Legionnaires Disease Outbreak Hong Kong update 5 March 2020

A Legionnaires Disease outbreak occurred in Hong Kong between 1st – 29th February 2020 with seventeen (17) patients diagnosed with no fatality reported by CHP.

The total number of cases reported by CHP is lower than 17 reported here because additional cases residing physically close (<1000m) to the Choi Hung MTR station and the Ngau Chi Wan market were excluded without any evidence of the distinction. Ngau Chi Wan market is a very popular wet market in the area, located on Clearwater Bay road, directly above the Choi Hung MTR station, it is high traffic area, used by people from the local estates, and the surrounding districts.

Popular Ngau Chi Wan Wet Market located above Choi Hung MTR station

In total 15 cases were declared by CHP, twelve (12) male, and three (3) female, most were elderly residing near Choi Hung / Ping Shek Estate in Hong Kong, most with underlying disease.

At least two Legionnaires disease cases (refer to the table below, cases 12 and 13) were not counted as part of this cluster, yet both people reside nearby, approx. 1000m from buildings with confirmed cases, and well within the typical range of infection caused by cooling towers.

Cases

click for larger image

CHP also reported on 4 March 2020, specimens from two (2) more patients, that is eight (8) in total, match the samples from two Choi Hung MTR station cooling towers taken before the towers were disinfected (by implication sampled before 4 Feb. 2020). What is unclear, the initial 6 patients were reported on 14-2-2020, and three weeks later the additional pair were reported.

The CHP report on 4 March 2020 [link] that the Choi Hung MTR cooling towers have been disinfected and the water sampling test result (not provided) was stated to be lower than the action level. However, the tower installation date is not reported therefore it is unclear which COP would be relevant. Assuming CHP refers to the latest 2016 COP, it can be deduced that the Legionella sampling result was <10 cfu/mL and the Heterotrophic Colony count (also known as the plate count) sampling was <100 000 cfu/mL.

The CHP report concludes with a total of 27 cases for 2020, compared with 105 cases in 2019, which equates to 25% of cases in 2019 cases.

UPDATE 6 March 2020

EMSD.gov.hkissued a press release for its regular Legionella testing [link] on 6 March 2020 with routine and epidemiological investigation information, for the latter, in the attachment annex 2 [link] titled Building locations of fresh water cooling towers detected with total legionella count at/above upper threshold (1,000 cfu/ml) with nuisance notices issued under PHMSO, the annex states that the MTR Choi Hung Station had a nuisance notice issued showing total 1700 cfu/ml Legionella count (above the action level).

EMSD press release dated 6-3-2020

Legionnaires Disease Outbreak Hong Kong update 1 March 2020

One late additional case was reported on 29-2-2020 involving a male admitted to hospital twice. Initially, the patient was admitted on 4 Feb. 2020, with pneumonia and discharged on 19 Feb. 2020, and then admitted again on 24 Feb. 2020 and Legionnaires Disease diagnosed. [CHP]

This additional case involved a male patient, aged 71 with underlying illnesses, who lives in Wong Shek House, Ping Shek Estate, Kwun Tong.

Given the initial onset date of this case and proximity, residing in Ping Shek Estate approx. 100m from the early cases involving Kam Shek House, this case must be classified as part of the Legionnaires’ Disease outbreak.

16 Feb 2020 Cooling Tower, Choi Hung, Hong Kong

Although MTR cleaning tower maintenance/inspection was witnessed on 16-2-2020, CHP has not released any further details.

Outbreak History

Legionnaires Disease Outbreak Hong Kong update 18 Feb 2020

Two (2) more Legionnaires Disease infections were reported on 18-2-2020, bringing the total number of Hong Kong cases to twenty two (22) and sixteen (16) of those reside near Choi Hung. The new cases report by CHP include:

  1. A male patient, aged 94 with underlying illness, who lives in Hung Shek House, Ping Shek Estate, Kwun Tong
  2. A female patient, aged 52 with underlying illness, who lives in Block 2, 22 Wing Ting Road, Ngau Chi Wan (Fire Service Married Quarters)
Legionnaires Disease Outbreak Location Map

The CHP report [link] lists fourteen (14) cases, attributing two cases (12 and 13) as residing in a different area, although physically close to the Choi Hung area, approx. 1000m from the buildings implicated in Choi Hung, Kowloon.

In earlier CHP reporting it’s noted that the Choi Hung MTR station has four cooling towers samples were taken before they were disinfected on 4 and 12 Feb 2020. And these match specimens from six (6) patients in the Choi Hung Area.

The novel coronavirus covid19 epidemic has increased awareness and heightened surveillance in Hong Kong. Since both diseases present with similar symptoms and both involve pneumonia, further Legionnaires Disease infections will be detected and diagnosed in the coming months.

legionella, legionnaires disease outbreak, Choi Hung, Ping Shek, cooling towers, Kowloon, pneumonia, Hong Kong

previous update:

Legionnaires Disease Outbreak Hong Kong update 17 Feb 2020

CHP reported one (1) additional Legionnaires Disease case on 17-2-2020, including the two nearby Kwun Tong cases, that brings the total number of cases to fourteen (14) so far in the Choi Hung and Ping Shek area. As reported by CHP all 14 cases involve persons with unspecified underlying illness.

The new case is a 72 year old male residing in Kam Shek House, Ping Shek Estate, the same building as previous case numbers 4, 5 and 8 (refer to map) reported more than ten days ago, that’s significant because the incubation period is normally 2-10 days.

Given the typical 2-10 day incubation period, this gentleman probably contracted the disease between 7 and 15 Feb. 2020, which is after the date CHP reported the Choi Hung MTR cooling towers were allegedly disinfected on the 4 Feb. 2020.

So far CHP has reported that six (6) cases match the specimens taken from the Choi Hung MTR station cooling towers before 4-2-2020, the exact date is not clear.

And MTR staff were witnessed working on one set of the Choi Hung MTR cooling towers on Sunday 16-2-2020, near the Leung Chung road / Ngau Chi Wan village sitting-out area (refer photo below)

Legionnaires Disease and novel coronavirus covid19 have similar presentations, considering the heightened surveillance and awareness surrounding the novel coronavirus covid19 it is inevitable that previously undiagnosed and unreported cases of Legionnaires Disease will be also be discovered.

Additional Hong Kong Legionnaires Disease Cases

In addition to the ongoing Choi Hung / Pink Shek outbreak, three (3) new cases were reported on 17-2-2020 residing in different areas of the city.

  1. A male patient, aged 56 with underlying illnesses, who lives in 1H Sands Street, Central and Western District (Kennedy Town)
  2. A male patient, aged 85 with underlying illnesses, who lives in Ma Tong Tsuen, Chuen Lung, Tsuen Wan;
  3. A male patient, aged 52 with underlying illnesses, who lives in 7 Sau Fu Street, Yuen Long.

Outside Choi Hung, there are six (6) cases in total with no apparent connection to the Choi Hung Outbreak. However, it must be said that the CHP reporting is vague.

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previous update:

http://www.kelcroftasia.com/2020/02/11/legionella-outbreak-hong-kong/

Legionnaires Disease & the Built Environment

Legionnaires Disease Outbreak Hong Kong update 16 Feb 2020

On 16 Feb 2020, the video shows the MTR staff conducting maintenance/inspection on the MTR cooling towers near Ngau Chi Wan Gardens, Choi Hung, Hong Kong

Legionnaires Disease Outbreak Hong Kong update 14 Feb 2020

Legionnaires disease outbreak

Update 2 14-2-2020 @ 21:35

CHP reported on 14-2-2020 that 6 out of the eleven (11) cases apparently match the sequence type identified in two of the four MTR Choi Hung station cooling towers, effectively confirming the MTR cooling towers are one source of the Legionella.

CHP also reports two further Legionnaires Disease SP1 cases on 14-02-2020 although attributing these new cases to a new cluster in Kwun Tong district.

  • A male patient, aged 56 with underlying illness, who lives in Choi Hay House, Choi Fook Estate
  • A male patient, aged 62 with underlying illness, who lives in Wang Kwong Building, 33 Ngau Tau Kok Road

These new two cases reside approx 1000m from the first eleven (11) cases, probably part of the same outbreak, a very popular wet market is located over the Choi Hung MTR station.

CHP link

Legionnaires disease outbreak

Updated 14-Feb-2020 @ 2:27 am

MTR Choi Hung Cooling Towers shutdown

One additional Legionnaires Disease case was reported by CHP bringing the total number of confirmed cases to eleven (11) cases, all located the area around the Ping Shek / Choi Hung estate area in Hong Kong [CHP link].

Legionnaires disease outbreak

The 11th patient is an 82-year-old male living in Kam Hon House that is very close to a previously reported case in the adjacent Kam Wan House, Choi Hung Estate.

MTR Cooling Towers Implicated

CHP reports that three (3) out of the four (4) cooling towers at the Choi Hung MTR station had Legionella Pneumophilia count above the action level!

Presumably, 1,000 cfu/ml, however, no data is given in the CHP report, and the Legionella outbreak is not mentioned on the EMSD website, the MTRC website or in local media (checked 1:10 am on 14-2-2020).

In the CHP press release at 23:55 PM on 13-3-2020, CHP recommended closing and disinfecting all the cooling towers today (13-3-2020) due to the high Legionella pneumophilia count in the samples collected before the first disinfection on 4 February 2020. Remember that the first CHP report issued on 1 Feb 2020 confirmed four cases in that area [CHP link].

12 Feb 2020

updated 12-2-2020 7.22 pm

Still no reporting in the media, and also no update from CHP so far.

11 Feb 2012 (first published)

Legionnaires disease outbreak

Whilst the novel coronavirus attracts headlines, Hong Kong has a Legionnaires’ disease outbreak in progress, centered around Ping Shek/Choi Hung Estate, Hong Kong.

Legionnaires’ Disease is a serious, pneumonia type illness ( learn more about Legionella )

There are ten confirmed cases so far, all are reported to be living near the Ping Shek/Choi Hung Estate area of the city, and confirmed cases within the last eleven days.

Legionnaires disease outbreak

There are also three other confirmed Legionnaires disease cases, one located in Lee Uk Tsuen, one located in Tung Tau Tsuen, Yuen Long, and one in Deep Water bay Road, which has not been connected to the main cluster so far.

CHP update 11-2-2020 [ link ]

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