So far in series nine of Call the Midwife we've had everything from obstetric fistulas to haemochromatosis – and this in episode four Dr Turner (Stephen McGann) and young Dr Kevin McNulty (Lee Armstrong) come up with another diagnosis of an "-osis".


Here's what you need to know about histoplasmosis and its connection with pigeon-keeping:

What is histoplasmosis?

A disease which mainly affects the lungs. It's caused by breathing in spores of a fungus called "hisoplasma capsulatum" often found in decaying bird (or bat) droppings – and it can be extremely dangerous if allowed to escalate.

Histoplasmosis is usually transmitted when those fungal spores become airborne. Construction and demolition projects (like the slum clearances in Call the Midwife) are a particular danger because contaminated soil is stirred up, releasing the spores.

These infectious elements are then inhaled and settle into the lungs.

Phil Daniels plays George Benson in Call the Midwife

Why does it affect pigeon breeders?

Pigeon breeders (or "fanciers") work closely with the birds, putting them at risk of breathing in the fungal spores from contaminated soil. George Benson (Phil Daniels) is particularly at risk because the droppings have been building up for so many years, and because nearby demolition work is helping release the spores from the ground.

Also at risk are farmers, landscapers, gardeners and people who work on the land – for obvious reasons. Construction workers must be aware of the dangers of disturbing infectious elements in soil, and cave explorers should beware the spores from bat droppings.

A side note: histoplasmosis is different from "bird fancier's lung" (BFL), which also affects pigeon keepers. This is a type of "hypersensitivity pneumonitis" triggered by exposure to specific proteins present in birds' droppings (or feathers). BFL causes the lungs to become inflamed and has its own set of symptoms, including chronic breathlessness.

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What are the symptoms of histoplasmosis?

This disease is a tricky one to spot, because it can often seem like a common cold or pneumonia or the flu. Chronic histoplasmosis can sometimes look a lot like the infectious disease tuberculosis (TB), which is what Dr Turner (Stephen McGann) and Fred Buckle (Cliff Parisi) originally suspect.

Call the Midwife

A mild case of histoplasmosis may not even cause symptoms of any kind. But other sufferers will experience a range of symptoms which can include fever, chills, a headache, muscle aches, chest discomfort, and a cough which may bring up blood.

While the disease doesn't always cause issues, it's particularly dangerous for those with weaker immune systems, including infants and old people.

Left untreated, histoplasmosis can lead lead to heart problems (e.g. pericarditis), ulcers in the oesophagus or vocal cord, parotitis, adrenal insufficiency, uveitis, meningitis, acute respiratory distress syndrome, and a variety of other serious issues.

At its worst, the disease can develop into "disseminated histoplasmosis" which will affect nearly any part of the body. This can be fatal.

What is the treatment for histoplasmosis?

People with a mild form of the disease often get better on their own, but anti-fungal medication is needed to treat cases which have become severe, chronic or disseminated.

These days, the oral drug itraconazole is often used, with courses lasting from months to a year. Serious fungal infections can also be treated with Amphotericin B, a drug that's been in use since 1958 which is usually administered by injection into a vein.


Call the Midwife continues on Sundays at 8pm on BBC One