Parainfluenza VirusParainfluenza Virus

Case Study # 2

Galarah D GolanbarChristopher KwonVanessa Munoz

Case study

• A 13 month old child has a runny nose, mild cough, and a low grade fever for several days. The cough got worse and sounded like “barking”. The child made a wheezing sound when agitated. The child appeared well except for the cough. A lateral X-ray examination of the neck showed a subglottic narrowing.

Background information• Parainfluenza virus (PIV)

– Negative sense, single-stranded RNA virus– Varies in size and shape

• Averaging in diameters of 150-300 nm– Account for a large percentage of pediatric respiratory

infections, second to respiratory syncitial virus.– Major cause of croup– Divided into 4 types

• Type 1 is the most frequent in children, followed by type 3 and type 2.

• Type 4 is less likely to cause a severe illness.

• Self- limited infection– Can manifest repeatedly throughout life

Described Symptoms• Coryza

– Symptoms of a common head cold• nasal congestion• runny nose• Sore throat• cough

– Inflammation of nasal cavity mucous membrane, affecting upper respiratory tract

• Viral croup– Inflammation of the larynx and upper airway

• Results in narrowing of the airway– Characterized by a barking cough, inspiratory stridor, and a variable

amount of respiratory distress that develops over a brief period. • Stridor

– A high pitched, breathing sound caused by turbulent flow of air, usually caused by a blockage in breathing

– Inspiratory stridor (a sound heard in inspiration through a spasmodically closed glottis)

Described Symptoms• Retractions

– Intercostal retractions: retractions of the chest cavity• The inward movement of the chest due to

decreased pressure in the chest cavity.• Usually an indicator for difficulty in breathing

• The virus will cause a diffused inflammation with erythema and edema in the tracheal walls that will affect the mobility of the vocal cords.– The subglottic region of the child’s upper airway is

narrow. So, a small amount of edema will significantly restrict airflow.

Other causative agents

• Viruses from the Paramyxoviridae family– Mumps, measles, and respiratory syncitial virus (RSV)

• Can also cause sporadic cases of croup• Adenovirus

– Infection of the respiratory tract, as well as eyes, intestines, and urinary tract

• Pneumonia– Inflammation of the lungs caused by bacteria, viruses, or other

microorganisms

– Leading cause of death in children worldwide

• Influenza A and B– Both caused by viruses in the family Orthomyxoviridae

Differential Diagnosis• There are several differential diagnoses listed:

Acute laryngotracheobronchitis

Spasmodic croup Epiglottitis

Bacterial tracheitis Peritonsillar abscess Retropharyngeal abscess

Diphtheria Angioneurotic edema

Burns or thermal injury

Smoke inhalation Neoplasm or hemangioma

Foreign body

Extrinsic obstruction by a vascular ring

Acute laryngeal fracture

Arnold-Chiari malformation

Dandy-Walker malformation

Laryngomalacia Subglottic stenosis Laryngeal papillomatosis

Parainfluenza virus : Current Diagnosis• Pulse Oximetry

• Monitors oxygen saturation in the blood.• Used to evaluate the severity of the illness.

• Laryngoscopy• Direct: An examination used to look inside the throat with a small

camera.• Used in severe cases of parainfluenza virus infection.

• Indirect: done with a small handheld mirror to look at the back of the throat.

Techniques and Tests for Diagnosis

• Diagnostic Techniques:– Radiographic Studies

• Posteroanterior (PA) radiography of the neck

– Only confirms 50% of cases

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Parainfluenza virus : Current Diagnosis

• Lab tests:Lab tests:– Viral cultures

• Requires several days to see the results. More helpful epidemiologically than clinically.

– Immunofluorescence and enzyme immunoassay methods

• Done in vitro and tests the nasopharyngeal washings of infected patients.

– CBC:• Complete Blood Count measures:

– Red blood cell (RBC), white blood cell (WBC), total hemoglobin in blood, hematocrit (fraction of blood composed of RBCs), and mean corpusular volume (MCV, which measures size of RBCs)

– RNA amplification– Hemadsorption

Final Diagnosis

Treatment

• No vaccine or direct treatment for the virus. Instead, treatment is focused on managing the symptoms.

• Based on the severity of symptoms, mainly of croup:– Croup severity ranges from mild or moderate, to

severe– Severity of the infection is based upon five factors:

• Level of consciousness, Cyanosis, Stridor, Air Entry and Retractions

Treatment• Analgesics• Ribavirin • Cool mist and oral intake of fluids

– Common types of treatment, as can be done at home– Cool mist helps to soothe inflamed mucosa

• Nebulized epinephrine– Used for moderate to severe croup patients to alleviate symptoms

• Corticosteroids– Orally administered– To treat airway inflammation and edema

• Heliox– Breathing gas composed of a mixture of helium and oxygen

• Intubation– Rare, done only in severe cases

References1. 1.      Viral Croup: A Current Perspective. Leung, A.K.C., Kellner, J.D., Johnson, D.W. Journal of

Pediatric Health Care November/December (2004): 297-301.

2. 2.      Infections: Croup. Dowshen, S., Homeier, B.P. Nemours Foundation. May, 2005.

3. 3.      Parainfluenza virus infections. Vega, R.M. eMedicine from WebMD. Sept. 24, 2007.

4. 4.      Evaluation of Stridor and Wheezing. Holinger, L.D. Journal of Children’s Memorial Hospital, Chicago. Spring, 1998.

5. 5.      Definition of Human Parainfluenza Virus. (http://www.medterms.com/script/main/art.asp?articlekey=31631)

6. 6.      Viral Croup: A Current Perspective. Leung, A.K.C., Kellner, J.D., Johnson, D.W. Journal of Pediatric Health Care November/December (2004): 297-301.

7. 7.      Human Parainfluenza Virus Type 4 Infections: A report of 20 cases from 1998 to 2002. Billaud et al. Journal of Clinical Virology 34 (2005) 48–51.

8. 8.      Clinical courses of croup caused by influenza and parainfluenza virus. Peltola, V., Heikkinen, T., & Ruuskanen, O. The Pediatric Infectious Disease Journal 21 (2002)

9. 9.      Acute Epiglottitis. Jaffe, J.E. eMedicine.com by WebMD. (http://www.emedicine.com/Radio/topic263.htm)

10. 10.Parainfluenza Virus. Parija, S.C., Marrie, T.J. eMedicine.com by WebMD. (http://www.emedicine.com/MED/topic1733.htm)

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quantitative reverse transcription-pcr-enzyme hybridization assay. Journal of Clinical Microbiology 34:1914-1917, 1996.

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5.      15.Steele RW: Pneumonia in children: Current status of diagnosis and treatment. Journal of Respiratory Diseases 8:63-73, 1987.

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