period, family members and other contacts of diphtheria patients must be watched for symptoms and tested to see if they are carriers. They are usuallygiven antibiotics for seven days and a booster shot of diphtheria/tetanus toxoid.