What is an upper respiratory tract infection?
An upper respiratory tract infection (URTI) is a condition that affects the upper part of the respiratory system, which includes the nose, throat, pharynx (the cavity behind the nose and mouth), and larynx (voice box). This type of infection is commonly referred to as the common cold or a viral upper respiratory tract infection.
What causes an upper respiratory tract infection?
Most upper respiratory tract infections are caused by viruses. These viruses include:
Rhinovirus
- Symptoms: Sneezing, runny nose, nasal congestion, sore throat, cough, headache, and mild fever.
- Distinguishing features: It is the most common cause of the common cold, and infections peak in the fall and spring. It affects all age groups but is particularly common in children.
Influenza virus
- Symptoms: Sudden onset of high fever, chills, muscle aches, headache, sore throat, cough, and fatigue.
- Distinguishing features: More severe symptoms than other URTIs; annual outbreaks, primarily in the winter; higher risk of severe illness in the elderly, young children, and those with chronic health conditions.
Respiratory syncytial virus (RSV)
- Symptoms: Runny nose, decrease in appetite, coughing, sneezing, fever, and wheezing.
- Distinguishing features: This is common in infants and young children. The peak season is late fall to early spring. In severe cases, it can cause bronchiolitis and pneumonia.
Adenovirus
- Symptoms: Sore throat, fever, cough, conjunctivitis, and sometimes gastrointestinal symptoms like diarrhea.
- Distinguishing features: Can cause a wide range of illnesses, including conjunctivitis and gastroenteritis; affects people of all ages but is more common in children; outbreaks can occur in crowded settings such as schools and military camps.
Parainfluenza virus
- Symptoms: Cough, runny nose, fever, and sore throat; can cause croup (barking cough and hoarseness) in young children.
- Distinguishing features: Different types (HPIV-1, HPIV-2, HPIV-3) cause infections at different times of the year; HPIV-1 and HPIV-2 commonly cause croup, more severe in young children and immunocompromised individuals.
Coronavirus (excluding SARS-CoV-2)
- Symptoms: Mild to moderate respiratory symptoms include cough, runny nose, sore throat, and fever.
- Distinguishing features: The common cold is a common cause, peaking in winter and early spring, and most cases are mild infections.
Enterovirus
- Symptoms: Fever, runny nose, sneezing, cough, body and muscle aches, and sometimes rash and conjunctivitis.
- Distinguishing features: It is more common in summer and fall, can affect all age groups, but is more common in children, and can cause various illnesses, including hand, foot, and mouth disease.
Human metapneumovirus (hMPV)
- Symptoms: Runny nose, cough, sore throat, and fever; can lead to bronchiolitis and pneumonia in severe cases.
- Distinguishing features: It is similar to RSV in terms of symptoms and seasonality (late winter to early spring); it affects infants, young children, and older adults.
Epstein-Barr virus (EBV)
- Symptoms: Sore throat, fever, swollen lymph nodes, and fatigue; can cause infectious mononucleosis (mono).
- Distinguishing features: Symptoms are often more prolonged and severe than those of other URTIs; they are common in adolescents and young adults and transmitted through saliva.
Human bocavirus
- Symptoms: Runny nose, cough, wheezing, and fever.
- Distinguishing features: It is common in young children and associated with respiratory infections, particularly those with preexisting respiratory conditions. It can occur year-round, with a peak in winter and spring.
Why are upper respiratory tract infections so common?
Upper respiratory tract infections are highly prevalent due to several factors. These infections are primarily caused by viruses, such as the common cold virus (rhinovirus), influenza, and respiratory syncytial virus (RSV). The viral nature of these infections contributes to their high prevalence, as viruses can spread rapidly from person to person through respiratory droplets, direct contact, and contaminated surfaces.
Another reason for the high prevalence of upper respiratory tract infections is their high transmissibility. Viruses causing URTIs can easily spread in crowded places such as schools, workplaces, and public transportation. This makes it difficult to control outbreaks, especially during peak seasons like winter when people tend to spend more time indoors.
The incubation period for many upper respiratory tract infections is short, often just a few days, which means that infected individuals can spread the virus before they even realize they are sick. This asymptomatic transmission further contributes to the widespread nature of these infections.
Additionally, upper respiratory tract infections have a relatively low mortality rate. While they can cause significant discomfort and illness, they are rarely life-threatening for most healthy individuals. This low mortality rate means that people often do not take extreme precautions to avoid infection, contributing to their ongoing spread. Because these infections are typically mild and self-limiting, individuals might not seek medical care or take strict preventive measures, which allows the infections to circulate widely in the community.
Lastly, the human immune system’s partial immunity to many viral strains causing upper respiratory tract infections also plays a role. After an infection, immunity to a specific strain is often short-lived, and the existence of numerous viral strains means that individuals can be repeatedly infected throughout their lives.
What are the typical symptoms of an upper respiratory tract infection?
The symptoms of an upper respiratory tract infection can vary but typically include:
- Runny or stuffy nose: Mucus production increases, causing nasal congestion or a runny nose.
- Sore throat: Inflammation of the throat leads to pain and discomfort, especially when swallowing.
- Cough: This is often due to irritation or postnasal drip (mucus draining down the back of the throat).
- Sneezing: A reflex to clear the nasal passages of irritants.
- Fever: A mild increase in body temperature is common, though not always present.
- Headache and body aches: General discomfort and aches can occur, particularly with the flu.
Can you tell from your symptoms which virus you have?
It is challenging to determine which specific virus is causing an upper respiratory tract infection based on symptoms alone. Most viruses produce similar symptoms, and only specific tests can identify the exact virus. However, some clues can help differentiate:
- Flu: Symptoms such as high fever, severe body aches, and extreme fatigue are more indicative of the flu.
- Common cold: A common cold typically has a gradual onset of symptoms, such as a runny nose, sore throat, and mild cough.
- RSV: This virus often causes more severe symptoms in young children, such as wheezing and difficulty breathing.
What is the recommended treatment for an upper respiratory tract infection?
The treatment for an upper respiratory tract infection focuses on relieving symptoms, as antibiotics are ineffective against viruses. Here are some common treatments:
- Rest: Adequate rest helps the body fight off the infection.
- Hydration: Drinking plenty of fluids helps keep the throat moist and loosens mucus.
- Over-the-counter medications: Medications such as acetaminophen or ibuprofen can reduce fever and relieve pain. Decongestants and antihistamines can help alleviate nasal congestion and runny nose.
- Humidifiers: Using a humidifier can add moisture to the air, easing breathing and soothing irritated nasal passages.
- Saltwater gargle: Gargling with salt water can help relieve a sore throat.
In most cases, upper respiratory tract infections resolve on their own within a week to ten days. However, if symptoms persist or worsen or if breathing becomes difficult, it is important to seek medical attention.
References
- Zhu, Q., Li, M., & Zhu, X. (2023). “Expert consensus on the diagnosis, treatment, and prevention of respiratory syncytial virus infections in children.” World Journal of Pediatrics, 19(1), 3-12. DOI: 10.1007/s12519-023-00674-1.
- Moriyama, M., Hugentobler, W. J., & Iwasaki, A. (2023). “Seasonality of respiratory viral infections.” Annual Review of Virology, 10, 25-47. This review addresses the seasonal patterns of various respiratory viruses, including those responsible for the common cold. Available from: Annual Reviews.
- Eccles, R. (2023). “Common cold.” Frontiers in Immunology. This review discusses the symptomatology and treatments for the common cold, as well as new developments in the field. Available from: Frontiers in Immunology.
- Smith, C., & Evans, C. (2023). “Predisposing factors to acquisition of acute respiratory tract infections in the community: a systematic review and meta-analysis.” BMC Infectious Diseases. Available from: BMC Infectious Diseases.
- Systematic Reviews Journal. (2023). “Systematic review of patient-oriented interventions to reduce unnecessary use of antibiotics for upper respiratory tract infections.” Systematic Reviews. Available from: BMC Systematic Reviews.
- Heikkinen, T., & Järvinen, A. (2003). “The common cold.” The Lancet, 361(9351), 51-59. DOI: 10.1016/S0140-6736(03)12162-7.