Case Based Pediatrics For Medical Students and Residents
Department of Pediatrics, University of Hawaii John A. Burns School of Medicine
Chapter VI.10. Pertussis
Leo U. Pascua, MD
March 2002

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In December, a 2 year old female presents to the office with a chief complaint of afebrile nocturnal coughing for 3 days. Her past medical history is significant for atopic dermatitis (uses topical hydrocortisone), as well as multiple visits for wheezing episodes which respond well to nebulized albuterol. Gastroesophageal reflux had been explored and ruled out based on history. The family history is positive for maternal, paternal and sibling asthma. She is a recent immigrant and may not have had all her immunizations.

Exam: VS T37.0, P110, R40, BP 100/60, oxygen saturation 97% in RA. All growth parameters are at the 10th percentile. She is somewhat tired and clingy but alert. HEENT significant for mild nasal congestion. Heart regular without murmurs. Extensive and diffuse biphasic wheezing is heard in the lungs. Occasional coughing is heard in the office during the clinic visit. No flaring, retractions or cyanosis is observed. She has lichenified skin over her extremities.

A presumptive diagnosis of reactive airway disease is made, and he is discharged to home on oral albuterol and prednisone. She returns 2 days later, without much improvement. A CXR is unremarkable. Amoxicillin is empirically added to her regimen. She returns 2 days later with increased coughing and tachypnea with an oxygen saturation of 94% in room air. A repeat CXR shows a suggestion of a RLL infiltrate. A presumptive diagnosis of pneumonia is made and she is admitted to a general hospital for further evaluation and management of pneumonia and asthma exacerbation. CBC is normal. RSV ELISA and pertussis fluorescent antibody from the nasopharynx are negative. A pertussis culture is obtained. She improves and is discharged home in 3 days on amoxicillin/clavulanate.

She returns to the office 3 days later with increasing coughing and hypoxia (oxygen saturation 92%). She is admitted to a tertiary care hospital for management. An RSV ELISA and pertussis fluorescent antibody are again negative. Her earlier pertussis culture is negative. An infectious disease consult is obtained. Based on her clinical presentation of hypoxia and repetitive coughing; a working diagnosis of pertussis is made. Erythromycin and supportive care are initiated. A report is made to the Department of Health. Household contacts are subsequently interviewed, and erythromycin prophylaxis is started in all contacts.

After 7 days, she improves and is discharged to home to complete her course of erythromycin.


Bordetella pertussis is a gram negative coccobacilli that is the cause of an acute respiratory illness initially characterized by protracted coughing. With respect to the differential diagnosis, protracted coughing can also be caused by Mycoplasma, parainfluenza or influenza viruses, enteroviruses, respiratory syncytial virus, or adenoviruses. The majority of cases occur from July through October. Pertussis is extremely contagious, with attack rates as high as 100% in susceptible individuals exposed to aerosol droplets at close range. Day care centers have the potential for high exposure rates. B. pertussis does not survive for prolonged periods in the environment. Although a person may be fully immunized, either actively or passively, the rate of subclinical infection is as high as 50%. Neither natural disease nor vaccination provides complete or lifelong immunity against reinfection or disease (1). Protection against typical disease begins to wane 35 years after vaccination and is unmeasurable after 12 years. Adults in the United States, e.g., day care center operators, baby-sitters, etc., have inadequate antibody to B. pertussis (2).

B. pertussis produces an array of biologically active substances which are responsible for attachment to ciliated respiratory epithelial cells, inhibited clearance of organisms and local epithelial damage. In addition, pertussis incites histamine sensitivity, insulin secretion and leukocyte dysfunction. There are 3 post-incubation stages: 1) catarrhal, 2) paroxysmal, and 3) convalescent.

After an incubation period from 3 to 12 days, the catarrhal stage is marked by: congestion, rhinorrhea, low-grade fever, sneezing, and lacrimation. As symptoms wane, the paroxysmal coughing stage begins which can be characterized by one or more of the following: 1) Intermittent, irritative hacking paroxysmal coughing, 2) Choking, gasping, eyes watering and bulging, 3) Occasional coughing up of mucous plugs, 4) Post-tussive exhaustion, 5) Coughing in long spasms with the face turning red, or sometimes blue. The coughing wanes and improves during the convalescent stage. Each stage lasts about 2 weeks. However, immunized children do better, with shortening of all stages. Conjunctival hemorrhages and petechiae on the upper body are common due to all the coughing,

Pertussis should be suspected in a patient who complains of incessant coughing for 2 weeks, especially if nothing else shows up on the physical exam. Fever, sore throat, and conjunctivitis usually accompany adenoviral infections. Mycoplasma usually has a history of fever, headache, and rales. Chlamydia trachomatis presents with purulent conjunctivitis, tachypnea, rales or wheezes. Leukocytosis (normal small cells, rather than the large atypical lymphocytes seen with viral infections) due to absolute lymphocytosis occurs in the late catarrhal and paroxysmal stages. Neutrophilia would suggest a different diagnosis or secondary bacterial infection.

The chest radiograph shows perihilar infiltrates or edema and variable degrees of atelectasis. Parenchymal consolidation also suggests secondary bacterial infection. Pneumothorax, pneumomediastinum, and air in soft tissues sometimes occur. Isolation of B. pertussis in a culture is the gold standard and is a more sensitive and specific method of diagnosis than direct fluorescent antibody (DFA) testing of nasopharyngeal secretions. Cultures are positive during the catarrhal stage and escalating paroxysmal stage. However, a false negative can occur in those who have received amoxicillin or erythromycin. A flexible swab kept in the posterior nasopharynx until the patient coughs, is one way to obtain the specimen. DFA testing of nasopharyngeal secretions is rapid, but is highly dependent on the experience of the lab technician.

Infants under 6 months of age have a higher morbidity and mortality risk. Those under 2 months of age have the highest reported rates of pertussis-associated hospitalization (82%), pneumonia (25%), seizures (4%), encephalopathy (1%), and death (1%). The principal complications of pertussis are: apnea, secondary infections (such as otitis media and pneumonia), and physical sequelae of forceful coughing.

PICU care with artificial ventilation is usually limited to infants under 3 months of age, and is suggested with the presence of apnea and cyanosis. Secondary bacterial pneumonia (Staphylococcus aureus, S. pneumonia, mouth flora) is another cause for admission and his heralded by fever, tachypnea, respiratory distress between paroxysms, and absolute neutrophilia.

Coughing transiently increases the intrathoracic and intra-abdominal pressure resulting in conjunctival hemorrhages, petechiae on the upper body, epistaxis, hemorrhage in the central nervous system and retina, pneumothorax and subcutaneous emphysema, and umbilical and inguinal hernias.

CNS abnormalities occur and are almost always the result of hypoxemia and hemorrhage associated with coughing or apnea in young infants (due to laryngospasm, vagal stimulation just before a coughing episode, from obstruction during an episode, or from hypoxemia following an episode). Seizures are usually the result of hypoxemia. Also, pneumonia can precipitate SIADH, resulting in hyponatremic seizures.

Reversible bronchiectasis or pseudobronchiectasis occurs commonly after pertussis. The bronchi may appear cylindrically dilated on bronchography, but usually resolved in about 4 months.

Patients with significant respiratory infections should be hospitalized if they are less than 3 months of age, (other causes of pneumonia presenting during the first weeks of life include C. trachomatis, genital Mycoplasma, Ureaplasma urealyticum, and occasionally bacteria such as Haemophilus species, streptococci, and Bordetella pertussis. Other indications for hospitalizations include: severe coughing paroxysms, cyanosis, poor social support, or an infection in a high risk patient (prematurity, cardiac disease, chronic pulmonary disease, neuromuscular disorder, etc.).

Admission orders should include:

Cardiorespiratory monitoring, continuous pulse oximetry, apnea monitor.

Detailed cough records (cyanosis, tachycardia, bradycardia, presence of coughed up mucus plug; post-tussive exhaustion and/or unresponsiveness).

Documentation of feeding, vomiting, and weight change.

Prn oxygen, stimulation, or suctioning (note: suctioning of nose, oropharynx, or trachea always precipitates coughing, occasionally causes bronchospasm or apnea, and should be done prn only).

Avoidance of large volume feedings.

Medication order should include: erythromycin (estolate form preferred) 4050 mg/kg/day div qid (max 2 g/day 24 hr) x 14 days.

Nursing orders should include:

Respiratory isolation for at least 5 days after start of erythromycin.

Restricting visitation of coughing family members who might be spreading pertussis to others in the hospital (until they have taken erythromycin for 5 days).

Management orders of household close contacts should include:

Erythromycin, 40-50 mg/kg/day divided qid (max 2 g/day 24 hr) for 14 days to all household and close contacts, i.e., day care, regardless of age, history of immunization, or symptomatology.

Pertussis-containing vaccine to all unimmunized contacts younger than 7 years.

Hospital discharge criteria should include clinical improvement plus: no intervention required during coughing, adequate nutrition, absence of complications, and the parents are prepared for further home care.

Primary prevention with pertussis vaccine is key. The vaccine currently used in the primary immunization series is a safer acellular vaccine composed of a suspension of inactivated B. pertussis, combined with diphtheria and tetanus (DT) toxoids and aluminum-containing adjuvants (DTaP vaccine).

For historic purposes, the adverse effects of the older whole cell vaccine (DTP, which is no longer used) are mentioned below. It resulted in more frequent pain, swelling, erythema, and systemic reactions, such as fever, fretfulness, crying, drowsiness, and vomiting. Febrile seizures, albeit rare, occurred within 48 hr and were brief, generalized, self-limited, and occurred more commonly in those with a history of seizures. Collapse or shock-like state (hypotonic-hyporesponsive episode) was rare, uniquely associated with pertussis vaccine, and has no permanent neurologic sequelae. Very rarely, pertussis vaccine was associated with acute neurologic illness in children who were previously normal. Severe adverse events, such as death, encephalopathy, onset of a seizure disorder, developmental delay, or learning or behavioral problems, have occurred in individuals temporally associated with pertussis immunization or alleged to be causally associated. These adverse effects are less likely to occur with the generation of the currently used acellular vaccine (DTaP), which has supplanted the DTP series.

Some parents have refused pertussis vaccine because of its adverse effects. Many parents believe that herd immunity will protect their children. The concept of herd immunity is that if 99% of the population is immune, then the infection can never find enough susceptible hosts to sustain itself and the few susceptible individuals within the population are unlikely to be exposed to the infection. However, herd immunity does not apply to pertussis since pertussis immunity declines substantially with age. Most teens and adults are susceptible, even if they were immunized as children. Although teens and adults with pertussis will manifest with only mild to moderate respiratory symptoms, they represent a large population of susceptible individuals who can sustain an epidemic, and thus expose unimmunized infants and children, who may have more severe infections and complications.


Questions

1. In the case, the patient's presentation and clinical course were consistent with pertussis, yet the pertussis culture was negative. Why?
. . . . . a. A false negative can occur in those who have received amoxicillin.
. . . . . b. A false negative can occur in those who have received albuterol.
. . . . . c. A false negative can occur in those who have a history of asthma.
. . . . . d. Direct fluorescent antibody (DFA) testing of nasopharyngeal secretions is the gold standard and is a more sensitive and specific method of diagnosis than culture.
. . . . . e. Cultures usually become positive only during the latter convalescent phase.

2. What etiology of sudden onset of coughing in an active infant can be effectively ruled out with a CXR?
. . . . . a. Mycoplasma
. . . . . b. Parainfluenza
. . . . . c. Enterovirus
. . . . . d. Respiratory syncytial virus
. . . . . e. Foreign body aspiration
. . . . . f. None of the above

3. Match the clinical manifestation to the disease process
a. Fever, sore throat, and conjunctivitis1. Mycoplasma
b. Fever, headache, and rales2. Adenovirus
c. Purulent conjunctivitis and tachypnea3. Chlamydia
d. Choking, gasping, eyes watery and bulging4. Pertussis

4. An experienced ward nurse asks you to correct an admission order for pertussis. Which component is incorrect ?
. . . . . a. "Continuous cardiorespiratory monitoring".
. . . . . b. "Document episodes of cyanosis or post-tussive exhaustion".
. . . . . c. "Daily weights".
. . . . . d. "Deep suctioning q 3h".
. . . . . e. "Instruct parent regarding maximal size of feedings.

5. Case management dilemma scenario: You are the admitting intern on the wards. It is 3 PM on a Friday afternoon. A patient is transferred from a neighbor island with a diagnosis of pertussis, complete with positive direct fluorescent antibody (DFA). The summary of PE findings by the community PMD includes petechiae on the upper body, epistaxis, and umbilical hernia. Upon admission to the ward you repeat the physical exam and also note retinal hemorrhages, which are confirmed by an ophthalmologist who just happens to be around. The parents have returned to the neighbor island for the weekend to fulfill important obligations and have already made arrangements to return on Monday. Given the presence of retinal hemorrhages, do you make a referral to Child Protective Services?


References

1. Long SS. Pertussis. In: Behrman RE, Kliegman RM, Arvin AM, Nelson WE (eds). Nelson Textbook of Pediatrics, 15th ed. 1996, Philadelphia: W.B. Saunders Company, CD-ROM version.

2. Cherry JD. Pertussis in adults. Ann Intern Med 1998;128:64.

3. Diphtheria, tetanus, and pertussis: recommendations for vaccine use and other preventive measures. Recommendations of the Immunization Practices Advisory committee (ACIP). MMWR Recomm Rep 1991;Aug8;40(RR-10):1-28.

4. Centers for Disease Control and Prevention. Pertussis Vaccination: Use of acellular pertussis vaccines among infants and young children. Recommendation of the Advisory Committee on Immunization Practices (ACIP). MMWR Recomm Rep 1997;Mar28;46(RR-7):1-25.

5. Recommended childhood immunization schedule--United States, 2000. Morb Mortal Wkly Rep 2000;Jan21;49(2):35-8,47.

6. Aoyama T, Murase Y, Kato M, et al. Efficacy and immunogenicity of acellular pertussis vaccine by manufacturer and patient age. Am J Dis Child 1989;134:655.


Answers to questions

1.a. A false negative can occur in those who have received amoxicillin.

2. None of the choices are correct. Choices a and e are the closest to being correct, but technically, these answers are incorrect. Mycoplasma pneumonia might show up as a pneumonia on a CXR, but this would be non-specific for mycoplasma. Additionally, some mycoplasma infections may not cause a pneumonia. Foreign body aspiration might show up on a CXR, but these often require special views such as an expiratory view or a lateral decubitus view. Foreign body aspiration is frequently occult.

3. a-2, b-1, c-3, d-4

4.d. Suctioning of nose, oropharynx, or trachea always precipitates coughing, occasionally causes bronchospasm or apnea, and should be done prn only.

5. Increased intrathoracic and intra-abdominal pressure during coughing can result in conjunctival hemorrhages, petechiae on the upper body, epistaxis, hemorrhage in the central nervous system and retina, pneumothorax and subcutaneous emphysema, and umbilical and inguinal hernias. A child protective services report is not necessarily indicated since pertussis could cause this. Other clinical or psychosocial findings inconsistent with pertussis may lead one to report this to child protective services.


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