What is Sporotrichosis?
Sporothrix schenckii, often shortened to S. schenckii, is a type of fungus that leads to a condition known as Sporotrichosis. This fungus can take two forms: a string-like formation (referred to as “hyphal”) when it’s cooler than 37°C, or a rounded, budding form (yeast-like) at 37°C or higher. This change in form helps identify when the fungus changes from a mold to a yeast. Various types of S. schenckii exist, with the S. schenckii complex being the most common in America, Asia, and Africa. Other types, such as S. brasilienis, known for infecting cats in Brazil, and S. Mexicana and S. globose, are found globally.
Sporotrichosis is contracted when the fungus comes into contact with your skin, typically through contaminated soil, plants, or organic matter. It then usually appears as small bumps or blisters that become open sores, mostly affecting the local lymphatic system, which is part of your immune system that helps fight infections. The disease comes in three forms: skin-based, lung-based, and widespread throughout the body. The skin-based form is the most common. People with compromised immune systems, chronic lung disease, alcohol use disorder, or diabetes are at a higher risk of the disease spreading throughout the body. Protecting your skin by wearing gloves and long sleeves when handling soil can lower your risk of getting the disease.
The best way to confirm if someone has sporotrichosis is to culture and test for the fungus. The first choice for treatment is a medication called itraconazole.
What Causes Sporotrichosis?
The S. schenckii, a type of fungus, was first discovered in 1896 by Benjamin Schenx, a medical student at Johns Hopkins Hospital. It was once believed that a disease called sporotrichosis was caused by just this one type of fungus. However, we now know that there are several species involved in causing this disease, including S. brasilienis, S. globosa, and S. Mexicana. Therefore, the term S. schenckii is now used to refer to this group of related fungi, sometimes being called the S. schenckii complex or S. schenckii “in a broad sense”.
Sporotrichosis, the disease caused by these fungi, has been found in many different animals, such as cats, dogs, pigs, horses, rats, and armadillos.
Risk Factors and Frequency for Sporotrichosis
Sporotrichosis is a disease that is prevalent all over the world, especially in the tropical and subtropical regions of the Americas. It’s more common in places like the southern coasts and river valleys of North America. Certain people are more at risk for getting this disease due to their jobs such as rose gardeners, farmers, miners, horticulturists, and those who hunt armadillos.
The cause of the disease, S. schenckii, is often found in soil, plants, and plant products, meaning people who work closely with these materials need to be cautious. You can also get this disease from animals, especially cats, through bites or scratches. It’s worth noting that Brazil recently dealt with a large outbreak of this disease spread by cats, with over 4,000 cases reported in Rio de Janeiro.
Anyone can get sporotrichosis, regardless of their age or gender. It all depends on their exposure to the sources of the disease in their jobs or their environments. For instance, in Uruguay, it affects more men and people who hunt armadillos, while in India, it’s more common in women because they are more often involved in agricultural work.
Signs and Symptoms of Sporotrichosis
Sporotrichosis is a disease that can show up anywhere from a few days to three months after exposure. The disease can take various forms, including skin infections, lung infections, or widespread infections.
The skin form typically happens after minor skin injuries and is quite common among people who regularly handle roses. Initially, bumpy red spots may appear, which can be smooth or rough and typically involve lymph vessels. These spots usually don’t cause pain, even if they ulcerate or break open. People with this type of sporotrichosis won’t generally have other symptoms or issues showing up on lab tests.
Lung sporotrichosis may result in symptoms like coughing, mild fever, and weight loss. It’s more likely to occur in middle-aged men who have chronic lung problems, people who abuse alcohol or have used steroids, and those with conditions like diabetes, sarcoidosis, or weakened immune systems. A chest X-ray might show one or two spots where tissue is breaking down, leading to lung problems if not treated. The diagnosis can be confirmed with a Gram stain or sputum culture.
Widespread infections usually occur in patients with weakened immune systems. This severe form of sporotrichosis can cause lung abscesses, affect the liver and spleen, and spread to the esophagus, colon, bone marrow, and lymph nodes.
Testing for Sporotrichosis
To definitively diagnose a fungal infection such as sporotrichosis, a laboratory culture test is performed. This test demonstrates the unique properties of the fungus. For skin sporotrichosis, a doctor would take a sample of tissue from the skin lesion or extract some pus for testing. For sporotrichosis that affects the lungs, a similar process is needed, although sputum (the mixture of saliva and mucus coughed up from your respiratory tract) is used. If the disease spreads throughout the body, a diagnosis can be made using tests on urine, blood, and joint fluid.
To see if the yeast cells are present, a solution called potassium hydroxide might be used to reveal their distinctive cigar-shaped buds or asteroid bodies. Other methods such as PCR (a method to make many copies of a specific DNA segment), ELISA test (a test that uses antibodies and color change to identify a substance), antibody detection, and a skin test specifically created to identify sporotrichosis can be used. However, these tests do not have a standardized process and may not always be reliable.
Treatment Options for Sporotrichosis
Before the 1990s, a drug called potassium iodide was the go-to treatment for certain health conditions. However, potassium iodide could have some negative side effects. So in the 1990s, a different drug, called itraconazole, was introduced and has since become the preferred treatment.
Different doses of itraconazole are used to treat different conditions. For skin-related issues, a smaller dose is usually sufficient. However, for lung-related conditions, a larger dose could be necessary.
As for children, the dose depends on their weight. For children who weigh up to 20 kg, a lower dose is given.
Itraconazole shouldn’t be given to pregnant patients. If they have to be treated after 12 weeks of pregnancy, another drug called amphotericin B is used instead. This, however, is only used in serious cases where the condition has spread to different parts of the body or the patient’s immune system is compromised.
Preventing the conditions that itraconazole treats can also involve dressing appropriately to avoid puncture wounds. This could include wearing gloves, long sleeves, and heavy boots.
What else can Sporotrichosis be?
When diagnosing skin sporotrichosis, doctors consider other medical conditions that might cause similar skin problems. These include:
- Nocardiosis (an infection caused by Nocardia, a type of bacteria that can affect the skin, lungs, and other parts of the body)
- Cutaneous leishmaniasis (a skin infection caused by a parasite transmitted by sandflies)
- Francisella tularenis (bacterial infection causing tularemia or “rabbit fever”)
- Fusarium (a type of fungal infection)
- Different kinds of mycobacterial infections (infections caused by various Mycobacterium bacteria, including Mycobacterium marinum, Mycobacterium kansai, and Mycobacterium tuberculosis)
In addition to these, problems that can cause skin lesions similar to plaque sporotrichosis are also considered:
- Blastomycosis (a fungal infection that usually affects the lungs but can also cause skin sores)
- Paracoccidioidomycosis (a fungal infection that can cause mouth sores and skin issues)
- Chromoblastomycosis and Lobomycosis (other types of fungal skin infections)
- Psoriasis (an autoimmune disease that causes red, scaly patches on the skin)
- Pyoderma gangrenosum (a rare skin condition that causes large, painful sores)
