Skip to main content

Table 2 Controlled experiments that evaluate the protective efficacy of RB51 in comparison only with unvaccinated controls

From: A review of three decades of use of the cattle brucellosis rough vaccine Brucella abortus RB51: myths and facts

Experiment (reference)

Vaccine

Dose

Nº bovines

Nº infected (%)a

Relative Risk (CI)b

Attributable fraction (%)c

1 [128]d

RB51

1.0 × 1010

10

2 (20.0)

4.0 (1.11–14.35)

75.0

Saline

 

10

8 (80.0)

  

2 [64]e

RB51

1.0–3.0 × 109

15

0 (0.0)

29.7 (1.92–458.3)

96.6

Saline

 

6

6 (100)

  

3 [129]f

RB51

1.0 × 109

4

4 (100)

0.66 (0.46–0.95)

NCg

RB51

1.0 × 1010

26

12 (46.0)

1.44 (0.83–2.49)

30.0

Saline

 

15

10 (67.0)

  

4 [61]h

RB51

1.5 × 1010

20

7 (35.0)

2.46 (1.02–5.88)

59.3

Saline

 

13

11 (84.6)

  

5 [65]i

RB51

1.0 × 1010

28

24 (85.7)

1.08 (0.87–1.33)

7.69

Saline

 

14

13 (92.8)

  
  1. aIn all experiments, infection was defined by bacteriological isolation of the B. abortus 2308 challenge strain but the methodology was not always similarly thorough (compare footnotes d, e, f, h and i)
  2. bRelative Risk (RR) is the ratio of the probability of infection in the unvaccinated (control) and vaccinated groups. CI, confidence interval
  3. cPopulation attributable fraction (AF) estimates the proportion of infection cases that could be avoided by vaccination
  4. dIn Experiment 1, the samples cultured were limited to vaginal fluids and milk obtained on day 3 and 14 after parturition, and parotid, iliac and mammary lymph nodes obtained at necropsy two months after parturition but only in non-excretors; lungs and abomasal fluids of fetuses were also examined
  5. eIn Experiment 2, the results of two groups vaccinated with 1 × 109 and 3 × 109 CFU are pooled; a thorough bacteriological search was performed, including samples of milk, vaginal fluids, placenta, and, after necropsy, mammary gland, spleen, liver, and the most important lymph nodes
  6. fIn Experiment 3, the bacteriological search included only the animals that could be necropsied and observed for abortion
  7. gNC, not calculable
  8. hIn Experiment 4, specimens of parotid, retropharyngeal, prescapular, supramammary, internal iliac, and bronchial lymph nodes, mammary gland, lung, spleen, liver, milk, vaginal swab and placentome were cultured
  9. iIn Experiment 5, challenge was performed 4, 5 and 6 years after vaccination (results are pooled) and specimens of lymph nodes (bronchial, hepatic, internal iliac, mandibular, mesenteric, parotid, prescapular, retropharyngeal, and suprammamary), lung, liver, spleen and caruncle or placentome, plus samples of milk and mammary tissue were cultured
Back to article page

BMC Veterinary Research

ISSN: 1746-6148

Contact us