- Email: [email protected]
Leptospirosis in New Zealand
92
T H E ROYAL COLLEGE OF PATHOLOGlSTS OF AUSTRALlA
THE MICROBIOLOGICAL BACKGROUND TO THE LEPTOSPIRA A N D LEPTOSPIROSIS
FAINE, S. Departtnent of Microbiology, Monash University Medical School, Melbourne, Victoria Leptospires are bacteria with cell walls, flagellar analogues (axial filaments) and a surlounding sheath (envelope). With each of these structures is associated one or more antigens of chemical composition and serological specificity. Antigens include (1) a serotype-specific somatic lipopoly-saccharide (LPS), relatively non-toxic; (2) axial filament antigens, cross-reacting broadly according to immunoglobulin class of antibody; ( 3 ) envelope antigens, which can confer immunity, as can the somatic LPS. Each group may be developed further fcr studying diagnosis and epidemiology, identification and classification and preventive immunization. Current research on the pathogenesis of leptospirosis suggests that toxic factors may cause the characteristic but non-specific lesions.
LEPTOSPIROSIS I N NEW ZEALAND
CmiSTMAs, B. W. National Health Institute, Wellington, New Zealand Leptospirosis has been a notifiable human infection in New Zealand since 1956. The incidence has steadily increased until the infection now ranks as one of the most common of the notifiable diseases. Between 1961 and 1970 more than 2,000 cases were reported and in 1971, 860 cases were notified, the highest annual total yet recorded. In New Zealand, human leptospirosis usually presents as a benign meningeal syndrome that responds well to massive doses of penicillin. The disease occurs most commonly among dairy farmers fot whom it has become a significant occupational risk. Because of the substantial increase in the incidence of the infection, a collaborative study was undertaken to investigate a seasonal outbreak occurring in a dairy farming district in the North Island. In this study the epidemiological and clinical features of 47 acute cases from 39 farms were investigated. All the patients had worked in milking sheds or had been in close contact with dairy herds. Blood cultures collected from all patients within 48 h of the onset of their illness were positive in 75”,, of cases. Leptospira from this outbreak were subsequently identified as belonging to two serotypes, L . pomona and L. hardjo. L. hardjo was also isolated from a calf on one of the farms from which a positive human case had been reported. This is the first time L . hardjo has been identified in New Zealand.
IMPORTANCE OF LEPTOSPIRAL INFECTION I N DOMESTIC ANIMALS AND ITS RELATION TO H U M A N DISEASE
SULLIVAN, N . D. Veterinary School, University of Melbourne, Parkville, Victoria Four leptospiral serotypes have been isolated from domestic animals in Australia-pomona from cattle, sheep and pigs, tarassovi from pigs, hardjo from cattle and copenhageni (icterohaemorrhagiae) from dogs. Leptospirosis is a disease of economic importance in cattle and pigs and these species are the main sources of infection for man as a consequence of leptospiruria lasting for weeks or months. In pigs, pomona infection of sows causes abortion and neonatal mortality; tarassovi can Iesult in a similar infertility problem. In cattle, the acute form of pomona infection with intravascular haemolysis and haemoglobinuria is seen in calves. In cows, late abortions result from an intrauterine foetal leptospirosis. The significance of tarassovi for cattle is uncertain. Hardjo causes an ‘atypical’mastitis in milch cows with abortion as a sequel; haemoglobinuria is not a feature of infection with this serotype. Interstitial nephritis is the most characteristic pathological feature of leptospiral infection in animals and is a consistent sequel of pomona infection in pigs and cattle. During the last few years an upsurge in the incidence of hardjo infection in cattle has occurred, and this has been reflected in an equal increase in hardjo infection in man.
T H E ROYAL COLLEGE OF PATHOLOGlSTS OF AUSTRALlA
THE MICROBIOLOGICAL BACKGROUND TO THE LEPTOSPIRA A N D LEPTOSPIROSIS
FAINE, S. Departtnent of Microbiology, Monash University Medical School, Melbourne, Victoria Leptospires are bacteria with cell walls, flagellar analogues (axial filaments) and a surlounding sheath (envelope). With each of these structures is associated one or more antigens of chemical composition and serological specificity. Antigens include (1) a serotype-specific somatic lipopoly-saccharide (LPS), relatively non-toxic; (2) axial filament antigens, cross-reacting broadly according to immunoglobulin class of antibody; ( 3 ) envelope antigens, which can confer immunity, as can the somatic LPS. Each group may be developed further fcr studying diagnosis and epidemiology, identification and classification and preventive immunization. Current research on the pathogenesis of leptospirosis suggests that toxic factors may cause the characteristic but non-specific lesions.
LEPTOSPIROSIS I N NEW ZEALAND
CmiSTMAs, B. W. National Health Institute, Wellington, New Zealand Leptospirosis has been a notifiable human infection in New Zealand since 1956. The incidence has steadily increased until the infection now ranks as one of the most common of the notifiable diseases. Between 1961 and 1970 more than 2,000 cases were reported and in 1971, 860 cases were notified, the highest annual total yet recorded. In New Zealand, human leptospirosis usually presents as a benign meningeal syndrome that responds well to massive doses of penicillin. The disease occurs most commonly among dairy farmers fot whom it has become a significant occupational risk. Because of the substantial increase in the incidence of the infection, a collaborative study was undertaken to investigate a seasonal outbreak occurring in a dairy farming district in the North Island. In this study the epidemiological and clinical features of 47 acute cases from 39 farms were investigated. All the patients had worked in milking sheds or had been in close contact with dairy herds. Blood cultures collected from all patients within 48 h of the onset of their illness were positive in 75”,, of cases. Leptospira from this outbreak were subsequently identified as belonging to two serotypes, L . pomona and L. hardjo. L. hardjo was also isolated from a calf on one of the farms from which a positive human case had been reported. This is the first time L . hardjo has been identified in New Zealand.
IMPORTANCE OF LEPTOSPIRAL INFECTION I N DOMESTIC ANIMALS AND ITS RELATION TO H U M A N DISEASE
SULLIVAN, N . D. Veterinary School, University of Melbourne, Parkville, Victoria Four leptospiral serotypes have been isolated from domestic animals in Australia-pomona from cattle, sheep and pigs, tarassovi from pigs, hardjo from cattle and copenhageni (icterohaemorrhagiae) from dogs. Leptospirosis is a disease of economic importance in cattle and pigs and these species are the main sources of infection for man as a consequence of leptospiruria lasting for weeks or months. In pigs, pomona infection of sows causes abortion and neonatal mortality; tarassovi can Iesult in a similar infertility problem. In cattle, the acute form of pomona infection with intravascular haemolysis and haemoglobinuria is seen in calves. In cows, late abortions result from an intrauterine foetal leptospirosis. The significance of tarassovi for cattle is uncertain. Hardjo causes an ‘atypical’mastitis in milch cows with abortion as a sequel; haemoglobinuria is not a feature of infection with this serotype. Interstitial nephritis is the most characteristic pathological feature of leptospiral infection in animals and is a consistent sequel of pomona infection in pigs and cattle. During the last few years an upsurge in the incidence of hardjo infection in cattle has occurred, and this has been reflected in an equal increase in hardjo infection in man.