Meningitis is the inflammation of the meninges, which are the membrane linings of the brain and spinal cord. While most of the causes of meningitis include viruses and bacteria, sometimes fungal infections also cause meningitis.
Cryptococcal meningitis (CM) is one such fungal infection caused by fungi Cryptococcus neoformans and Cryptococcus gattii. This infection can sometimes affect healthy people but is more commonly seen in immune-compromised patients and as an opportunistic infection in persons having AIDS. It is termed as Cryptococcosis or cryptococcal disease.
Causes, Risk Factors And Spread Or Transmission Of Cryptococcal Meningitis
The Cryptococcus fungus is present almost everywhere in the soil, bird droppings or trees debris. The spread may commonly occur due to breathing in microscopic airborne spores. While healthy people can fight with the infection with minimal complaints or mild respiratory discomfort; people with a weak immune system are at risk of more serious consequences.
Cryptococcosis or Cryptococcal meningitis is caused when the fungal infection from the lungs spreads to the brain. Cryptococcal meningitis is not contagious and does not spread from person to person. The fungal infection spreads from some other part of the body through bloodstream, direct introduction into the bloodstream or when a site near the central nervous system gets infected.
The fungal infection in persons with AIDS and weak immune system can remain latent and may spring up during particular conditions causing more serious disease and can even spread to other parts of the body. Persons at risk of cryptococcal meningitis include people suffering from leukemia, sarcoidosis, cirrhosis, lymphoma, diabetes, undergoing organ transplant or those on long term medications like steroids or others that weaken the immune system.
People living in certain areas can be at an increased risk of fungal lung infections; pregnant women, premature and low birth weight babies are at risk too.
Symptoms Of Cryptococcal Meningitis
The presentation of cryptococcal meningitis (CM) may develop gradually over a period of few days to few weeks. Symptoms include headache, fever, neck stiffness, may be accompanied with nausea and vomiting, increased sensitivity to light (photophobia), confusion, hallucinations or alteration in mental status and behavioral changes.
Meningitis needs to be attended immediately and treatment should begin at the earliest. If cryptococcal meningitis (CM) is left untreated it can lead to more grave consequences like accumulation of fluid in the brain (hydrocephalus), brain damage, coma and sometimes loss of hearing. This can be more serious in AIDS patients. In some cases, cryptococcal meningitis (CM) can prove to be fatal.
Diagnosis Of Cryptococcal Meningitis
Clinical signs and physical examination reveals typical signs of meningitis, fever, neck stiffness, increased heart rate and sometimes altered mental status. Blood tests and other laboratory investigations are done to determine the infection.
Cerebrospinal fluid (CSF), a fluid present in the spinal cord, is collected by the procedure called spinal tap. Blood and CSF are tested and cultured for the presence of the cryptococcal fungi. Confirming and determining the specific type of fungal organism causing meningitis is important to plan the further plan of management. Specialized lab tests are performed depending on the suspected fungal type and their presence is confirmed.
Imaging studies like MRI or CT scan of brain may be taken if required. In some cases, imaging studies are important to determine the presence of mass lesion in the brain or hydrocephalus, to determine the increased risk of spinal tap or lumbar puncture and to plan diagnosis and management accordingly.
Treatment Of Cryptococcal Meningitis
Once the fungal infection of cryptococcal meningitis is confirmed, an antifungal treatment, mostly in high doses is given. The goal of treatment is to stop or control the infection and reduce mortality in severe cases.
The medications, doses and length of therapy depend on the severity of infection, type of fungi, immune status of the person and other pre-existing illnesses. In case of persons with a weakened immune system like those suffering from AIDS, cancer treatment or diabetes, a longer duration of treatment may be required.
Prevention Of Cryptococcal Meningitis
As the causative fungal organisms are present in soil everywhere, avoiding soil and environments that can be contaminated may help in preventing cryptococcal infection to some extent. Persons with HIV infection need to avoid exposure as much as possible. Those persons who are at greater risk or those who have a weak immune system, can prevent cryptococcal infection by trying to avoid exposure to bird droppings, digging soil and related activities, especially when staying in regions more likely to be affected with spores or fungi.
- Targeted Screening – This approach can help in preventing morbidity and death due to cryptococcal meningitis, especially in HIV-infected persons. In this, a chemical marker for cryptococcal infection can be detected in early stages, even before the onset of disease symptoms. For persons tested positive, appropriate anti-fungal treatment can be started thus reducing the chances of cryptococcal infection further developing into meningitis.
- Dipstick Test – This new dipstick test helps to detect cryptococcal antigen in a blood sample and detect early as well as advanced cryptococcal infections. The test is simple, inexpensive and gives results in minutes. The test accuracy is almost 95% and can be conveniently performed to identify and manage cases of cryptococcal infections.
Cryptococcal infections and their development into cryptococcal meningitis is a matter of concern in immune-compromised and HIV-infected persons. Additional care, proper medical facilities, prophylactic and preventive therapy, regular screening and ability of healthcare facilities to perform diagnostic or dipstick tests is essential.