Can this fungus affect your lungs too? Let's learn about Histoplasmosis!

Have you ever heard of a disease called ``Histoplasmosis''? The name may sound a little strange. But it is a fungal infection that can affect our lungs and is something to be careful about. This fungus lives in the soil, especially in soil that contains bird or bat droppings. We get this disease if we breathe in dust that contains this fungus.

What exactly is Histoplasmosis?

Simply put, histoplasmosis is an infection of our lungs caused by a type of fungus called ``Histoplasma capsulatum`` (``Histoplasma capsulatum`` or ``H. capsulatum``). This fungus is found in the soil in many parts of the world, and is common in countries like America. This fungus can also be found in our Sri Lanka, especially in the soil around bat caves, old buildings, and bird farms. It enters our bodies when we breathe in dust containing these fungal spores.

Are there different types of this disease?

Yes, there are several main types of histoplasmosis. Doctors determine these types based on how long you have had symptoms and whether it has spread to other parts of your body.

1. Acute pulmonary histoplasmosis

This is the most common type of infection. About 10% of people infected with the fungus develop pneumonia-like symptoms. These include fever, cough, and difficulty breathing. However, if you are infected with a low-grade infection, symptoms may be mild and last for several months. This is called a subacute stage.

2. Chronic cavitary pulmonary histoplasmosis

This is a long-term condition. It is more common in people with lung diseases such as emphysema or COPD (Chronic Obstructive Pulmonary Disease). Symptoms may be milder than in the acute form, but night sweats and weight loss may occur. Symptoms can last for months, even years. It can look a bit like tuberculosis. If left untreated, the damage to the lungs will gradually increase.

3. Progressive disseminated histoplasmosis

This is when the H. capsulatum fungus spreads from the lungs to other parts of the body. This usually happens in people who have very weak immune systems. For example, people with advanced HIV infection. This can cause progressively worsening shortness of breath, fatigue, weight loss, and skin ulcers.

In addition, there are types of histoplasmosis that affect the brain (central nervous system histoplasmosis) and those that affect the eyes (ocular histoplasmosis).

How common is histoplasmosis?

In fact, it is estimated that about 75% of adults living in areas where the fungus `H. capsulatum` is common have been infected with this fungus at some point. However, most people do not develop any symptoms.

What does this fungus do to our bodies?

Imagine, you inhale this `H. capsulatum` fungus with dust. Then it goes straight to your lungs. There, this fungus goes inside our white blood cells and changes from a `mold` form into a `yeast` form that can infect.

In most people, the immune cells in the body either destroy the fungus or form special coverings called ``granulomas`` that surround the fungus and keep it from harming the body. As a result, we don't experience any symptoms.

However, sometimes this can become a disease:

• If you inhale a large amount of fungus at once, your immune system may be overwhelmed, causing flu-like symptoms and difficulty breathing.
• If you have lung diseases like COPD, this fungus can continue to damage your lungs.
• If your immune system is weak (e.g., those with HIV or those taking immunosuppressive drugs), this fungus can use your immune cells to spread to other parts of your body. This can cause life-threatening complications.

What are the symptoms of histoplasmosis?

Symptoms of histoplasmosis may include:

• Fever
• Cough
• Sweating
• Difficulty breathing (dyspnea)
• Chest pain
• Headache (headache)
• Muscle pain
• Red, lumpy rash on the lower legs (erythema nodosum)

People with chronic cavitary pulmonary histoplasmosis may also experience night sweats and weight loss. Importantly, about 90% of people who inhale the fungus H. capsulatum do not develop any symptoms, or the symptoms resolve on their own.

What causes this disease?

The cause of this is a fungus called ``Histoplasma capsulatum``. As we mentioned earlier, it is caused by inhaling mold spores from soil that contains this fungus. This fungus thrives in soil that contains bat droppings and bird droppings. It is found in many parts of the world:

• In the Ohio and Mississippi River valleys of America.
• In Central and South America.
• In Africa.
• In Asia.
• In Australia.

Most people do not get sick from breathing in this fungus, but some people, especially those who inhale a large amount of the fungus at once or those with certain health conditions, may develop symptoms.

Who is at higher risk for this?

You are at higher risk if your job or hobbies involve stirring up dust in areas where there is a lot of this fungus. Examples:

• Spelunking.
• Farming.
• Raising chickens or other birds.
• Demolishing old buildings, construction work. Imagine, when you're cleaning out an old house that hasn't been used for years, if there are bats on the roof, and that excrement is mixed with the dust? There's a risk if you breathe it in.

Who is at higher risk of developing histoplasmosis, either acutely or chronically?

• For those with a weak immune system. The main reasons for this are HIV infection and taking immunosuppressive medications.
• For those with COPD or emphysema.
• For people over 55 years of age and babies under 1 year of age.

What are the possible complications of histoplasmosis?

There are several serious complications that can arise from this:

• Scarring or other damage to the lungs.
• Fibrosing mediastinitis - This is scarring of the area between the lungs.
• `Acute Respiratory Distress Syndrome (ARDS)`.
• Central nervous system histoplasmosis - If the fungus spreads to the brain, symptoms such as brain swelling, headache, confusion, difficulty thinking, and paralysis may occur.
• Ocular histoplasmosis - If the fungus spreads to the eyes, vision may be impaired or lost.
• Spread to other parts of the body, such as the liver, spleen, bone marrow, and skin.

How do you diagnose this disease?

A doctor may test your blood, urine, sputum from your lungs, bone marrow, or a sample of affected tissue to diagnose the disease. These samples may be used to:

• A culture of the fungus `H. capsulatum` is attempted. This is the best way to diagnose histoplasmosis. However, this can take a long time, up to several weeks. In severe cases, your doctor may start treatment without waiting for the results.
• We are looking for the yeast form `H. capsulatum`.
• You are tested for signs (antigens or antibodies) of H. capsulatum in your body.

In addition, chest X-rays or CT scans are done to look for changes or damage caused by H. capsulatum. The types of tests your doctor uses depend on what type of histoplasmosis you have and how severe your symptoms are.

What are the diagnostic tests?

In addition to X-rays and CT scans, a doctor may take fluid or tissue samples to look for signs of H. capsulatum or to culture it. These samples can be taken in the following ways:

• Urine or sputum tests : You urinate into a cup (a urine test) or sputum into a tube (a sputum test).
• Blood tests : A doctor will take a little blood from your arm with a needle.
• Biopsy : A sample of tissue is taken through a small incision or with a needle. In a bone marrow biopsy, a sample is taken from inside the hip bone.
• Bronchoscopy : A doctor will look inside your lungs using a thin, lighted tube (a bronchoscope). At this time, a procedure called a bronchoalveolar lavage (BAL) may be done. This involves "washing" small areas of your lungs with a liquid, collecting the liquid, and sending it to a lab for testing.

How is histoplasmosis treated?

Histoplasmosis is treated with antifungal medications, if necessary. If you have mild symptoms, they haven't been present for a long time, and you're not at high risk of developing a serious infection, your doctor may decide to wait a while before giving you medication right away.

Is there a complete cure for this?

Yes, histoplasmosis can often be cured with antifungal medications in people with healthy immune systems. Your doctor may prescribe medications such as:

• `Itraconazole`
• Amphotericin B (AmB)
• `Corticosteroids` (These are given in some special cases, such as to reduce swelling)

What happens if left untreated?

If your immune system is working well and you don't have any other underlying conditions, histoplasmosis can usually go away on its own. However, if left untreated, it can sometimes spread to other parts of the body, especially if your immune system isn't working properly. It can also cause lung damage in people with underlying lung conditions.

Can histoplasmosis be prevented?

If you live in an area where this fungus is common, it can be very difficult to avoid breathing in the fungus `H. capsulatum`. While it's impossible to completely prevent it, there are a few things you can do to reduce your risk:

• Avoid areas with dusty soil or where birds or bats live.
• If your job or hobby requires you to be in contact with soil that may contain H. capsulatum, wear an N95 mask. It will filter the air you breathe to some extent.

What can I expect if I get histoplasmosis?

What happens when you get histoplasmosis depends on how severe it is and whether you have other underlying conditions. For people with a healthy immune system and mild symptoms, your doctor may decide to "watch and wait" without medication. If your immune system is weak or you are very sick, you may need to take antifungal medication for at least a year.

Treatment usually lasts 6-12 weeks or longer for acute pulmonary histoplasmosis. In chronic or severe cases, antifungal medications may be required for at least a year.

What are the chances of surviving this disease?

Most people with healthy immune systems (about 96%) recover from histoplasmosis with treatment. However, some studies suggest that the mortality rate among people with weakened immune systems may be between 25% and 37%. That's why people with weakened immune systems need to be especially careful.

How do I take care of myself?

If you have a weakened immune system, or if you have COPD or emphysema, you should take extra steps to reduce your risk of histoplasmosis. If you live in an area where H. capsulatum is common, ask your doctor if there are any special precautions you can take to protect yourself.

When should I see a doctor?

If your symptoms, such as fever, cough, and shortness of breath, don't improve within a week, or if they get worse over time, see a doctor. Tell your doctor if you have been exposed to this fungus through your job or hobbies, or if you have traveled to an area where this fungus is present.

When should I go to an Emergency Treatment Unit (ETU) ?

If your immune system is weak and you have symptoms of an infection, you should talk to a doctor or go to the emergency room right away. If you have severe symptoms, go to the nearest emergency room. Such symptoms include:

• High fever (over 103 Fahrenheit/40 Celsius).
• Severe or sudden difficulty breathing.
• Chest pain.
• If you cough up blood.
• Disorientation or other mental changes.
• Seizures.
• Blue color of the skin, lips, or fingernails (`cyanosis` - this is a sign of low oxygen in the blood).

What questions should I ask the doctor?

It may be helpful to ask a doctor questions like these:

• Am I at increased risk of developing severe histoplasmosis?
• What special steps should I take to reduce my risk of histoplasmosis?
• What symptoms should I look out for?
• When should I go to the emergency room?

Finally, things to remember (Take-Home Message)

Histoplasmosis is a fungal infection that affects your lungs. It can be difficult to avoid if you live in an area where this fungus thrives. But most cases are not serious and resolve on their own.

However, if you have a lung condition or a weakened immune system, you are at higher risk of serious complications from histoplasmosis. Therefore, it is important that you and your doctor work together to develop a plan to protect your health and be alert for any symptoms. Don't panic, awareness is the best defense!

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