Ministry of Shipping and Island Policy

BackgroundLegionnaires' disease continues to be a public health concern in passenger ships. This study was scheduled in order to investigate Legionella spp. colonization of water distribution systems (WDS), recreational pools, and air-conditioning systems on board ferries and cruise ships in an attempt to identify risk factors for Legionella spp. colonization associated with ship water systems and water characteristics.MethodsWater systems of 21 ferries and 10 cruise ships including WDS, air conditioning systems and pools were investigated for the presence of Legionella spp.ResultsThe 133 samples collected from the 10 cruise ships WDS, air conditioning systems and pools were negative for Legionella spp. Of the 21 ferries WDS examined, 14 (66.7%) were legionellae-positive. A total of 276 samples were collected from WDS and air conditioning systems. Legionella spp. was isolated from 37.8% of the hot water samples and 17.5% of the cold water samples. Of the total 96 positive isolates, 87 (90.6%) were L. pneumophila. Legionella spp. colonization was positively associated with ship age. The temperature of the hot water samples was negatively associated with colonization of L. pneumophila serogroup (sg) 1 and that of L. pneumophila sg 2 to 14. Increases in pH ≥7.8 and total plate count ≥400 CFU/L, correlated positively with the counts of L. pneumophila sg 2 to 14 and Legionella spp. respectively. Free chlorine of ≥0.2 mg/L inhibited colonization of Legionella spp.ConclusionWDS of ferries can be heavily colonized by Legionella spp. and may present a risk of Legionnaires' disease for passengers and crew members. Guidelines and advising of Legionnaires' disease prevention regarding ferries are needed, in particular for operators and crew members.

The proposals of Calvert and Hollingdale (Journal, 13, 127; 14, 234, 379; 18, 141) are of considerable interest. Soviet research work similarly leads to the conclusion that the principle of anti-clockwise rotation of the line of sight is the best if not the only way to solve the problem of manœuvring in fog whilst using radar. A rule of manœuvre embodying this principle was described in Morskoi Flot No. 5, 1958 and later proposed by the Soviet Delegation at the Safety of Life at Sea Conference in London in 1960. The instructions to Soviet ships on the use of radar for collisionavoidance were published and deposited with I.M.C.O. as an official document. Some years later Die Seewarte (Hamburg, October 1961) and Navigation (Paris, July 1962) published an account of an electronic manœuvre indicator constructed in the U.S.S.R. and described in Morskoi Flot No. 2, 1959. The trials of this instrument were described in Morskoi Flot No. 12, 1964. These publications should be of interest to members of this Institute.