Seroepidemiological Survey of Bovine Leukaemia Virus Infection in Canadian Cattle

Samagh, B. S.; Kellar, J A

doi:10.1007/978-94-011-9090-9_60

Cited by 6 publications

(4 citation statements)

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“…In 1980, national prevalence of BLV infection in Canadian dairy herds was estimated at 40.5%, while only 9.3% of tested cattle were positive (Samagh and Kellar, 1982). However, 15-20 years later, infection levels appeared to have increased substantially.…”

Section: Introductionmentioning

confidence: 96%

Herd-level risk factors for infection with bovine leukemia virus in Canadian dairy herds

Nekouei

VanLeeuwen

Sánchez

et al. 2015

Preventive Veterinary Medicine

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Section: Introductionmentioning

confidence: 96%

Herd-level risk factors for infection with bovine leukemia virus in Canadian dairy herds

Nekouei

VanLeeuwen

Sánchez

et al. 2015

Preventive Veterinary Medicine

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“…In North America, prevalence of the infection has been high and appears to have a rising trend (Samagh and Kellar, 1982;Richardson and Macaulay, 1992;Sargeant et al, 1997;VanLeeuwen et al, 2001;VanLeeuwen et al, 2005;VanLeeuwen et al, 2006;Bartlett et al, 2014). For instance, in Prince Edward Island, Canada, herd-level prevalence of BLV was 49.2% in 1989 (Richardson and Macaulay, 1992), increased to 63.3% in 1998 (VanLeeuwen et al, 2001), and is currently at 90% based on a survey of bulk tank milk in all dairy herds in the province completed in 2013 (O.…”

Section: Introductionmentioning

confidence: 98%

Carryover of bovine leukemia virus antibodies in samples from shared milk meters

Nekouei

Sánchez

Keefe

2015

Journal of Dairy Science

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Screening for infectious diseases of cattle using milk from the dairy herd improvement (DHI) sampling process is very convenient. However, when samples from shared milk meters are used, carryover of antibodies or other diagnostic targets can complicate the interpretation of the diagnostic test results for diseases, including bovine leukosis. The objectives of this study were (1) to assess the potential for carryover of antibodies against bovine leukemia virus (BLV) in milk samples obtained from shared meters, and (2) to determine if adjustment of the diagnostic test cut-off value would improve the test characteristics for meter-collected milk ELISA results. Eight dairy farms were randomly selected from herds with a wide range of BLV prevalence levels in Prince Edward Island, Canada. Within each chosen farm, 2 to 4milk meters were randomly selected. During the routine procedures of DHI sampling, 2 simultaneous milk samples, 1 hand-collected at the beginning of milking (after udder preparation) and the other from the corresponding milk meter, were taken from all lactating cows (n=236) that were milked at the selected meters (n=26). The sequence of cows using each meter was recorded. All samples were tested for BLV antibodies using a commercial indirect ELISA. Antibody carryover potential was assessed in meter-collected samples which were preceded by other cows using the same meters. Applying the hand-collected sample results as our reference standard, a new cut-off was defined for meter-collected samples to optimize the test characteristics. At the standard cut-off value of the diagnostic test, 110 (46.6%) of the hand-collected and 136 (57.6%) of the meter-collected samples were positive. For low-titer cows (e.g., true negatives), the likelihood of antibody carryover significantly increased as the titer of preceding cows increased, whereas this change was not substantial for high-titer cows. The odds of obtaining false diagnoses in meter-positive samples became larger with increase in the titer of preceding cows. A suspicious category for meter ELISA results was defined, and a retest was recommended for the cows falling into this category. This strategy effectively assisted in reducing the number of consequent false-positive results. When DHI-collected samples are used, carryover can affect the interpretation of dichotomous test results and may require adjustment of assay cut-off values.

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“…Immunologically relevant proteins of the BLV virion include the membrane glycoproteins gp51 and gp30 and the major core protein p24 (DESHAYES et al, 1977(DESHAYES et al, , 1980. Several reports have shown that BLV-infection is widespread in cattle from the American continent ( M A R~N et al, 1978;SAMAGH and KELLAR, 1982; DIGIACOMO, 1992). Economically, it is important due to restrictions in importation of seropositive animals and culling of clinically affected animals.…”

Section: Introductionmentioning

confidence: 99%

Bovine Leukaemia‐virus Infection in Costa Rica

Jiménez

Bonilla²,

Dolz³

et al. 1995

Journal of Veterinary Medicine, Series B

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Summary The geographical distribution of bovine leukaemia‐virus (BLV)‐infected herds in Costa Rica and the isolation of BLV from cases of enzootic bovine leukosis are presented. It was found that BLV is prevalent throughout the country, affecting mostly dairy cattle (Bos taurus) located in the highlands around the central valley of Costa Rica. By contrast, beef cattle (Bos indicus) raised in the lowlands were affected to a lesser extent. One out of four isolates of BLV obtained from local cattle with lymphosarcomatous tumours was analysed and had similar physical, serological and biological characteristics to a reference strain of BLV isolated in the USA. However, different patterns of recognition of BLV‐protein p24 were observed among naturally infected cattle using the western‐blotting technique.

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Seroepidemiological Survey of Bovine Leukaemia Virus Infection in Canadian Cattle

Cited by 6 publications

References 0 publications

Herd-level risk factors for infection with bovine leukemia virus in Canadian dairy herds

Herd-level risk factors for infection with bovine leukemia virus in Canadian dairy herds

Carryover of bovine leukemia virus antibodies in samples from shared milk meters

Bovine Leukaemia‐virus Infection in Costa Rica

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