Sporadic Legionnaires’ disease in commercial truck drivers could be attributed to vehicle windshield wiper fluid

By Colin Lightfoot, M.Sc. Infection and ImmunityMar 10 2022Reviewed by Aimee Molineux

Inhalation of aerosols containing Legionella bacteria can result in a common severe form of pneumonia called Legionnaires’ disease.

The most common reservoirs of Legionella bacteria are contaminated artificial water systems that have become stagnant or have not been maintained correctly with adequate disinfection.  This leads to the proliferation of the bacteria.

The source of most cases of Legionnaires’ disease mainly remains unknown.

One of the main professions that are linked to increased risk of Legionnaires’ disease is commercial truck driving. Vehicle-related exposures to Legionnaires’ disease in industrial settings are typically viewed as secondary to outside sources, such as warm water systems, and so are rarely examined, even though vehicle-related reservoirs of Legionella bacteria have been identified as potential sources.  

Previous research has identified the use of windshield wiper fluid without added screen wash as a potential risk factor for exposure to Legionella spp. in commercial truck driving.

In a recent study published in Emerging Infectious Diseases, two cases of Legionnaires’ disease diagnosed via urine antigen test (UAT) were reported that were linked to windshield wiper fluid contaminated with Legionella spp.

The study

The Barcelona Public Health Agency (PHAB) obtained a case report of Legionnaires' disease in a 59-year-old male in December 2019. The development of symptoms had started a week prior to the diagnosis. The patient went to the hospital on December 13 and was diagnosed with Legionnaires' disease by UAT.

Due to a paucity of productive secretions, a respiratory specimen was not obtained. The patient was admitted to the hospital for a brief stay, and his clinical progress was uneventful. He finished the remainder of his antimicrobial medicine therapy after discharge and appeared to be on the mend.

The patient was asked to complete a structured epidemiologic questionnaire following the case being reported. The questionnaire was formulated to obtain information regarding patient demographics, activities, personal risk factors, and potential exposures.

The patient was a smoker and had a history of type 2 diabetes and hypertension. The patient’s profession was a commercial truck driver with a regular driving route to an industrial estate to collect merchandise. The truck was privately owned, purchased second-hand, and was owned by the patient for approximately 1.5 years prior to infection. The patient stated that the windshield wiper fluid did not contain screen wash.

There were no other detected cases of Legionnaires’ disease within the same time period related to the patient’s residence or working area. Environmental inspectors obtained samples from the patient’s windshield wiper fluid two weeks after the patient was interviewed. The inspectors collected a 2000 mL water sample that was stored in a sterile container and tested for the presence of L. pneumophila.

Legionella selective media was used to culture the sample, but the test was negative. However, further testing was performed via real-time PCR which revealed that the specimen was PCR positive for L. pneumophila. The patient was informed of the results and advice was provided regarding the cleaning procedures for the windshield wiper fluid tank.

Another case of Legionnaires’ disease was detected in a commercial truck driver via UAT on September 17, 2020. UAT discovered a new case of Legionnaires' disease in a commercial truck driver on September 17, 2020. Due to a paucity of respiratory secretions, a respiratory sample could not be obtained. The patient was a 58-year-old male who smoked and had been diagnosed with chronic obstructive lung disease previously. He was momentarily hospitalized, but following antimicrobial medicine treatment, he recovered. His driving trips frequently took him through industrial estates in Barcelona.

During the same time span, no other instances that could be epidemiologically connected to this incidence were discovered.

The patient reported daily use of the same truck and confirmed he did not add screen wash to the windshield wiper fluid tank, he also explained that the fluid had not been changed for more than six months.

Samples from the windshield wiper fluid tanks were obtained and analyzed by culture and PCR, of which both were negative for L. pneumophila. However, Legionella spp. was observed to be present via culture at a concentration of 6.3 x 10³ CFU/L. As a result, public health inspectors advised that the windshield wiper tank be disinfected, and that screen wash fluid be added on a regular basis.

Implications

From these results, it could be suggested that windshield wiper fluid could serve as potential reservoirs for Legionella spp. and therefore be a source of sporadic Legionnaires’ disease, particularly in commercial truck drivers.

A suggestion that is both simple and possibly effective would be to add screen wash to the windshield wiper fluid tanks and to empty the tanks following periods of unuse.