In the Wesley Ridge Retirement Community, the outbreak of Legionnaires’ disease continues to spread.  There are now 39 confirmed cases of the disease and five deaths.  However, health officials believe that there have not been any new cases since measures have been taken to prevent further infection.  Rather, the new cases are due to a lag time before laboratory confirmation of the source of the infection.  This outbreak has been linked to contaminated water in several water sources and an air-conditioning cooling tower.

Wesley Ridge claims that it has always followed state and federal regulations.

“We have not gone beyond industry standards,” Wesley Ridge said in a statement obtained by The Columbus Dispatch. “We are not aware of a retirement community that has a preventative program in place in terms of regularly monitoring bacteria levels in their potable water.”

The Columbus Dispatch notes that Ohio law “does not require Legionella-specific prevention measures.”

Legionnaires’ disease is a type of pneumonia that is caused by the bacteria Legionella.  An infected person is not contagious and new cases come from exposure to the bacteria from a contaminated water source.  Common sources of contaminated water inhalation are showers, hot tubs, and air-conditioning units.  Symptoms of Legionnaires’ include a high fever, cough, chills, and possibly muscle pain and headaches.  In order to confirm a diagnosis, a chest x-ray and lab tests are usually required.

Exposure to the bacteria does not necessarily mean that the person will get sick.  Individuals that are most likely to fall ill are those that are older, smoke, already suffer from a chronic lung condition, or have a weak or compromised immune system.  In the Wesley Ridge Retirement Community, all of the affected individuals are expectedly older.  They range from 63 to 99 years of age and 32 were hospitalized.  Given the vulnerable nature of this population, it is understandable that this is one of the larger Legionnaires’ outbreaks.

The Centers for Disease Control and Prevention (CDC) monitors and tracks reported cases of Legionnaires’ through a national surveillance system.  Between 2000 and 2009, there was a 217 percent increase in the number of Legionnaires’ cases in the U.S.  There were 1,110 in 2000 and 3,522 in 2009.  As a result, the CDC has added measures to help assess the source of these infections to be better able to prevent them.

According to the Ohio Department of Health, there are a number of steps that can be taken to fix the problem once it has been identified. When Legionella is identified in a water system, the CDC recommends that steps be taken to remove the bacteria from the water, a process known as remediation. Superheating or superchlorinating the water system will typically be used to eradicate the bacteria. However, these techniques don’t usually lead to permanent removal, so a long term plan for prevention of Legionella growth is almost always necessary.

In recent years, there have been a number of other outbreaks of Legionnaires’ around the world.  Four cases of the disease in April 2013 were linked to travel through the Melbourne airport, but public health officials never found the cause.  Ten cases, including three deaths, were linked to a Chicago hotel in the summer of 2012, where the decorative fountain was suspected to be the source of infection.

In 1985, a large outbreak of Legionnaires’ was found at the Stafford District General Hospital.  There were 68 confirmed cases treated at the hospital, 22 of which died.  A further 35 cases were suspected, but never confirmed.  All of the cases were linked to visits to the hospital.  Given that many hospital visitors have a compromised immune system, the outbreak is not surprising.

In 2011, a University of Louisville professor determined how Legionnaires’ bacteria proliferate and cause disease. Yousef Abu Kwaik, the Bumgardner Endowed Professor in Molecular Pathogenesis of Microbial Infections at UofL, and his colleagues believe the study’s findings could help lead to development of new antibiotics and vaccines.

“The bacteria live on an ‘Atkins diet’ of low carbs and high protein, and they trick the host cell to provide that specialized diet,” Abu Kwaik said. “Bacteria need to live on high protein and amino acids as sources of nutrition and energy in order to replicate in a host. This is what causes pulmonary disease. No one has known how they generate sufficient sources of nutrients from the host to proliferate. Our work is the first to identify this process for any bacteria that cause disease.”