Antibodies against Apicomplexa protozoa and absence sarcocysts in heart tissues from horses in southern Brazil

Abstract

Sarcocystis spp., Neospora spp., and Toxoplasma gondii are Apicomplexa protozoa that can infect horses. This study aimed to investigate the occurrence of antibodies against Sarcocystis spp., Neospora spp., and T. gondii in horses slaughtered in southern Brazil. The presence of histological lesions, tissue cysts, and Sarcocystis spp. DNA in the hearts of these horses was also investigated. A total of 197 paired serum and heart samples were evaluated by serology and direct microscopic examination; 50 of these samples were subjected to histopathological and PCR analyses. Antibodies against at least one of the protozoa were detected in 146 (74.1%) of the serum samples. The frequencies of positive serology were: 36% (71/197) against Sarcocystis spp., 39.1% (77/197) against Neospora spp., and 47.2% (93/197) against T. gondii. No cysts, Sarcocystis spp. DNA, or histopathological lesions were observed in myocardial tissue samples. The frequencies of antibody seropositivity against Sarcocystis spp., Neospora spp., and T. gondii showed that horses are frequently infected by these parasites in southern Brazil. The absence of sarcocysts in horse tissues is compatible with their role as aberrant/accidental hosts in the life cycle of Sarcocystis spp.. Keywords: Accidental hosts, epidemiology, Sarcocystis spp., Neospora spp., Toxoplasma gondii. ResumoSarcocystis spp., Neospora spp. e Toxoplasma gondii são protozoários que pertencem ao filo Apicomplexa e que podem afetar equinos. O objetivo deste estudo foi investigar a ocorrência de anticorpos contra Sarcocystis spp., Neospora spp. e T. gondii. A presença de lesões histológicas, cistos teciduais e DNA de Sarcocystis spp. no miocárdio de equinos abatidos no sul do Brasil também foi investigado. Um total de 197 amostras de soro juntamente com as respectivas amostras de coração, foram avaliadas por sorologia e exame microscópico direto. Destas amostras, 50 foram selecionadas e submetidas a análise histopatológica e PCR. Anticorpos contra pelo menos um dos protozoários foi detectado em 146 (74,1%) das amostras de soro. As frequências de sorologia positiva foram: 36% (71/197) para Sarcocystis spp., 39,1% (77/197) para Neospora spp. e 47,2% (93/197) para T. gondii. Não foram encontradas lesões histopatológicas, cistos e DNA de Sarcocystis spp. nas amostras de miocárdio dos equinos. As frequências de soropositividade para Sarcocystis spp., Neospora spp. e T. gondii mostra que os equinos podem ser frequentemente infectados por estes parasitas no sul do Brasil. A ausência de sarcocistose no coração dos equinos é compatível com seu papel como hospedeiro errático/acidental no ciclo de vida deste protozoário.

Brazilian Horses from Bahia State Are Highly Infected with Sarcocystis bertrami

“…and the parasite could not be found in any examined heart [ 18 ]; in contrast, these authors detected 73.9% (34/46) of Sarcocystis sp.-infected animals when other tissues (esophagus, diaphragm, skeletal muscle and tongue) from the same 46 horses were examined for the parasite. Based on our results and in previous reports [ 18 , 29 ], S. bertrami has a low tropism for equine heart tissues, whereas gluteal muscle, esophagus, diaphragm and tongue are more often infected by the parasite.…”

“…It is worth noting that the only published Brazilian study that aimed to detect Sarcocystis sp. in heart tissues from 197 horses had negative results [ 29 ]. In a report from China, heart samples of 46 horses were tested for Sarcocystis sp.…”

A Systematic Review and Meta-Analysis on the Occurrence of Toxoplasmosis in Animals Slaughtered in Brazilian Abattoirs

“…A total of 57 peer-reviewed published articles studying the prevalence of toxoplasmosis in animals slaughtered in Brazilian abattoirs were found ( Table S2 ) [ 9 , 10 , 11 , 12 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 ,…”

Sarcocystis neurona and related Sarcocystis spp. shed by opossums (Didelphis spp.) in South America

“…IFAT has been conducted with cutoffs between 1:20 and 1:80. Even in some studies using low cutoffs (1:25 or 1:50), the frequencies of antibodies in horses were below 50% (Antonello et al, 2015;Cazarotto et al, 2016;Koch et al, 2019;Portella et al, 2017;Spohr et al, 2018). It is noteworthy that serological studies conducted using SnSAG4 ELISA reported higher antibody frequencies (higher than 60% in most regions) than studies conducted using IFAT (Table 2).…”