Acute Aspergillus Pneumonia (After Heavy Exposure)

Last reviewed: 11 March 2026

Key points

Acute Aspergillus pneumonia is a rare lung infection caused by inhaling very large numbers of Aspergillus fungal spores.
It can occur in people with normal immune systems, usually after a single heavy environmental exposure.
Typical exposures include mouldy hay, compost, bark chippings, agricultural dust, or similar environments with high fungal spore levels.
Symptoms resemble severe pneumonia and include fever, breathlessness and cough.
Diagnosis requires specialist tests because the illness can resemble other lung diseases such as bacterial pneumonia or hypersensitivity pneumonitis.
Treatment usually requires hospital care and antifungal medication.

Overview
Symptoms
Causes
Diagnosis
Treatment
Prognosis
Common questions
When to seek medical advice
Author and review information
References

Overview

Acute Aspergillus pneumonia is a rare form of lung infection caused by fungi from the genus Aspergillus. It is sometimes described as Aspergillus pneumonitis after heavy exposure.

Unlike most forms of aspergillosis, which occur in people with weakened immune systems or pre-existing lung disease, this condition can occasionally occur in otherwise healthy individuals.

Most reported cases follow a short but intense exposure to very large numbers of fungal spores. These exposures may occur in environments where organic material is decomposing.

Examples include:

handling mouldy hay or grain
working with compost or tree-bark chippings
agricultural or forestry work
heavy exposure to organic dust
rare events such as near-drowning in contaminated water

In these situations, a large number of fungal spores may be inhaled over a short period. In rare cases this appears to overwhelm the lung’s natural defence systems and cause infection or severe inflammation.

Researchers are also examining whether heavy exposure to mould in damp indoor environments may occasionally contribute to illness, although the relationship between household mould exposure and fungal lung infection remains complex and is still being studied.

Symptoms

Symptoms usually develop within days of exposure and may resemble severe pneumonia.

fever (often above 38°C)
shortness of breath
wheezing
rapid or shallow breathing
persistent cough
cough producing mucus
chest pain that worsens when breathing deeply
fatigue or weakness

In severe cases symptoms may worsen rapidly and require hospital treatment.

Causes

Acute Aspergillus pneumonia is usually associated with sudden inhalation of very large numbers of fungal spores.

Aspergillus fungi are common in the natural environment and are found in:

soil
compost
decaying plant material
organic dust
damp or mouldy environments

Most people breathe in small numbers of these spores every day without becoming ill. Normally the lungs clear them efficiently using mucus and immune defence mechanisms.

In rare circumstances, however, extremely heavy exposure may overwhelm these defences and lead to infection or severe inflammation in the lungs.

Researchers are still studying why this occurs in only a small number of individuals. Possible contributing factors include:

extremely high spore exposure
temporary irritation or damage to the airway lining
individual variation in immune response

Diagnosis

Diagnosing acute Aspergillus pneumonia can be difficult because its symptoms are similar to several other lung conditions.

It may be confused with:

bacterial pneumonia
viral pneumonia
hypersensitivity pneumonitis (extrinsic allergic alveolitis)
other inflammatory lung diseases

A careful medical history is important, particularly recent exposure to environments with high fungal spore levels.

Tests used in diagnosis may include:

chest X-ray
CT scan of the lungs
sputum or respiratory samples for fungal testing
blood tests
bronchoscopy to obtain lung samples

These investigations help doctors confirm the presence of Aspergillus and rule out other causes of pneumonia.

Treatment

Patients with suspected acute Aspergillus pneumonia usually require hospital assessment and monitoring.

Treatment commonly includes:

intravenous antifungal medication
oxygen therapy if breathing is affected
supportive care for pneumonia

Antifungal medications used may include:

voriconazole
isavuconazole
amphotericin B in some situations

Early diagnosis and treatment are important because severe fungal pneumonia can worsen quickly if untreated.

Prognosis

The outlook depends on the severity of the illness and how quickly treatment begins.

Many patients recover with appropriate antifungal therapy and supportive care. However, untreated fungal pneumonia can be life-threatening.

Common questions

Is this condition common?

No. Acute Aspergillus pneumonia is rare, particularly in people with normal immune systems.

Can normal household mould cause pneumonia?

Everyday exposure to mould spores is extremely common and rarely causes infection. Most reported cases involve unusually heavy exposure to large numbers of spores.

Is this the same as invasive aspergillosis?

No. Invasive aspergillosis usually occurs in people with severely weakened immune systems, such as those receiving chemotherapy or transplantation.

Is Aspergillus pneumonia contagious?

No. It cannot spread from one person to another.

When to seek medical advice

persistent fever and cough
breathlessness after heavy mould or dust exposure
worsening chest pain or breathing difficulty
symptoms of pneumonia that do not improve

Urgent medical care is required if breathing becomes severely difficult or symptoms worsen rapidly.

Author and review information

Author: Aspergillosis Website Editorial Team

Audience: Patients, carers, GPs and non-specialists