Table 1.
Characteristics of selected infectious microorganisms transmitted via the airborne route of exposure
| Organism | Characteristics | Disease | Reservoir |
|---|---|---|---|
| Aspergillus spp. | Fungus, a mold with spherical spores ~1 µm in diameter, variety of species including Aspergillus fumigatus, Aspergillus flavus, Aspergillus nidulans, Aspergillus terrus, and Aspergillus niger | Aspergillosis, aspergilloma (fungus ball), allergic sinusitis, and allergic bronchopulmonary disease | Environment, compost and plant, material, soil, dust, building materials |
| Blastomyces dermatitidis | Fungus; 8–15 µm spherical yeast cells | Flu-like illness, chronic lung disease | Moist soil enriched with decomposing organic debris |
| Coccidioides immitis | Fungus; 5 µm alternating barrel-shaped arthrospores | Coccidioidomycosis/ San Joaquin Valley fever | Desert soils with intermittent wet and hot dry cycles |
| Cryptococcus neoformans | Fungus; vegetative form (yeast cell) 2.5–10 µm, basidiospores 1.8–3 µm | Cryptococcosis | Pigeon droppings debris and soil associated with birds |
| Enteric viruses | Virus; RNA/DNA, ~20–100 nm | Gastrointestinal symptoms, meningitis, encephalitis, respiratory infections | Infected persons, surfaces |
| Histoplasma capsulatum | Fungus; dimorphic 2–5 µm oval cells | Flu-like symptoms, chronic lung disease, dissemination to other organ systems | Environment |
| Influenza viruses | Virus; single-stranded RNA, three distinct types (i.e., A, B, and C), 80–120 nm | Influenza, pneumonia, acute respiratory distress | Human respiratory secretions; avian flu associated with birds |
| Legionella pneumophila and Legionella spp. | Bacterium; vegetative Gram-negative bacillus, 0.5–1 µm by 2 µm | Legionnaires’ disease and Pontiac fever | Ubiquitous in fresh and waste water environments, an intercellular parasite of protozoa |
| Measles virus (MeV) | Virus, enveloped, negative – sense, single-stranded RNA hantavirus, 100–250 nm | Rubeola: acute, febrile disease with an exanthematous rash, dry cough, sore throat, headache | Human – only known reservoir |
| Middle East respiratory syndrome – associated coronavirus (MERS-CoV) | Virus, enveloped, positive-sense single-stranded RNA | Acute respiratory distress syndrome, multi-organ failure, septic shock, death | Infected persons, bats and camels reservoirs |
| Mycobacterium tuberculosis | Bacterium; acid-fast, 0.2–0.6 µm by 1–10 µm | Tuberculosis | Infected persons |
| Severe acute respiratory syndrome – associated coronavirus (SARS-CoV) | Virus; RNA with helical symmetry, positive-sense single-stranded RNA | Acute respiratory distress | Infected persons |
| Sin nombre virus (SNV) | Virus; negative – sense, single-stranded RNA hantavirus | Hantavirus pulmonary syndrome (HPS) | Rodent urine, saliva, and feces especially Peromyscus maniculatus (deer mouse) |
| Varicella-zoster virus (VZV) | Virus; double-stranded DNA, 150–200 nm | Chickenpox | Humans – only known reservoir; virus may be dormant until reactivates as shingles |