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Opportunistic infections can be viral, bacterial, fungal, or parasitic in nature
Opportunistic infections occur in people with weakened or impaired immune systems. When the immune system is compromised, almost any infection can become an opportunistic infection.
Opportunistic infections can be viral, bacterial, fungal, or parasitic in nature. Here are common examples by category.
What are examples of opportunistic infections caused by viruses?
- Cytomegalovirus: Family of opportunistic viruses, most commonly associated with respiratory infection
- Human polyomavirus 2 or John Cunningham virus: Known to cause progressive multifocal leukoencephalopathy
- Human herpesvirus 8 or Kaposi sarcoma-associated herpesvirus: Associated with Kaposi sarcoma, a type of cancer
What are examples of opportunistic infections caused by bacteria?
- Clostridium difficile: Causes gastrointestinal infection and diarrhea
- Legionella pneumophila: Causes Legionnaires disease, a respiratory infection
- Mycobacterium avium complex: Group of two bacteria (M. avium and M. intracellulare), typically co-infect, leading to a lung infection called mycobacterium avium-intracellulare infection
- Mycobacterium tuberculosis: Causes tuberculosis, a respiratory infection
- Pseudomonas aeruginosa: Can cause respiratory infections, frequently associated with cystic fibrosis
- Salmonella: Causes gastrointestinal infections
- Staphylococcus aureus: Causes skin infections and sepsis, including methicillin-resistant Staphylococcus aureus
- Streptococcus pneumoniae: Causes respiratory infections
- Streptococcus pyogenes: Causes a variety of pathologies, including impetigo and strep throat, as well as other more serious illnesses
What are examples of opportunistic infections caused by fungi?
- Aspergillus: Commonly associated with respiratory infection
- Candida albicans: Associated with oral thrush and gastrointestinal infection
- Coccidioides immitis: Causes coccidioidomycosis or Valley Fever
- Cryptococcus neoformans: Causes cryptococcosis, which can lead to pulmonary infection as well as nervous system infections such as meningitis
- Histoplasma capsulatum: Causes histoplasmosis and often involves respiratory infection
- Microsporidia: Can cause microsporidiosis in immunocompromised human hosts
- Pneumocystis jirovecii or Pneumocystis carinii: Causes pneumocystis pneumonia, a respiratory infection
What are examples of opportunistic infections caused by parasites?
- Cryptosporidium: Infects the gastrointestinal tract, causing diarrhea
- Toxoplasma gondii: Causes toxoplasmosis, which is dangerous in unborn babies if pregnant women are infected
What are common signs and symptoms of opportunistic infections?
Symptoms of opportunistic infections vary depending on the organ and the pathogen involved and may include:
- Fever
- Productive cough
- Breathlessness
- Painful blisters on skin and over the genital area
- Candidiasis (oral or vaginal thrush)
- Skin infections and rashes
- Unexplained weight loss
- Loss of vision
- Headaches
- Joint pain
- Swelling
- Severe, chronic diarrhea
- Seizures
- Fatigue
- Dysphagia (difficulty swallowing)
- Odynophagia (pain when swallowing)
- Confusion
- Night sweats/chills
- Enlarged lymph nodes
What are common causes and risk factors of opportunistic infections?
People with weakened immune systems, including those with human immunodeficiency virus (HIV), are more likely to contract opportunistic infections.
The immune system defends the body against potentially harmful pathogens, such as allergies and infections. White blood cells are the most important component of a healthy immune system. A low white blood cell count can be caused by a variety of factors, including medications, infection, and certain diseases. Individuals may be unable to fight illnesses if their white blood cell count is low, leading to opportunistic infections.
Common sources of pathogens that cause opportunistic infections include:
- Untreated water or soil
- Unwashed foods, undercooked eggs or meat, unpasteurized dairy or juices, or raw, sprouted grains
- Contact with the bodily fluids of infected individuals
- Contact with animal feces
Risk factors for opportunistic infections include:
- Diagnosis of HIV/AIDS
- History of cancer
- Immunosuppressive agents/long-term corticosteroid therapy
- Primary immunodeficiency, such as severe combined immunodeficiency or selective immunoglobulin A deficiency.
Common disturbance of the host immunity that may lead to opportunistic infections include:
- Administration of immunosuppressants or steroid therapy
- Advanced HIV
- Chemotherapy
- Skin injuries (surgery)
- Antibiotic use resulting in the disruption of the normal flora in the body
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How are opportunistic infections prevented?
If you acquire an opportunistic infection, there are antiviral, antibiotic, and antifungal medications that can help. After effectively treating an opportunistic infection, you may continue to use the same or a different drug to keep the infection from recurring.
Prevention tips for opportunistic infections include:
Safe food preparation
- Some illnesses can enter your body through the food and water you consume.
- Do not consume raw milk or cheese, raw fruit juices, or raw seed sprouts.
- Avoid drinking water from lakes and rivers.
- Use bottled water wherever possible.
Caution around animals
- Make sure that your pets are vaccinated and that your cat stays indoors.
- After touching animals, wash your hands.
- When changing cat litter, use gloves.
- When working in soil, stay away from animal excrement.
Caution around people
- Stay away from sick people, especially those with diseases such as pneumonia or tuberculosis.
- Wipe down exercise equipment using your own towel.
- Never share needles with other people.
- Practice good sexual hygiene.
- Wear masks and gloves when going outside.
- Keep up with doctor appointments, vaccinations, and immunizations.
Working closely with your doctor and taking reasonable measures can help you lower your risk of opportunistic infections.
