Pertussis, more commonly known as whooping cough, is a contagious, respiratory disease caused by the bacterium Bordetella pertussis. The illness is typically characterized by a prolonged paroxysmal cough that is often accompanied by an inspiratory whoop. Disease presentation can vary with age and history of previous exposure or vaccination.
Young infants may present to a clinic or hospital with apnea and no other disease symptoms. Adults and adolescents with some immunity may exhibit only mild symptoms or have the typical prolonged paroxysmal cough. In all persons, cough can continue for months.
Reservoirs: Humans are the only reservoir.
Incubation period: Typical incubation period is 7–10 days (range 5–21 days).
Who gets pertussis?
Pertussis can occur in people of all ages. Pertussis is most severe in infants less than one year old. More than half of these infants who get the disease must be hospitalized. Older children and adults can also get pertussis as protection against pertussis decreases over time, but it is usually not as serious. Many infants who get pertussis catch it from their older brothers and sisters, or from their parents or other caregiver who might not even know they have the disease.
How do people get pertussis?
Pertussis is very easily spread from person to person, especially before coughing starts. A person can spread pertussis up to three weeks after symptoms appear. When an infected person talks, coughs or sneezes, the bacteria are released into the air and enter another person’s body through the nose, mouth or throat. People can also become sick if they come in contact with the mucus or saliva (spit) from an infected person.
1. Catarrhal (one to two weeks): mild symptoms of upper respiratory tract inflammation gradually develop with coryza and an intermittent non-productive cough.
2. Paroxysmal (four weeks or longer): spasms of cough, that occur without taking a breath, that may end with a gasp, whoop, or vomiting (post-tussive emesis). Adolescents and adults may have less dramatic symptoms.
3. Convalescent (two to six weeks or longer): gradual resolution of the paroxysmal coughing. Death and serious complications occur mainly in infants and can include apnea, malnutrition, pneumonia, pulmonary hypertension, seizures and encephalopathy. Older individuals may suffer from sleep deprivation, sweating, syncope, rib fractures, hernia and urinary incontinence.
Younger patients have a greater chance of complications from pertussis than older patients. The most common complication is secondary bacterial infection, which is the cause of most pertussis-related deaths.
Pneumonia occurs in one out of 20 cases; this percentage is higher for infants younger than age 6 months.
Infants are also more likely to suffer from such neurologic complications as seizures and encephalopathy, probably due to the reduction of oxygen supply to the brain. Other less serious complications include ear infection, loss of appetite, and dehydration. Adults with pertussis can have complications such as pneumonia (up to 5% of cases) and rib fracture from coughing (up to 4% of cases). Other reported side effects include (among others), loss of consciousness, female urinary incontinence, hernias, angina, and weight loss.
How do I know if my child has pertussis?
The diagnosis of pertussis is usually made based on its characteristic history and physical examination. A laboratory test may be done, which involves taking a specimen from the back of the patient’s throat (through the nose).
Prevention of Pertussis (Whooping Cough)
The best way to prevent pertussis infection is to get the pertussis vaccine. The pertussis vaccine does not contain live bacteria and cannot give you the infection.
Early treatment of pertussis cases (within first two weeks of paroxysmal cough) is essential in preventing secondary transmission. Initiating treatment more than three weeks after onset of paroxysmal cough is unlikely to be beneficial and should be limited to situations in which there is on-going contact with high-risk individuals.
Antibiotics used for treatment and prevention
The antibiotics and dosages used for treatment and post-exposure disease prevention (often referred to as “chemoprophylaxis”) Antibiotics given early in the catarrhal stage may attenuate the disease; when given during the paroxysmal stage communicability is reduced but there is little effect on the course or duration of illness.
Azithromycin, clarithromycin, erythromycin and trimethoprim-sulfamethoxazole decrease levels of B. pertussis DNA from the nasopharynx, thus decreasing infectivity five days after starting treatment with any of these agents. In principle, chemoprophylaxis of asymptomatic contacts helps to interrupt transmission by eliminating the organism during the incubation period.
Azithromycin and erythromycin are both pregnancy category B (minimal risk); clarithromycin and trimethoprim-sulfamethoxazole are category C and should be used in consultation with a prenatal care provider.