Academic journal article Perspectives in Public Health

Compost and Legionella Longbeachae: An Emerging Infection?

Academic journal article Perspectives in Public Health

Compost and Legionella Longbeachae: An Emerging Infection?

Article excerpt

INTRODUCTION

The term Legionnaires' disease (LD) was first coined in 1976, after 182 attendees at a meeting of the American Legion showed symptoms of a mystery illness. it took a further six months before the causative agent in the outbreak, a Gram-negative rod, was identified and named Legionella pneumophila.1 Since then, over 50 species of Legionella have been identified, with 64 serotypes.

Despite the numerous pathogenic species found, L. pneumophila is the main causative agent of human disease. An international-collaborative study by Yu and colleagues, comparing the most common causative agents in cases of sporadic community-acquired legionellosis from the United States (72.2% of cases reviewed), italy (12.6%), Switzerland (6.1%), New Zealand (4.3%) and Australia (4.7%), cited L. pneumophila as the agent responsible for 91.5% of cases of Legionellosis; the second most commonly isolated species, Legionella longbeachae, was present in 3.9% of cases.2 Despite the low representation worldwide, L. longbeachae plays a significant role in the burden of legionellosis in the southern hemisphere; in the study by Yu, 14 of the 20 L. longbeachae isolates came from Australia and New Zealand.2 A review of legionellosis survey data in Southern Australia from 1996 to 2000 reported that 42% of cases were attributable to L. longbeachae, compared with 51% due to L. pneumophila.3 in western Australia, between 1999 and 2010, 87% of diagnosed cases of LD were caused by L. longbeachae, whereas only 9% of cases were caused by L. pneumophila.4 Similarly, in New Zealand, the Ministry of Health found that, in 2011, L. longbeachae was responsible for more cases than L. pneumophila, with 42% and 30% of laboratory-reported cases of infection, respectively.5 Human infection with L. longbeachae has also been noted in the United States,6 Japan7 and Thailand, where Phares et al.8 found that L. longbeachae was responsible for 5% of clinically defined cases of pneumonia in a rural district, whereas L. pneumophila was not reported.

Historically, the incidence of infection with L. longbeachae in europe has been low; however, as noted by whiley and Bentham, the number of cases of infection appears to be increasing.9 in 2012, Lindsay et al.10 noted that L. longbeachae had been cited as the causative agent in only 11 cases of infection in the United Kingdom since 1984; seven of these occurred in Scotland. Further work revealed that from 2008 to date, 26 cases of L. longbeachae infection had been reported in Scotland; in most cases, the patient had been in contact with commercially available growing media before the onset of symptoms11 (personal communication, Dr Kevin Pollock/ross Campbell, Health Protection Scotland). in addition, an atypical case of L. longbeachae cutaneous infection in a female patient in the United Kingdom was recently described.12

This article presents a review of the literature currently available examining Legionella spp in the compost habitat, particularly the status of L. longbeachae infection. work was completed using web of Knowledge and PubMed searches including, but not limited to, individual and combinations of the following terms: 'Legionella', 'Legionnaires' disease', 'Pontiac fever', 'Legionella longbeachae', 'soil', 'compost', 'growing media', 'garden', 'amoeba', 'PCr', 'diagnosis', 'biofilm', 'source', 'water'. Searches were not truncated by date, although the relatively recent discovery of this organism reduces the amount of searchable literature available.

INFECTION

Infection with Legionella spp can be symptomatic or asymptomatic: hospital patients and healthy individuals have been shown to experience increased antibody titres to Legionella antigens without showing clinical signs of infection.13,14 Symptomatic infection will generally present as legionellosis in one of two distinct clinical manifestations: Pontiac fever (PF) - a self-limiting influenza-like illness; or LD - a more serious pneumonia that can be fatal. …

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