Aspergillosis is the collective term used to describe all disease entities caused by any one of more than 35 pathogenic and allergenic species of Aspergillus.

Introduction
A. fumigatus is responsible for most cases of invasive aspergillosis, almost all cases of chronic aspergillosis, and most allergic syndromes.

A. flavus is more prevalent in some hospitals and causes a higher proportion of cases of sinus and cutaneous infection and keratitis than A. fumigatus.

A. niger can cause invasive infection but more commonly colonizes the respiratory tract and causes external otitis.
Epidemiology

Aspergillus has a worldwide distribution, most commonly growing in decomposing plant materials and in bedding.

Aspergilli are found in indoor and outdoor air, on surfaces, and in water from surface reservoirs.

The required size of the infecting inoculum is uncertain; however, only intense exposures e.g., during construction work, handling of moldy bark or hay, or composting are sufficient to cause disease in healthy immuno competent individuals.

Allergic syndromes may be exacerbated by continuous antigenic exposure arising from sinus or airway colonization or from nail infection.

Incubation period:
The incubation period of invasive aspergillosis after exposure is highly variable, extending in documented cases from 2 to 90 days.

Thus community-acquired acquisition of an infecting strain frequently manifests as invasive infection during hospitalization, although nosocomial acquisition is also common.

Risk Factors and Pathogenesis
The primary risk factors for invasive aspergillosis are
Profound neutropenia and glucocorticoid use
Advanced HIV infection
Relapsed leukemia.

Many patients have some evidence of prior pulmonary disease-typically, a history of pneumonia or chronic obstructive pulmonary disease.

Glucocorticoid use does not appear to predispose to invasive Aspergillus sinusitis but probably increases the risk of dissemination after pulmonary infection.

Patients with chronic pulmonary aspergillosis have a wide spectrum of underlying pulmonary disease, often tuberculosis or sarcoidosis.

Patients are immunocompetent except that a genetic defect in mannose-binding protein is common.

Clinical Features
Invasive Sinusitis

The sinuses are involved in 5-10% of cases of invasive aspergillosis, especially in patients with leukemia and recipients of hematopoietic stem cell transplants. In addition to fever, the most common features are nasal or facial discomfort, blocked nose, and nasal discharge sometimes bloody.

Disseminated Aspergillosis
In the most severely immuno compromised patients, Aspergillus disseminates from the lungs to multiple organs most often to the brain but also to the skin, thyroid, bone, kidney, liver, gastrointestinal tract, eye, and heart valve.
Aside from cutaneous lesions, the most common features are gradual clinical deterioration over 1-3 days, with low-grade fever and features of mild sepsis, and multiple nonspecific abnormalities in laboratory tests.

Cerebral Aspergillosis
Hematogenous dissemination to the brain is a devastating complication of invasive aspergillosis. Single or multiple lesions may develop. In acute disease, hemorrhagic infarction is most typical, and cerebral abscess is common. Rarer manifestations include meningitis, mycotic aneurysm, and cerebral granuloma.

The presentation can be either acute or subacute, with mood changes, focal signs, seizures, and decline in mental status.

Cerebral granuloma can mimic a primary or secondary tumor.

Endocarditis
Most cases of Aspergillus endocarditis are prosthetic valve infections resulting from contamination during surgery.
Native valve disease is reported, especially as a feature of disseminated infection and in persons using illicit IV drugs.

Cutaneous Aspergillosis
Dissemination of Aspergillus occasionally results in cutaneous features, usually an erythematous or purplish nontender area that progresses to a necrotic eschar. Direct invasion of the skin occurs in neutropenic patients at the site of IV catheter insertion and in burn patients..

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