ARI: What It Is, Cold Viruses, and Causes of the Disease

ARI is not a single virus but a group of diseases: more than 200 pathogens produce a similar picture with a runny nose, sore throat, and cough. We explain how ARI differs from acute respiratory disease and the common cold, which viruses are behind it, and when it is time to see a doctor.

ARI: What Kind of Disease It Is

Acute respiratory viral infection is a general term for acute inflammatory diseases of the respiratory tract and lungs caused by viruses with a tropism for the ciliated epithelium of the respiratory tract. It is the most widespread group of diseases in the world: it accounts for up to half of all acute illnesses. The group includes influenza, COVID-19, rhinovirus, respiratory syncytial, and adenovirus infections.

Respiratory viruses cause more than 500 million colds a year. An adult on average has ARI 2–3 times a year; young children more often, up to 10 times in the first year. "Acute" means limited duration, "respiratory" means involvement of the nose, throat, trachea, and lungs, and "viral" means the cause is a virus, not a bacterium. In most cases the illness resolves on its own: the immune system clears the virus from the body.

Acute Respiratory Disease and ARI: What the Difference Is

Acute respiratory disease is a broader concept: it includes both viral and bacterial causes, and ARI is merely a subset of it. The diagnosis is often made clinically as acute respiratory infection or acute respiratory disease, and the exact pathogen is confirmed only by laboratory tests. A specific virus cannot be identified by symptoms: the picture is similar across different pathogens.

The common cold usually refers to a mild ARI with predominant involvement of the nasal passages.

Which Viruses Cause the Common Cold

The common cold is caused by more than 200 different viruses, the most common type being rhinoviruses. The main pathogens of ARI belong to five families: paramyxoviruses, orthomyxoviruses, picornaviruses, adenoviruses, and coronaviruses. Infection with several pathogens at once is possible.

The viruses are highly contagious: they spread by airborne droplets, through close contact, and via objects — they survive on hands and surfaces for up to 24 hours. A person is contagious from the end of the incubation period; with a cold, from a few days before symptoms appear until they resolve, usually 1–2 weeks, and longer in young children. There is no vaccine against the common cold, and the flu vaccine does not protect against colds.

How a Viral Cold Manifests

Symptoms increase gradually over 2–3 days. The main signs:

• stuffy or runny nose, sneezing;
• sore throat, hoarse voice;
• cough, fatigue, malaise;
• fever, muscle aches, loss of taste and smell, pressure in the ears and face.

Early symptoms — headache, sneezing, chills, sore throat — last 1–2 days; later, nasal discharge, congestion, and cough appear. Usually there is improvement within 1–2 weeks, some symptoms persist for 10–14 days, and longer in young children; they may be irritable, eat and sleep poorly, and breathe through the mouth. A rare symptom is febrile seizures at a temperature of 38 °C or higher in 2–5% of children aged 6 months to 5 years.

Influenza resembles a cold but is more severe: a cold develops gradually and mainly affects the nose and throat, while influenza develops within a few hours and feels like exhaustion. Statistically, cough and shortness of breath are slightly more common with RSV infection, and fever and headache with influenza, but these associations are not statistically significant.

When to See a Doctor

Reasons to see a doctor are a high temperature lasting longer than 3 days, worsening symptoms, shortness of breath or chest pain, no improvement after 10 days, or a cough lasting longer than 3 weeks. Separately — a cold against the background of diabetes, heart, lung, or kidney disease, or weakened immunity, for example during chemotherapy, and any concern about a child's condition.

The doctor assesses the clinical picture and, if necessary, orders laboratory tests. Antibiotics do not work for a cold: they act on bacteria, not viruses. Complications are possible — bronchitis, pneumonia, sinusitis, otitis; the risk is higher with asthma, weakened immunity, and other respiratory conditions.

ARI by itself is not a reason to call an ambulance. You should call 103 or 112 for shortness of breath and difficulty breathing, or confusion.

This material is for reference: it explains terms and signs but does not replace a doctor's consultation.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer