Respiratory infections are common illnesses that affect the lungs, airways, and breathing. Symptoms can range from mild to severe depending on the type of infection. Doctors use various methods to diagnose if a respiratory infection is present and determine the cause. This article will explore the main techniques doctors use to identify respiratory infections.
Looking at Signs and Symptoms
The first way doctors can identify a respiratory infection is by looking at the signs and symptoms reported by the patient. Common symptoms of respiratory infections include:
- Coughing
- Sore throat
- Runny or stuffy nose
- Fever
- Headache
- Fatigue
- Shortness of breath
- Wheezing
- Chest pain
The type and severity of symptoms can provide clues as to the kind of respiratory infection. For example, influenza typically causes high fever, body aches, fatigue, and cough. Meanwhile, the common cold generally leads to a runny nose, sneezing, sore throat, and mild cough.
Doctors will ask questions about the symptoms to get details on when they started, how severe they are, and whether other accompanying symptoms are present. This helps them narrow down the list of possible respiratory infections.
Physical Exam
After discussing symptoms, the doctor will conduct a physical exam. This involves checking vital signs like temperature, heart rate, blood pressure and oxygen saturation. Fever often indicates an infection. Rapid heart rate and breathing can signal respiratory distress.
Doctors also examine the nose, throat, ears and chest by looking, listening and feeling for abnormalities. Signs like enlarged lymph nodes, inflamed throat, wheezing, crackles, and reduced breath sounds can point to certain respiratory conditions.
Medical History
The patient’s medical history provides critical background information. The doctor asks about any past respiratory illnesses, chronic medical conditions, medications, allergies, recent travels, sick contacts and occupational hazards.
For instance, a history of asthma or COPD raises suspicion for an exacerbation of the underlying disease. Recent exposure to ill family members or coworkers makes contagious viruses more likely. Immunosuppressing drugs or conditions increase the risk of bacterial and fungal pneumonia.
Diagnostic Testing
In addition to the clinical evaluation, doctors rely on laboratory and imaging tests to confirm and specify the respiratory infection:
Blood Tests
A complete blood count looks for elevated white blood cells, indicating an infection or inflammation. The levels of specific white blood cell types can point to viral or bacterial causes.
Other blood tests like blood cultures, serology and antigen testing can identify or rule out specific infectious organisms like bacteria, fungi and viruses.
Sputum Tests
A sputum sample coughed up from the lungs is sent for gram stain and culture to uncover likely pathogens. They also analyze sputum consistency and color for clues about the infection type.
Nasopharyngeal Swabs
Swabbing the nose and throat produces samples that can reveal viruses like influenza, RSV and COVID-19 through rapid antigen tests, PCR molecular tests and viral cultures.
Urinalysis
A UTI that spread to the kidneys can cause pneumonia-like symptoms. Urinalysis helps identify such cases.
Chest X-ray
Chest x-rays visualize lung abnormalities like fluid, pneumonia, and abscesses that signal infection. The pattern and location of changes provides useful diagnostic information.
CT Scans
If chest x-rays are inconclusive, CT scans give more detailed lung images to pinpoint abnormalities. CT angiograms also check for pulmonary emboli that mimic respiratory infections.
Pulse Oximetry
Pulse oximetry measures oxygen saturation in the blood. Low levels warrant further respiratory assessment.
Making the Diagnosis
Doctors compile the clinical picture from the symptoms, history, exam findings and test results to reach a diagnosis. The definitive diagnosis can get complicated because many respiratory infections share similar features. Additionally, some people get co-infections from multiple pathogens that overlap. Common respiratory infections diagnosed include:
Common Cold
The common cold causes congestion, runny nose, sore throat and cough. Testing identifies the causative virus, usually rhinovirus, coronavirus, adenovirus or RSV.
Influenza
The flu manifests with fever, body aches, headaches, and dry cough. Testing confirms influenza A or B. Bacterial co-infection can occur.
COVID-19
COVID-19 commonly causes fever, cough, sore throat, and shortness of breath. Testing detects SARS-CoV-2 virus.
Pneumonia
Bacterial, viral or fungal pneumonia inflames the lungs’ air sacs. Symptoms include cough, phlegm, fever, chills, and trouble breathing. Chest imaging, sputum tests and blood tests determine the infectious agent.
Bronchitis
Acute bronchitis stems from viruses in most cases while bacteria cause chronic bronchitis. Chest congestion, cough, wheezing and phlegm are typical symptoms.
Sinusitis
Sinus infections provoke facial pain, congestion, and colored nasal discharge. Diagnosis relies on physical exam of sinuses and ruling out allergies.
Pharyngitis
Strep throat is a bacterial pharyngitis causing sore throat, fever, swollen neck glands and white patches on the tonsils. Rapid strep tests and throat cultures confirm the diagnosis.
Laryngitis
Viral laryngitis leads to a hoarse voice and throat pain from swelling of the vocal cords. Symptoms give a straightforward diagnosis.
Tonsillitis
Inflamed tonsils from viruses or bacteria produce sore throat, trouble swallowing, fever and enlarged tonsils with white streaks. Diagnosis is by clinical exam and culture swab.
Acute Bronchiolitis
Bronchiolitis from viruses like RSV cause wheezing and breathing problems in infants. Doctors diagnose it based on age, respiratory distress and ruling out other causes.
Pertussis
The bacteria Bordetella pertussis causes the prolonged cough of pertussis or whooping cough. PCR tests of nasal swabs confirm the diagnosis.
Tuberculosis
TB is a bacterial lung infection that leads to cough, weight loss, fever, and night sweats. Tests like chest x-rays, sputum cultures and TB skin tests identify tuberculosis.
Home Care
For milder respiratory infections like the common cold, doctors often recommend home care for symptom relief. This includes:
- Drinking plenty of fluids
- Getting extra rest
- Using a humidifier
- Gargling with warm salt water
- Soothe a sore throat by eating soft foods and sipping warm broths or tea
- Reduce fever with acetaminophen or ibuprofen
- Treat cough with throat lozenges, honey, or over-the-counter cough medicine
- Use decongestants for congestion relief
Doctors also advise limiting contact with others to prevent spreading the infection. Follow-up with a doctor if symptoms persist beyond 10-14 days.
Medical Treatment
Doctors prescribe medications to treat certain respiratory infections:
Antibiotics for Bacterial Infections
Bacterial pneumonia, sinusitis, bronchitis, tonsillitis, and pertussis require antibiotic therapy. The chosen antibiotic depends on the type of bacteria and severity of illness.
Antivirals for Influenza
Antiviral drugs help shorten the duration of the flu and reduce complications. They work best when started quickly after symptom onset.
Supplemental Oxygen
Low oxygen levels may necessitate oxygen delivered through a nasal cannula, face mask or high flow device.
Bronchodilators
Medications like albuterol open constricted airways in illnesses like asthma and COPD exacerbations that restrict breathing.
Corticosteroids
Steroids help reduce lung inflammation associated with infections. Inhaled steroids are preferred over oral forms for respiratory illnesses.
Immunoglobulins
IV immunoglobulin therapy boosts the immune system to combat serious respiratory infections.
Lung Clearance Techniques
Chest physiotherapy helps clear mucus through coughing, vibration and draining of the lungs.
When to See a Doctor
See a doctor right away if you experience:
- Difficulty breathing or shortness of breath at rest or with exertion
- Chest pain with breathing
- Bluish lips or face indicating lack of oxygen
- Ribs pulling in with breathing
- High fever above 101 F
- Confusion or excessive drowsiness
- Coughing up bloody, brown or green phlegm
- Dehydration symptoms like dizziness, dry mouth, and dark urine
Seek prompt medical care if you are in a high-risk group, including:
- Infants under 3 months old
- Adults over 65 years old
- Pregnant women
- People with chronic heart or lung conditions
- Immunocompromised individuals
- Nursing home residents
Also consult a doctor if symptoms are severe or persist beyond typical timeframes. Be sure to call ahead so they can prepare for your visit and protect against transmission.
Prevention
You can take measures to prevent respiratory infections:
- Get recommended vaccines like the flu shot and pneumococcal vaccines
- Wash hands frequently and avoid touching the face
- Practice social distancing when respiratory viruses are circulating
- Avoid exposure to cigarette smoke and air pollution
- Clean and disinfect high-touch surfaces regularly
- Avoid sharing personal items like cups, utensils and towels
- Wear a face mask in crowded public settings
- Stay home when sick and avoid close contact with anyone showing symptoms
Healthy lifestyle habits also support respiratory health. Manage underlying medical conditions, exercise regularly, drink plenty of fluids, and get adequate sleep. A balanced diet helps boost immunity. Managing stress and avoiding smoking also help defend against respiratory infections.
Conclusion
Doctors employ a combination of approaches to determine if a respiratory infection is present. A thorough history and physical exam lays the initial foundation. Lab tests like blood work, sputum analysis and nasal swabs provide confirming evidence. Imaging techniques like x-rays and CT scans visualize lung abnormalities. The final diagnosis integrates these clinical findings with the symptoms and illness time course. Home remedies can ease milder respiratory infections. More serious infections require prescription medications and even hospitalization. Preventive actions help reduce the likelihood of developing respiratory infections.
