Causes, Effects Symptoms And Signs Of Pertussis (Whooping Cough)

 

Pertussis commonly called whooping cough is a highly contagious bacterial disease caused by Bordetella pertussis. In some countries, this disease is called the 100 days' cough or cough of 100 days.


Symptoms are initially mild, and then develop into severe coughing fits, which produce the namesake high-pitched "whoop" sound in infected babies and children when they inhale air after coughing. The coughing stage lasts approximately six weeks before subsiding.

Prevention by vaccination is of primary importance given the seriousness of the disease in children. Although treatment is of little direct benefit to the person infected, antibiotics are recommended because they shorten the duration of infectiousness.

It is estimated that the disease currently affects 48.5 million people yearly, resulting in nearly 295,000 deaths.

Signs and symptoms

The classic symptoms of pertussis are a paroxysmal cough, inspiratory whoop, and fainting and/or vomiting after coughing.

The cough from pertussis has been documented to cause subconjunctival hemorrhages, rib fractures, urinary incontinence, hernias, post-cough fainting, and vertebral artery dissection.

Violent coughing can cause the pleura to rupture, leading to a pneumothorax. If there is vomiting after a coughing spell or an inspiratory whooping sound on coughing, the likelihood almost doubles that the illness is pertussis. On the other hand, the absence of a paroxysmal cough or posttussive emesis makes it almost half as likely.


The incubation period is typically seven to ten days with a range of four to 21 days and rarely may be as long as 42 days, after which there are usually mild respiratory symptoms, mild coughing, sneezing, or runny nose.

This is known as the catarrhal stage. After one to two weeks, the coughing classically develops into uncontrollable fits, each with five to ten forceful coughs, followed by a high-pitched "whoop" sound in younger children, or a gasping sound in older children, as the patient struggles to breathe in afterwards (paroxysmal stage).

Fits can occur on their own or can be triggered by yawning, stretching, laughing, eating or yelling; they usually occur in groups, with multiple episodes every hour around the clock.

This stage usually lasts two to eight weeks, or sometimes longer. A gradual transition then occurs to the convalescent stage, which usually lasts one to two weeks.

This stage is marked by a decrease in paroxysms of coughing, both in frequency and severity, and a cessation of vomiting.

A tendency to produce the "whooping" sound after coughing may remain for a considerable period after the disease itself has cleared up.

Prevention

The primary method of prevention for pertussis is vaccination. There is insufficient evidence to determine the effectiveness of antibiotics in those who have been exposed but are without symptoms.

Prophylactic antibiotics, however, are still frequently used in those who have been exposed and are at high risk of severe disease (such as infants).

Vaccine

Pertussis vaccines are effective, routinely recommended by the World Health Organization and the Center for Disease Control and Prevention, and saved over half a million lives in 2002.

The multi-component acellular pertussis vaccine, for example, is between 71-85% effective with greater effectiveness for more severe disease.

Despite widespread use of the vaccine however, pertussis has persisted in vaccinated populations and is today one of the most prevalent vaccine-preventable diseases in Western countries.

Recent resurgences in pertussis infections are attributed to a combination of waning immunity and new mutations in the virus that existing vaccines are unable to effectively control.

Immunization against pertussis does not confer lifelong immunity, a 2011 study by the CDC indicated that the duration of protection may only last three to six years.

This covers childhood, which is the time of greatest exposure and greatest risk of death from pertussis.

For children, the immunizations are commonly given in combination with immunizations against tetanus, diphtheria, polio and haemophilus influenzae type B at ages two, four, six, and 15–18 months. A single later booster is given at four to six years of age.

(US schedule). In the UK, pertussis vaccinations are given at 2, 3 and 4 months, with a pre-school booster at 3 years 4 months.

Dr. Paul Offit, chief of the Director of the Vaccine Education Center at the Children's Hospital of Philadelphia, comments that the last pertussis vaccination people receive may be their booster at age 11 or 12 years old. However, he states that it is important for adults to have immunity as well to prevent transmission of the disease to infants.

While adults rarely die if they contract pertussis after the effects of their childhood vaccinations have worn off, they may transmit the disease to people at much higher risk of injury or death.

To reduce morbidity and spread of the disease, Canada, France, the U.S. and Germany have approved pertussis vaccine booster shots. In 2012, a federal advisory panel recommended that all U.S. adults receive vaccination.

Later that year, health officials in the UK recommended the vaccination of pregnant women (between 28 – 38 weeks of pregnancy) in order to protect their unborn children.

Designed to protect babies from birth until their first standard vaccination at eight weeks of age, this vaccine was introduced in response to the ongoing outbreak of pertussis in the UK, the worst in over a decade.

The pertussis booster for adults is combined with a tetanus vaccine and diphtheria vaccine booster; this combination is abbreviated "Tdap" (Tetanus, diphtheria, acellular pertussis).

It is similar to the childhood vaccine called "DTaP" (Diphtheria, Tetanus, acellular Pertussis), with the main difference that the adult version contains smaller amounts of the diphtheria and pertussis components — this is indicated in the name by the use of lower-case "d" and "p" for the adult vaccine.

The lower-case "a" in each vaccine indicates that the pertussis component is acellular, or cell-free, which improves safety by dramatically reducing the incidence of side effects. Adults should request the Tdap instead of just a tetanus vaccination in order to receive the multi-vaccine.

The pertussis component of the original DPT vaccine accounted for most of the minor local and systemic side effects in many vaccinated infants (such as mild fever or soreness at the injection site).

The newer acellular vaccine, known as DTaP, has greatly reduced the incidence of adverse effects compared to the earlier "whole-cell" pertussis vaccine, however the efficacy of the acellular vaccine declines faster that the whole-cell vaccine.

Infection with pertussis induces incomplete natural immunity that wanes over time. Natural immunity lasts longer than vaccine-induced immunity, with one study reporting maximum effectiveness as long as 20 years in the former and 12 in the latter.

Outbreaks

In April and May 2012, pertussis was declared to be at epidemic levels in the US state of Washington. In September 2012, a similar epidemic of pertussis was seen in parts of the United Kingdom, with several babies dying as a result.

In December 2012, the state of Vermont declared a pertussis epidemic. The state of Wisconsin has the highest incidence rate, however it has not released an official epidemic declaration.