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The coughing stage lasts for approximately six weeks before subsiding. In some countries, this disease is called the 100 days' cough or cough of 100 days because of its length.
A similar, milder disease is caused by B. parapertussis.
The pertussis component of the 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).
Unlike some vaccines, immunization against pertussis does not confer life-long immunity. While adolescents and adults rarely die if they contract pertussis after the effects of their childhood vaccinations have worn off, they may be very sick and may transmit the disease to infants and other people at much higher risk of death. To reduce morbidity and spread of the disease, Canada, France, the U.S. and Germany have approved booster shots for adolescents, adults, or both, but other countries adhere to the tradition of discontinuing pertussis vaccination after the age of seven. Even where they are available, most adults have not received booster shots and lack immunity to the disease.
Infection with pertussis induces temporary natural immunity, but—like the vaccine—does not confer a lasting protective immunity.
The newer acellular vaccine, known as DTaP, has greatly reduced the incidence of adverse effects compared to the earlier "whole-cell" pertussis vaccine. An acellular vaccine preparation for adults and adolescents has been approved in Canada, Europe, and the United States. In the U.S., the Food and Drug Administration has authorized both the use of the vaccines Boostrix (GlaxoSmithKline) for 10-18 year olds in May 2005, with an expanded indication to age 64 in December 2008, and Adacel (Sanofi Pasteur) for 11-64 year olds in August 2005. These vaccines are recommended for all teens and adults within the indicated age ranges, except for those with a history of adverse reaction to the whole-cell pertussis vaccines.
Much of the controversy surrounding the DPT vaccine in the 1970s and 1980s related to the question of whether the whole-cell pertussis component caused permanent brain injury in rare cases, called pertussis vaccine encephalopathy. Despite this possibility, doctors recommended the vaccine due to the overwhelming public health benefit, because the claimed rate was very low (one case per 310,000 immunizations, or about 50 cases out of the 15 million immunizations each year in the United States), and the risk of death from the disease was high (pertussis killed thousands of Americans each year before the vaccine was introduced). Eventually evidence against the hypothesized existence of pertussis vaccine encephalopathy mounted to the point that in 1990, the Journal of American Medical Association called it a "myth" and "nonsense".
However, before that point, criticism of the studies showing no connection and a few well-publicized anecdotal reports of permanent disability that were blamed on the DPT vaccine gave rise to anti-DPT movements in the 1970s. The negative publicity and fear-mongering caused the immunization rate to fall in several countries, including Great Britain, Sweden, and Japan. In many cases, a dramatic increase in the incidence of pertussis followed.
Unscientific claims about the vaccine pushed suppliers of the vaccines out of the market. In the United States, low profit margins and an increase in vaccine-related lawsuits led many manufacturers to stop producing the DTP vaccine by the early 1980s. By 1985, manufacturers of vaccines had difficulty obtaining liability insurance. The price of the DTP vaccine skyrocketed, leading to shortages around the country. Only one manufacturer of the DTP vaccine remained in the U.S. by the end of 1985. To avert a vaccine crisis, Congress in 1986 passed the National Childhood Vaccine Injury Act (NCVIA), which established a federal no-fault system to compensate victims of injury caused by mandated vaccines. The majority of claims that have been filed through the NCVIA have been related to injuries allegedly caused by the whole-cell DTP vaccine.
The concerns about side effects led Yuji Sato to introduce a safer acellular version of the pertussis vaccine for Japan in 1981. The acellular pertussis vaccine was approved in the United States in 1992 for use in the combination DTaP vaccine. Research has shown the acellular vaccine to be safer, with fewer reports of adverse effects.
Although the whole-cell DTP vaccine is no longer used in the United States, it is still purchased by the World Health Organization and distributed to developing nations because of its much reduced cost compared to the acellular DTaP vaccine.
There is newly emerging evidence that some strains of the bacteria that cause pertussis have become resistant to the acellular version of the vaccine which is leading to a rise in the incidence of whooping cough in the wealthy countries that use it.
Most healthy older children and adults will have a full recovery from pertussis, however those with comorbid conditions can have a higher risk of morbidity and mortality.
Infection in newborns is particularly severe. Pertussis is fatal in an estimated one in 100 infants under 6 months, and fatal in one in 200 infants aged 2 to 12 months. Infants under one are also more likely to develop complications (e.g., pneumonia (20%), encephalopathy, seizures (1%), failure to thrive, and death (0.2%)). Pertussis can cause severe paroxysm-induced cerebral hypoxia and apnea. Reported fatalities from pertussis in infants have increased substantially over the past 20 years.
for pertussis per 100,000 inhabitants.]]
Worldwide whooping cough affects 48.5 million people yearly resulting in nearly 295,000 deaths. This is despite generally high coverage with the DTP and DTaP vaccines, pertussis is one of the leading causes of vaccine-preventable deaths world-wide. Ninety percent of all cases occur in developing countries.
Before vaccines, an average of 157 cases per 100,000 persons were reported in the U.S., with peaks reported every two to five years; more than 93% of reported cases occurred in children under 10 years of age. The actual incidence was likely much higher. After vaccinations were introduced in the 1940s, incidence fell dramatically to less than 1 per 100,000 by 1970. Incidence rates have increased somewhat since 1980.
Pertussis is the only vaccine-preventable disease that is associated with increasing deaths in the U.S. The number of deaths increased from 4 in 1996 to 17 in 2001, almost all of which were infants under one year. In Canada, the number of pertussis infections has varied between 2,000 to 10,000 reported cases each year over the last 10 years. Australia reports an average of 10,000 cases a year, but the number of cases has increased in recent years. In 2010 ten infants in California died and health authorities declared an epidemic. Doctors had been misdiagnosing the infants' condition despite having seen infants on multiple visits.
Efforts to develop an inactivated whole-cell pertussis vaccine began soon after B. pertussis was grown in pure culture in 1906. In the 1920s Dr. Louis W. Sauer developed a vaccine for whooping cough at Evanston Hospital (Evanston, IL). In 1925, the Danish physician Thorvald Madsen was the first to test a whole-cell pertussis vaccine on a wide scale. He used the vaccine to control outbreaks in the Faroe Islands in the North Sea. In 1942, the American scientist Pearl Kendrick combined the whole-cell pertussis vaccine with diphtheria and tetanus toxoids to generate the first DTP combination vaccine. To minimize the frequent side effects caused by the pertussis component of the vaccine, the Japanese scientist Yuji Sato developed an acellular pertussis vaccine consisting of purified haemagglutinins (HAs: filamentous strep throat and leucocytosis-promoting-factor HA), which are secreted by B. pertussis into the culture medium. Sato's acellular pertussis vaccine was used in Japan since the autumn of 1981. Later versions of the acellular pertussis vaccine used in other countries consisted of additional defined components of B. pertussis and were often part of the DTaP combination vaccine.
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