Pertussis
Encyclopedia
Pertussis, also known as whooping cough (icon or ˈ), is a highly contagious bacterial disease caused by Bordetella pertussis
. 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 for approximately six weeks before subsiding. In some countries, this disease is called the 100 days' cough or cough of 100 days.
Prevention via vaccination
is of primary importance as treatment is of little clinical benefit to the person infected. Antibiotic
s, however, do decrease the duration of infectiousness and are thus recommended. It is estimated that the disease currently affects 48.5 million people yearly, resulting in nearly 295,000 deaths.
after coughing. The cough from pertussis has been documented to cause subconjunctival hemorrhage
s, rib fracture
s, urinary incontinence, hernias, post-cough fainting
, and vertebral artery dissection
. If there is vomiting after a coughing spell or an inspiratory whooping sound on coughing, the likelihood that the illness is pertussis is nearly doubled. 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 in infants or young children, 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.
of nasopharyngeal swabs on Bordet-Gengou medium
, polymerase chain reaction
(PCR), direct immunofluorescence
(DFA), and serological
methods. The bacteria can be recovered from the patient only during the first three weeks of illness, rendering culturing and DFA useless after this period, although PCR may have some limited usefulness for an additional three weeks. For most adults and adolescents, who often do not seek medical care until several weeks into their illness, serology may be used to determine whether antibody against pertussis toxin
or another component of B. pertussis is present at high levels in the blood of the patient. By this stage they have been contagious for some weeks and may have spread the infection to many people. Because of this, adults, who are not in great danger from pertussis, are increasingly being encouraged to be vaccinated.
A similar, milder disease is caused by B. parapertussis
.
. 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).
s 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 vaccines for example is between 71-85% effective with greater effectiveness for more severe disease.
The duration of protection is between five to ten 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.
A 2011 study by the CDC indicated that the duration of protection may only last three to six years. 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.
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).
Immunization against pertussis does not confer life-long immunity. 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 death. To reduce morbidity and spread of the disease, Canada, France, the U.S. and Germany have approved booster shots. 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 effect
s compared to the earlier "whole-cell" pertussis vaccine.
The most serious side effects of earlier "whole-cell" pertussis immunizations were neurological
: and included seizure
s and hypotonic episodes. In addition, a number of children suffered allergic and adverse reactions to the pertussis vaccination, including severe seizures.
is currently the first line treatment. Newer macrolides are frequently recommended due to lower rates of side effects. Trimethoprim-sulfamethoxazole may be used in those with allergies to first line agents or in infants who have a risk of pyloric stenosis
from macrolides. Effective treatments of the cough
associated with this condition have not yet been developed.
, encephalopathy
, earache, or seizure
s.
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 two months, and fatal in one in 200 infants aged two 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.
-preventable deaths world-wide. 90% 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 four 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 ten 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. In the US pertussis in adults has increased significantly since about 2004.
and Octave Gengou
, who also developed the first serology and vaccine. The complete B. pertussis genome
of 4,086,186 base pairs was sequenced in 2004.
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 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.
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).
No studies showed a causal connection, and later studies showed no connection of any type between administration of the DPT vaccine and permanent brain injury. The alleged vaccine-induced brain damage proved to be an unrelated condition, infantile epilepsy
. 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 DPT vaccine by the early 1980s.
In 1982, the television documentary "DTP: Vaccine Roulette" depicted the lives of children whose severe disabilities were inaccurately blamed on the DPT vaccine by reporter Lea Thompson. The negative publicity generated by the documentary led to a tremendous increase in the number of lawsuits filed against vaccine manufacturers. By 1985, manufacturers of vaccines had difficulty obtaining liability insurance. The price of the DPT vaccine skyrocketed, leading to shortages around the country. Only one manufacturer of the DPT 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 DPT vaccine.
The concerns about side effects led Yuji Sato to introduce an even 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.
Bordetella pertussis
Bordetella pertussis is a Gram-negative, aerobic coccobacillus of the genus Bordetella, and the causative agent of pertussis or whooping cough. Unlike B. bronchiseptica, B. pertussis is non-motile. Its virulence factors include pertussis toxin, filamentous hæmagglutinin, pertactin, fimbria, and...
. 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 for approximately six weeks before subsiding. In some countries, this disease is called the 100 days' cough or cough of 100 days.
Prevention via vaccination
Vaccination
Vaccination is the administration of antigenic material to stimulate the immune system of an individual to develop adaptive immunity to a disease. Vaccines can prevent or ameliorate the effects of infection by many pathogens...
is of primary importance as treatment is of little clinical benefit to the person infected. Antibiotic
Antibiotic
An antibacterial is a compound or substance that kills or slows down the growth of bacteria.The term is often used synonymously with the term antibiotic; today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic has come to denote a broader range of...
s, however, do decrease the duration of infectiousness and are thus recommended. 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 vomitingVomiting
Vomiting is the forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose...
after coughing. The cough from pertussis has been documented to cause subconjunctival hemorrhage
Subconjunctival hemorrhage
thumb|right|250px| A stress induced subconjunctival hemorrhage in the left eye one week after hemorrhaging. Same hemorrhage four weeks after hemorrhaging. Some of the blood in the [[sclera]] has turned yellow, like a bruise....
s, rib fracture
Rib fracture
A rib fracture is a break or fracture in one or more of the bones making up the rib cage.The first rib is rarely fractured because of its protected position behind the clavicle . However, if it is broken serious damage can occur to the brachial plexus of nerves and the subclavian vessels...
s, urinary incontinence, hernias, post-cough fainting
Syncope
In phonology, syncope is the loss of one or more sounds from the interior of a word; especially, the loss of an unstressed vowel. It is found bothin Synchronic analysis of languages and Diachronics .-Found synchronically:...
, and vertebral artery dissection
Vertebral artery dissection
Vertebral artery dissection is a dissection of the inner lining of the vertebral artery, which is located in the neck and supplies blood to the brain. After the tear, blood enters the arterial wall and forms a blood clot, thickening the artery wall and often impeding blood flow...
. If there is vomiting after a coughing spell or an inspiratory whooping sound on coughing, the likelihood that the illness is pertussis is nearly doubled. On the other hand, the absence of a paroxysmal cough or posttussive emesis makes it almost half as likely.
The incubation period
Incubation period
Incubation period is the time elapsed between exposure to a pathogenic organism, a chemical or radiation, and when symptoms and signs are first apparent...
is typically seven to ten days in infants or young children, 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.
Diagnosis
Methods used in laboratory diagnosis include culturingMicrobiological culture
A microbiological culture, or microbial culture, is a method of multiplying microbial organisms by letting them reproduce in predetermined culture media under controlled laboratory conditions. Microbial cultures are used to determine the type of organism, its abundance in the sample being tested,...
of nasopharyngeal swabs on Bordet-Gengou medium
Bordet-Gengou agar
Bordet-Gengou agar is a type of agar plate optimized to isolate Bordetella, containing blood, potato extract, and glycerol, with an antibiotic such as cephalexin or penicillin and sometimes nicotinamide...
, polymerase chain reaction
Polymerase chain reaction
The polymerase chain reaction is a scientific technique in molecular biology to amplify a single or a few copies of a piece of DNA across several orders of magnitude, generating thousands to millions of copies of a particular DNA sequence....
(PCR), direct immunofluorescence
Direct fluorescent antibody
Direct fluorescent antibody is a laboratory test that uses antibodies tagged with fluorescent dye that can be used to detect the presence of microorganisms. This method offers straightforward detection of antigens using fluorescently labeled antigen-specific antibodies...
(DFA), and serological
Serology
Serology is the scientific study of blood serum and other bodily fluids. In practice, the term usually refers to the diagnostic identification of antibodies in the serum...
methods. The bacteria can be recovered from the patient only during the first three weeks of illness, rendering culturing and DFA useless after this period, although PCR may have some limited usefulness for an additional three weeks. For most adults and adolescents, who often do not seek medical care until several weeks into their illness, serology may be used to determine whether antibody against pertussis toxin
Pertussis toxin
Pertussis toxin is a protein-based AB5-type exotoxin produced by the bacterium Bordetella pertussis, which causes whooping cough. PT is involved in the colonization of the respiratory tract and the establishment of infection...
or another component of B. pertussis is present at high levels in the blood of the patient. By this stage they have been contagious for some weeks and may have spread the infection to many people. Because of this, adults, who are not in great danger from pertussis, are increasingly being encouraged to be vaccinated.
A similar, milder disease is caused by B. parapertussis
Bordetella parapertussis
Bordetella parapertussis is a small Gram-negative bacterium of the genus Bordetella which is adapted to colonise the mammalian respiratory tract. Pertussis caused by B. parapertussis manifests with similar symptoms to B. pertussis-derived disease but tends to be generally less severe. Immunity...
.
Prevention
The primary method of prevention for pertussis is vaccinationVaccination
Vaccination is the administration of antigenic material to stimulate the immune system of an individual to develop adaptive immunity to a disease. Vaccines can prevent or ameliorate the effects of infection by many pathogens...
. 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 vaccinePertussis vaccine
Pertussis vaccine is a vaccine used against Bordetella pertussis.It is a component of the DPT vaccine.Older versions of the vaccine involved inactivated cells. Newer versions are acellular, and are less likely to provoke a febrile state....
s are effective, routinely recommended by the World Health Organization
World Health Organization
The World Health Organization is a specialized agency of the United Nations that acts as a coordinating authority on international public health. Established on 7 April 1948, with headquarters in Geneva, Switzerland, the agency inherited the mandate and resources of its predecessor, the Health...
and the Center for Disease Control and Prevention, and saved over half a million lives in 2002. The multi-component acellular pertussis vaccines for example is between 71-85% effective with greater effectiveness for more severe disease.
The duration of protection is between five to ten 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
Tetanus
Tetanus is a medical condition characterized by a prolonged contraction of skeletal muscle fibers. The primary symptoms are caused by tetanospasmin, a neurotoxin produced by the Gram-positive, rod-shaped, obligate anaerobic bacterium Clostridium tetani...
, diphtheria
Diphtheria
Diphtheria is an upper respiratory tract illness caused by Corynebacterium diphtheriae, a facultative anaerobic, Gram-positive bacterium. It is characterized by sore throat, low fever, and an adherent membrane on the tonsils, pharynx, and/or nasal cavity...
, 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.
A 2011 study by the CDC indicated that the duration of protection may only last three to six years. Dr. Paul Offit
Paul Offit
Paul A. Offit, M.D., is an American pediatrician specializing in infectious diseases and an expert on vaccines, immunology, and virology. He is the co-inventor of a rotavirus vaccine that has been credited with saving hundreds of lives every day. Offit is the Maurice R...
, chief of the Director of the Vaccine Education Center at the Children's Hospital of Philadelphia
Children's Hospital of Philadelphia
The Children's Hospital of Philadelphia is one of the largest and oldest children's hospitals in the world. CHOP has been ranked as the best children's hospital in the United States by U.S. News & World Report and Parents Magazine in recent years. As of 2008, it was ranked #1 in the nation for...
, 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.
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).
Immunization against pertussis does not confer life-long immunity. 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 death. To reduce morbidity and spread of the disease, Canada, France, the U.S. and Germany have approved booster shots. 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
DPT vaccine
DPT refers to a class of combination vaccines against three infectious diseases in humans: diphtheria, pertussis and tetanus...
, has greatly reduced the incidence of adverse effect
Adverse effect
In medicine, an adverse effect is a harmful and undesired effect resulting from a medication or other intervention such as surgery.An adverse effect may be termed a "side effect", when judged to be secondary to a main or therapeutic effect. If it results from an unsuitable or incorrect dosage or...
s compared to the earlier "whole-cell" pertussis vaccine.
The most serious side effects of earlier "whole-cell" pertussis immunizations were neurological
Neurology
Neurology is a medical specialty dealing with disorders of the nervous system. Specifically, it deals with the diagnosis and treatment of all categories of disease involving the central, peripheral, and autonomic nervous systems, including their coverings, blood vessels, and all effector tissue,...
: and included seizure
Seizure
An epileptic seizure, occasionally referred to as a fit, is defined as a transient symptom of "abnormal excessive or synchronous neuronal activity in the brain". The outward effect can be as dramatic as a wild thrashing movement or as mild as a brief loss of awareness...
s and hypotonic episodes. In addition, a number of children suffered allergic and adverse reactions to the pertussis vaccination, including severe seizures.
Management
The treatment of pertussis is generally ineffective at changing clinical outcomes thus prevention is of primary importance. Antibiotics do however decrease the duration of infectiousness and thus prevent spread. The antibiotic erythromycinErythromycin
Erythromycin is a macrolide antibiotic that has an antimicrobial spectrum similar to or slightly wider than that of penicillin, and is often used for people who have an allergy to penicillins. For respiratory tract infections, it has better coverage of atypical organisms, including mycoplasma and...
is currently the first line treatment. Newer macrolides are frequently recommended due to lower rates of side effects. Trimethoprim-sulfamethoxazole may be used in those with allergies to first line agents or in infants who have a risk of pyloric stenosis
Pyloric stenosis
Pyloric stenosis is a condition that causes severe vomiting in the first few months of life. There is narrowing of the opening from the stomach to the intestines, due to enlargement of the muscle surrounding this opening , which spasms when the stomach empties...
from macrolides. Effective treatments of the cough
Cough
A cough is a sudden and often repetitively occurring reflex which helps to clear the large breathing passages from secretions, irritants, foreign particles and microbes...
associated with this condition have not yet been developed.
Prognosis
Common complications of the disease include pneumoniaPneumonia
Pneumonia is an inflammatory condition of the lung—especially affecting the microscopic air sacs —associated with fever, chest symptoms, and a lack of air space on a chest X-ray. Pneumonia is typically caused by an infection but there are a number of other causes...
, encephalopathy
Encephalopathy
Encephalopathy means disorder or disease of the brain. In modern usage, encephalopathy does not refer to a single disease, but rather to a syndrome of global brain dysfunction; this syndrome can be caused by many different illnesses.-Terminology:...
, earache, or seizure
Seizure
An epileptic seizure, occasionally referred to as a fit, is defined as a transient symptom of "abnormal excessive or synchronous neuronal activity in the brain". The outward effect can be as dramatic as a wild thrashing movement or as mild as a brief loss of awareness...
s.
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 two months, and fatal in one in 200 infants aged two 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.
Epidemiology
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 vaccineVaccine
A vaccine is a biological preparation that improves immunity to a particular disease. A vaccine typically contains an agent that resembles a disease-causing microorganism, and is often made from weakened or killed forms of the microbe or its toxins...
-preventable deaths world-wide. 90% 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
Incidence (epidemiology)
Incidence is a measure of the risk of developing some new condition within a specified period of time. Although sometimes loosely expressed simply as the number of new cases during some time period, it is better expressed as a proportion or a rate with a denominator.Incidence proportion is the...
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 four in 1996 to 17 in 2001, almost all of which were infants under one year. In Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
, the number of pertussis infections has varied between 2,000 to 10,000 reported cases each year over the last ten years. Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
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. In the US pertussis in adults has increased significantly since about 2004.
History
B. pertussis was isolated in pure culture in 1906 by Jules BordetJules Bordet
Jules Jean Baptiste Vincent Bordet was a Belgian immunologist and microbiologist. The bacterial genus Bordetella is named after him.-Biography:Bordet was born at Soignies, Belgium...
and Octave Gengou
Octave Gengou
Octave Gengou was a Belgian bacteriologist. He researched with Jules Bordet the Bordetella pertussis bacteria.- Biography :...
, who also developed the first serology and vaccine. The complete B. pertussis genome
Genome
In modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA....
of 4,086,186 base pairs was sequenced in 2004.
Efforts to develop an inactivated whole-cell pertussis vaccine
Vaccine
A vaccine is a biological preparation that improves immunity to a particular disease. A vaccine typically contains an agent that resembles a disease-causing microorganism, and is often made from weakened or killed forms of the microbe or its toxins...
began soon after B. pertussis was grown in pure culture in 1906. In the 1920s, Dr. Louis W. Sauer
Louis W. Sauer
Louis Wendlin Sauer was a pediatrician who became known for perfecting the vaccine used to prevent pertussis , saving countless lives around the world. Sauer was born in Cincinnati, met his wife Mira while he was in Germany as he was a medical student, and established a practice at Evanston...
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
Diphtheria
Diphtheria is an upper respiratory tract illness caused by Corynebacterium diphtheriae, a facultative anaerobic, Gram-positive bacterium. It is characterized by sore throat, low fever, and an adherent membrane on the tonsils, pharynx, and/or nasal cavity...
and tetanus
Tetanus
Tetanus is a medical condition characterized by a prolonged contraction of skeletal muscle fibers. The primary symptoms are caused by tetanospasmin, a neurotoxin produced by the Gram-positive, rod-shaped, obligate anaerobic bacterium Clostridium tetani...
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 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.
Society and culture
Much of the controversy surrounding the DPT vaccineDPT vaccine
DPT refers to a class of combination vaccines against three infectious diseases in humans: diphtheria, pertussis and tetanus...
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).
No studies showed a causal connection, and later studies showed no connection of any type between administration of the DPT vaccine and permanent brain injury. The alleged vaccine-induced brain damage proved to be an unrelated condition, infantile epilepsy
Epilepsy
Epilepsy is a common chronic neurological disorder characterized by seizures. These seizures are transient signs and/or symptoms of abnormal, excessive or hypersynchronous neuronal activity in the brain.About 50 million people worldwide have epilepsy, and nearly two out of every three new cases...
. 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
Anecdotal evidence
The expression anecdotal evidence refers to evidence from anecdotes. Because of the small sample, there is a larger chance that it may be true but unreliable due to cherry-picked or otherwise unrepresentative of typical cases....
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 DPT vaccine by the early 1980s.
In 1982, the television documentary "DTP: Vaccine Roulette" depicted the lives of children whose severe disabilities were inaccurately blamed on the DPT vaccine by reporter Lea Thompson. The negative publicity generated by the documentary led to a tremendous increase in the number of lawsuits filed against vaccine manufacturers. By 1985, manufacturers of vaccines had difficulty obtaining liability insurance. The price of the DPT vaccine skyrocketed, leading to shortages around the country. Only one manufacturer of the DPT 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
National Childhood Vaccine Injury Act
The National Childhood Vaccine Injury Act of 1986 was enacted in the United States to reduce the potential financial liability of vaccine makers due to vaccine injury claims. The legislation was aimed at ensuring a stable market supply, and to provide cost-effective arbitration for vaccine...
(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 DPT vaccine.
The concerns about side effects led Yuji Sato to introduce an even 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.