pertussis

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What Is Pertussis? : 

What Is Pertussis? Pertussis is a respiratory system infection caused by the bacterium Bordetella pertussis. It is characterized by severe coughing spells that may end in a "whooping" sound when the infected person inhales. The first symptoms are like a cold-sneezing, runny nose, nasal congestion, slight fever, and a dry cough that may get worse at night. Severe coughing can lead to vomiting and may make it hard for a person to eat or drink. Because adults and adolescents with pertussis may have milder symptoms, they usually don't know they have the disease.

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People get pertussis by breathing in tiny droplets released into the air by an infected person's cough or sneeze. Pertussis can last for several weeks or longer. It is typically treated with antibiotics. Patients with this disease are advised to avoid contact with anyone, particularly infants and children.

What is bordetella pertussis? : 

What is bordetella pertussis? It is an aerobic, non-motile, gram-negative coccobacillus that attaches to and multiplies on the respiratory epithelium, starting in the nasopharynx and ending primarily in the bronchi and bronchioles.

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Bordetella pertussis colonizes the cilia of the mammalian respiratory epithelium Generally, it is thought that B.pertussis does not invade the tissues, but some recent work has shown the bacterium in alveolar macrophages

Pathogenesis : 

Pathogenesis The disease pertussis has two stages; The first stage: colonization, is an upper respiratory disease with fever, malaise and coughing, which increases in intensity over about a 10-day period. During this stage the organism can be recovered in large numbers from pharyngeal cultures, and the severity and duration of the disease can be reduced by antimicrobial treatment. Adherence mechanisms of B. pertussis involve a "filamentous hemagglutinin" (FHA), which is a fimbrial-like structure on the bacterial surface, and cell-bound pertussis toxin (PTx). Short range effects of soluble toxins play a role as well in invasion during the colonization stage.

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Colonization of tracheal epithelial cells by Bordetella pertussis

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The second or toxemic stage: follows relatively nonspecific symptoms of the colonizaton stage. It begins gradually with prolonged and paroxysmal coughing that often ends in a characteristic inspiratory gasp (whoop( During the second stage, B. pertussis can rarely be recovered, and antimicrobial agents have no effect on the progress of the disease. As described below, this stage is mediated by a variety of soluble toxins.

Toxins Produced by B. pertussis : 

Toxins Produced by B. pertussis B. pertussis produces a variety of substances with toxic activity in the class of exotoxins and endotoxins. It secretes its own invasive adenylate cyclase which enters mammalian cells This toxin acts locally to reduce phagocytic activity and probably helps the organism initiate infection. This toxin is a 45 kDa protein that may be cell-associated or released into the environment. The organisms can still colonize but cannot produce the lethal disease.

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The adenylate cyclase toxin is a single polypeptide with an enzymatic domain and a binding domain that will attach to host cell surfaces. The adenylate cyclase toxin is only active in the eukaryotic cell

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It produces a highly lethal toxin which causes inflammation and local necrosis adjacent to sites where B. pertussis is located. It produces a substance called the tracheal cytotoxin which is toxic for ciliated respiratory epithelium and which will stop the ciliated cells from beating. The toxin kills ciliated cells and causes their extrusion from the mucosa and so causes fever It produces the pertussis toxin, PTx, a protein that mediates both the colonization and toxemic stages of the disease.

How is whooping cough transmitted ? : 

How is whooping cough transmitted ? Whooping cough is highly contagious and is spread among people by direct contact with fluids from the nose or mouth of infected people. People contaminate their hands with respiratory secretions from an infected person and then touch their own mouth or nose. In addition, small bacteria-containing droplets enter the air during coughing or sneezing. People can become infected by breathing in these drops

symptoms of pertussis : 

symptoms of pertussis Pertussis has three stages that are characterized by different symptoms. Following a 7-10 day incubation period, a person with pertussis disease will move through these stages: The catarrhal stage is the first stage, which involves the non-specific symptoms of runny nose, sneezing, low-grade fever, and mild cough. This stage lasts 1-2 weeks, and the cough gradually becomes more severe as a person progresses through this stage.

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The paroxysmal stage involves numerous, rapid bursts of coughing (called paroxysms), and is when pertussis is first suspected and diagnosed. The bouts of coughing may be so severe that the person will turn blue, and the need for oxygen so extreme that the person will inhale strongly enough to cause an inspiratory whoop. The paroxysms of coughing are most frequent at night, and can occur up to 15 times in a 24 hour time period. The cough gradually increases in frequency and severity for the first week of this stage, remains constant for 2-3 weeks, and then begins a decline. The convalescent stage involves the gradual cessation of the cough and recovery from pertussis. The cough slowly decreases in frequency and loses the paroxysmal strength. This stage can last from weeks to months.

How is whooping cough diagnosed? : 

How is whooping cough diagnosed? laboratory tests can be carried out. Culture of the bacterium Bordetella pertussis from nasal secretions can establish the diagnosis. Another test that has been used to successfully identify the bacterium and diagnose pertussis is the polymerase chain reaction (PCR) test that can identify genetic material from the bacterium in nasal secretions.

treatment : 

treatment Because pertussis is a bacterial infection, it is treated with antibiotics. such as erythromycin and amoxicillin can make the symptoms go away more quickly. Unfortunately, most patients are diagnosed too late, when antibiotics aren't very effective. However, the medicines can help reduce the patient's ability to spread the disease to others

Expectations (prognosis) : 

Expectations (prognosis) In older children, the outlook is generally very good. Infants have the highest risk of death, and need careful monitoring

Complications : 

Complications Pneumonia Convulsions Seizure disorder (permanent) Nose bleeds Ear infections Brain damage from lack of oxygen Bleeding in the brain (cerebral hemorrhage) Mental retardation Slowed or stopped breathing (apnea) Death

Prevention : 

Prevention A TDaP vaccine (tetanus, diphtheria, pertussis) or pertussis-only vaccine helps protect children against this disease. Vaccination starts in infancy. A booster shot (a lower dose of the infant pertussis vaccine) is approved for kids aged 10 to 18. The booster shot may help reduce the the number of pertussis cases in adolescents and adults

summary : 

summary Hello. You can call me B. pertussis. I'm a Gram Negative bacteria. I am spread to people by respiratory droplets. I cause whooping cough, which can be highly fatal in infants. How do I do this? I get into the throat and make toxins. First I give you a cough, then your throat swells up. If it swells up enough, it can block your airway, giving your breathing a "whooping" sound

References : 

References Braman SS. Postinfectious cough: ACCP evidence-based clinical practice guidelines. Chest. 2006;129(1):138S-146S. US Food and Drug Administration. First Combination Vaccine Approved to Help Protect Adolescents Against Whooping Cough. Rockville, MD: National Press Office; May 3, 2005. Talk Paper T05-17.

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