Download Pertussis, more commonly known as whooping cough, is

Pertussis, more commonly known as whooping cough, is a bacterial
infection of the upper respiratory system.
LEARNING OBJECTIVE [ edit ]
Describe the mechanism of action and causes of pertussis causing bacteria
KEY POINTS [ edit ]
Whooping cough is caused by the bacteria Bordetella pertussis, which infects the respiratory
system.
There is no zoonotic reservoir of Bordetella pertussis, meaning that humans appear to be the
only host of this bacteria.
Bordetella pertussis produces a number of virulence factors, notably Ptx, which inhibits the
ability of phagocytes to respond to infections. This helps Bordetella pertussis spread throughout a
host.
TERMS [ edit ]
lymphocytes
type of white blood cells in the vertebrate immune system
zoonotic
of or relating to zoonosis, the transmission of an infectious disease between species.
glottis
an organ of speech, located in the larynx, and consisting of the true vocal cords and the opening
between them
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Pertussis
Pertussis, also known as whooping cough,
is an infection of the respiratory system
characterized by a "whooping" sound that
an afflicted person makes when breathing
inwards. Only 50% of patients actually
display the classic sound as they attempt
to draw breath over a partially
closed glottis. In the U.S., the infection
was responsible for 5,000 to 10,000
deaths per year before a vaccine was
developed and made
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available. Vaccination has transformed this. Between 1985 and 1988, fewer than 100 children
died from pertussis. In 2000, according to the WHO, around 39 million people worldwide
were being infected annually. Of these, about 297,000 died.
Causes of Pertussis
Pertussis is caused by the bacteria, Bordetella pertussis, a gramnegative, aerobic coccobacillus capsulate of the genus Bordetella . Bordetella pertussis infects
its host by colonizing lungepithelial cells. The bacterium contains a surface protein,
filamentous haemagglutinin adhesin, which binds to the sulfatides found on the cilia of
epithelial cells. Once anchored, the bacterium produces tracheal cytotoxin, which stops the
cilia from beating. This prevents the cilia from clearing debris from an organism's lungs, and
the body responds by sending the host into a coughing fit. These coughs expel some bacteria
into the air, which are free to infect other hosts. There does not appear to be a zoonotic
reservoir for B. pertussis. Humans are its only host. The bacterium is spread by airborne
droplets, and its incubation period is one to two weeks.
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B. pertussis has the ability to inhibit the function of a host'simmune system, through
virulence factors. Its virulence factors include pertussis toxin, filamentous hæmagglutinin,
pertactin, fimbria, and tracheal cytotoxin. The pertussis toxin, or PTx, inhibits G protein
coupling that regulates an adenylate cyclase-mediated conversion of ATP to cyclic AMP. The
end result is that phagocytes convert too much ATP to cyclic AMP, which can cause
disturbances in cellular signaling mechanisms. This prevents phagocytes from correctly
responding to an infection. PTx, formerly known as lymphocytosis-promoting factor, causes a
decrease in the entry of lymphocytes into lymph nodes. This can lead to a condition known as
lymphocytosis, which is a large increase in the number of lymphocytes in an organism's
blood.
Bordetella pertussis
Bordetella pertussis, the bacteria that causes whooping cough