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Pure white gold : Subclinical mastitis in dairy camels in
Kenya with a special focus on Streptococcus agalactiae 
M. Seligsohn, Dinah
(2021)
Doctoral thesis, Department of Clinical Sciences, Swedish
University of Agricultural Sciences (Sweden), 141p
 Abstract
In the drylands of the Horn of Africa, camels are
fundamental for food and nutritional security due to their
ability to produce milk despite limited access to feed and
water. Subclinical mastitis (SCM) is common in the region and
has a negative impact on food security and household income. In
this thesis project, we investigated the prevalence, aetiology
and potential biomarkers of SCM. Antibiotic susceptibility was
assessed and the molecular epidemiology of Streptococcus
agalactiae (SRA) investigated through genomic and phylogenetic
analysis. In total, 804 udder quarters in 206 lactating camels
were screened using the California Mastitis Test and milk was
sampled for bacteriological culture. Whole-genome sequencing was
carried out on 122 SRA genomes collected from camel milk and
extramammary sources. The prevalence of SCM at quarter, camel
and herd level was 26%, 46% and 100% respectively and SCM was
associated with a higher age, later stage in lactation and
lesions on the udder or teats. The most common udder pathogen
was SRA, followed by non-aureus staphylococci and Staphylococcus
aureus. Tetracycline resistance was widespread among SRA
isolates. Most SRA isolates from milk belonged to sequence type
(ST) 616 and showed signs of adaptation to the mammary gland.
However, there was a high nasal prevalence in healthy camels and
the same STs were found in milk and extramammary isolates,
suggesting a more complex epidemiology than previously assumed.
Udder health in camels could be improved with the development of
informed control strategies adapted to the local context.
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