The Fungus Among Us: Cryptococcus

In my last blog, I alluded to some medications that can affect the liver.

Medications used to treat infections caused by fungus is one such family of drugs and when they are used, blood tests are done on a periodic basis to help monitor the health of the liver.

Courtesy of Dr J.W. Kronstad - UBC

While fungal diseases have always been an issue in patients with compromised immune systems, one such fungal disease affects individuals with normal immune systems.

Our neurology department has seen several cases of an emerging fungal disease.  The author of this week’s blog is Dr Nicki Davis who has been collecting data on these cases.

This infection, which can affect your pet in British Columbia more than any other place in the world, is a fungus known as Cryptococcus, or shortened simply to “Crypto”. This is a new type of this fungus that has arrived in BC and that can infect both you and your pet(s) if you are both exposed to it at the same time but this fungal infection cannot be passed between people and animals or vice versa. The area with the highest infection rate is the southeast coast of Vancouver Island but the fungus is found on the British Columbia Lower Mainland as well. Within these areas, the fungus grows not only on decaying Douglas Fir or Western Hemlock trees but in the soil around those trees as well as in the water in that area. Where the presence of that fungus has been established, the main risk factors for an animal to become infected include logging or construction that disrupts the soil, owners that have either visited a botanical garden or gone hiking and animals that are considered high-energy and are allowed off leash when outdoors. Unfortunately the risk factors are difficult to avoid, so early recognition of infection is important.

Courtesy of Dr J.W. Kronstad - UBC

Infection occurs when small, microscopic forms of the fungus, known as spores, are inhaled. After infection, signs usually show up within 6-7 months and can vary considerably. Possible signs of infection include nasal discharge, sneezing, skin ulcers as well as more severe signs like loss of balance, walking in circles and having seizures. All that is needed to diagnose an infection of Cryptococcus is a small amount of blood. A screening-test known as an antigen titer is run and this can tell with considerable accuracy if your pet is positive or negative. If the result is positive, other tests such as cultures from the nose, skin, or spinal fluid should be performed to tell exactly what form of Cryptococcus is causing the infection and what drugs will work best to treat your pet.

Several different types of medications can be used to treat Cryptococcus and these may be given by mouth or intravenously, depending on how severely affected your pet is. Treatment is generally administered for a period of at least 6 months, however some animals need to remain on medication for life if signs recur after treatment is stopped. Cryptococcus can be difficult to treat, especially in dogs. We are trying to introduce drug formulations that are more effective, less expensive and less toxic than those currently available and we will let you know about these exciting developments soon.

Additional scientific articles on Cryptococcus gattii in BC: