High Prevalence of Prototheca bovis Infection in Dairy Cattle with Chronic Mastitis in Ecuador

Abstract

The genus Prototheca, a unicellular, non-photosynthetic, yeast-like microalgae, is a pathogen of concern for the dairy industry. It causes bovine mastitis that currently cannot be cured, and hence generates significant economic losses in milk production. In this study, for the first time in Ecuador, we identify Prototheca bovis as the etiologic agent of chronic mastitis in dairy cattle. Milk samples (n = 458) of cows with chronic mastitis were cultured on Sabouraud Dextrose Agar (SDA). Microscopy and cytB gene sequencing were used to identify Prototheca, whereby Prototheca bovis was isolated from 15.1% (n = 69) of the milk samples, one of the highest infection rates that can be found in the literature in a “non-outbreak” situation. No other Prototheca species were found. We were unable to isolate the alga from environmental samples. We showed that P. bovis was relatively resistant to disinfectants used to sterilize milking equipment on the cattle farms where it was isolated. We discuss how to avoid future infection and also hypothesize that the real prevalence of Prototheca infection in bovine mastitis is probably much higher than what was detected. We recommend a protocol to increase the diagnostic yield in the bacteriology laboratory.

Prototheca spp. in Bovine Infections

“…Indeed, currently, the only control option consists of culling of infected cows [11]. Treatments of infected quarters must be avoided [6]. Post-partum control of healthy cows is mandatory, and bulk milk from negative animals should be weekly examined for the occurrence of Prototheca spp.…”

“…Bovine protothecosis is reported to occur worldwide, in the presence of large dairy herds, mostly in tropical and temperate areas [2]. Predisposing factors to protothecosis are reported to be unclean or repeated intramammary infusions, and antibiotic drug treatments in the udder, where Prototheca would act as an opportunistic pathogen favored by antibiotic-induced suppression of the local flora [3][4][5][6][7][8]. Prototheca spp.…”

“…Bovine mammary gland can be infected by P. bovis following teat trauma by mechanical milking, and subsequent contamination of the teat orifice by environmental organic matter [13,14]. Infection of the mammary gland is often subclinical, without any visual sign, and can be revealed by raised somatic cell count only, although the high result is not continuous [6,15].…”

Alternatives to Antimicrobial Treatment in Bovine Mastitis Therapy: A Review

“…It is defined as inflammation of the mammary gland caused by many different bacteria strains [ 7 ], as well as fungi such as Candida spp. [ 8 ] and algae such as Prototheca [ 9 ]. Literature data show that more than 140 microorganisms are associated with the aetiology of mastitis, indicating that the most common mastitis-associated bacteria include Staphylococcus aureus , Streptococcus agalactiae , Escherichia coli , and Streptococcus uberis [ 10 ], making the treatment approach complex.…”

Development of unconventional treatments for mastitis in dairy cattle

“…Bovine mastitis is the most common disease affecting dairy farms around the world. The economic losses associated with mastitis derive mainly from reduced milk production and, to a lesser extent, culling of lactating animals, veterinary costs, and milk quality penalties ( Mylostyvyi et al, 2021a , b ; Huilca-Ibarra et al, 2022 ). Mastitis is caused by a wide range of pathogenic agents that penetrate the lacteous glands and multiply in the udder.…”