Like every summer, the legionella has made its appearance in Spain. The Extremadura Health Service has so far reported ten cases, of which six remain hospitalized, two have been discharged and two have died, a 54-year-old woman and a 70-year-old man, both with advanced oncological diseases.
The Junta de Extremadura has specified in a press release that it is not an outbreak of legionella as there is no epidemiological link between the cases. The only point of union, although “very weak”, that has been found is that most of the cases have been for work or residence in the San Jorge de Cáceres area. Likewise, the regional Executive has insisted that “there is no community risk” for health in the city of Cáceres.
Here we answer some of the key questions about this disease:
-What is legionella?
It is a bacterium of which 50 species and 70 serogroups are known, although new species continue to be described. The best known is Legionella pneumophila, which comprises 16 serogroups, and it is serogroup 1 that causes around 70-90% of human infections. Other species that have been identified as a cause of disease in man are L. longbeachae, L. micdadei, L. bozemanii and L. dumoffii, according to the protocol for surveillance of legionellosis of the Carlos III Health Institute.
-What disease does it cause?
Legionella can cause an environmental disease called legionellosis. It was first identified in 1976 after studying an outbreak of pneumonia in Philadelphia. The disease can present itself in two forms, one more serious than the other. Pontiac fever is the non-pneumonic form and is mild and self-limited. In 2 to 5 days, the patient recovers spontaneously. The most worrisome form, pneumonic, has a rapid and potentially fatal course without adequate treatment.
-What is the origin?
The bacterium is found in low concentrations in the surface waters of rivers and lakes in both natural and man-made aquatic environments. It passes from these natural reservoirs to the water supply systems of cities and is incorporated into domestic water installations or other installations that require the use of water for their operation. The stagnation of water, the presence of silt, sediments, corrosion debris together with the existence of biofilms and temperatures between 25º and 45º are conditions that play an important role in the persistence of the bacteria and provide favorable conditions for its growth. and multiplication. Bacteria are dispersed by aerosols (showers, bathrooms with water movement, irrigation systems, cooling towers, etc.), indicates the same document from the Carlos III Health Institute. Cases occur most often in late summer and fall.
-How is it spread?
By air through inhalation of aerosols contaminated with the bacteria. Infection can also occur by aspiration of contaminated water or ice, especially in vulnerable hospitalized patients, or by exposure of the newborn during water births. There is no direct transmission from person to person, they point out on the WHO website.
Who is at higher risk of getting sick?
People with respiratory tract disorders (smokers, people with chronic lung disease, etc.) are at greater risk, as well as those with a weakened immune system, either due to diseases or treatments that cause immunosuppression. Most infections occur in middle-aged or older adults. Rarely, children can get the infection. When this happens, the disease is less severe.
-What are the symptoms?
The nonpneumonic form, Pontiac fever, manifests with flu-like symptoms (fever, chills, headache, malaise, and muscle pain) and usually subsides within 2 to 5 days. The incubation period ranges from a few hours to a maximum of 48 hours. There are no known cases of death associated with this type of infection.
Legionnaires’ disease, the pneumonic form, has an incubation period of 2 to 10 days, although periods of up to 16 days have been reported in some outbreaks. Initial symptoms are fever, loss of appetite, headache, malaise, and lethargy. Some patients also report muscle pain, diarrhea, and confusion. An initial mild cough is usually seen, although up to 50% of patients may have phlegm. In about a third of cases, these are expectorated with blood (hemoptysis).
-Which is the treatment?
The nonpneumonic form of the infection is self-limited and does not require medical intervention, including antibiotics. Legionnaires’ disease always requires antibiotic treatment once the diagnosis has been established.
-Prevention
The WHO proposes the application of control measures that minimize the proliferation of Legionella and the diffusion of aerosols, which includes good maintenance of facilities and equipment, in particular through their systematic cleaning and disinfection, and the application of other physical measures ( thermal) or chemical (biocides) to limit proliferation as much as possible.