A review on bovine besnoitiosis: a disease with economic impact in herd health management, caused byBesnoitia besnoiti(Franco and Borges, )

Abstract

Bovine besnoitiosis is caused by the largely unexplored apicomplexan parasite Besnoitia besnoiti. In cows, infection during pregnancy often results in abortion, and chronically infected bulls become infertile. Similar to other apicomplexans B. besnoiti has acquired a largely intracellular lifestyle, but its complete life cycle is still unknown, modes of transmission have not been entirely resolved and the definitive host has not been identified. Outbreaks of bovine besnoitiosis in cattle were described in the 1990s in Portugal and Spain, and later several cases were also detected in France. More cases have been reported recently in hitherto unaffected countries, including Italy, Germany, Switzerland, Hungary and Croatia. To date, there is still no effective pharmaceutical compound available for the treatment of besnoitiosis in cattle, and progress in the identification of novel targets for intervention through pharmacological or immunological means is hampered by the lack of molecular data on the genomic and transcriptomic level. In addition, the lack of an appropriate small animal laboratory model, and wide gaps in our knowledge on the host-parasite interplay during the life cycle of this parasite, renders vaccine and drug development a cost- and labour-intensive undertaking.

Bovine besnoitiosis (Besnoitia besnoiti) in an Irish dairy herd

“…Severe acute disease is characterised by pyrexia, subcutaneous oedema, stiffness of the limbs due to swollen joints; conjunctivitis, nasal discharge, photophobia, inspiratory dyspnoea, reduced milk yield and orchitis in bulls (Álvarez-García and others 2013, Cortes and others 2014). Chronic disease is characterised by skin lesions, the presence of macroscopic scleral conjunctival and vestibulo-vulval cysts, and a gradual deterioration in body condition.…”

“…Sterility (aspermatogenesis) in males is caused by a necrotising orchitis leading to atrophy and induration of the testes. The cysts in the scleral (bulbar) conjunctiva are clinically pathognomonic and develop six to seven weeks post infection (Jacquiet and others 2010,Olias and others 2011, Álvarez-García and others 2013, Cortes and others 2014). …”

A small-molecule cell-based screen led to the identification of biphenylimidazoazines with highly potent and broad-spectrum anti-apicomplexan activity

“…This broad-spectrum anti-parasite pattern offers promising perspectives, particularly for veterinary applications. Considering the lack of efficient treatment against besnoitiosis [25,26], the imidazo[1,2-b]pyridazine 8f is particularly attractive in regard to its exceptional potency against B. Besnoiti in vitro growth. These compounds could therefore represent new attractive leads in the field of anti-apicomplexan drug research.…”

From the mainland to Ireland – bovine besnoitiosis and its spread in Europe

“…Economic losses are associated with sterility in bulls, the reduced value of the hides of affected animals, poor body condition, decreased milk production and occasionally abortions and deaths (Alvarez-García and others 2014b, Cortes and others 2014). It has been suggested that transmission mainly occurs through direct contact between cattle (Alvarez-Garcia and others 2013).…”