Leptospira interrogans serotype pomona infection in pigs: prevention of leptospiruria by immunisation before exposure to a natural infection

Fourteen of 24 pigs were immunised with repeated injections of killed cultures of Leptospira serotype pomona administered over a three-week period. The remaining 10 pigs served as controls.

Five days after immunisation all pigs were exposed to the same natural infection by being housed together for 12 weeks in a pen which received effluent from other pens containing infected pigs.

Neither leptospiruria nor kidney lesions were detected in any of the immunised pigs. In contrast, leptospiruria and kidney lesions occurred in all the controls.

The development of serum agglutinins after immunisation and before exposure suggested that this could be used as an index of adequate antigenic stimulation.     

Phage typing of staphylococci isolated from dairy cows in New Zealand

Four red deer calves (Cervus elaphus) died with severe nephritis apparently associated with infection by Leptospira interrogans serovar pomona. The sera of 12 in-contact red deer calves were examined for leptospiral agglutinins and nine showed titres to pomona consistent with recent infection. Two also showed titres of 1:100 to serovar hardjo. The urine of five of these in-contact calves was examined periodically over a period of nine months. All were initially leptospiruric, four being infected with pomona and one with hardjo. In four animals leptospiruria could only be detected for up to six months, but one animal infected with pomona was leptospiruric for at least eight months.

The apparent source of infection was from infected cattle, and it is suggested that deer are unlikely to act as maintenance hosts for serovar pomona.     

Some Observations on the Diagnosis and Epidemiology of Leptospirosis in Swine

The results of combined epidemiological, clinical, serological, bacteriological and histopathological studies following an outbreak of disease caused by L. pomona on a farm stocked with cattle, sheep, pigs, goats and horses maintained for experimental purposes, are reported.

The incidence of infection was high in horses, cattle and pigs. A few low titres were seen in sheep. The goats were not infected. Apart from a single bovine abortion all the clinical symptoms observed occurred in pregnant sows. Seven of these aborted or gave birth to stillborn pigs within a six week period.

Fifteen species of wildlife were trapped or shot on the farm during the year following the outbreak. L. pomona was isolated from four skunks and a porcupine. Epidemiological studies indicated that wildlife reservoir hosts were the primary source of infection for the domestic livestock.

Leptospiruria and the serological response were studied in a group of eight infected sows. Microscopic agglutination titres of 10² or less could not be associated with leptospiruria and the duration of leptospiruria was found to range from a few weeks to over two years in individual sows. Direct dark-field examination of urine proved superior to guinea-pig inoculation as a method of detecting leptospiruria and it is suggested that the former technique could be adopted with advantage as a routine aid to diagnosis.

     

The epidemiological interpretation of serological responses to leptospiral serovars in sheep.

Serum samples were examined for evidence of leptospiral agglutinins from 928 sheep from 45 lines and kidneys from 12 of these lines for evidence of leptospiral infection. All sheep had been submitted for slaughter at meat works in the Manawatu.

Serological results were analysed using the results at a minimum serum dilution in the microscopic agglutination test (MAT) of 1:24 and at a minimum dilution of 1:48. It was shown that a minimum dilution of 1:24 resulted in many non-specific or cross-reactions. A minimum dilution of 1:48 was more accurate for detecting the serological prevalence of specific agglutinins to leptospires in ovine sera. Twenty percent of the sheep had titres of 1:48 or greater to hardjo, 3.8% to pomona, 2.6% to tarassovi, 2.3% to copenhageni and 2.7% to ballum. No titres of 1:48 or greater to australis were detected. Serovar hardjo was isolated from the kidneys of three animals in one line.

Eighteen months later 291 serum samples and 95 urine samples were collected from live animals on the property from which the three hardjo infected animals originated. No titres to hardjo were detected in the sera of lambs, but a serological prevalence of 44% and 84% to this serovar was demonstrated in the hoggets and ewes respectively. No leptospires were demonstrated in any of the urine samples.

These results show that sporadic infection of sheep with hardjo can occur but they also indicate that infection with this serovar is not endemic and that sheep are unlikely to act as maintenance hosts for hardjo in New Zealand.     

Haemolytic disease associated with Leptospira Interrogans serovar pomona in red deer calves (Cervus elaphus)

Three red deer calves (Cervus elaphus) died with a haemolytic disease associated with infection by Leptospira interrogans serovar pomona.

Infection within the herd was more prevalent than disease. Sera from 16 herd mates were tested by the microscopic agglutination test (MAT) and 12 had leptospiral titres, the majority to serovar pomona. A few calves had titres to balcanica and hardjo.

Urine was obtained for culture from six of these calves and serovar pomona was isolated from five with titres to pomona, and hardjo from one with a litre to hardjo but not pomona.

A fourth calf died with severe nephritis but a diagnosis of leptospirosis was not confirmed in this case.     

Leptospirosis in pigs: The effectiveness of streptomycin in stopping leptospiruria

A trial was conducted to assess the efficacy of a single intra-muscular injection of 25mg per kg of streptomycin in stopping leptospiruria in growing pigs exposed to a natural infection.

The investigation involved 54 pigs, 10–12 weeks old, that were free of serological evidence of infection with serotypes pomona or tarassovi at the start of the trial. The animals were kept in pens in a finishing house through which flowed effluent from other pens containing infected pigs. Urine samples were collected from each pig three times weekly until it was slaughtered for bacon at 20–24 weeks old.

Leptospiruria was first detected between 16 and 74 days after exposure. Twenty-one of 37 pigs which showed leptospiruria were injected with streptomycin. Leptospirae were detected in 11 of 185 (5.9%) subsequent urine samples from these 21 treated animals and serotype pomona was cultured from the kidney of 1 of the 10 animals that were examined from this group at slaughter.

Following the initial detection of leptospiruria in the 16 un-treated pigs, 179 of 211 (84.8%) subsequent urine samples con-tained leptospirae, which were also cultured from the kidneys of 4 out of 11 of these animals.     

Leptospira interrogans serovar pomona vaccines with different adjuvants in cattle

Three groups of four heifers were vaccinated twice, 11 weeks apart. One group received a commercial pomona vaccine with aluminium hydroxide adjuvant, the second a similar experimental vaccine, and the third a Freund's compete adjuvant (FCA) vaccine. After 47 weeks, the heifers were challenged with at least 65 × 10⁸ virulent serovar pomona organisms.

All vaccinated animals resisted the challenge, and leptospirae were only found in urine from unvaccinated controls.

The outcome of the challenge was not predictable from microscopic agglutination, cold and warm complement fixation, and growth inhibition titres.

The FCA vaccine gave rise to considerably higher antibody responses than the two aluminium hydroxide vaccines, which gave similar responses.     

Values for Selected Serum Analytes during Experimental Ichthyophthirius multifiliis Infection of Channel Catfish

Abstract

Channel catfish Ictalurus punctatus were exposed to a sublethal dose of infectious Ichthyophthirius multifiliis theronts, and eight serum analytes were measured. Sequential serum samples from each fish were collected for serum immediately before exposure, 4 d postexposure (PE), and 11 d PE. All fish developed moderately heavy infections with the parasite as indicated by the development of cutaneous lesions 5 d PE to infective theronts. Small but statistically significant changes in total protein, creatinine, and alkaline phosphatase values occurred after acute infection with I. multifiliis. Serum concentrations of glucose, albumin, urea nitrogen, alanine aminotransferase, and aspartate aminotransferase remained constant, indicating little disturbance of liver or kidney functions detectable by a serum biochemical profile established during an acute infection with I. multifiliis.     

Systemic mycoses of two cats

Calves vaccinated twice with one commercial pomona vaccine had serum MAT titres up to 1:300, warm CFT titres of 1:20 and cold CFT titres of up to 1:80. A second commercial vaccine did not elicit any detectable antibodies.

All calves, vaccinated as well as unvaccinated, showed a rapid rise in antibody levels, detectable with all three tests, following challenge with 38 × 108 pomona organisms.     

Epidemiology of leptospirosis in dairy farm workers in the Manawatu. Part II. A case-control study of high and low risk farms

Subsequent to a cross-sectional serological survey of Manawatu dairy farm workers, a case-control study was carried out to investigate the correlation between titres to leptospiral serovars in workers and those in cattle in their herds. A total of 52 herds was investigated, 25 of which were ‘high risk’ where milkers had titres of 1:96 or greater, and 27 were case-controls where milkers had no detectable agglutinin titres at a minimum serum dilution of 1:24.

The serological prevalence of titres to hardjo in cattle on ‘high risk’ farms (76.5%) was significantly higher (P<0.05) than on the case-control farms (60.0%). The geometric mean titres of seropositive cattle on ‘high risk’ farms were also significantly higher (P<0.0l) than in the cattle from the case-control farms, especially in the younger cohorts. These findings suggest that there was active endemic hardjo infection in the two- to three-year-old cattle on the ‘high risk’ farms.

Titres to pomona were demonstrated in only 5.2% of the cattle from both types of farm. Workers with titres to pomona tended to be from farms on which stock, especially calves, were bought-in and pigs were kept.

Conventional measures for protecting milkers from contact with infected urine appeared to be ineffective and it is concluded that prevention of leptospirosis in dairy farm workers can only be achieved by elimination of infection in the herd by vaccination of cattle.     

An unusual serological response in cattle after use of a commercial leptospiral combined hardjo-pomona vaccine

Vaccination of four calves with Leptavoid (Wellcome New Zealand Limited) gave rise to Leptospira interrogans serovars hardjo and pomona microscopic agglutination test titres that could not be distinguished in magnitude from post-infection titres. Vaccination of four calves with Lepto-3 (ICI Tasman Limited) gave rise to much lower titres.

Revaccination of cows with Leptavoid caused a rise in hardjo titres which was significantly greater than after use of Lepto-3.

The possibility that titres were due to the simultaneous infection with serovars pomona and hardjo of only the animals vaccinated with Leptavoid must he discounted.     

Bovine leptospirosis in Northland

Extract

The following figures of the incidence of Leptospira pomona infection on farms in Northland are for the 1952 season up to the end of November, and were provided by all veterinary surgeons in Northland in -response to a questionnaire.     

Leptospirosis in Colombia: Isolation ofLeptospira SPP. from the kidneys of brown rats (Rattus Norvegicus) trapped on infected piggeries

Summary Leptospira interrogansserotypes pomonaand icterohaemorrhagiaewere isolated from the kidneys of Rattus norvegicustrapped on pomonainfected piggeries.The isolation of pomonafrom one of 111cultured kidneys, although of interest, strongly suggests that this rat does not play an important part in the epidemiology of infection by this serotype. Kidney tubular degeneration, focal mononuclear infiltrations and fibroplasia are morphological traces which remain after an attack of leptospirosis. The high percentage (48.6)of these lesions found in the rat kidneys examined does not seem to be related to serotype pomonabut to icterohaemorrhagiae.The importance of this last serotype in swine in the Cauca Valley has yet to be assessed.

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Leptospirosis En Colombia: Aislamiento DeLeptospira SPP. De Riñones De Ratas Pardas (Rattus Norvegicus) Atrapadas En Porquerizas Infectadas

Resumen Se aislóLeptospira interrogans serotipospomona eicterohaemorrhagiae de riñones deRattus norvegicus atrapadas en porquerizas infectadas porpomona. El aislamiento depomona de 1/111 riñones cultivados, aunque de interés, sugiere que esta rata no desempeña parte importante en la epidemiología de las infecciones por este serotipo.Degeneración tubular renal, infiltración mononuclear focal y fibroplasia son huellas morfológicas que quedan después de un ataque de leptospirosis. El alto porcentaje (48.6) de estas lesiones encontradas en los riñones de las ratas examinadas no parece estar relacionado con el serotipopomona sino con elicterohaemorrhagiae. La importancia de este último seroptipo en cerdos en el Valle del Cauca no se ha evaluado todavía.

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Leptospiroses En Colombie: Isolement DeLeptospira SPP. De Reins De Rats Bruns (Rattus Norvegicus) Captures Dans Des Porcheries

Résumé Les sérotypespomona eticterohaemorrhagiae deLeptospira interrogans ont été isolés de reins deRattus norvegicus capturés dans des porcheries infectées de (pomona?). L'isolement depomona sur une seule des 111 cultures de rein effectuées, bien qu'interessant, suggère fortement que ce rat ne joue pas un rôle important dans l'épidémiologie de l'infection par ce sérotype.La dégénerescence tubulaire des reins, des infiltrations ponctuelles par des monocucléaires et l'aspect fibreux constituent les traces morphologiques qui demeurent après une attaque de leptospirose. Le pourcentage élevé (48,6) de ces lésions trouvées dans les les reins des rats examinés semble être plus en rapport avec le sérotypeicterohaemorrhagiae qu'avec le sérotypepomona. L'importance du sérotypeicterohaemorrhagiae chez le porc de la Cauca Valley est encore à vérifier.

     

A leptospirosis outbreak in a piggery

A newly established piggery experienced an abortion storm that was diagnosed as being caused by Leptospira pomona. Serumantibody titres and urine culture indicated the rapid spread of infection within the piggery, and established the period since infection began. This showed the origin of infection to beone of the piggeries from which stock were purchased.

Histological and microbiological studies indicated the continuing presence of L. pomona as the cause of abortion. Initial treatment with dihydrostreptomycin and “Leptovax” had no effect on preventing infection, and the subsequent use of “Terramycin” caused little modification to the spread of infection or prevention of abortions. The spread of leptospirosis through the herd resulted in a marked increase in the number of piglets aborted or born dead and, subsequently, a poor survival rate of piglets reared through to slaughter. Efforts are being made to control leptospirosis within the piggery, but eradication is currently considered to be almost impossible.     

PRRSV感染仔猪肾组织的超微病理变化分析

猪繁殖与呼吸综合征病毒（PRRSV）是能引起仔猪高死亡率的疾病,给养猪业带来极大的经济损失。本研究对PRRSV感染仔猪肾组织的病毒定位及产生的超微病理变化进行观察,以期了解PRRSV对肾组织细胞以及血液循环的影响。主要采用透射电镜技术结合血清生化检测、免疫组织化学染色（IHC）,对仔猪感染PRRSV后肾组织进行超微病理学观察及分析。结果发现,PRRSV感染后引起肾组织损伤,病毒主要分布于肾小球、坏死的肾小管上皮细胞胞质及巨噬细胞胞质内;肾小球内足细胞足突广泛融合或微绒毛化,内皮细胞肿胀;肾小管上皮细胞线粒体肿胀、嵴断裂、溶解;间质炎性细胞浸润。PRRSV通过巨噬细胞内复制随血液扩散至肾组织,引起损伤;根据透射电镜观察结果,足细胞足突融合,肾小球血管内皮细胞损伤引起微血栓形成,说明PRRSV感染仔猪后影响了肾小球滤过率,同时,对肾血液微循环系统造成损伤。本研究为阐明PRRSV的感染致病机制提供理论基础。     

Leptospirosis: II. Investigation of clinical disease in dairy cattle in the Waikato district of New Zealand

Investigations were carried out in 1975, 1976 and 1977 in 16 dairy herds where leptospiral abortions were suspected and in five other herds where clinical disease was not present. Both Leptospira interrogans serovars pomona and hardjo were isolated from cattle in herds with leptospirosis, but only pomona was recovered from those that had aborted. There was no evidence that hardjo caused clinical disease in dairy cattle in the Waikato district.

It was found that 73% of the cows that aborted and 19% of other animals in the same herds had microscopic agglutination test titres to pomona of 1:2 000 or greater. By contrast, only 2% of cattle in herds without clinical evidence of leptospirosis had such titres. One cow retained a titre of 1:2 000 or greater to pomona for 7 months; titres of this order had a shorter duration in other cows. Leptospiruria occurred in 50% of cows that had aborted and in 9% of in-contact cows in the same herds. Only 0.7% of cows had leptospiruria in the herds with no clinical disease. Ten of 35 cows shedding pomona still had leptospiruria one month later.

It was concluded that clinical leptospirosis should be diagnosed by testing a sample of the herd, rather than just individual cows, because of the variability and persistence of leptospiruria and serological titres in cows with and without clinical signs. Although hardjo is common in cattle in the Waikato district, it was not found to cause abortion in cattle.     

Protection of pregnant swine by vaccination against leptospira infection

SUMMARY The protection conferred on pregnant gilts by 2 commercially available Leptospira interrogans serovars pomona and tarassovi bacterins was evaluated. Gilts vaccinated either 3, 6 or 12 months prior to natural challenge with L. interrogans serovar pomona had significantly lower abortion rates (2% vs 69%) and foetal mortality rates (14% vs 57%) than unvaccinated controls. One vaccine was significantly superior to the other and contained approximately twice the number of L. interrogans serovar pomona organisms per vaccine dose. Neither vaccine protected against renal colonisation but vaccination reduced urinary excretion of leptospires. Both vaccines reduced agglutinating antibody response to infection, as measured by the microscopic agglutination (MA) test. This may prevent the detection of a carrier animal by serology. Foetal pigs did not develop specific MA titres. Cultural methods were not reliable in making a diagnosis of foetal infection. Histopathology of foetal liver and kidneys helped in making a diagnosis of foetal infection.     

Prevention of Leptospira interogans serovar pomona infection in cattle

A commercial hardjo-pomona vaccine which has previously been shown to be effective against hardjo infection was tested against pomona. Following challenge all 11 six-month-old non-vaccinated calves seroconverted and pomona was isolated from blood or urine on at least one occasion from nine of them. Pomona was isolated once only, on the third day after challenge, from the blood of one of 11 vaccinated calves.     

Isolation of Leptospira interrogans serovars tarassovi and pomona from dogs

Extract

This communication reports the isolation of Leptospira inter-rogans serovars tarassovi and pomona from dogs in New Zealand.     

The effects of the conjunctival Brucella vaccine on some biochemical parameters in sheep

The genus Brucella causes significant economic losses due to infertility, abortion, stillbirth or weak calves, and neonatal mortality in livestock. Brucellosis is still a zoonosis of public health importance worldwide. In the past, vaccination was administered subcutaneously and nowadays, the conjunctival vaccine is administered. There is no definite information about the changes of the biochemical parameters and antibody response after conjunctival vaccination. In this study, the investigation of the changes in the levels of some biochemical parameters due to the conjunctival vaccination for brucellosis was aimed. Thirty sheep were used as an animal material. The vaccine was done single dose against Brucella melitensis and the blood was drawled from Vena jugularis during 4 months. Antibody levels were determined by serum tube agglutination test. Alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), glucose, total protein, and albumin levels were measured using commercial autoanalyzer in sera. The antibody titers (p?<?0.001) increased significantly at first month compared to the pre-vaccination, but at the second month began to fall. There was no statistically significant changes in glucose, AST, ALT activity after vaccination (p?>?0.005). The significant amount of total protein and ALP decreased after vaccination (p?<?0.005). LDH levels and total protein levels were significantly increased (p?<?0.005). In conclusion, conjunctival vaccine was considered to be used as a safe to protect the sheep from brucellosis and the results of the study may be used to improve the efficiency of brucellosis eradication programs within livestock management.