Blastomycosis

A fungus hiding in the soil in the woods

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What is Blastomycosis?

Blastomycosis is due to an infection by the fungus Blastomyces dermatitidis. This fungus, as microscopic airborne spores, can be breathed in to the lungs creating an infection. The fungus is normally found in the soil in certain region, especially in moist soil around decaying wood and leaves. About half infected do not have any symptoms, while others develops a flu-like illness.

Some develop frank lung infections, which can then spread to the skin and bones. For some this can be a very serious disease.

What is the disease like?

Only about half of those infected have symptoms. These symptoms develop 2 weeks to 3-4 months after breathing in the fungus. The disease can seem like the flu - fever, chills, general muscle aches, cough, chest pain, and joint pain. It can cause a serious pneumonia. 

The disease can cause different types of pneumonia and different lung abnormalities. These can be very serious and require intubation, including ARDS, which can make people very sick, as well as cavitary lesions (like TB), consolidated pneumonia and other diffuse spread of the fungi throughout the lungs.

Can the fungus spread?

In some cases, the fungi can spread infecting other parts of the body. Skin is most commonly affected after the lungs - and is often mistaken for other infections.

Bone lesions occur in 1 in 4 who have Blasto spread from the lungs. The spine and pelvis are often involved; it can cause abscesses, arthritis, and destructive bone lesions.

Some infections can spread to the brain and meninges, causing meningitis or abscess in the brain. (This can lead to Diabetes Insipidus, causing excessive thirst.

This is not Diabetes Mellitus, which is more common and unrelated).

Others may have genital or urinary infections  - prostate infections or testicular swelling or ovarian abscesses. It can affect many other parts of the body as well.

The disease is often mistaken for other diseases. This is unfortunate because the disease can be fatal. It requires treatment that is different from other infections that look like it - because these infections are often caused by bacteria.

Can I get sick from someone who has Blastomycosis?

No. The fungus does not spread from a patient to a visitor.

The fungus can spread if traumatically inoculated into your skin, such as by a knife. This could happen to a surgeon in surgery or a pathologist examining a sample or doing an autopsy, who then sticks themselves with the blade that is covered with the infected material they are examining.

How does it spread?

You breathe in the microscopic fungi spores or it can be spread . Warmer temperatures in the body can lead to the spores becoming yeast and spreading throughout the lungs and the body.

Traumatic inoculation can also spread the disease. This can happen from animal bites or scratches contaminated by soil, a laboratory or autopsy accident, or any outdoor trauma where the spores from the soil enter the wound. 

Where is it found?

The fungus is scattered throughout parts of the US and Canada. It is found in different parts of the Ohio and Mississippi river valleys, all the way down to Louisiana and Mississippi. Other areas have the fungus around the Great Lakes - Wisconsin, Minnesota, Michigan, upstate New York, Ohio, northern Indiana and a bit of northern Illinois, as well as Ontario. It is also found in the St Lawrence River Valley, affecting those in Quebec, as well.

There's been an outbreak in Wisconsin - among those who visited Little Wolf River in Waupaca County near New London in the summer of 2015.

The infection can also be found around the world - Africa, India, and the Middle East.

It is found in moist places - with decaying trees and leaves, especially after rainfall or near streams.

A brief visit to these areas can lead to an infection.

Who is at risk?

Anyone can get the infection. Those at most risk from the disease are those with weak immune systems - such as from HIV or also from diabetes.

Those at most risk are those out in wooded areas, especially if working with soil. This includes forestry workers, tree cutters, hunters, campers, and farmers. There were some whose occupational exposure was through "prairie dog relocation" which included excavating old prairie dog tunnels - or digging up soil contaminated by the fungus.

How can I prevent blastomycosis?

In areas with a large amount of fungus, it's hard to avoid it if you're outside. Those who have weaker immune systms should avoid wooded areas, especially with moist soil near streams or after the rain. 

For those who will be working in area at risk, there are N95 masks that can be worn to avoid the airborne infection.

How many people get this?

The disease is not reportable everywhere, so we do not know for sure how many people are infected in the US each year. Because not everyone develops the disease - and many do not have severe disease - we likely miss many cases. Some states have doctors report all cases (Louisiana, Michigan, Minnesota, Mississippi, and Wisconsin). From what we do know, there are probably 1 or 2 people infected per every 100,000 each year - in areas where the disease is prevalent.

How do you treat Blastomycosis?

Blasto is often treated incorrectly and assumed to be a bacterial infection. Standard antibiotics that fight bacteria do not work on this fungus. There are special treatments like ketoconazole or itraconazole pills that can treat milder infections. More serious infections need IV antifungal treatment like amphotericin B, as well as steroids. Patients may need to be intubated in an intensive care unit if they become very sick.

Is there a vaccine?

No

How do you test for it?

Because it is a rare disease, it is often not noticed and not tested for. Only specific tests for Blasto will recognize it. Samples of tissue from skin, lungs, or other affected organs may be examined under a microscope or a laboratory may try to grow samples to see if they are this fungus. There are antigen and antibody tests, but these are imperfect (as are skin reactivity testing).

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