Following an outbreak of a particular strain of pneumonia that infected many delegates during an American Legion Convention in Pennsylvania in 1976, the term ""Legionnaires' illness"" was first used. The disease's causative bacteria was eventually identified as Legionella pneumophila and isolated. The Legionella bacteria have been linked to Pontiac fever and Legionnaires' disease, two different disorders. A serious form of pneumonia is legionnaires' disease. The main signs of pontiac fever include fever and muscle aches (but not pneumonia). In this document, we only discuss legionellosis.
Why does Legionnaires' illness exist?
The genus Legionella contains the bacteria that causes Legionnaires' disease. There are numerous Legionella species that can cause the disease, but 85–90% of cases are caused by Legionella pneumophila. Species of Legionella are typically present in all freshwater aquatic settings. They can endure the wet conditions for several months and proliferate when there is organic debris and algae present.
What symptoms and indicators are present in Legionnaires' disease?
A severe form of pneumonia known as Legionnaires' disease often appears 2 to 10 days following exposure to the Legionella bacterium. Early warning indicators and symptoms include: Headache muscle ache overall unwell feeling Other symptoms and indicators may appear after a few days, and they may include: 104-105°F or up to 40-40.5°C fever signs of the digestive system (nausea, vomiting, diarrhea) wet cough chest pain respiratory issues or shortness of breath Dizziness or other mental modifications (disorientation, hallucination, loss of memory) The majority of patients get pneumonia, a condition when part of the air sacs in the lungs swell with fluid or pus. If symptoms of pneumonia appear, speak with a doctor or other healthcare provider for advice. Legionnaires' illness must be diagnosed through laboratory testing. It can take many weeks for full healing. Of the known cases of Legionnaires' illness, 15–25% have resulted in death.
How is the sickness of the legionnaires diagnosed and treated?
Laboratory tests that are not often administered to patients with fever and pneumonia are required to differentiate Legionnaires' disease from other kinds of pneumonia. In order to do the necessary tests, the doctor must be told if there is a chance of exposure to the Legionella bacterium. Laboratory tests that isolate Legionella from respiratory secretions (sputum) or tests of a patient's blood or urine are used to confirm the diagnosis. Antibiotics are used to treat legionnaires' illness. Early intervention lowers the likelihood of significant consequences.
How is the Legionnaire's illness spread?
Legionella is typically found in soil and water, although an outbreak of the disease is not always linked to this presence. The Legionella germs can also enter the lungs through aspiration, albeit it is less frequent. Aspiration is described as the direct or indirect admission of a liquid or solid through the mouth cavity, nasal cavity, or lower respiratory system. In other words, aspiration happens when anything enters the lungs as opposed to traveling from the mouth or nose to the stomach (other than air). Neither proof of human-to-human transfer nor proof of human-to-animal transmission has been discovered. Warm, stagnant water can encourage the growth of germs, including Legionella. When circulating air in a building takes up water droplets contaminated with Legionella, the infection can spread through ventilation systems. The germs can reach the lung if the droplets are small enough to be breathed.
How does the Legionella bacteria spread indoors?
Large air-conditioning systems include cooling towers. They are employed to chill water and remove extra heat by evaporation. Through spray nozzles, warm water enters the cooling tower's top (as shown in Figure 1). The air is pumped through the tower by fans while the water flows through the nozzles, creating small aerosols that maximize interaction between the water and the air. Splash bars are positioned below the nozzles to stop droplets from fusing together to form larger ones. Some of the water evaporates as the aerosols descend, cooling the water. The fans blowing air through the tower chill the water as well. The air stream created by the fans disperses some droplets, referred to as drift, outside of the tower. A drift eliminator installed at the top of the tower reduces this water loss. At the base of the tower, where it gathers, the cool water is pushed back for another cycle. Evaporative condensers (Figure 2) resemble cooling towers in both design and operation. Legionella and other bacteria may be present in cooling towers and evaporative condensers due to circulating air or water. Legionella thrives in warm, stagnant water, especially when scale and algae are present. If there is a gap between the air conditioning system's ducts and those of the cooling tower or evaporative condenser, legionella can enter and be spread by aerosolized drift or evaporate. Legionella has also been discovered in humidifiers, whirlpool spas, hot tubs, public spas, faucets, and showerheads. It is not known whether Legionella enters a building's water from municipal feeder systems or adjacent contaminated cooling towers.
Who has a higher risk of contracting Legionnaires' disease?
Legionnaires' disease usually affects people 40 years or older, although cases have been reported in all age groups. People that have underlying health conditions are at an increased risk of getting sick. This concern includes people with: Cancer Diabetes Kidney or liver failure Chronic lung diseases (like emphysema or chronic obstructive pulmonary disease (COPD)) Smoking may also increase the risk of illness.
What occupations are at risk for Legionnaires' disease?
Workers most at risk are those with occupations that require them to work in sealed buildings including those workers who maintain water cooling towers in air conditioning systems. Since Legionella is found naturally outdoors near water sources, some outdoor occupations may be considered at risk as well; however, the number of bacteria found in these locations is generally not high enough to cause disease in people. Soil disturbed in areas where surface or aerosolized water discharge occurs has the potential to cause exposure to the microorganism In a few cases, the Legionella bacteria from cooling towers has survived and spread into the air of ventilation systems and air ducts for distances of several kilometers.
How can we prevent Legionnaires' disease?
The likelihood of Legionella exposure may be reduced by good engineering practices which includes proper maintenance and operation of air and water handling systems and mist-producing devices. These devices include shower heads, hot tubs, humidifiers, and whirlpool bathtubs. In all cases, follow the manufacturer's instructions for operation, cleaning, and maintenance. Cooling towers and evaporative condensers should be inspected and thoroughly cleaned at least once a year. Corroded parts, such as drift eliminators, should be replaced. Algae and accumulated scale should be removed. These measures will not only control the growth of bacteria, but will also maintain operating efficiency. Never enter a confined space without proper instruction or training. All safety procedures must be followed if required to enter a confined space for cleaning or de-scaling. Cooling water should be treated constantly. Ideally, an automatic water treatment system should be used that continuously controls the quality of the circulating water. Fresh air intakes should not be built close to cooling towers to reduce the risk of contaminated aerosols from entering the ventilation system. Air filters should be examined, cleaned and/or replaced periodically and tested for leaks. Hot water tanks and water systems which might provide ideal conditions for the growth of Legionella, should be cleaned and flushed regularly to prevent the water from stagnating."""