Week 4: Lower Respiratory Infections

Hello everyone, this week in lecture we discussed lower respiratory infections.  I was particularly interested in the discussion of Legionella and Legionnaires’ disease.  Legionella pneumophila is responsible for roughly 90% of cases of Legionnaires’ disease.  Legionella is found primarily in water sources such as lakes, rivers, water distribution centers, cooling centers, fountains and potable water.  Legionella is contracted via inhalation of infectious aerosols.  There are 15 different serotypes of Legionella, serotype one being the most common serotype seen in infections.  Serotypes 4 and 6 are the next most common serotypes seen.  This bacterium is not spread by person to person contact.  The first symptoms of Legionnaires’ disease are non-specific.  Initial symptoms include fever, chills, cough, muscle pain, headache, chest pain, and diarrhea.  Pneumonia follows as well as possible renal failure, additional gastrointestinal problems, liver function abnormality, and central nervous system problems such as delirium, disorientation, confusion, and rare seizures. 

            Legionnaires’ disease occurs as sporadic cases, epidemic outbreaks, and as nosocomial infections.  Legionnaires’ disease has an incidence of roughly 8,000-18,000 cases per year in the United States.  The mortality rate is 10%-15% in healthy individuals and up to 75% in the immunocompromised.  Individuals predisposed to Legionnaires’ include cigarette smokers, the elderly, individuals with chronic lung disease, and people of immunosuppressive drugs.

            The following is a video from the BBC concerning windshield-wiper fluid contaminated with Legionella in the United Kingdom.  It was found that professional drivers in the UK are five times more likely to contract Legionnaires’ due to increased likelihood of contact with contaminated windshield wiper fluid.  

http://www.bbc.co.uk/news/10306411