Intramammary infection in the one humped Kenyan camel camelus dromedarius with streptococcus species and its influence on subclinical mastitis

Abstract

Camels are kept for milk production in many arid and semi arid lands (ASAL) of Africa and Asia. They are adapted to survive in these arid lands and produce milk for a long period even under unfavourable conditions. In Kenya, the ASAL area is over 70% and camel milk is the main protein supplement to the pastoralists in these areas. Despite their importance as milk producing animals, knowledge regarding under health and milk hygiene is non-existent in Kenya. Information on mastitis screening tests and their relevance for application to the camel is lacking.

The present study was carried out to characterize streptococcus species associated with sub clinical mastitis in the Kenya camel (under ranch conditions) and their effect on milky yield. The aim was also to assess the value of inflammatory markers, thus California mastitis test (CMT), Conductivity and somatic cell counts (SCC) as indicators of sub clinical mastitis test (CMT), Conductivity and SCC. The investigation took a period of 11 months. A total of 435 milk samples were collected. Infection status of quarters was determined by bacteriological analysis of milk samples.

Bacterial growth was detected in 290 of 435 milk samples cultured while 145 samples did not yield any growth. Of the total bacterial isolates, streptococci were the most frequently isolated representing 46.9%. The most frequently isolated sub clinical mastitis streptococcus pathogens were group D(non-enterococci) streptococci that formed 63.7% of the total streptococcal isolates. The varidans and enterococci streptocci formed 23.1% and 2.2% respectively. Streptococcus dysgalactiae identified, as Lancefield type G was 7.7% while Streptococcus agalactiae (Lancefield type B) was only 3.3%. The group D and G streptococci were classified as environmental streptococci while group B was classified as infectious streptococci. Therefore, the environmental streptococcal pathogens were responsible for the sub clinical mastitis in the camels investigated.

Infection with infectious (pathogenic) streptococci showed a low mean milk yield as compared to infection with environmental streptococci. However, there was a general decrease in mean milk yield in all infected quarters. Milk conductivity increased with infection. Conductivity of milk samples from quarters infected with infectious streptococci was higher than that of quarters infected with environmental streptococci. A number of quarters with elevated conductivity showed a somatic cell count (SCC) of more than 5 x 105 cells ml-1 when infected by infectious streptococci and some environmental streptococci had higher mean values for SCC than those quarters with environmental streptococci. Conductivity when used together with SCC proved to be more accurate as sub clinical mastitis indicator in camels. However, mean conductivity for CMT positive cases was higher. The main conclusions in this study were that sub clinical mastitis in camels is due to streptococcal species especially environmental streptococci. The bovine sub clinical mastitis detection methods cannot apply to the camelidae.