If neutropenia is a risk factor for aspergillosis, why do people with HIV not have an increased incidence of the disease?
- submitted by J.P. Yu
- submitted by J.P. Yu
The problem with experts is that they do not know what they do not know. NNT.
Initially, Aspergillosis was considered an AIDS-defining oppurtunistic infection in the initial case definition of AIDS by the CDC (1982). By 1984, that was dropped because there was lack of evidence that either CD4 lymphopenia or HIV-infection increased the risk of invasive aspergillosis.
In one case-control study (1998), 1.6% of subjects had detectable aspergillus species in their sputum. Of those 19, two had CD4 counts > 100 (118 & 210), the others had a level
Macrophages are the first line of defense. In an in vitro model of the human alveolus, it was shown that macrophages alone were not able to suppress the growth, but the combination of macrophages and amphotericin B had efficacy (re: J Infect Dis 2007; 195: 455). It has also been shown that aspergillus suppresses functional T-cell responses (re: Blood 2005; 105: 2258).
The incidence of invasive aspergillosis after autologous HSCT was 0.5% at 12 months follow-up, 2.3% after allogenic HSCT from an HLA-matched related donor, and 3.2% after an HLA-mismatched related donor. The incidence after lung transplantation was 2.4%, 0.8% after heart transplant, 0.3% after liver transplant, and 0.1% after kidney transplant. A. fumigatus was seen in 56%, A. flavus in 18.7%, and A. terreus in 16% (re: Med Mycol 2005; 43 S1: S49).
In a retrospective study, post-mortem, 6.9% of medical patients had evidence of invasive aspergillus, of which 70% did not have any underlying hematological malignancy. COPD and liver failure are recognized as risk factors (re: CID 2007; 45: 1058).