Research has indicated that Legionella is an opportunistic pathogen, which (theoretically) means that under normal circumstances, it does not cause full-blown Legionnaires’ Disease, and will only strike when conditions are right.

Originally, it was reported that Legionnaires’ Disease is usually contracted through inhalation of aerosols of water droplets containing the organism, and that those who get the disease are primarily the old, the very young, and the immunocompromised, with death occurring in 15 – 30% of the cases. However, there have been several intriguing cases throughout the history of this disease. Four supposedly healthy middle-aged men who worked at an automotive plant in Ohio contracted Legionnaires’ Disease in 2001, two of whom died. A medical practitioner supposedly caught Legionnaires’ Disease from his pneumonic patient in what was possibly the first person-to-person transmission case of the disease. In the USA, three people came down with the disease, and the source of the organism (L. longbeachae) was traced back to commercial potting soil, which all three had been using. This was not the first case where the organism originated from soil – in 1984, a gravedigger contracted the disease, and Legionellawas isolated from the graveyard soil. This suggests that Legionella may be found in more habitats and spread in more ways that we have not yet discovered, and that even supposedly healthy individuals may fall victim to Legionnaires’ Disease.

It would be ridiculous to say that Legionnaires’ Disease is not important, or that it does not – and never will – pose as significant a threat as, say, Bubonic Plague or tuberculosis. For just as the plague thrived at a time when regulations on sanitation did not exist and hygiene was practically nil, and that the typhoid fever and cholera organisms still glory in contaminated waters, Legionnaires’ Disease is an important disease of the modern world, encouraged and spread by modern technology itself. Even if we try to comfort ourselves by saying that Legionnaires’ Disease will only plague the aged and the sick, the fact remains that our modern environment is no longer friendly to our immune system. Smog and haze and noxious fumes emitted by vehicles and machines are among the biggest threats to our lungs’ primary defence systems, thus making even the most healthy of us susceptible to infection (of course the degree of susceptibility will differ).

Even as children are being born everyday, our citizens grow old and become increasingly prone to disease. The water supply in many places such as Melbourne, Australia have already become tainted withLegionella infestation, and conditions are hard to reverse. The emergence of high-rise buildings with centralised air-conditioning systems and the increasing usage of misting machines, spas and air-conditioning (among others) facilitate propagation of the agents of this disease. Even if the people are healthy enough not to develop Legionnaires’ Disease, more than 90% of them will get Pontiac Fever or Sick Building Syndrome, thus contributing to ill-productivity in the workplace and, by extrapolation, posing as an economic problem if not a health one.

However, there is no reason to panic unnecessarily. If detected early on, Legionnaires’ Disease can be treated successfully by antibiotic therapy, usually erythromycin (which is a common antibiotic and has no nasty side effects) alone, but sometimes used in conjunction of rifampicin – although in more severe cases, organ damage may occur due to the spread of disease. Besides, the chances of you catching it from someone else who has it are very, very small – which you should be extremely thankful for, seeing as it’s a respiratory disease and is transmitted by air.