**5. Prevalence of mastitis pathogens and somatic cell counts**

In Mexico, the prevalence of mastitis pathogens in BTM SCC from 224 milk samples of 112 herds was as follows; *Mycoplasma* spp were isolated from 62 herds (55%), *S. aureus* from 34 cattle barns, *S. uberis* and CNS were isolates from milk from 42 herds (37.5%) and from 43 (38.3%) bulk tank milk samples. The geometric mean of SCCs was 465, 000 cells/ml. No significant differences were observed in SCCs between *Mycoplasma* spp, *S. aureus* and *Streptococcus* spp positive and negative herds (P>0.5) (Miranda-Morales, *et al.,* 2008).

In Latin America, few data had been carried out regarding microorganism's prevalence and SCC in cases of clinical and subclinical mastitis. Nonetheless, regarding bovine mastitis, Calvinho *et al*, (2005) assessed the primary pathogens prevalence, and its relation with the general udder health status in Argentina from 1983 to 2001. The subclinical mastitis showed a prevalence of 25.3% of *S. aureus* in the 80's and through the years it has been decreasing until a level of 13.9% in 2000. This situation was also observed regarding *S. agalactiae,* which has been reducing its prevalence from 8.8 to 1.6%; *Streptococcus* spp from 19.3 to 6.5% and coliforms from 2.7 to 2%. The prevalence observed for the same pathogens causing clinical mastitis, were low prevalence levels for *S. aureus , S. agalactiae* and coliforms respectively from 34.45 to 29.2%, 13 to 3.9%, and from 20 to 4.4%. In contrast the CNS, *S. dysgalactiae* and *Streptococcus* spp registered rising prevalence from 2.1 to 12.7%, 1.7 to 15.9%, and from 6.4 to 19.8% respectively. This situation was also seen among SCC registering levels of 400, 000 to 900, 000 cells/ml in the 80's, since after a sustained decrease in the SCC from BTM in recent years; in 2004 ranging around 300, 000 cells/ml, and in 2005, an average of 384, 000 cells/ml (SAGPyA, 2005). The producers have been implemented systematically control programs based on hygiene and antibiotic therapy, there has been a decrease in the prevalence of contagious pathogens and environmental relative increase, however it should be noted that the SCC values remain high compared with those of countries with high dairy development. In Perú, Ortiz, *et al*., 2006, assessed the SCC in dairy herds of different technological levels in Arequipa, milk samples were collected twice in 2005. The stables were stratified according to their technological level in high, medium and low. The general average of SCC were 505 x 103 x 103 ± 150 cells/ml, and significant differences between technology levels were identified as SCC were 353, 559 and 603 x 103 cells/ml for high, medium and low, respectively (p <0.05), feature explained by the dilution of somatic cells in a greater volume of milk and a more rational application of best practices to prevent and control mastitis in the most sophisticated stables. On the other hand, limited access to training adversely affects low-technology. In a study by Moraga *et al* (1994) in Chile, the prevalence of bovine mastitis in the years 1972 to 1992; subclinical mastitis in 1972 was 45.42%, and by 1992 the prevalence had reduced to 38.65%, traduced on a 14.90%. Regarding clinical mastitis a continuous prevalence reduction of 12.86% from 74.41% to 64.84% was determined during the same period. Furthermore, the SCC were reduced from 1,983,310 cells/ml to 1,055,240 cells/ml, in these 20 years. These decrements on the severity of subclinical mastitis obeys the current control measures spread in the early 70's, such as post-milking disinfection of teats and drying therapy used in the 66.7% of the farms studied as well as the general infrastructure improvement. Finally despite the progress, acceptable control mastitis levels have not yet been reached.

366 Milk Production – An Up-to-Date Overview of Animal Nutrition, Management and Health

*Streptococcus spp, Escherichia coli,* and SCN.

products during shelf-life (Hayes & Boor, 2001). The laboratory pasteurization count (LPC), another selective count, estimates the number of thermoduric bacteria, mainly from the surfaces of poorly cleaned farm equipment that will survive a laboratory-scale batch pasteurization process. Thermoduric bacteria have been associated with spoilage of pasteurized milk. The Coliform count (CC) measures the number of coliform bacteria in milk, organisms primarily coming from the cow's environment, therefore high CC will give an estimation of the production sanitary status and practices. Coliforms can also incubate on

The results from a case–control study indicated that TAC and PIC were mostly related to cow and stall hygiene, whereas LPC and CC were related to equipment hygiene (Elmoslemany *et al*., 2009; Jayarao *et al*., 2004), and included among the bacteria groups associated with bovine IMI are *Staphylococcus aureus, Streptococcus agalactiae, Mycoplasma spp,* 

In Mexico, the prevalence of mastitis pathogens in BTM SCC from 224 milk samples of 112 herds was as follows; *Mycoplasma* spp were isolated from 62 herds (55%), *S. aureus* from 34 cattle barns, *S. uberis* and CNS were isolates from milk from 42 herds (37.5%) and from 43 (38.3%) bulk tank milk samples. The geometric mean of SCCs was 465, 000 cells/ml. No significant differences were observed in SCCs between *Mycoplasma* spp, *S. aureus* and

In Latin America, few data had been carried out regarding microorganism's prevalence and SCC in cases of clinical and subclinical mastitis. Nonetheless, regarding bovine mastitis, Calvinho *et al*, (2005) assessed the primary pathogens prevalence, and its relation with the general udder health status in Argentina from 1983 to 2001. The subclinical mastitis showed a prevalence of 25.3% of *S. aureus* in the 80's and through the years it has been decreasing until a level of 13.9% in 2000. This situation was also observed regarding *S. agalactiae,* which has been reducing its prevalence from 8.8 to 1.6%; *Streptococcus* spp from 19.3 to 6.5% and coliforms from 2.7 to 2%. The prevalence observed for the same pathogens causing clinical mastitis, were low prevalence levels for *S. aureus , S. agalactiae* and coliforms respectively from 34.45 to 29.2%, 13 to 3.9%, and from 20 to 4.4%. In contrast the CNS, *S. dysgalactiae* and *Streptococcus* spp registered rising prevalence from 2.1 to 12.7%, 1.7 to 15.9%, and from 6.4 to 19.8% respectively. This situation was also seen among SCC registering levels of 400, 000 to 900, 000 cells/ml in the 80's, since after a sustained decrease in the SCC from BTM in recent years; in 2004 ranging around 300, 000 cells/ml, and in 2005, an average of 384, 000 cells/ml (SAGPyA, 2005). The producers have been implemented systematically control programs based on hygiene and antibiotic therapy, there has been a decrease in the prevalence of contagious pathogens and environmental relative increase, however it should be noted that the SCC values remain high compared with those of countries with high dairy development. In Perú, Ortiz, *et al*., 2006, assessed the SCC in dairy herds of different technological levels in Arequipa, milk samples were collected twice in 2005. The stables were stratified according to

*Streptococcus* spp positive and negative herds (P>0.5) (Miranda-Morales, *et al.,* 2008).

residual films of improperly cleaned milking equipment (Reinemann *et al.,* 2003).

**5. Prevalence of mastitis pathogens and somatic cell counts** 

In Mexico, Infante, *et al*., (1999), observed in a commercial dairy herd (282 cows) in lactation a sudden atypical clinical mastitis outbreak with 28 cases of severe purulent mastitis, hard swollen mammary glands and lacking systemic signs of illness. The treatment non- responsive cases (Table 1) suggested the spreading through the milking machine and other management practices, further cultures determined the presence of *Mycoplasma californicum* and *Mycoplasma canadense*. A second study performed by Miranda-Morales, *et al*., (2008), revealed that *Mycoplasma* spp were present in the 55% of the 62 herds included, also that *S. aureus* was present in the 30% of cattle barns and that *S. uberis* and CNS were present in 42 herds (37.5%) and 43 herds (38.3%) according to the BTM samples, respectively. The geometric mean of SCCs was 465, 000 cells/ml and no significant differences were observed among *Mycoplasma* spp, *S. aureus* and *Streptococcus* spp positive and negative herds (P> 0.5) (Table 2 and 5).

Overall, prevalence of mastitis is over 10%, in samples of direct milk *Staphylococcus aureus* has a prevalence >30% in contrast to an <5% prevalence of *Streptococcus agalactiae*, and a prevalence between 15 and 41% has been reported for CNS. *Mycoplasma* has been reported in a few prevalence studies and environmental mastitis pathogens have an average prevalence of >15%. However in BTM *Staphylococcus aureus* have registered consistently high figures from 30% and up to 74%, followed by the prevalence values of *Streptococcus agalactiae* around 40%, and in BTM *Mycoplasma* spp had variable prevalence figures ranging from 50% to 85%. Regarding SCC, values of 100, 000 – 700, 000 cells/ml are associated to the presence of *Staphylococcus aureus* and *Streptococcus agalactiae.* For *Mycoplasma* spp, SCC values are > 200, 000 cells/ml, and SCC of 100, 000 and up to 500, 000 cells/ml are associated to CNS infection. Currently, in America, BTM-SCC values are around > 200, 000 cells/ml, therefore milk quality requirements are barely meet except for some regions that had achieved SCC levels of < 200, 000 cells/ml, and low prevalence of mastitis associated pathogens. Therefore, herd overall studies are mandatory for mastitis control programs including duration of lactation, season, milk production and parity. But will also be guided by the prevalence of mastitis pathogens and by the, geographic region and production practice.


**Table 3.** SCC values of BTM milk samples associated with mastitis pathogens of some regions worldwide.


**Table 4.** General overview of mastitis prevalence.


**Table 5.** Prevalence of contagious mastitis pathogens in BTM.

## **Author details**

368 Milk Production – An Up-to-Date Overview of Animal Nutrition, Management and Health

worldwide.

Country BTM SCC Reference

**Table 3.** SCC values of BTM milk samples associated with mastitis pathogens of some regions

Zurita., *et al*., 1972 1 137 48,81% Moragay., *et al*., 1993 30 2 321 41,10% Chaves., *et al*., 1996 19 37% Calvinho., *et al*., 2001 86 62,8% Sampimon., *et al*., 2009 49 1 960 10,8% Castillo., *et al*., 2009 2 116 72,61%

> *Staphylococcus aureus*

Kunkel, 1985 2346 *- - 1.3%*  Guillemette., *et al*., 1992 *- 6% -* 

Kirk., *et al*., 1997 267 *- - 78.2%*  Fox., *et al*., 2003 664 *- - 14%*  Sato, 2004 118 *71.6% - -*  Sato, 2004 40 *27.55% - -*  Riekerink., *et al*., 2006 258 74 % 1.6 % 1.9% Howard, 2006 7 57.1% - - Ghazaei, 2006 48 - - 85,25%

Reference No. of Dairy herds No. of

**Table 4.** General overview of mastitis prevalence.

Schoonderwoerd., *et al*.,

Miranda-Morales., *et al*.,

Richard & Riekerink., *et* 

1993

2008

*al.*, 2010

Reference Dairy herds

**Table 5.** Prevalence of contagious mastitis pathogens in BTM.

studied

Keefe., *et al*., 1997 *70% 18%* 

Seattle, USA 93 533 000 cells/ml Fox L.K. *et al.*, 2003 Argentina 7358 384 000 cells/ml SAGPyA, 2005 Peru 15 500 000 cells/ml Ortiz Z.C. *et al*., 2006 Argentina 51 250 000 cells/ml Vissio, C., *et al.*, 2007 Mexico 112 465 000 cells/ml Miranda-Morales R.E., *et al.*, 2008

bovine

*Streptococcus agalactiae*

*- 43% -* 

112 30% - 55%

226 74% 4% -

Gland infected (%)

> *Mycoplasma*  spp

Erika Margarita Carrillo-Casas *Departamento de Biología Molecular e Histocompatibilidad, Hospital General "Dr. Manuel Gea González", México* 

Rosa Elena Miranda-Morales

*Laboratorio de Micoplasmosis, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, México* 

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