Salmonella saint-paul infection in calves.

A natural outbreak of Salmonella saint-paul infection in two Institute herds was monitored clinically, bacteriologically and immunologically. This paper describes the findings in calves. Morbidity and mortality became apparent 30 days after S. saint-paul was first isolated on routine sampling of neonatal calf faeces. All heifer calves were treated with a tetracycline or ampicillin preparation when they showed clinical signs of disease, while the effects of intradermal vaccination with heat-killed S. saint-paul were assessed in a proportion of the bull calves. Antibiotic treatment reduced mortality and the number of persistent excretors; vaccination did not affect mortality but, if given during the first week of life, reduced the duration of faecal excretion. Calves which were untreated and unvaccinated, or vaccinated when older than 16 days, excreted S. saint-paul for periods of up to 18 months. Of six ''recovered'' calves, which had been negative on faecal culture for 5-8 weeks, four yielded S. saint-paul at necropsy. Agglutinating antibody titres were highest in those unvaccinated calves which were persistent excretors.     

Studies on the isolation of Salmonella dublin.

Abattoir drain swabs, bovine faeces and a few other veterinary samples were examined for the presence of Salmonella dublin. Three selective agar media and four enrichment broths were investigated. The two most efficient plating media were deoxycholate citrate agar and brilliant green MacConkey agar. Wilson and Blair''s bismuth sulphite agar (de Loureiro''s modifications) was least successful. Selenite F broth, whether incubated at 37 or 43 degrees C., was better than the other enrichment broths used which contained a triphenyl methane dye as one of the selective ingredients.     

A milk-borne outbreak due to Salmonella dublin.

Salmonella dublin is primarily adapted to bovines and is a relatively rare cause of human illness. An outbreak is described in which it was estimated that at least 700 persons were infected from milk which had not been subjected to heat treatment. Although the organism was isolated from retail samples of milk, investigations at the dairy farm were inconclusive and a number of questions are posed. Attention is drawn to the value of inter-disciplinary cooperation in the investigation of the outbreak.     

Experimental Salmonella infection in calves: 2. Virulence and the spread of infection

Calves with a serum `H'' titre of 1/160 developed a chronic form of salmonellosis after infection with S. dublin. Their growth rate was severely retarded by this illness. An aerogenic strain of S. dublin was found to be much more virulent than an anaerogenic strain. Faecal samples were superior to mouth swabs in detecting animals carrying S. dublin.     

The epidemiology of Salmonella dublin infection in a dairy herd: II. Serology

A number of serological tests were evaluated in a study of Salmonella dublin infection in a dairy herd. None of the tests used detected either of the two carrier animals from which Salmonella dublin was isolated at slaughter 7 and 17 months after the herd infection. The complement fixation tests used proved to be a better guide to the presence of recent herd infection than the conventional `O'' or `H'' agglutination tests.     

Assessment of the excess risk of Salmonella dublin infection associated with the use of certified raw milk

The risk of serious illness attributable to infection with Salmonella dublin associated with the consumption of certified raw milk in California was evaluated. Data were derived from case reports of S. dublin isolations from persons in the State of California during the period 1980-83 and from production figures for raw milk from the major supplier. It is estimated that more than one-third of reported S. dublin infections in California in the first 4 years of this decade were attributable to raw milk consumption. Among raw milk consumers, it is estimated that more than 95 percent of reported S. dublin infections were acquired from raw milk; this proportion corresponds to a rate of reported S. dublin infections acquired from raw milk in the range of 8 to 35 cases per 100,000 users per year. It appears that immunocompromised persons are at exceptionally high risk of becoming seriously ill or dying from S. dublin exposure, and therefore raw milk is a particular health hazard for such persons.     

The epidemiology of Salmonella dublin infection in a dairy herd: I. Excretion and persistence of the organism

This paper describes the epidemiologically relevant events that took place in a dairy herd infected by Salmonella dublin. The evidence presented indicates that it may be possible to eliminate infection from the farm and that residual infection or persistent excretion are uncommon. In two animals infection persisted, in one instance in the tonsil and in the other in the gall bladder. In this latter case the infection remained from the neonatal period until adulthood. It is possible that both these animals are relevant in a more general context and are indicative of the source of infection in outbreaks in which the origin of infection cannot be determined by more routine examinations.     

The epidemiology of Salmonella infection of calves: the role of dealers

Salmonellas were detected in the environment of 10 of the 12 calf dealers' premises studied. The cleaning and disinfection routines were often ineffective and salmonellas were isolated from 7.6% and 5.3% of the wall and floor samples before disinfection and 6.8% and 7.6% afterwards. Eight different salmonella serotypes were detected, of which the commonest were Salmonella typhimurium, predominantly phage type DT204C, and S. dublin. Plasmid profiles were used to fingerprint S. typhimurium DT204C and the results indicated that with the exception of one of the premises, prolonged salmonella-persistence in the environment was not occurring. Three separate epidemics of salmonellosis in calves were studied by use of plasmid profile analysis. The results illustrated the role of delers, and their subcontractors, in the dissemination of salmonellas. The study concludes with suggestions for methods to reduce the spread of salmonellas in the calf marketing chain.     

Salmonella dublin abortion in cattle: I. Observations on the serum agglutination test

The somatic and flagellar serum agglutinin titre were determined in paired samples obtained from seventy-seven cases of bovine abortion associated with Salmonella dublin infection. The cases could be divided into four serological groups with an active infection being demonstrated in most cases. The serum agglutination test was shown to be a relatively specific diagnostic test but was of more limited value in the retrospective identification of convalescent cases.     

Experimental Salmonella infection in calves: 1. The effect of stress factors on the carrier state

Four calves were infected with 2·4 × 10⁸ S. dublin and penned separately. Fluctuations in environmental temperature did not affect the symptoms of the disease or the duration of excretion. Faecal samples were superior to rectal swabs for detecting excretors.     

The effect of storage in slurry on the virulence of Salmonella dublin.

The mouse was used as a model to determine whether storage of Salmonella dublin in slurry and in broth reduces the virulence of the organism. No reduction in virulence of S. dublin stored in slurry for 36 days or in maintenance broth for 70 days was observed. The disease hazard involved in pasture-spreading of slurry contaminated with salmonellas is related to factors other than virulence.     

Salmonella dublin infection in adult cattle: a slaughter house and knackery survey in South West Wales.

A survey was carried out between June 1970 and December 1971 in which gall bladders from cattle either slaughtered for food consumption or disposed of through knackeries were cultured for salmonellas. Salmonella dublin was isolated from 28 of 1917 gall-bladders of adult cattle killed in the slaughterhouse at Carmarthen, and from 23 of 197 gall-bladders obtained from adult cattle sent to a knackery at Abergwili, near Carmarthen. The results are compared with a similar survey carried out in 1947 and 1948. Between June and November 1971 gall-bladders and uteri were also obtained from a slaughterhouse in Newcastle Emlyn, North Carmarthenshire, and a knackery in Tanygroes, South Cardiganshire. S. dublin was cultured from two gall-bladders but from none of the uteri of the 161 slaughterhouse cases. Seven of the 46 cows from the knackery yielded S. dublin on culture: 2 in the gall-bladder only, 3 in the uterus only and 2 in both gall bladder and uterus.