Occurrence of Campylobacter fetus subsp. venerealis and Tritrichomonas foetus dna in bulls from Alagoas State, Brazil

Ocorrência de dna de Campylobacter fetus subsp. venerealis eTritrichomonas foetus em touros no Estado de Alagoas, Brasil

Bovine reproductive diseases influence herd’s reproduction efficiency and, consequently, lead to significant economic losses. Moreover, lower reproduction success can be related to the presence of specific pathogens that in most cases are not diagnosed (BELLOWS et al., 2002).

Bovine genital campylobacteriosis and trichomoniasis are caused by Campylobacter fetus subsp. venerealis and Tritrichomonas foetus, respectively. The infection caused by classical agents mainly happens at coitus through natural service (BONDURANT, 2005). These diseases have been mainly reported in extensive cattle production system due to the adopted reproduction management practices, which are often based on natural bred (MOLINA et al., 2013).

The infected bull becomes a reservoir and does not present the clinical signs of both diseases, fact that allows agents to long insidiously in herds. The difficulty in identifying the infected bulls, along with inappropriate management practices, makes intra-herd pathogen outbreak easy (MADOROBA et al., 2011).

Reproductive losses resulting from the herein addressed diseases are represented by infected animals’ discharge and replacement (MADOROBA et al., 2011). Moreover, lack of diagnosis and monitoring are some of the factors contributing to the limited knowledge about the adverse effects caused by these diseases (MICHI et al., 2016).

Although bovine genital campylobacteriosis and trichomoniasis are Compulsory Notification Diseases (CND), there is no specific regulation about the need of diagnostic tests applied for bull trading purposes (MICHI et al., 2016). Such lack of regulation may favor the shortage of information about the real epidemiologic situation of such diseases (SWAI et al., 2005).

The aim of the present study was to diagnose infection caused by C. fetus subsp. venerealis and T. foetus in producer bulls from breeder farms located in Alagoas State, Brazil.

The occurrence rate of infection caused by C. fetus subsp. Venerealis was 4.9% (8/162) and of 3.0% (5/162) for T. foetus when the PCR method was adopted. Isolation did not show T. foetus in any of the assessed samples.

Results of infections caused by C. fetus subsp. venerealis and T. foetus in bulls distributed by property are shown in Table 1. Co-infections were not observed in the analyzed animals; however, of the five propertys presenting positive animals, two (40.4%) had animals positive for Campylobacter fetus subsp. fetus or Tritrichomonas foetus.

Table 1
Occurrence of infections caused by Campylobacter fetus subsp. venerealis and Tritrichomonas foetus in bulls distributed by rural property focused on bovine reproduction in Alagoas State, Brazil.

The present study is pioneer in reporting infection caused by C. fetus subsp. venerealis and T. foetus in bulls from Alagoas State, Brazil. The herein recorded results are similar to records from other Brazilian states (LEAL et al., 2012; OLIVEIRA et al., 2015), as well as from foreign countries, where there is prevalence lower than 10% (SWAI et al., 2005; MADOROBA et al., 2011; MOLINA et al., 2013). Higher infection prevalence has been reported; however, it is worth highlighting that variations in outcomes may result from sampling design, animal’s age, sanitation and reproductive management, and from the adopted diagnostic method. Madoroba et al. (2011) state that other variables, such as herd size and geographic area, can influence results in different researches.

Despite the low C. fetus subsp. venerealis (4.9%) and T. foetus (3.0%) occurrence in the present study, the importance of including the diagnosis of these agents in bulls from breeders focused on reproduction is noteworthy. These animals are reservoirs and can spread the agents through natural bred or through artificial insemination with contaminated semen (EAGLESOME; GARCIA, 1997; CAMPERO; COBO, 2006). Infections caused by these pathogens are enzootic, mainly in beef cattle bred in extensive cattle production systems, wherein sanitation control is poor and animals reproduce through natural bred, clean-up bull and artificial insemination with contaminated semen (BONDURANT, 2005).

Since bulls are asymptomatic, they should not stay with the herds, because the newly acquired animals in it must be infection-free. That is the reason why regulation tests must be conducted before the breeding season. Brazil does not have specific Bovine Genital Campylobacteriosis and Trichomoniasis control and eradication programs; however, it is recommended to replace the infected animals by younger bulls with health certificate (TRUYERS et al., 2014; YINZHU et al. , 2014). With regard to Campylobacteriosis, it is possible associating antibiotics and vaccination (BONDURANT, 2005), but antibiotic therapy presents limited efficacy (MICHI et al., 2016).

Reproduction management in the visited breeders associates artificial insemination and natural bred with clean-up bull in females who did not have pregnancy confirmation 30 days after artificial insemination. It is known that the natural bred with infected animals and the use of clean-up bull in positive herds are risk factors for these sexually transmitted diseases (PELLEGRIN et al., 1999). The use of contaminated semen in association with natural bred are risk factors that enable C. fetus subsp. venerealis and T. foetus outbreak maintenance in bovine herds; consequently, these cows can be infected and infect other bulls in the herd (HANCOCK et al., 2015).

Collections showed that breeders who had positive animals recorded bull:female relation 1:30, on average, thus evidencing the possible outbreak potential of these pathogens in females. Such result can considerably influence herd reproduction indices. It is essential identifying infected bulls due to epidemiological aspects, since these animals can have contact with a large number of females throughout the reproduction period, fact that can facilitate agent transmission (HUM et al., 2009; MSHELIA et al., 2010). According to the review carried out by Bondurant (2005), T. foetus transmission rate through natural bred from infected bulls to susceptible females varies from 30% to 70%. The study conducted by Waldner et al. (2017) showed that herds presenting at least one infected bull had their pregnancy rates 2.35 times lower than herds without contaminated bulls.

With regard to the number of breeders with positive animals, 40% and 30% of them had at least one animal infected with Campylobacter fetus subsp. venerealis and T. foetus, respectively. One hundred percent (100%) of these breeders were located in East Alagoas State and traded reproducers with neighbor regions. However, based on the adopted sampling design, it is not possible stating that animals bred in the East region are more prone to infections caused by these agents, since the sanitation and reproductive managements adopted in all its properties were similar. The study carried out by Molina et al. (2013) in Argentina did not show homogeneous distribution of these diseases among different regions countrywide. They also indicated that the risk factors are similar for both infections.

It was observed that 100% of breeders have miscarriage records. Infection caused by C. fetus subsp. venerealis leads to reproductive issues such as temporary infertility, heat repetition, embryonic death and miscarriage (JIMENEZ et al., 2011). Besides the aforementioned clinic signs, pyometra was observed in approximately 5% of cows with Trichomoniasis, due to the bacterial contamination that happens when the fetus is lost (BURNS et al., 2010).

The lack of infected-animal diagnosis enables agent maintenance, and consequences deriving from the infection mainly compromise cows’ reproductive function (GONZÁLEZ-CARMONA et al., 2012; YAO et al., 2015). Thus, it is possible recording significant losses due to infertility and miscarriages, and it increases the interval between labors and calf production decrease (MARDONES et al., 2008).

Most positive samples in our study were from bulls in the mean age group 3.5 years. However, the age of animals positive for C. fetus subsp. venerealis and T. fetus in property B was 5 years or older. Young and old bulls present different ability to harbor C. fetus subsp. venerealis and T. foetus. The mucosa of bulls older than 5 years has a larger number of folds and deeper crypts, which can reduce oxygen supply and favor the susceptibility to infections caused by anaerobic microorganisms (CLARK et al., 1974). Overall, young bulls can produce less smegma in their penile mucosa, where folds and crypts are poorly developed. Such process impairs the establishment and persistence of microorganisms. In addition, one must take into account that young animals are more resistant to infection (EAGLESOME, GARCIA, 1997; MICHI et al., 2016).

Co-infections of both agents were not observed in the present study; however, two breeders (A and B) had Campylobacter fetus subsp. venerealis and T. foetus positive animals. Biological material collection in these two rural properties was performed before the bred season, and it may have favored a more precise diagnosis of both agents. The biological material collection time can influence infection-prevalence results, since the concentration of these agents in the preputial smegma tend to be weaker during the bred season (MOLINA et al., 2013).

It was not possible isolating T. foetus in any of the collected samples. These results are similar to those recorded by Rocha et al. (2009) and Mai et al. (2013), who did not isolate T. foetus in bull preputial-wash samples. The non-isolation of the agent may due to the parasite’s low concentration in the analyzed samples, since 3.0% of the samples were positive in PCR. The PCR technique is the most sensitive in comparison to isolation, because it enables detecting the parasite’s DNA even at low concentrations (MUTTO et al., 2006).

Although the parasite was not detected in the culture, it was possible visualizing mobile and round-shaped structures during the microscopic analysis. T. foetus morphological changes into the pseudocysts form have been reported (PEREIRA-NEVES et al., 2003; PEREIRA-NEVES; BENCHIMOL, 2009). Pereira-Neves et al. (2011) demonstrated that T. foetus pseudocysts are found in the fresh preputial smegma from bulls. These changes can be attributed to stress conditions such as room temperature variations and inhibitors of cultivation medium constituents (ONDRAK, 2010).

Regular bull-monitoring programs concerning venereal diseases become necessary, since they aim at reducing infection risks and, consequently, at improving bovine reproduction indices in order to increase production, profitability and sustainability, mainly when it influences the number of calves born per year. It is worth taking into account that this is one of the most important variables affecting the economic efficiency in bovine herds (COLLANTES-FERNÁNDEZ et al., 2014).

The occurrence of infections caused by C. fetus subsp. venerealis and T. foetus in bulls from Alagoas State, Brazil was confirmed. Accordingly, it is recommended to conduct laboratory examinations focused on sexually transmitted diseases in rural properties breeding reproducers in order to reduce the financial impacts caused by them.

The authors are grateful to CAPES for the PhD scholarship and to CNPq for the productivity scholarship granted to the last author (process n. 305072/2015-3).