Parainfluenza

Direct-acting antiviral drugs

In the therapy of respiratory viral infections, which include parainfluenza, drugs with a direct effect on the pathogen are used. One of the key agents with a broad spectrum of activity is umifenovir (known by the brand name Arbidol). This drug is effective not only against influenza A and B viruses, but also against other ARVI pathogens, including parainfluenza virus type 3, adenovirus, respiratory syncytial virus, rhinovirus type 14, and the SARS coronavirus. Its standard dosing regimen involves taking 200 mg four times a day for five days.

Physicians also have zanamivir in their arsenal. This drug has strict age restrictions and is approved for use only in patients over seven years of age. An important contraindication to its prescription is a history of bronchospasm. Zanamivir is administered by inhalation (10 mg twice daily for a five-day course) and is distinguished by acting exclusively locally, without exerting a systemic effect on the patient's body.

Drugs with comprehensive effects and interferons

A separate group consists of drugs that affect both the virus itself and human immune mechanisms. However, caution should be exercised when choosing them: many widely advertised remedies lack an adequate evidence base because they have not undergone randomized, double-blind, placebo-controlled trials. This category includes Kagocel, an immunomodulator whose mechanism of action is based on inducing the production of "late interferon" (a mixture of alpha and beta interferons). Another drug, Ingavirin, is active against influenza A and adenoviral infection, although the exact mechanism of its action is not fully understood. Its use requires starting therapy at the very first symptoms, strictly no later than 36 hours from the onset of the disease. Ingavirin is contraindicated in children under 18 and pregnant women, is incompatible with other antiviral agents, and may cause allergic reactions.

Interferon-series drugs possess a broad antiviral spectrum upon intranasally and parenterally administration. Pathogenetically, their use is most justified precisely as prophylaxis to prevent the development of the disease after contact with a source of infection. Modern practice utilizes:

• Recombinant intranasal interferon alfa-2b;
• Interferon gamma;
• Combination therapy with both types of interferons.

Anti-epidemic measures and prophylaxis

Nonspecific prophylaxis of respiratory infections is based on the strict isolation of infected individuals. To this end, medical care is shifted as much as possible to the home or outpatient settings. During outbreaks, the following restrictions are introduced:

• Keeping patients at home and prohibiting them from visiting pharmacies and polyclinics;
• Cancellation of visits by relatives to patients in hospitals;
• Introduction of a mask mandate in transport, crowded places, and infection foci;
• Restriction of children's access to mass events.

In the event of a rapid rise in morbidity, organized groups are segregated for a period of 10–14 days. Hospitalization for epidemiological indications is carried out regardless of the severity of the condition if the patient lives in a dormitory, barracks, orphanage, or boarding school.

Drug prophylaxis during the epidemic season may include taking umifenovir (200 mg per day for 10 days), intranasal administration of alpha-interferon (in short courses up to three weeks), or the use of specific anti-influenza agents (oseltamivir, rimantadine). Emergency prophylaxis with any of these drugs is effective only if started no later than two days after contact with an infected person.

Clinical and laboratory diagnostics

Diagnostic workup begins with a thorough history taking. It is important to assess the dynamics: respiratory viral infections often start acutely with a predominance of intoxication syndrome (chills, fever of 38–40°C, malaise, headache, and muscle pain). From the second or third day, catarrhal symptoms join, such as nasal congestion, sore throat, dry cough, and soreness behind the sternum. The epidemiological history should reveal contacts with acute respiratory infection patients, group morbidity, and take into account the patient's premorbid background (heart and lung pathologies, immunodeficiencies).

During the physical examination, attention is paid to:

1. Pronounced intoxication and fever.
2. Facial hyperemia and scleral vessel injection.
3. Oropharyngeal changes: edema, bright faucial hyperemia, granularity of the posterior pharyngeal wall, and the presence of multiple hemorrhages.
4. Auscultatory findings: harsh breathing and dry rales.

Laboratory methods include a complete blood count (leukopenia, neutropenia, and normal ESR are typical in an uncomplicated course), rapid diagnostics by rhinocytoscopy (detection of viral RNA in nasal scrape smears using fluorescent antibodies within 3–4 hours), and retrospective serological diagnostics. The latter involves examining paired sera by complement fixation (CF) and hemagglutination inhibition (HI) assays at the peak of the disease and during convalescence to document a rising antibody titer.

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Signs of a severe course of viral infections (hemorrhages, encephalopathy, respiratory failure)
• Specific routine prophylaxis: types of vaccines (live, split vaccines, subunit vaccines)
• Indications for vaccination and identification of high-risk groups for severe disease
• Features of the use of rimantadine and oseltamivir during the epidemic period

Other topics in the "Respiratory Infections" section

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