What is Cryptococcus?
Cryptococcus is a type of fungus that often leads to an infection called cryptococcosis. This infection is usually found in individuals with a weakened immune system, and is uncommon among those who are healthy. The two types of this fungus that typically cause infections in humans are Cryptococcus neoformans and Cryptococcus gatti. This fungus can be widespread in certain parts of the world, and people commonly come into contact with it through exposure to soil or bird droppings.
What Causes Cryptococcus?
Cryptococcal species are a type of fungus that have a capsule-like appearance. They cause disease mainly in individuals with weak immune systems. Common conditions that are linked with the development of cryptococcal disease include AIDS, diabetes, chronic liver disease, chronic kidney disease. Also, long-term use of steroids and patients who have undergone organ transplantation are commonly associated with this fungal disease.
Risk Factors and Frequency for Cryptococcus
Cryptococcosis is a global health issue, with about 1 million cases reported worldwide each year, and tragically leading to roughly 625,000 deaths. In the United States, the estimated rate of Cryptococcosis is between 0.4-1.3 cases per 100,000 people, and 2-7 cases per 100,000 people with AIDS. The disease can be fatal, with a death rate of about 12%. Although the number of cases has dropped significantly in the past 20 years due to improved anti-viral treatments, it remains a concern. It’s important to note that different types of cryptococcal infections are associated with different patient groups: Cryptococcus neoformans tends to infect patients with weakened immune systems, while Cryptococcus gattii often infects people with healthy immune systems.
Signs and Symptoms of Cryptococcus
Cryptococcus neoformans and Cryptococcus gatti are two types of fungi which cause similar illnesses. These fungi enter our bodies through the lungs, typically, when we inhale. Even though the lungs are the entrance point, the most common serious effect of this infection is a condition called meningoencephalitis, which affects the brain and the spinal cord. Symptoms usually appear within 1-2 weeks and can include fever, tiredness, headache, a stiff neck, sensitivity to light, and nausea and vomiting. In some extreme cases, the disease can lead to a coma or even death. It’s also possible, though rare, for symptoms like a cough, difficulty breathing, or a skin rash. On physical examination, doctors might find specific neurological abnormalities, as well as indications of increased pressure inside the skull.
- Entry of fungi through the lungs
- Condition predominantly affecting the brain and spinal cord
- Symptoms typically appearing 1-2 weeks after exposure
- Common symptoms including fever, tiredness, headache, stiff neck, sensitivity to light, nausea and vomiting
- Potential for coma or death in severe cases
- Rare symptoms include cough, difficulty breathing, and skin rash
- Possible findings of specific neurological abnormalities and indications of raised pressure inside the skull on physical examination
Testing for Cryptococcus
If a patient is experiencing symptoms linked to the central nervous system, the first step often involves using imaging technology, like an X-ray, to scan the brain. This is done to check for increased pressure in the cerebrospinal fluid, which surrounds the brain and spinal cord. If meningitis caused by a fungus called Cryptococcus is suspected, a sample of the cerebrospinal fluid is examined through several tests.
These tests usually reveal a low white blood cell count, low glucose, and high protein levels but in about 25-30% of cases, the results could be completely normal. Cultures, or grown samples, of the infected fluid often show cream-colored colonies in about a week. A quick method to identify the Cryptococcus fungus is staining the fluid with Indian ink.
The most definite way to diagnose the infection involves detecting the cryptococcal antigen in the cerebrospinal fluid or in a blood sample. Several methods can be used for this, such as latex agglutination, enzyme-linked immunosorbent assay (ELISA), and lateral flow assay.
When Cryptococcus infection is found in a blood culture or at least two different sites, it’s defined as ‘disseminated’. This term refers to an infection that has spread to other parts of the body outside of the initial site. This type of infection is commonly seen in people with HIV or other conditions that lower the immune system’s ability to fight off germs and diseases.
Treatment Options for Cryptococcus
Treatment for cryptococcal infections, a type of fungal infection, depends on where the infection is in the body and how severe it is. According to the 2010 IDSA Guidelines, if a person who has a healthy immune system is suspected of having a mild to moderate cryptococcal infection in the lungs, they can be treated with a medicine called fluconazole, taking it once a day for 6-12 months. This is also the suggested treatment for cryptococcal infections that are not in the lungs or brain, as long as it’s certain that the disease hasn’t spread to the brain. While a spinal tap can be done to rule out a silent brain infection, it can be skipped for patients with a healthy immune system who aren’t showing any brain-related symptoms.
For more severe cases involving infections in the brain or in persons whose immune systems are weakened, the treatment has three parts. The first part, which aims to stop the growth of the fungus, involves two drugs, Amphotericin B and flucytosine, taken for at least two weeks. This is followed by eight weeks of the same treatment with fluconazole. After which, a repeat check of the spinal fluid is suggested to make sure the fungi are clearing out and none are left in the fluid.
The last part, fluconazole maintenance, is generally given for a year. It can be stopped if the patient’s immune system recovers, as indicated by a specific kind of white blood cell count (CD4) raising to more than 100 cells/microL.
On top of this, it’s essential to monitor and control intracranial pressure, which means the pressure inside the brain. This is important in reducing deaths associated with cryptococcal meningitis, a condition where the fungus infects the membranes around the brain and spinal cord. To control this pressure, a lumbar puncture, ventricular drain, or a ventriculoperitoneal shunt may be used. Other medications commonly used to lower pressure in the brain in bacterial meningitis are not recommended for cryptococcal meningitis.
Improving the patient’s immune status is key to recovery. So, if the patient has HIV, anti-HIV medication is given a few weeks after starting the fungal infection treatment. For patients who have undergone organ transplantation, the dose of immune-suppressing drugs might be slowly reduced, so long the risk of organ rejection is controlled.
Deaths from cryptococcal infections have drastically reduced because of advancements in anti-HIV treatments. However, patients with a severe form of the disease, indicated by extreme confusion or disorientation, a high amount of the fungal antigen (toxin or other foreign substance) in the spinal fluid, and a low count of white blood cells in the spinal fluid often have worse survival rates.
What else can Cryptococcus be?
- Infection by a type of amoeba called Acanthamoeba
- Common type of skin cancer known as Basal cell carcinoma
- A fungal infection usually affecting the lungs called Histoplasmosis
- Lipomas which are benign fatty lumps that grow under the skin
- Molluscum contagiosum, a relatively common viral infection of the skin
- Pneumocystis jiroveci pneumonia (PJP), a serious infection that causes inflammation and fluid build-up in the lungs
- Syphilis, a sexually transmitted infection
- Toxoplasmosis, a disease caused by a common parasite
- Tuberculosis, a dangerous lung infection
