In the last two decades the incidence of pertussis has increased worldwide, including Europe and the USA.
The causes are not yet known, but there believed to be a combination of factors, such as loss of efficacy of the vaccine in adults vaccinated long ago, vaccination failures in children population (at least 3 doses of the vaccine is required for effective immunization) and a greater ability of medicine to diagnose the disease.
Despite the vaccination each 2 to 5 years localized outbreaks of pertussis occur in nearly all countries (not necessarily simultaneously). These data indicate that vaccination is effective in preventing the disease, but does not eliminate the circulation of bacteria. Where there is an accumulation of susceptible individuals, either due to lack of vaccination or loss of effectiveness of it with time, pertussis reappears with time.
The human being is the only animal that houses the bacteria Bordetella pertussis. Pertussis is a highly contagious disease, the transmission being done via aerosol droplets and airway discharged to the environment, especially during coughing. After an episode of cough bacteria is thrown into the air and can infect people in a radius larger than 1.5 meters. The transmission with hands is another important route of spread of the disease.
Thus in any case with contagious infection of the respiratory tract, the transmission of viruses and bacteria is by air expelled during speaking, sneezing and coughing. However, the main route of transmission is usually the hands, which are often brought to the mouth and nose of the individual thus contacting contaminated secretions, becoming an important reservoir of germs. To reduce the risk of contamination avoid close, prolonged contact with infected people with respiratory infections and wash hands frequently, as same objects handled by sick individuals can spread germs. Once there are bacteria or viruses on your hand, and by just scratching the nose you can become contaminated.
After exposure to Bordetella pertussis, the average incubation time is 7 to 10 days. When symptoms occur, the disease can be divided into 3 stages:
1. Catarrhal stage
The catarrhal stage is the first stage of pertussis and lasts 1 to 2 weeks. The symptoms are similar to a common respiratory virus, with fever, rhinitis, malaise, conjunctivitis, sneezing and coughing. This is the stage where the disease is more contagious.
2. Paroxysmal stage
At the end of the catarrhal stage the cough that was weak becomes increasingly frequent and stronger. The coughing attacks become violent and can last more than a minute. The patient has trouble breathing during crises and usually makes loud noises, like a hiss inspired when the airway is compressed by coughing. The coughing fits can be so intense that cause vomiting and exhaustion. Seizures are more common at night and the patient may have more than 20 episodes over the 24 hours. The coughing spells last up to 6 weeks, being the most intense in the first two.
3. Stage of convalescence
After 6 weeks of paroxysmal stage, the disease begins to relieve coughs, staying still for almost 1 month, but now without the paroxysms. However, seizures may return at this stage if the patient has the chance to present another airway infection such as the flu, for example.
Adults may have pertussis if they have not been properly vaccinated or if the vaccine has lost potency over the years. In this group pertussis may not show typical symptoms and stages described above, especially if the patient has already been vaccinated. The most common symptom of pertussis in adults is intense coughing spells, which may lead to vomiting and last up to 3 months.
The main complications of pertussis occur in children, especially in children under 6 months. The problems are usually secondary to violent bouts of coughs and include:
Most cases of deaths from pertussis occur in children less than 6 months old, the very group that has not yet completed the series of five vaccines. The mortality rate is 1% of cases. The younger is the child, the greater is the risk.
When pertussis occurs in children under 1 year of age, hospitalization is usually required to assist in hydration and nutrition. Cough suppressants do not work and now its use is discouraged. Antibiotics against Bordetella pertussis are started early to reduce the length of illness and transmission rate. After 5 days of antibiotics, the patient no longer transmits the bacterium.
The antibiotic prophylaxis is recommended for all family members or people who have had close contact with the patient during the 21 days preceding the onset of symptoms, regardless of age or vaccination status.
The current vaccination schedule of the Ministry of Health indicates a total of 5 doses of DTaP DTP diphtheria, tetanus and pertussis (whooping cough) to be given at 2, 4 and 6 months, with booster doses at 15 months and 4 years of age. With the increasing incidence of pertussis among adolescents and adults, some doctors are suggesting a new booster dose at the age of 11.
The vaccine greatly reduces the chance of contamination, but like any vaccine it is not 100% effective, especially if the last dose was given many years ago.