March 5, 2020

CDC Report Attributes Fatal Case of Legionnaires’ Disease to Home Exposure

CDC released a report last week of a fatal case of Legionnaires’ disease that occurred in 2018. An investigation determined that the source of the infection was the patient’s home, after water samples at the hospital where the patient had been admitted for treatment tested negative for Legionella bacteria. According to CDC, the incident makes clear that populations at risk for Legionnaires’ disease—such as individuals who are immunocompromised, as this patient was—may be exposed to the bacteria via home water sources.

In January 2018, a Wisconsin resident aged 70–79 years, who had previously been diagnosed as immunodeficient, was admitted to a local hospital for a rash and fever thought to be a reaction to antibiotics. The patient also complained of a cough and shortness of breath, but a chest radiograph was normal.

Five days later, as the fever continued and the cough worsened, a new chest radiograph revealed an opacity in the upper right lung. A urinary antigen test and culture of the patient’s bronchoalveolar lavage (BAL) fluid for Legionella were ordered. The patient was treated with antibiotics but passed away a few days later from cardiopulmonary arrest secondary to septic shock. The urinary antigen test resulted in a negative, but L. pneumophila was later isolated from the specimen culture.

In accordance with hospital policy, nine water sources at the facility where the patient may have been exposed were tested for Legionella, but all results came back negative. As the investigation continued, water samples from the patient’s home were taken and tested positive. The Legionella samples from the home matched 99.7 percent of the allele content as those from the patient’s BAL culture. Investigators determined the home was the probable source of infection. A second individual living in the home was not infected.

The number of reported confirmed Legionnaires’ disease cases increased 4.5-fold nationwide between 2000 and 2015. According to CDC, the Wisconsin case highlights the risk posed by the disease to immunocompromised people, the need to understand the burden and risk from the disease, and the value of testing lower respiratory tract specimens for both patient treatment and public health investigations.