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Biological Health Hazard – Legionellosis: Minnesota


Published Date: 2016-09-13 17:07:39
Subject: PRO/EDR> Legionellosis – USA (07): (MN) elderly, comments
Archive Number: 20160913.4484996

re: ProMED-mail. Legionellosis – USA (06): (MN) elderly 20160911.4480033
Date: Mon 11 Sep 2016
From: Richard Danila <> [edited]

I am in charge of investigating this outbreak. As of [12 Sep 2016] 8 am, we have 5 confirmed cases and one additional confirmed case whose exposure history to the area is unconfirmed. The 5 cases range in age from 58 to 89 [years]. All were hospitalized and 3 remain hospitalized. Their onset dates range from [4 Aug to 1 Sep 2016]. All were diagnosed by urinary antigen [for _Legionella pneumophila_ serogroup 1] but we are in the process of attempting to obtain lower respiratory system cultures from patients. We are looking for possible community water sources including water towers and have facilitated remediation of known sources. This is an active investigation in progress.

Richard N Danila, PhD
Assistant State Epidemiologist
Minnesota Department of Health

ProMED-mail thanks Dr Danila for his prompt comments on the ongoing epidemiologic investigation of the outbreak of legionnaires’ disease in Minnesota. We look forward to further updates. – Mod.ML

Date: Mon 12 Sep 2016
From: Denis Green <> [edited]

I think you will have to change your thinking on LD [legionnaires’ disease].

“Legionnaires’ disease [LD] is spread by inhaling the fine spray (aerosols) from water sources containing _Legionella_ bacteria. It is not spread person-to-person, and a person cannot get it by consuming water.” [This is a quote extracted from the news report in ProMED-mail post Legionellosis – USA (06): (MN) elderly 20160911.4480033.]

How many reports would you like on people getting LD from drinking water?

A post taken from my discussion group: “Good morning everyone from Benidorm. [Benidorm is a city in the province of Alicante in eastern Spain on the Mediterranean coast.] In my opinion, the case of LD transmitted person-to-person in Portugal is perfectly possible and real [1]. The proximity of the mother and her sick son and coincidence in the strain of the bacteria [_Legionella pneumophila_ serogroup 1] make the possibility more than true. Therefore, we must consider that it is an exceptional situation, but may have an impact on health workers or relatives serving LD patients.

“Many times, we have seen infections have been transmitted through a very rare form but as an isolated phenomenon and is not usual.”

[Denis Green also cited in his submission as supporting person-to-person transmission of legionnaires’ disease: Love WC, Chaudhuri AKR, Chin KC, Fallon R. Possible case-to-case transmission of legionnaires’ disease. The Lancet 1978; 312(8102): 1249.; see below]

1. Correia AM, Gonçalves J, Gomes JP, et al. Probable person-to-person transmission of legionnaires’ Disease. N Engl J Med 2016; 374(5): 497-8; available at [see below].

Denis Green

[ProMED-mail thanks Denis Green for his continued contributions on legionnaires’ disease.

The reference in the New England Journal of Medicine (2016) on the outbreak in Portugal that supports possible person-to-person transmission of legionnaires’ disease is reproduced below:

“Legionnaires’ disease is an often severe form of pneumonia that is typically acquired by susceptible persons (such as, elderly persons and smokers) through inhalation of aerosols that contain legionella species [1-4]. A cluster of cases of this disease occurred in Vila Franca de Xira, Portugal, in 2014 [5].

“One of the 1st cases of disease in this cluster occurred in a 48 year old man (Patient 1), a smoker, who had been employed since [6 Oct 2014], as a maintenance worker at an industrial cooling tower complex in Vila Franca de Xira that was subsequently found to be contaminated with _Legionella pneumophila_ [5]. He returned to the home that he shared with is mother in Porto (approximately 300 km [186 mi] from Vila Franca de Xira) on [11 Oct 2014] and again on the evening of [19 Oct 2014] (Figure 1). His symptoms began on [14 Oct 2014] and on [19 Oct 2014], he had severe respiratory symptoms, including an intense cough. During that night, his mother (Patient 2) took care of him until he was admitted to the hospital (Centro Hospitalar do Porto) approximately 8 hours later. On [22 Oct 2014], he was transferred to another hospital to receive extracorporeal membrane oxygenation.

“On [27 Oct 2014], Patient 2, who was a previously healthy 74 year old woman, began to report fever, cough, and loss of appetite. She was admitted to the same hospital on [3 Nov 2014] with septic shock due to pneumonia, and she died on [1 Dec 2014]. Patient 1 died on [7 Jan 2015].

“Urine specimens obtained from both patients showed positive results on testing for legionella antigens with the use of a commercial enzyme immunoassay (Binax), and legionella was grown in culture from respiratory secretions. _L. pneumophila_ serogroup 1 was identified, and strains were sent to the National Institute of Health in Lisbon for sequence-based typing and whole-genome sequencing (details are provided in the Methods section in the Supplementary Appendix, available with the full text of this letter at Samples from the patients were obtained and processed more than 2 weeks apart (for culture and sequence-based typing) and 4 weeks apart (for whole-genome sequencing) to minimize the risk of cross-contamination. Both strains showed the novel ST1905 profile (identified as the causative strain in the cluster [5]), and whole-genome sequencing revealed no nucleotide differences within the region that spanned approximately 3.47 Mb of the genome sequence. This genome matched the one identified in the cluster-related isolates.

“An investigation headed by the General Directorate of Health showed that _L. pneumophila_ ST1905-associated disease occurred in people who lived or stayed in Vila Franca de Xira between [14 Oct 2014], when the cluster began, and [21 Nov 2014], when it was considered to be controlled. Patient 2 had remained in Porto during these months, and to the best of our knowledge, she was the only person infected with _L. pneumophila_ ST1905 who was not geographically linked to the cluster epicenter. Later investigation revealed that Patient 2 had never been to Vila Franca de Xira, and during the cluster period, no additional cases of legionnaires’ disease occurred in Porto.

“Patients 1 and 2 lived alone in Porto, and their house consisted of small non-ventilated rooms without air-conditioning units or room humidifiers. Collected water samples from the bathroom and the kitchen and a swab of the shower drain were negative for legionella. Patient 1 did not take water from Vila Franca de Xira to Porto.

“We suspect that person-to-person transmission probably occurred when Patient 2 cared for her severely ill son. Factors that suggest person-to-person transmission are the severity of the respiratory symptoms in Patient 1, the very close contact that occurred during the 8 consecutive hours when Patient 2 took care of Patient 1, and the small area of the non-ventilated room where this contact took place. In addition, the timeline of the events was highly coherent (that is, the symptoms in Patient 2 developed 1 week after the close contact with Patient 1; this is consistent with the typical incubation period of legionnaires’ disease — a median of 6 to 7 days) [1].”

[The figure and references are available at the source URL above.]

The reference in The Lancet (1978) that Denis Green cites as supporting possible person-to-person transmission of legionnaires’ disease is reproduced in part below:

“One of us treated a local general practitioner for pneumonia in 1974. The clinical features suggested infection with _Mycoplasma pneumoniae_, _Chlamydia_ B, or _Coxiella [burnetii]_, but serology was negative. The doctor himself was convinced that he had contracted the infection from a patient whom he had attended 2 weeks earlier and had sent to hospital with severe pneumonia which had developed during a holiday in Benidorm. Sera taken from the patient during his illness have proved, in retrospect, that he had legionnaires’ disease (titres of 1:512 rising to 1:1024). No acute-phase serum was available from the general practitioner but a sample taken more than 3 years later had an antibody titre of 1 :512.

“This is strong circumstantial evidence of case-to-case transmission, not previously demonstrated.”

ProMED-mail previously posted a news report that concerned the 2016 New England Journal of Medicine article (reference 1 above). See Legionellosis – Portugal: (LI) 2014, fatal, person-to-person transmission 20160205.3998447. In the moderator comments of this post, I concluded, “This now apparently is the 1st documented transmission of legionnaires’ disease from 1 person to another.”

With regard to aspiration as an additional mode of transmission, the following with 6 references can be found in my moderator comments in ProMED-mail post Legionellosis – USA (06): (MN) elderly 20160911.4480033: “Some patients who are prone to aspiration, for example, the debilitated elderly, may develop legionnaires’ disease following aspiration _Legionella_-contaminated potable water (1-3). Aspiration of _Legionella_-contaminated water is also the obvious source for neonatal legionnaires’ disease that has occurred following use of _Legionella_-contaminated home birthing pools (4-6).” – Mod.ML

A HealthMap/ProMED-mail map can be accessed at:]

See Also

Legionellosis – USA (06): (MN) elderly 20160911.4480033
Legionellosis – USA (05): (New York City), apartment complex 20160803.4390843
Legionellosis – USA (04): (IL) vet home, updated water treatment, new cases, RFI 20160728.4377020
Legionellosis – USA (03): (NC) hotel susp, alert 20160701.4320222
Legionellosis – USA (02): (MI) fatal, nosocomial, 2014-15, RFI 20160414.4159246
Legionellosis – Portugal: (LI) 2014, fatal, person-to-person transmission 20160205.3998447

Legionellosis – USA: (MI) fatal, corrosive water supply, lg. bldgs, 2014-15, RFI 20160115.3937657
Legionellosis – Portugal: (PO) 20150912.3640216

Legionellosis – Portugal (04): (LI) fatal, update 20141117.2963740
Legionellosis – Portugal (03): (LI) fatal, update 20141115.2957899
Legionellosis – Portugal (02): (LI) fatal, update 20141111.2946728
Legionellosis – Portugal: (LI) fatal 20141109.2941607

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