Parainfluenza - Causes, Symptoms and Treatments

Human parainfluenza virus (HPIV) infections are a leading cause of upper and lower respiratory tract illness throughout the world. About 40% of acute respiratory infections in children are attributed to HPIV's. HPIV's affect all age groups, but serious infections tend to occur among elderly patients and those who are immunocolllprolllised. The viruses can cause repeated infections throughout the life span, but they are usually mild and short­lived.

There are four serotypes of HPIV, and each has different clinical and epidemiological features. HPIV-1 is the leading cause of croup in children, but both HPIV­1 and HPIV-2 can cause upper and lower tract respiratory illness. HPIV-3 is usually associated with bronchiolitis and pneumonia, whereas HPIV-4 is infrequently detected. Serological studies have shown that 90% to 100% of children aged 5 years and older have antibodies to HPIV-3, 75% have antibodies to HPIV-1 and 58% have antibodies to HPIV-2. HPIV-1 tends to occur biennially in the fall; HPIV-2 causes annual or biennial fall outbreaks; and HPIV-3 occurs annually during the spring and early summer months. All of the HPIV's can be infectious throughout the year.

Causes of Parainfluenza:

HPIV's are single-stranded RNA virions. Transmission occurs through direct contact and by inhalation of droplets. The incubation period depends upon the infecting virus-for HPIV-3 it's generally 24 to 48 hours; for HPIV-I it's 4 to 5 days.

Signs and symptoms of Parainfluenza:

Parainfluenza symptoms at onset include fever, moderate inflammation of the nasal mucous membrane with profuse nasal discharge, moderate sore throat, and dry cough. Malaise is directly related to the intensity of the fever, which usually does not exceed 101°F (38.3° C). In many cases, a characteristic barking cough (usually occurring at night) and hoarseness are prominent. Acute laryngotracheobronchitis, the most severe form of croup in children, can cause life-threatening respiratory distress and often requires hospitalization.

Shortness of breath and rigors usually accompany pneumonia, and auscultation of the lung fields may reveal moist rales, bronchophony, egophony, or whispered pectoriloquy. Tactile fremitus and tubular breath sounds may indicate acute bronchitis. Exacerbations of chronic bronchitis and asthma symptoms may also occur.

Diagnosis for Parainfluenza:

Most cases of HPIV are diagnosed clinically based on presenting symptoms. When absolutely necessary to distinguish between the four serotypes, the virus can be confirmed by isolation and identification of the virus in cell culture or by direct detection of the virus in respiratory secretions using immunofluorescence, enzyme immunoassay, or polymerase chain reaction assay. A significant rise in specific IgG or IgM antibodies in a serum specimen is also diagnostic.

A chest X-ray is the most effective method for detecting pneumonia. The differential diagnosis includes pertussis, respiratory syncytial virus, adenovirus, Group A or B streptococcal infection, mycoplasma pneumonia, and Chlamydia trachomatis, Staphylococcus aureus, Pseudomonas aeruginosa, and Haemophilus influenzae infection.

Treatment of Parainfluenza:

Currently no specific therapy exists beyond supportive measures such as rest and adequate fluid intake for mild cases. Acetaminophen may be given to relieve fever and other symptoms to allow for proper rest. To avoid the risk of Reye's syndrome with influenza, acetaminophen is preferable to aspirin if children require analgesics or antipyretics. Antitussives may be prescribed to suppress cough. Mild croup symptoms can often be alleviated with steam. Treatment of severe infection emphasizes airway maintenance.

Special considerations and prevention tips of Parainfluenza:

1. Wash hands thoroughly before and after patient contact, performing invasive procednres, and dressing changes. Dispose of tissues and dressings in a moisture-resistant container for proper disposal.

2. Pediatric patients may require a mist tent; adult patients may require supplementary oxygen.

3. Monitor proper diet and fluids.

4. Encourage the patient to move, cough and deep breathe every 2 hours.

5. Assess the patient's breath sounds frequently. Observe for the development of secondary bacterial infections.

6. Dispose of bed linens appropriately.

7. Promote regular bathing and proper hygiene.

Instruct the patient to cover the mouth when coughing or sneezing, and to appropriately dispose of infected tissues. Encourage children to maintain good personal hygiene, to wash hands thoroughly with soap and water, and to avoid sharing items such as cups, glasses, and utensils. Breast feeding during the first few months of life should also be encouraged, as passively acquired maternal antibodies play a role in the protection against HPIV types 1 and 2. Teach patients and parents how to monitor for signs of impending respiratory failure and the importance of seeking immediate medical care.