Aspergillosis

What is Aspergillosis?

Aspergillosis consists of a wide-spectrum of clinical pathology. It is an infection, a growth, or an allergic response caused by the Aspergillus fungus. Aspergillus are common in the soil and decaying vegetation. Colonisation of parts of the body by Aspergillus fungus is common.

However certain sites are involved more common than others, including:

lungs
sinuses
central nervous system
bones
eyes
heart
kidney
skin
ears
urinary tract, including bladder and urethra

Although the above listed may be involved, Aspergillus primarily affects the lungs. It causes 4 main syndromes, including allergic bronchopulmonary aspergillosis (ABPA), chronic necrotizing aspergillus pneumonia, aspergilloma, and invasive aspergillosis.

Statistics on Aspergillosis?

Aspergillosis is common in the community. Depending on which type of aspergillosis, the figures vary. However it is fair to say that aspergillosis is common in the group of patients where their immune system is affected. This include those with HIV infection, and on medications that suppress immune system in transplant patients.

Other vulnerable groups include:

cancer patient undergoing chemotherapy.
intensive care unit patients on multiple antibiotics.

Risk Factors for Aspergillosis

Because of the abundance of aspergillus organisms in the environment, exposure to their spores is a frequent event. However, disease development due to fungi invasion occurs primarily in the state where there is reduced immunity. Any factors that lead to this will predispose the individuals to aspergillosis.

This includes:

Neutropenia(low white cell count that is important to fight infection)
corticosteroid use
HIV infection
allogenic stem cell transplant recipients
graft versus host disease
solid tumours

Progression of Aspergillosis

Aspergillosis occur in many organs in the body. With invasive aspergillosis, significant mortality ensues. However with other clinical diseases of aspergillosis, some will resolve spontaneously with suitable drugs, and some will go onto a chronic 'on and off' course of disease progression. Sometimes chronic aspergillus pneumonia (infection of the lung tissue by aspergillus fungi) can lead to severe complications such as diminished pulmonary function, and eventually death. The reason for this is the disease often remains undiagnosed and elusive.

How is Aspergillosis Diagnosed?

Because the patient is usually having reduced immune system and diagnosis of aspergillosis is difficult if it involves internal organs, the usual routine blood tests will be done, including:

full blood count
urea and electrolytes
liver function test
coagulation studies: this is looking at how well the blood is functioning to stop bleeding

Prognosis of Aspergillosis

Because aspergillosis can present in many ways, their prognoses differ as well. The one with poorest prognosis is invasive pulmonary aspergillosis. Also the prognosis depends on the underlying condition the patient has, for example a person during terminal HIV disease with AIDS would be having a worse prognoses than those being treated in intensive care unit.

How is Aspergillosis Treated?

There are 3 components in the treatment of aspergillosis:

reduction of underlying risk factors
medical treatment
surgical treatment

Reversal of underlying risk factors:

this intend to improve the immune system of the patient. The current treatment option is to use granulocyte colony-stimulating factor (G-CSF) and interferon gamma to boost the body immune system. However this has not been uniformly successful.

Medical treatment:

antifungal drugs are the mainstay of treatment in terms of pharmacological options for aspergillosis. These drugs include conventional and liposomal amphotericin B, voriconazole, traconazole, and the newer agent called caspofungin (an echinocandin). If treatment is not successful or the the disease is aggressive, combination medications can be administered. The duration of therapy depends on many factors, including disease site, host's underlying disease, and response to the therapy.

Surgical treatment:

surgery can be used as diagnostic biopsy of the involved site. Sometimes surgical excision of the cavity can be performed in patients with single pulmonary lesion.

Aspergillosis References

DoctorFungus: Aspergillosis [online]. 2005. [Cited 2005 September 30th]. http://www.doctorfungus.org/mycoses/human/aspergillus/aspergillosis.htm
eMedicine: Aspergillosis [online]. 2005. [Cited 2005 September 30th]. Available from: URL: http://www.emedicine.com/med/topic174.htm
Up to Date: Clinical features and diagnosis of invasive aspergillosis [online]. 2005. [Cited 2005 September 30th]. Available from: URL: http://www.utdol.com/application/topic.asp?file=fung_inf/6397&type=A&selectedTitle=2~54
Up to Date: Treatment of invasive aspergillosis [online]. 2005. [Cited 2005 September 30th]. Available from: URL: http://www.utdol.com/application/topic.asp?file=fung_inf/7729