Scientific Papers

Seroprevalence of Chlamydia abortus and Brucella spp. and risk factors for Chlamydia abortus in pigs from China

Chlamydia abortus (C. abortus) and Brucella spp. are important zoonotic pathogens with a global distribution that infect a wide range of hosts, including goats, sheep, cattle, and pigs (Megid et al., 2010; Schautteet and Vanrompay, 2011). These pathogens are capable of causing abortion and infertility in animals, posing a significant threat to the advancement of animal husbandry (Es and L, 2012; Sachse et al., 2005). Furthermore, both pathogens can infect humans and represent a significant threat to public health (Everett, 2000; Gong et al., 2021).

Animals contract these two pathogens primarily through contact with contaminated substances from aborted fetuses or by ingestion of infected food. Transmission can occur naturally through mating or artificial insemination (Godfroid et al., 2013; Longbottom et al., 2002; Rodolakis and Yousef Mohamad, 2010; Schautteet and Vanrompay, 2011). Infected pregnant females may deliver preterm, stillborn, or mummified fetuses, depending on the timing of infection (Galińska and Zagórski, 2013; Phillips et al., 2019). Interestingly, C. abortus- and Brucella spp.-infected animals have similar characteristics, such as abortions in the last trimester, and the dam does not typically show any apparent symptoms before abortion, making it challenging to clinically differentiate between the two infections (Khan et al., 2021; Longbottom and Coulter, 2003). Furthermore, infected animals often exhibit subclinical or silent infections, making detection challenging and increasing the risk of pathogen transmission among herds (Borel et al., 2018; Olsen and Tatum, 2017).

Humans contract C. abortus and Brucella spp. primarily through the consumption of unpasteurized dairy products and undercooked meat or by handling aborted fetuses or infected animal placentas (Corbel et al., 2006; Qin et al., 2015; Zheng et al., 2018). C. abortus can cause severe pneumonia and miscarriages in pregnant women (Rohde et al., 2010; Zhu et al., 2022). Brucellosis poses a significant threat to human life and health, manifesting as a reproductive disorder, debilitating illness, and undulating fever (Megid et al., 2010). Multiple cases of Brucella spp. transmission from pigs to humans have been reported (Tian et al., 2017; Wang et al., 2019). Moreover, Chlamydia suis has been isolated from human nasal and pharyngeal swabs, suggesting the possible transmission of Chlamydia from pigs to humans (De Puysseleyr et al., 2017). Pigs, which are in close contact with humans, are at high risk of transmitting these two pathogens to humans.

China is the leading global producer and consumer of pork, with live pigs playing a crucial role in animal husbandry. However, information on the seroprevalence of C. abortus and Brucella spp. in pigs is limited, which impedes prevention and control efforts and increases the risk of transmission from pigs to humans. This study aimed to investigate the prevalence of C. abortus and Brucella spp. in pigs in China, identify potential risk factors, and propose measures and strategies to prevent and control their spread.

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