Definition and Overview

A non-bacterial lung infection is a respiratory illness that is caused by either a virus or fungus.

It is very important that the doctor correctly determines the cause of the respiratory condition as treatments can be very different. For example, antibiotics are given only when a pneumonia is confirmed to be caused by bacteria, which can include Legionella, Mycoplasma, Chlamydia, and Streptococcus pneumoniae. Giving antibiotics to patients who have either viral or fungal pneumonia can have serious complications such as developing resistance to the medication. This means that if the patient develops bacterial pneumonia later on, the body may no longer respond to the drug given before.

Most lung infections occur because of bacteria, with only around 30% attributed to a viral infection. It’s very rare to develop the illness because of fungi. However, a viral infection spreads more easily than the one caused by bacteria. These viruses are spread in many different ways. One is through aerosols, wherein droplets of the infected saliva or fluid are dispersed into the air and inhaled by others. It can also be spread by touching contaminated fluid. For example, a person who just sneezed can pass it on to someone he shook hands with after.

Causes of Condition

The lungs are a pair of elastic organs. They are sometimes described as sacs since they are filled with air. In the process of respiration, oxygen breathed through the nose or the mouth passes into the trachea or windpipe, delivering it to the bronchi, which are tube-like branches inside the lungs. The bronchi are connected to bronchioles, which are very small branches and are connected to the alveoli. The oxygen then travels through the alveoli, where it combines with the bloodstream. Carbon dioxide also passes through the alveoli for exhalation.

The lungs have their own protective covering called the pleura, but the organ itself can be very sensitive to many kinds of threats including pathogens like bacteria and virus. If these pathogens find themselves into the lungs, the lungs can become inflamed and be filled with pus and fluid, which can significantly reduce a person’s ability to breathe. When this happens, the affected individual begins to cough as a way of expelling whatever it is that’s causing irritation to the lungs.

Non-bacterial lung infections, including pneumonia, can develop because of the invasion of pathogens. It’s also possible that the virus that has caused a different illness to invade the lungs. A good example is when a person develops a cold or flu.

Although a non-bacterial lung infection can happen to anyone, some people have a higher risk. These include:

  • Children five years old and below
  • People who are 65 years old and above
  • Pregnant women
  • People whose immune system is compromised such as those who suffer from HIV or AIDS

    Key Symptoms

  • Dry cough

  • Chills
  • Shortness of breath
  • Fever
  • Chest pain
  • Nasal congestion
  • Presence of sputum when coughing
  • Headache
  • Fatigue
  • Sweating
  • Wheezing
  • Muscle pain
    Viral lung infections can begin slowly and cause the same symptoms as other common diseases such as flu. Although they are usually milder than bacterial infection, they must not be taken lightly as they can develop into something severe more quickly.

Who to See and Treatments Available

Patients who exhibit the symptoms listed above can consult a general physician, their family doctor, or an internist. Children, on the other hand, should be taken to a pediatrician while seniors may approach a geriatric care provider. This may be necessary if there are certain preexisting conditions that can worsen the lung infection.

During the consultation, the doctor will conduct a physical exam and listen to abnormal sounds in the lungs using a stethoscope.

The doctor may then recommend more tests to identify the cause of the infection. These include complete blood count (CBC). An elevated white blood cell count can indicate an infection while differentials can determine the cause. If the lymphocytes are high, the condition may be viral. Other tests include the analysis of the sputum culture and chest X-ray.

For treatment, antibiotics are not given for non-bacterial lung infection. Rather, patients are provided with anti-viral drugs. The doctor may also recommend medications and treatments to cope with the symptoms such as pain relievers for muscle pains or analgesics to help bring down the fever.

The doctor may advise the patient to take complete rest to allow the body’s immune system to fight off the virus and to drink plenty of fluids to regulate body temperature.

If the virus is caused by an existing illness, dealing with the condition may help in treating the non-bacterial lung infection. This may be necessary if anti-viral drugs do not work completely.

Depending on the immunity and how well the patient followed the doctor’s orders, non-bacterial lung infection should clear up within one week to three weeks. Otherwise, the patient should return to the doctor for further evaluation.

As a preventive measure, those who belong to the high-risk group should obtain a flu vaccine since flu is one of the most common causes of this type of infection.


  • Lee FE, Treanor J. Viral infections. In: Mason RJ, VC Broaddus, Martin TR, et al, eds. Murray and Nadel’s Textbook of Respiratory Medicine. 5th ed. Philadelphia, PA: Saunders Elsevier; 2010:chap 31.

  • Limper AH. Overview of pneumonia. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, PA: Saunders Elsevier; 2011:chap 97.

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