A parasitic infection that is a common cause of pneumonia in people with reduced immunity
People with reduced immunity, such as those who have AIDS (see HIV infection and AIDS) or those receiving chemotherapy, may develop a form of pneumonia called pneumocytis infection, caused by inhaling the Pneumocystis jiroveci (formerly known as Pneumocystis carinii) parasite. In people who have a healthy immune system, the parasite does not cause pneumonia. In developing countries, children who are malnourished often have the infection.
The symptoms of pneumocystis infection generally develop gradually over weeks, but, in some people, they may develop quickly. Symptoms include:
Shortness of breath on mild exertion.
As the infection progresses, shortness of breath may develop even at rest.
Pneumocystis infection is diagnosed by a physical examination, a chest X-ray or CT scan, or by examining a sample of sputum. Sometimes, the parasite is hard to isolate. In such cases, a bronchoscopy may be performed. In this procedure, secretions from the bronchi (the main airways of the lungs) and/or a piece of lung tissue are removed and examined for evidence of pneumocystis infection.
Once the infection has cleared up, you may need to continue taking low doses of antibiotics, depending on the cause of reduced immunity. People with AIDS require long-term antibiotics. Those receiving chemotherapy may need antibiotics until the therapy is finished.
Fewer than 1 in 10 cases of initial pneumocystis infection are fatal. However, without treatment with preventive antibiotics, the infection may recur. In the developed world, many people with HIV infection or AIDS are now treated for pneumocystis infection before their immunity is seriously impaired.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.