A cluster of three cases of leptospirosis in dairy farm workers in New Zealand.

AIMS: We report a cluster of three cases of leptospirosis on a New Zealand dairy farm, with regard to clinical, laboratory, and environmental findings. The cluster is discussed against the annual incidence of leptospirosis in humans and cattle, and the vaccination of cattle as one means of preventing human cases on farms. METHDOS: The three cases were investigated by case interview and review of clinical and laboratory information. A site visit was made to the farm to assess environmental risk. Relevant veterinary information relating to the cattle herds was reviewed. RESULTS: Most of the symptoms exhibited by the three patients were consistent with primary phase leptospirosis. Different methods of laboratory diagnosis were used with each case. However, two cases were confirmed as leptospirosis and in both the causative agent was Leptospira borgpetersenii serovar (sv) Hardjo. The third case had a milder illness, received doxycycline early, and was regarded as a 'probable' case as there were no confirmatory diagnostic results. All three cases had worked on the same dairy farm during their incubation period, where the highest risk environment was the milking shed and potential exposure to urine splashes from infected cattle. Also there were inadequacies in the herd vaccination programme. CONCLUSIONS: There are options for minimising risk to dairy farm workers in New Zealand. No human vaccine exists in this country. Leptospira borgpetersenii serovar (sv) Hardjo (serovar Hardjo) is endemic in New Zealand dairy cattle without causing apparent disease. L. Pomona is a sporadic infection but can cause abortions. A cattle vaccine against these serovars was introduced in New Zealand in 1979, after which there was a general fall in notifications of human cases of leptospirosis. This was attributed to the overall decrease in these two serovars among the livestock population. Vaccination of farm livestock for leptospirosis is an integral factor in preventing human cases. We note the New Zealand initiative to combine vaccination with a risk management programme operated by veterinarians, called Leptosure, to reduce the risk of human leptospirosis on dairy farms. The efficacy of using doxycycline as a prophylaxis for preventing human infection in trials is reviewed. Other preventative strategies include the use of personal protective equipment to cover the mouth and nose, eyes and all skin breaks, farm workers and rural clinicians being aware of the signs and symptoms of leptospirosis, and prompt treatment of cases with antibiotics.

An outbreak of Legionella pneumophila suspected to be associated with spa pools on display at a retail store in New Zealand.

AIM: To investigate and characterise a cluster of six cases of severe pneumonia in the Wellington region notified to Regional Public Health in November 2003. And to describe the public health response to an identified subgroup of Legionella infections. METHODS: The case definition was "a person admitted to Wellington or Hutt Hospital between 29 October 2003 and 9 November 2003 with severe pneumonia". The cluster was initially investigated by interviewing patients to obtain histories of activities and exposures, and by reviewing medical notes. Medical teams sent further clinical specimens for testing (sputum for polymerase chain reaction [PCR], convalescent Legionella serology, and urine for Legionella antigen testing). Further investigation of Legionella pneumophila cases involved obtaining detailed exposure histories, environmental investigations at the suspect source of infection, and taking water and biofilm swabs for Legionella detection and serotyping. RESULTS: Three cases from the cluster were confirmed as, or compatible with, Legionella pneumophila serogroup 2. With the other three cases there was evidence of infection with L. longbeachae (two cases) or respiratory syncytial virus (one case). Exposure histories for the L. pneumophila cases revealed that the three cases had visited a Lower Hutt retail outlet with operating spa pools on display. Legionella pneumophila serogroup 1 was cultured from one of three pools. All pools were positive for Legionella on direct fluorescent antibody testing. CONCLUSIONS: Although unproven, the display spa pools were considered to be the most likely source of Legionella infection in the three cases that had visited the retail outlet. Although Legionella isolated from the pools was a different serogroup from that identified in two cases, the pools were considered to be the most likely source of infection in view of inadequate chlorination of the waters. Public health intervention to address the immediate and longer-term health risks from the pools is described. This is the second outbreak of Legionella pneumophila linked to operating display spa pools in New Zealand and it appears to be the fourth recorded outbreak of Legionnaires' disease associated with operating spa pools on display.