*3.1.4. Chlamydia sp.*

Chlamydiosis is a disease with worldwide distribution that affects several species of mammals and especially birds. The main species causing disease is Chlamydia psittaci [37] and it is associated with pneumonia, conjunctivitis, enteritis, arthritis, pericarditis, orchitis and uterine infections, as being the last two related to cases of perinatal abor‐ tion and stillbirths [38].

The microorganism can enter through digestive, respiratory or venereal via and multiply in the epithelial cells that are carried by macrophages and disseminate by the chain of regional lymph nodes and remaining unapparent, but sometimes causes diseases in organs nearby routes for entrance of the agent. In genital infections, the semen may be contaminated and it is responsible for birth of the weak (which eliminate the bacteria during long period, there‐ fore they are an important vehicle for horizontal transmission of infection [39].

For diagnostic purposes, several serological tests can be performed and the agent detection can be performed through the isolation and PCR. However, fecal sample has little diagnostic value because studies have demonstrated the presence of Chlamydia in healthy pigs [40].

Although the main dissemination sources to be the asymptomatic animals, the infected ani‐ mals showing clinical signs of disease should be isolated and treated [41]. It is important to avoid the contact of pigs with birds and other species that are susceptible to Chlamydiosis.

### **3.2. Viral contaminants of semen**

Recently, a high number of viral agents have been detected in the semen of pigs. Those agents are mainly associated with reduction of the animal's reproductive performance and fertility problems [6]. Usually, the infections by virus is source of major concern to the swine producer than bacterial infections. This fact is due to characteristics of the viral agents, which can be eliminated at high loads before the first signs of the illness or when the signs are mild or unapparent, as causing a significant epidemiological problem. However, it is be‐ lieved the high virus load to be only removed via semen during viremia. During this period, the breeding male presents clinical signs, therefore it is generally removed. In any way, the control procedures are hindered because the animals can continue to eliminate the virus af‐ ter disappearance of the signs. In addition, the efficacy of the available commercial antiviral products are not commercially proved and may exhibit a high toxicity level to the semen.

Some major viral agents, which may be present in the genital tract and eliminated through semen, are summarized in the sequence.
