Excretion of Brucella abortus vaccine B19 strain during a reproductive cycle in dairy cows

Abstract

This paper aimed to determine the excretion period of B19 vaccine strain during a complete reproductive cycle (from estrus synchronization, artificial insemination, pregnancy and until 30 days after parturition) of dairy cows from 3 to 9 years old that were previously vaccinated from 3 to 8 months. Three groups were monitored with monthly milk and urine collection during 12 months: G1 with seven cows from 3 to 4 years old; G2 with three cows from 5 to 6 years old; and G3 with four cows from 7 to 9 years old. Urine and milk samples were submitted to bacteriological culture and urine and PCR reactions for detection of Brucella spp. and PCR-multiplex for B19 strain identification. Ring test (RT) was also performed in the milk samples, and serum samples were tested by buffered acidified plate antigen test (BAPA). All animals were serologically negative at BAPA and Brucella spp. was not isolated from both urine and milk samples. RT revealed 13/210 (6.2%) positive milk samples. PCR reactions detected DNA of Brucella spp. in 86/420 (20.5%) samples. In urine it was found a significantly higher frequency (35.2%; 74/210) than in milk (5.7%; 12/210), more frequently from the estrus to 150 days of pregnancy and after parturition (6.7%; 10/150), and from 150 days of pregnancy to parturition (3.4%; 2/60), and they were all identified as B19 strain. In three groups, intermittent excretion of B19 strain was detected mainly in urine samples, which confirmed its multiplication and persistence in cows for until 9 years.

Brucella abortus detected in cheese from the Amazon region: differentiation of a vaccine strain (B19) from the field strain in the states of Pará, Amapá and Rondônia, Brazil

“…The higher percentage of samples positive for the vaccine strain was most likely due to the intermittent excretion of this strain, which usually occurs in mammary lymph nodes. There is a higher rate of excretion during the estrus period and after parturition, when there is a long lactation period, resulting in a risk to public health (Pacheco et al 2012). Öngör et al (2006) evaluated 40 samples of illegally made cheese in Turkey (30 of the samples were cheeses made from sheep's milk, and 10 had been made from cow's milk).…”

“…According to a report by Pacheco et al (2012), the intermittent elimination of this strain can happen in milk until the animal is nine years old, with peaks during estrus periods, up to 150 days of pregnancy and postpartum. In view of these facts, it is necessary to assess the elimination period of this strain in the milk of immunized animals at the age recommended by the PNCEBT and to assess the occasional risk of infection to susceptible animals and to humans, especially consumers of milk and its by-products.…”

“…However, the B19 vaccine strain is pathogenic to humans, and there are published reports of accidental infection in veterinarians and vaccinators (Crawford et al 1990, Ashford et al 2004, Santos et al 2005. Pacheco et al (2012) reported that some animals that had been vaccinated at the prescribed age excreted the B19 vaccine strain intermittently in their milk and urine for up to nine years. They emphasized the importance of assessing the risk of infection by this strain in humans and animals.…”

Detection of Brucella spp., Campylobacter spp. and Listeria monocytogenes in raw milk and cheese of uninspected production in the metropolitan area of São Paulo

“…In addition, water pollution must be taken into consideration during sample analysis, as it may interfere with the viability of the cultures of Brucella and Listeria and impair DNA extraction and pathogen detection. Pacheco et al (2012) showed that the strain B19 of Brucella spp. was excreted in the milk and urine of vaccinated cattle in the State of São Paulo.…”

Control of Animal Brucellosis — The Most Effective Tool to Prevent Human Brucellosis

“…The appearance of a small percentage of vaccinated animals that may remain persistently infected with the S19 strain has also been described and may lead to abortions in adulthood [145]. In addition, vaccination may involve the excretion of the vaccine strain in milk and vaginal secretions [146,147]. Even so, although the possible excretion of Rev.…”