Aspergillosis

A fungus ball in the lungs may cause no symptoms and may be discovered only with a chest X-ray, or it may cause repeated coughing up of blood, chest pain, and occasionally severe, even fatal, bleeding.[2] A rapidly invasive Aspergillus infection in the lungs often causes cough, fever, chest pain, and difficulty breathing.

Poorly controlled aspergillosis can disseminate through the blood to cause widespread organ damage.[2] Symptoms include fever, chills, shock, delirium, seizures, and blood clots. The person may develop kidney failure, liver failure (causing jaundice), and breathing difficulties.[2] Death can occur quickly.

Aspergillosis of the ear canal causes itching and occasionally pain. Fluid draining overnight from the ear may leave a stain on the pillow. Aspergillosis of the sinuses causes a feeling of congestion and sometimes pain or discharge. It can extend beyond the sinuses.[17]

In addition to the symptoms, an X-ray or computerised tomography (CT) scan of the infected area provides clues for making the diagnosis. Whenever possible, a doctor sends a sample of infected material to a laboratory to confirm identification of the fungus.

Aspergillus 235 mags 3X3 copy

Aspergillosis is caused by Aspergillus, a common mold, which tends to affect people who already have a lung disease such as cystic fibrosis or asthma, or who cannot fight infection themselves.[3] The most common causative species is Aspergillus fumigatus.[18]

CT of a subpleural nodule (halo sign)[21]

On chest X-ray and CT, pulmonary aspergillosis classically manifests as a halo sign, and later, an air crescent sign.[22] In hematologic patients with invasive aspergillosis, the galactomannan test can make the diagnosis in a noninvasive way. False-positive Aspergillus galactomannan tests have been found in patients on intravenous treatment with some antibiotics or fluids containing gluconate or citric acid such as some transfusion platelets, parenteral nutrition, or PlasmaLyte.[23][24]

On microscopy, Aspergillus species are reliably demonstrated by silver stains, e.g., Gridley stain or Gomori methenamine-silver.[25] These give the fungal walls a gray-black colour. The hyphae of Aspergillus species range in diameter from 2.5 to 4.5 μm. They have septate hyphae,[26] but these are not always apparent, and in such cases they may be mistaken for Zygomycota.[25] Aspergillus hyphae tend to have dichotomous branching that is progressive and primarily at acute angles of around 45°.[25]

• 
  Pulmonary invasive aspergillosis in a person with interstitial pneumonia (autopsy material), using Grocott's methenamine silver stain
• 
  Angioinvasive pulmonary aspergillosis
• 
  Angioinvasive pulmonary aspergillosis (closeup)
• 
  Aspergillus vesicle (HE stain)

Prevention of aspergillosis involves a reduction of mold exposure via environmental infection-control. Antifungal prophylaxis can be given to high-risk patients. Posaconazole is often given as prophylaxis in severely immunocompromised patients.[27]

A systematic review has evaluated the diagnostic accuracy of polymerase chain reaction (PCR) tests in people with defective immune systems from medical treatment such as chemotherapy.[28] Evidence suggests PCR tests have moderate diagnostic accuracy when used for screening for invasive aspergillosis in high risk groups.[28] CT and MRI are vital to diagnosis, however it is always highly recommended to under go a biopsy of the area to confirm a diagnosis.[29][30][31]

The current medical treatments for aggressive invasive aspergillosis include voriconazole and liposomal amphotericin B in combination with surgical debridement.[32] For the less aggressive allergic bronchopulmonary aspergillosis, findings suggest the use of oral steroids for a prolonged period of time, preferably for 6–9 months in allergic aspergillosis of the lungs. Itraconazole is given with the steroids, as it is considered to have a "steroid-sparing" effect, causing the steroids to be more effective, allowing a lower dose.[33] Other drugs used, such as amphotericin B, caspofungin (in combination therapy only), flucytosine (in combination therapy only), or itraconazole,[34][35] are used to treat this fungal infection. However, a growing proportion of infections are resistant to the triazoles.[36] A. fumigatus, the most commonly infecting species, is intrinsically resistant to fluconazole.[37]

Aspergillosis is thought to affect more than 14 million people worldwide,[38] with allergic bronchopulmonary aspergillosis (ABPA, >4 million), severe asthma with fungal sensitization (>6.5 million), and chronic pulmonary aspergillosis (CPA, ~3 million) being considerably more prevalent than invasive aspergillosis (IA, >300,000). Other common conditions include Aspergillus bronchitis, Aspergillus rhinosinusitis (many millions), otitis externa, and Aspergillus onychomycosis (10 million).[39][40] Alterations in the composition and function of the lung microbiome and mycobiome have been associated with an increasing number of chronic pulmonary diseases such as COPD, cystic fibrosis, chronic rhinosinusitis and asthma.[41]

During the COVID-19 pandemic 2020/21, COVID-19-associated pulmonary aspergillosis was reported in some people who had been admitted to hospital and received longterm steroid treatment.[42]

While relatively rare in humans, aspergillosis is a common and dangerous infection in birds, particularly in pet parrots. Mallards and other ducks are particularly susceptible, as they often resort to poor food sources during bad weather. Captive raptors, such as falcons and hawks, are susceptible to this disease if they are kept in poor conditions and especially if they are fed pigeons, which are often carriers of "asper". It can be acute in chicks, but chronic in mature birds.

In the United States, aspergillosis has been the culprit in several rapid die-offs among waterfowl. From 8 December until 14 December 2006, over 2,000 mallards died near Burley, Idaho, an agricultural community about 150 miles southeast of Boise. Mouldy waste grain from the farmland and feedlots in the area is the suspected source. A similar aspergillosis outbreak caused by mouldy grain killed 500 mallards in Iowa in 2005.

While no connection has been found between aspergillosis and the H5N1 strain of avian influenza (commonly called "bird flu"), rapid die-offs caused by aspergillosis can spark fears of bird flu outbreaks. Laboratory analysis is the only way to distinguish bird flu from aspergillosis.

In dogs, aspergillosis is an uncommon disease typically affecting only the nasal passages (nasal aspergillosis). This is much more common in dolicocephalic breeds. It can also spread to the rest of the body; this is termed disseminated aspergillosis and is rare, usually affecting individuals with underlying immune disorders.

In 2019, an outbreak of aspergillosis struck the rare kakapo, a large flightless parrot endemic to New Zealand. By June the disease had killed seven of the birds, whose total population at the time was only 142 adults and 72 chicks. One fifth of the population was infected with the disease and the entire species was considered at risk of extinction.[43]

• Other ways in which aspergillus can cause disease in mammals:
  • Primary cutaneous aspergillosis
  • Aflatoxin

• Aspergillosis, MedlinePlus, US National Library of Medicine
• Aspergillus & Aspergillosis Website
• National Aspergillosis Centre, Manchester, UK