Various stages of the<unk> : Chest radiograph (A) and high-resolution computed tomography (B) at hospital admission, repeat high-resolution computerized tomography of the chest a week after hospital admission (C, D), shown in a 42-year-old male with severe pneumonia caused by L. pneumophila serogroup 11a People of any age may suffer from<unk> , but the illness most often affects middle-aged and older people, particularly those who smoke cigarettes or have chronic lung<unk> . Immunocompromised people are also at higher risk. Pontiac fever most commonly occurs in those who are otherwise healthy. The most useful diagnostic tests detect the bacteria in coughed-up mucus, find Legionella antigens in urine samples, or allow comparison of Legionella antibody levels in two blood samples taken 3–6 weeks apart. A urine antigen test is simple, quick, and very reliable, but only detects L. pneumophila serogroup 1, which accounts for 70% of<unk>  caused by L. pneumophila, which means use of the urine antigen test alone may miss as many as 30% of cases. This test was developed by Richard Kohler in 1982. When dealing with L. pneumophila serogroup 1, the urine antigen test is useful for early detection of<unk> s<unk>  and initiation of treatment, and has been helpful in early detection of outbreaks. However, it does not identify the specific subtypes, so it cannot be used to match the person with the environmental source of infection. The Legionella bacteria can be cultured from sputum or other respiratory samples. Legionella spp. stain poorly with Gram stain, stain positive with silver, and are cultured on charcoal yeast extract with iron and cysteine (CYE agar). A significant under-reporting problem occurs with legionellosis. Even in countries with effective health services and readily available diagnostic testing, about 90% of cases of<unk>  are missed. This is partly due to the<unk>  being a relatively rare form of pneumonia, which many clinicians may not have encountered before, thus may misdiagnose. A further issue is that people with legionellosis can present with a wide range of symptoms, some of which (such as diarrhea) may distract clinicians from making a correct diagnosis.
Legionnaires' disease
Freshers' flu
Lemierre's syndrome
Boutonneuse fever
Scarlet fever
Bartonellosis
Listeriosis
Metal fume fever