What Is Pertussis Toxin?

Pertussis is an acute respiratory infectious disease caused by Pertussis. Since the widespread immunization of pertussis vaccines, the incidence of this disease has been greatly reduced. The clinical characteristics of pertussis are that the cough gradually worsens, showing a typical paroxysmal, spasmodic cough, and a deep chicken cry-like inspiratory roar at the end of the cough. The duration of the disease is as long as 2 to 3 months.

Basic Information

English name

whooping cough

Visiting department

Respiratory Medicine

Common causes

Pertussis

Common symptoms

Paroxysmal, spastic cough,

Causes of pertussis

Pathogens and epidemiology:

Pathogen

Generally caused by Bordetella pertussis (referred to as Bordetella pertussis) infection, the same genus of bronchial sepsis and Bordetella parapertussis can also be caused. Bordetella pertussis is a gram-negative bacillus that can produce some pathogenic substances, including pertussis toxin, tracheal cytotoxin, adenylate cyclase toxin, heat-labile toxin, and endotoxin. Pertussis toxin can mobilize the lymphocytes in the lymphatic tissue of patients to the surrounding blood and trachea. Cytotoxin can specifically damage tracheal ciliary epithelial cells, making them degenerate and necrotic.

2. Epidemiology

Pertussis patients, recessive infections, and carriers are the sources of infection. The end of the incubation period to 2 to 3 weeks after the disease is the most contagious. Pertussis is transmitted by droplets from the respiratory tract, and children under the age of 5 have the highest susceptibility. Pertussis infection rates 10 years after vaccination in children are no different from those who did not receive the vaccine.

Pertussis clinical manifestations

Incubation period

The incubation period is 5 to 21 days, usually 7 to 14 days.

2. Staging

The typical course of a patient is 6-8 weeks, and the clinical course can be divided into 3 stages:

(1) Cataphase From the onset to the onset of spasm, usually 1 to 2 weeks. The initial symptoms are similar to colds. In addition to cough, there may be runny nose, sneezing, low fever, or dry cough. When other symptoms gradually disappeared, the cough worsened, day and night became severe, and gradually became spasm-like.

(2) The period of spasm cough is generally 2 to 4 weeks or more (several days to more than 2 months). Paroxysmal and spastic cough are characteristic of this period. During the attack, the cough appears in a string, coughing for more than ten or dozens of sounds, until the sputum is coughed or the contents of the stomach are spit out, followed by a deep inhalation, and a chicken-like inhalation roar is issued. When coughing violently, there may be incontinence, urinary incontinence, flexion of elbows with both hands, eyes open, red ears, red tears, tears, head tilt forward, open mouth and tongue, cyanosis, etc. The expression is extremely painful. The lighter is several times a day, and the heavy one is dozens of times a day, mostly at night. It can be induced when running, eating, being cold, smoking, crying, etc. There are usually no obvious signs before the attack.

(3) Recovery period Generally 1 to 2 weeks, the number of cough attacks is reduced, the degree is reduced, and paroxysmal spasms no longer appear. However, paroxysmal spasm can occur repeatedly if you encounter irritation such as thick smoke or a respiratory infection.

3. Pertussis in newborns and young babies

Newborns and young infants often have no typical spasms, often holding breaths and cyanosis after coughing for a few times, easily causing suffocation and convulsions. Breathing can stop during the exhalation period, and the heart rate first increases, then slows down or even stops. If artificial respiration and oxygen are not actively rescued in time, suffocation may result.

4 Pertussis in adults

Pertussis has increased in adolescents and adults in recent years. A group of adult whooping cough confirmed by bacterial culture, with an average age of 35 years, has typical symptoms and vomiting after spasm, but can also have a dry cough for only a few weeks with rare complications. Most patients can continue to work. Although I do not have much pain, they can be used as a source of infection, especially threatening children, and should be taken seriously.

Whooping cough check

White blood cell count

At the end of the catarrhal and spasmodic cough stage, the peripheral white blood cell count was significantly increased, reaching (20-50) × 10 ⁹ / L, and the lymphocytes accounted for 0.60-0.80 in the classification, and there were no naive cells. If there is a secondary infection, the lymphocytes are relatively reduced.

2. Bacterial culture

Positive results can be obtained by using nasopharyngeal swabs in the catarrhal and spasmodic cough stages, or collecting specimens using the cough-dish method, and thin-ginger (BG) medium for bacterial culture.

3. Fluorescent antibody staining

Nasopharyngeal swab smears, stained with fluorescent-labeled specific antibodies, and examination of pathogens under a fluorescent microscope have the advantage of rapid diagnosis, but this method is slightly less specific and is only used for auxiliary diagnosis.

4. Serology

Do double serum agglutination test and complement binding test, if the antibody titer increases, diagnosis can be confirmed. In recent years, enzyme-linked immunosorbent assays have been used to determine immunoglobulin M (IgM), immunoglobulin G (IgG), and immunoglobulin A (IgA) antibodies, which is helpful for early diagnosis. It is also possible to use a single recovery serum titer of 1: 320 as a positive diagnostic value.

5. Bacteria-specific nucleic acid detection

The DNA polymerase chain reaction (PCR) method can be used to amplify bacterial-specific nucleic acids, and this method has been reported to have good specificity and sensitivity.

Pertussis diagnosis

Epidemiological history

There was a history of contact with children with whooping cough within 1 to 2 weeks before the onset.

2. Clinical characteristics

The onset was slow, with fever and cold symptoms at the beginning of the disease, and the cough gradually worsened during the night. The episode was a nightly episode. After 1 week, a paroxysmal cough accompanied by inspiratory roar appeared repeatedly. Although the cough was severe, the lungs were normal. Physical signs.

3. Blood image

Leukocytes increased significantly, often reaching (30 to 50) × 10 ⁹ / L, and lymphocytes were as high as 0.50 to 0.70.

4. Etiology and serology

(1) Bacterial culture of pharyngeal swab and cough disc culture has a higher early positive rate.

(2) Positive results of nasopharyngeal swab smears with fluorescent antibody staining .

(3) Serological examination Enzyme-linked immunosorbent assay for detection of pertussis-specific immunoglobulin M (IgM) antibodies can be used for early diagnosis; double serum agglutination test and complement binding test, the titer has increased by 4 times, as a retrospective diagnosis.

Those who have 1, 2, 3 can do clinical diagnosis, and the pathogen and serology can be confirmed.

Differential diagnosis of pertussis

Foreign body in the trachea

Sudden onset, paroxysmal spasm, and history of foreign body inhalation.

2. hilar lymph node tuberculosis

Enlarged lymph nodes can also cause paroxysms when compressing the trachea, but there is no chicken-like breathing sound, which can be identified based on the history of tuberculosis exposure, the results of PPD (pure tuberculin pure protein derivative) skin tests, and imaging studies.

Pertussis Treatment

Control the source of infection

Isolate the child and quarantine the susceptible person in close contact for 21 days.

2. General Therapy

Isolate by airways, keep the air fresh, and avoid all the factors that can induce spasms. Intensive care to prevent complications and pay attention to nutrition. Infants should be given artificial respiration immediately when they are suffocated, given oxygen, and given spasm and sputum if necessary. Intravenous infusion of procaine can be used to reduce suffocation or convulsions, and it is necessary to pay attention to heart rate and blood pressure. When there is hypocalcemia, hypoglycemia, etc., symptomatic treatment should be given.

3. Antibiotic treatment

It can reduce infectivity, reduce symptoms and shorten the course of disease when it is used in the catarrhal phase or early cough phase. If used during the spasm cough period, the course of the disease cannot be shortened significantly. Erythromycin or roxithromycin is preferred, and the course of treatment is not less than 10 days, and the compound Xin Nuo Ming can also be used.

4. Treatment of complications

Sensitive antibiotics can be used for complicated pneumonia, and symptomatic treatment such as dehydration and antispasmodic can be used for encephalopathy.

Pertussis prevention

Automatic immunity

At present, the immunization of the triple vaccine has been popularized in China. For children under 7 years of age who have not been vaccinated in the last 6 months and patients with close contact disease, 1 dose of booster immunization is given.

2. Drug prevention

After close contact with the patient, erythromycin can be taken orally for 10 days for prevention.