Dear Followers:
I realize you can look this up for yourselves. But I am including it here for the benefit of
lazy hypochondriacs, to complete the current record and to allow you to compare
the “Official Version” with my personal recollections from yesterday. (I have read this rather carefully and can
find no mention whatsoever of “Delta Dawn.”
Making me suspect I had a country musical strain of Legionnaires’
Disease.)
Anyway, keep this on file, so when you’re in bed thinking of pouring
yourself a glass of water and you find yourself incapable of doing so you will
be able to understand why.
And hightail it straight to the Emergency Room.
Okay, here we go.
Legionnaires’ Disease – The
Official (Google) Version
Legionnaires' disease
(also legionellosis or Legion fever) is a form of atypical pneumonia caused by any species of Gram-negative aerobic bacteria belonging
to the genus Legionella.[1] Over
90% of cases of Legionnaires' disease are caused by Legionella pneumophila.
Other causative
species include L. longbeachae, L. feeleii, L. micdadei and L.
anisa. These species cause a less severe infection known as Pontiac fever, which resembles acute influenza.
These bacterial species can be water-borne or present in soil, whereas L.
pneumophila has only been found in aquatic systems, where it is
symbiotically present in aquatic-borne amoebae.[2] It
thrives in temperatures between 25 and 45 °C (77 and 113 °F), with an
optimum temperature of 35 °C (95 °F). During infection, the bacterium
invades macrophages and lung epithelial cells and replicates
intracellularly.[3][4]
Signs and symptoms
The incubation period of Legionnaires' disease—the
time between exposure to the bacteria and the appearance of symptoms— is
generally 2 to 10 days, and, rarely, up to 20 days.[5] The attack
rate is 0.1 to 5% of the general population, and 0.4 to 14% in hospitals,
where patients tend to be more susceptible.[5]
Those with
Legionnaires' disease usually have fever, chills, and a cough, which may be dry
or may produce sputum. Almost all with Legionnaires' experience fever,
while approximately half have cough with sputum, and one third cough up
blood or bloody sputum. Some patients also have muscle aches,
headache, tiredness, loss of appetite, loss of coordination (ataxia),
chest pain, or diarrhea and vomiting.[6] Up to half of those with
Legionnaires' have gastrointestinal symptoms, and almost half have neurological
symptoms,[5]
including confusion and impaired cognition.[7] "Relative bradycardia"
may also be present, which is low or low-normal heart rate despite the presence
of a fever.[8]
Laboratory tests may
show that patients' kidney functions, liver functions and electrolyte levels are abnormal, which may include low
sodium in the blood. Chest X-rays often show pneumonia with
bi-basilar consolidation. It is difficult to
distinguish Legionnaires' disease from other types of pneumonia by symptoms or radiologic
findings alone; other tests are required for diagnosis.
Persons with Pontiac
fever experience fever and muscle aches without pneumonia. They generally
recover in two to five days without treatment. The time between the patient's
exposure to the bacterium and the onset of illness for Legionnaires' disease is
two to ten days; for Pontiac fever, it is shorter, generally a few hours to two
days.
Mechanism
Legionella
enters the lung either by aspiration of contaminated water or inhalation of
aerosolized contaminated water or soil. There, the bacteria is phagocytized by macrophages, a
type of white blood cell, where it multiplies, causes
the death of the macrophage, at which point the bacteria are released from the
dead cell to infect other macrophages. Virulent strains of Legionella
kill macrophages by blocking the fusion of phagosomes with lysosomes inside the
host cell; normally the bacteria is contained inside the phagosome, which
merges with a lysosome, allowing enzymes and other chemicals to break down the
invading bacteria.[5]
Transmission
Legionnaires' disease
is transmitted by inhalation of aerosolized water and/or soil contaminated with the Legionella
bacteria. It is not airborne and Legionnaires' disease is not transmitted from
person to person. Rarely, Legionnaires' disease has been transmitted by direct
contact between contaminated water and surgical wounds.[6] It
thrives at water temperatures between 25 and 42 °C (77 and 117 °F),
with an optimum temperature of 35 °C (95 °F).[9]
Sources where temperatures allow the bacteria to thrive include hot-water
tanks, cooling towers, and evaporative condensers of large air-conditioning
systems, such as those commonly found in hotels and large office buildings.
Though the first known outbreak was in Philadelphia, Pennsylvania,
cases of legionellosis have occurred throughout the world.[5]
Reservoirs
L. pneumophila
thrives in aquatic systems where it is established within amoebae in a
symbiotic relationship. In the built environment, central air conditioning systems in office buildings,
hotels, and hospitals are sources of contaminated water.[9]
Other places it can dwell include cooling
towers used in industrial cooling systems, evaporative coolers, nebulizers, humidifiers, whirlpool spas, water
heating systems, showers, windshield washers, fountains, room-air
humidifiers, ice-making machines, and misting systems typically found in grocery-store
produce sections.[10][6]
The disease may also
be transmitted from contaminated aerosols generated in hot tubs if
the disinfection and maintenance program is not followed rigorously.[11]
Freshwater ponds, creeks, and ornamental fountains are potential sources of Legionella.[12] The
disease is particularly associated with hotels, fountains, cruise
ships, and hospitals with complex potable water systems and cooling
systems. Respiratory care devices such as humidifiers and nebulizers used with
contaminated tap water may contain Legionella species, so using sterile
water is very important.[13] Other sources include exposure to potting mix
and compost.[14]
Legionella
bacteria survive in water as intracellular parasites of water-dwelling
protozoae, such as amoebae. Amoebae are often part of biofilms, and
once Legionella and infected amoebae are protected within a biofilm,
they are particularly difficult to destroy.
Various stages of the disease: 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 Legionnaires' disease, but the illness most often affects
middle-aged and older persons, particularly those who smoke cigarettes or have chronic lung disease. Immunocompromised patients are also at
elevated risk. Pontiac fever most commonly occurs in persons who are otherwise
healthy.
Diagnosis
The most useful diagnostic
tests detect the bacteria in sputum, find Legionella antigens in urine
samples, or allow comparison of Legionella antibody levels in two blood
samples taken 3 to 6 weeks apart. A urine antigen test is simple, quick, and
very reliable, but it will only detect Legionella pneumophila serogroup
1, which accounts for 70 percent of disease caused by L. pneumophila
which means use of the urine antigen test alone may miss as many as 40% of
cases.[9] This
test was developed by Richard Kohler in 1982.[15] When dealing with Legionella
pneumophila serogroup 1, the urine antigen test is useful for early
detection of Legionnaire's disease and initiation of treatment, and has been
helpful in early detection of outbreaks. However, it will not identify the
specific subtypes, so it cannot be used to match the patient with the
environmental source of infection. The Legionella bacteria can be
cultured from sputum or other respiratory samples.Legionella stains
poorly with Gram stain, stains positive with silver, and is 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
percent of cases of Legionnaires' disease are missed. This is partly due to
Legionnaire's disease being a relatively rare form of pneumonia, which many
clinicians may not have encountered before and thus may misdiagnose. A further
issue is that patients with legionellosis can present with a wide range of
symptoms, some of which (such as diarrhea) may distract clinicians from making
a correct diagnosis.[16]
Treatment
Effective medications
include most macrolides, tetracyclines, ketolides, and quinolones.[6] Legionella
multiply within the cell, so any effective treatment must have excellent
intracellular penetration. Current treatments of choice are the respiratory
tract quinolones (levofloxacin, moxifloxacin, gemifloxacin) or
newer macrolides (azithromycin, clarithromycin, roxithromycin).
The antibiotics used most frequently have been
levofloxacin, doxycycline and azithromycin.
Macrolides
(azithromycin) are used in all age groups, while tetracyclines (doxycycline)
are prescribed for children above the age of 12 and quinolones (levofloxacin)
above the age of 18. Rifampicin can be used in combination with a
quinolone or macrolide. It is uncertain whether rifampicin is an effective
antibiotic to take for treatment. The Infectious Diseases Society of America
does not recommend the use of rifampicin with added regimens. Tetracyclines and erythromycin led
to improved outcomes compared to other antibiotics in the original American
Legion outbreak. These antibiotics are effective because they have excellent
intracellular penetration in Legionella-infected cells. The recommended
treatment is 5–10 days of levofloxacin or 3–5 days of azithromycin, but in
patients who are immunocompromised, have severe disease, or other pre-existing
health conditions, longer antibiotic use may be necessary.[6]
During outbreaks, prophylactic antibiotics have been successfully used to
prevent Legionnaires' disease in high-risk individuals who have possibly been
exposed.[6]
The mortality at the
original American Legion convention in 1976 was high (34 deaths in 180 infected
individuals[citation needed]) because the
antibiotics used (including penicillins, cephalosporins, and
aminoglycosides) had poor intracellular
penetration. Mortality has plunged to less than 5% if therapy is started
quickly. Delay in giving the appropriate antibiotic leads to higher mortality.
Prognosis
The fatality rate of
Legionnaires' disease has ranged from 5% to 30% during various outbreaks and
approaches 50% for nosocomial infections, especially when treatment
with antibiotics is delayed.[17] According to the journal Infection Control and Hospital Epidemiology,
hospital-acquired Legionella pneumonia has a fatality rate of 28%, and
the principal source of infection in such cases is the drinking-water
distribution system.[18]
Epidemiology
Legionnaires' disease
acquired its name in July 1976, when an outbreak of pneumonia
occurred among people attending a convention of the American Legion at the Bellevue-Stratford Hotel in Philadelphia. Of
the 182 reported cases, mostly men, 29 died.[19] On January 18, 1977, the
causative agent was identified as a previously unknown strain of bacteria,
subsequently named Legionella, and the species that caused
the outbreak was named Legionella pneumophila.[20][21]
Outbreaks of
Legionnaires' disease receive significant media attention. However, this
disease usually occurs in single, isolated cases not associated with any
recognized outbreak. When outbreaks do occur, they are usually in the summer
and early autumn, though cases may occur at any time of year. Most infections
occur in those who are middle-aged or older.[17] National surveillance
systems and research studies were established early, and in recent years[when?]
improved ascertainment and changes in clinical methods of diagnosis have
contributed to an upsurge in reported cases in many countries. Environmental
studies continue to identify novel sources of infection, leading to regular
revisions of guidelines and regulations. About 8,000 to 18,000 cases of Legionnaires'
disease occur each year in the United States, according to the Bureau of
Communicable Disease Control.[22]
Between 1995 and 2005,
over 32,000 cases of Legionnaires' disease and more than 600 outbreaks were
reported to the European Working Group for Legionella Infections The
data on Legionella are limited in developing countries and Legionella-related
illnesses likely are underdiagnosed worldwide.[5] Improvements in diagnosis
and surveillance in developing countries would be expected to reveal far higher
levels of morbidity and mortality than are currently recognised. Similarly,
improved diagnosis of human illness related to Legionella species and
serogroups other than Legionella pneumophila would improve knowledge
about their incidence and spread.
A 2011 study
successfully used modeling to predict the likely number of cases during
Legionnaires’ outbreaks based on symptom onset dates from past outbreaks. In
this way, the eventual likely size of an outbreak can be predicted, enabling
efficient and effective use of public health resources in managing an outbreak.[23]
History
The first recognized
cases of Legionnaires' disease occurred in 1976 in Philadelphia, Pennsylvania. Among more than 2000
attendees of a Legionnaires' convention held at the Bellevue-Stratford Hotel,
221 attendees contracted the disease and 34 of them died.[24]
In April 1985, 175
patients were admitted to the District or Kingsmead Stafford
Hospitals with chest infection or pneumonia. A total of 28 people died. Medical
diagnosis showed that Legionnaires' disease was responsible and the immediate
epidemiological investigation traced the source of the infection to the
air-conditioning cooling tower on the roof of Stafford District Hospital.
In March 1999, a large outbreak in the Netherlands
occurred during the Westfriese Flora flower exhibition in Bovenkarspel; 318
people became ill and at least 32 people died. This was the second-deadliest
outbreak since the 1976 outbreak and possibly the deadliest as several people
were buried before Legionnaires' disease had been diagnosed.
The world's largest
outbreak of Legionnaires' disease happened in July 2001 with patients appearing
at the hospital on July 7, in Murcia, Spain. More than 800 suspected cases were recorded by
the time the last case was treated on July 22; 636–696 of these cases were
estimated and 449 confirmed (so, at least 16,000 people were exposed to the
bacterium) and six died, a case-fatality rate around 1%.
In late September
2005, 127 residents of a nursing home in Canada
became ill with L. pneumophila. Within a week, 21 of the residents had
died. Culture results at first were negative, which is not unusual, as L.
pneumophila is a fastidious bacterium, meaning it requires specific
nutrients and/or living conditions in order to grow. The source of the outbreak
was traced to the air-conditioning cooling towers on the nursing home's roof.
As of 12 November
2014, 302 people have been hospitalized following an outbreak of Legionella in Portugal and
7 related deaths have been reported. All cases, so far, have emerged in three
civil parishes from the municipality of Vila Franca de Xira in the northern outskirts of
Lisbon, Portugal and are being treated in hospitals of
the Greater Lisbon area. The source is suspected to
be located in the cooling towers of the fertilizer
plant Fertibéria.[25]
As of 10 August 2015,
there have been over 110 confirmed cases and twelve deaths from the 2015 New York Legionnaires' disease outbreak in the New York City borough of the Bronx.[26] City health
inspectors identified Legionella in the cooling systems of five public
places: a hotel, Concourse Plaza Mall, a Verizon office, the
Streamline Plastic Company, and at a building in the Lincoln Hospital complex.[27] All of these places have since been
decontaminated, according to the city.[28]
