Mastitis
Pathogen Information: Streptococcus agalactiae
Introduction:
Streptococcus
agalactiae is a gram-positive bacterium and a highly contagious infectious
agent of the bovine mammary gland. The organism may persist on damaged teat
skin, elsewhere on the cow, and in the environment
Epidemiology/
Clinical particulars:
The risk
for contracting S. agalactiae mastitis is highest early in lactation and
increases with increasing parity. Streptococcus agalactiae is highly contagious
and is commonly spread on the hands of milkers or by contaminated milking
machinery.
The initial
course of Strep. agalactiae infection is mild to moderate mastitis which is
clinically indistinguishable from that caused by other organisms. There is
local inflammation of the udder with abnormal appearance to the milk, and there
may be a brief period of fever, but this is usually short-lived enough that it
is not observed. If there is no treatment of the initial infection, it will
become persistent. The cow will then have ongoing inflammation and periodic
flare-ups of clinical mastitis with progressive fibrosis of mammary tissue and
a resulting progressive decrease in milk production. Elevations in Somatic Cell
Counts of affected cows may be marked.
Diagnosis:
Standard
microbial culture techniques, used in conjunction with the CAMP test or a latex
agglutination test, are a reliable way to identify cows with Strep agalactiae
mastitis.
Specifics
of Therapy and Control:
Strep.
agalactiae is highly responsive to therapy with appropriate antimicrobial
drugs. It is important to quickly and appropriately treat clinical cases, as
the bacteria are highly contagious and spread easily throughout the herd. Strep
agalactiae can become a herd problem that requires herd culturing and treatment
to be brought under control. In herds where Strep agalactiae has not become a
widespread problem, it may be kept under control through the use of
post-milking teat dipping and antibiotic treatment at dry-off.
There is no
effective vaccine against Streptococcus agalactiae mastitis.
Link to
control and antimicrobial issues pages
