Aspergillus species are airborne mold pathogens responsible for ‘Aspergillosis’, an umbrella term for pulmonary diseases which encompasses a range of clinical syndromes. These include allergic broncho-pulmonary aspergillosis (ABPA) in patients with asthma or cystic fibrosis, aspergilloma (fungal ball) that affects patients with abnormal airways (chronic obstructive pulmonary disease, bronchiectasis, cystic fibrosis) or residual lung cavities, the semi-invasive chronic necrotizing aspergillosis (CNA), and invasive aspergillosis (IA), either angio-invasive or bronchio-invasive forms (IPA).
A. fumigatus is responsible for >90% of IA cases, with an estimated annual burden of 200,000 cases and high mortality rates (30-95%). Key susceptible groups include patients with acute leukemia, bone marrow and other transplant recipients and COPD (predicted as the third cause of mortality in the world by 2020). Chronic pulmonary aspergillosis (CPA) accounts for 3 million cases worldwide, including 1.2 million with tuberculosis sequelae and is associated with ~15% mortality (>450,000 deaths) in the developed world. IA in AIDS patients claims > 30,000 lives annually, while the burden of CPA is > 100,000 (www.GAFFI.org; The Fungal Infection Trust 2012).
However, these are most likely underestimates, since accurate clinical and epidemiological data regarding the incidence of invasive fungal infections (IFI) from developing regions of the world (e.g. Asia-Pacific) is meagre despite accounting for more than half of the world’s population. The paucity of reported literature reflects the absence of dedicated investigations into the prevalence of fungal infections, since many of these nations are economically disadvantaged and lack committed resources for such undertakings. A recent study did retrospective analysis of clinical specimens which were collected from ~1.1 million patients at 25 hospitals located across six Asian countries. Aspergillus species were the most common molds, with A. fumigatus as the leading species in all countries except India. In another study that looked at the burden of fungal infections in China, the rate of CPA with underlying respiratory disorders was calculated at 19.5 per 100,000 patients, while IA in cancer, transplantation, and ICU patients was estimated at 11.9 per 100,000 cases.
To date, nothing has been published regarding the incidence of aspergillosis within the immunocompromised and immunocompetent population in Cambodia. This is surprising, considering the vital association of aspergillosis with AIDS, cancer, and other underlying respiratory disorders. In the neighboring country of Thailand, CPA is estimated to occur at a rate of 20.1 per 100K patients, due to the high incidence of tuberculosis, while IA is predicted at an incidence rate of 1.4 per 100K cases. Similarly, the prevalence of tuberculosis in Vietnam led to CPA incidence rates of 61 per 100K, and IA of 15.99 per 100K. These high incidence rates of aspergillosis in countries lying in proximity to Cambodia underscores the importance of conducting surveillance and gathering epidemiological data for this country.
Patients who visit the hospital for treatment will most likely be suffering from aspergillosis that might go undiagnosed, unless proactive measures are undertaken for treatment and effective management of this disease. Thus, our research proposal is timely in initiating research into this disease, which will bridge the current gap in knowledge and provide essential data towards appropriate administration of medical care. This will be the foundation for the set-up of guidelines for aspergillosis diagnostic and treatment in Cambodia with the close collaboration of national authorities (Communicable Disease Control Department, Ministry of Health).