Immunisation against listeriosis in sheep using a live, attenuated vaccine was introduced in Norway in 1984. Since then 65,000 to 80,000 animals have been vaccinated annually. Information obtained by a questionnaire showed that the incidence of listeriosis decreased from approximately 4.0 per cent before the introduction of the vaccine to 1.5 per cent after vaccination started. The incidence of abortions was 0.7 per cent in vaccinated flocks compared to 1.1 per cent in unvaccinated flocks. There were a few adverse reactions in the vaccinated sheep.
Since its first isolation by Murray in 1926 Listeria monocytogenes has become recognized as a significant pathogen occurring worldwide and involving a wide range of wild and domestic animals including man. The first confirmed human listeriosis case in Canada was published by Stoot in 1951. A later survey based on records maintained at the Laboratory Centre for Disease Control, Ottawa showed 101 cases detected over a 21 year period in nine provinces. The overall mortality was 30%. The most frequently isolated serotype was 4b followed by 1 and 1b. Prior to the Nova Scotia epidemic (41 cases) of 1981, fewer than 15 cases per annum had been diagnosed based on hospital discharge records. The Nova Scotia epidemic was unique in that the source and mode of transmission of the organism were determined. Sixty-three strains isolated from this outbreak were typed, and with the exception of one 1a strain, were identified as 4b. These were subsequently classified mainly as phage type 00 042 0000 and 00 002 0000. Listeriosis appears to be a common infection in the animal population in Canada primarily in cattle, sheep, chinchillas, chickens and goats. Outbreaks have been described in rabbits, goats, and chinchillas. Chinchilla farms were affected in one outbreak (serotype 1) in Nova Scotia which was attributed to feeding a new batch of meal containing beet pulp. Many aspects of the epidemiology of listeriosis are obscure. A cycle involving contaminated soil and consumption of raw vegetables has been confirmed as the cause of the Nova Scotia epidemic and could explain a proportion of the sporadic cases.(ABSTRACT TRUNCATED AT 250 WORDS)
The records were reviewed of all patients treated at the Vancouver General Hospital over the 15 years from 1965 through 1979 for infections proved by culture to have been caused by Listeria monocytogenes. Although listeriosis is not common in humans, certain groups seem to be susceptible - immunocompromised patients, pregnant women, neonates and the elderly. All these groups were represented among the 22 cases reviewed. There were 17 adults, 3 of whom were pregnant women who had only a mild influenza-like illness. Of the remaining 14 adults 9 were immunocompromised and 5 apparently immunocompetent; 7 presented with meningitis and 7 with bacteremia only. Of the five infants with neonatal listeriosis, two had early-onset disease (bacteremia) and three had the late-onset form (meningitis). Seven patients were treated with penicillin alone, seven with ampicillin alone and eight with penicillin or ampicillin combined with kanamycin, gentamicin or chloramphenicol. There were eight deaths: several were directly attributable to the listeriosis, but in others the severity of the underlying illness was an important factor. Serotypes 1 and 4b were equally common among the 16 specimens of L. monocytogenes that were typed.
We examined specimens for L. monocytogenes using the "cold enrichment" technique of Gray et al. (J. Bacteriol., 55: 471, 1948) and a nalidixic agar plate (Ann. Inst. Pasteur 111: 90, 1966). Between 1974 and May 1981, we isolated L. monocytogenes from four of 5,255 specimens (rectal, vaginal and placental swabs; blood; spinal fluid; semen; necropsy material) which came from eight human populations (neonates, children, adult men, and pregnant and nonpregnant women) and from 161 animals. Three of the isolated strains were type 1, and they came from a newborn born at 32 weeks' gestation, that child's mother, and another woman who had recently delivered. The fourth (type 4b) came from a newborn twin born at 36 1/2 weeks' gestation. In June through October 1981, in 529 specimens, we isolated L. monocytogenes type 1/2 from two of four larvae tested (four earwigs and five slugs were all negative) and from three of 27 samples of fresh chicken liver (however, 18 samples of coleslaw were negative). At the same time, we isolated L. monocytogenes (not yet typed) from a rectal swab from one of 112 dogs examined. Rectal swabs from 107 cats were negative, as were vaginal swabs from 144 women and urine samples from 108 newborns.