Lower seroprevalence of Toxoplasma gondii in swine from central China after an outbreak of African swine fever

Abstract

Toxoplasma gondii is widespread worldwide and can infect swine. This study evaluated the seroprevalence of T. gondii in swine from central China after an outbreak of African swine fever (ASF). A total of 2683 swine serum samples were collected from farms in four provinces. Of the serum samples, 1.42% (38/2683) (95% CI, 1.03–1.94) tested positive for T. gondii IgG antibody by a modified agglutination test (MAT) (cut-off: 1:25). Comparing with the results of previous studies, specifically our survey from before the outbreak, the seroprevalence of T. gondii in swine from central China was significantly decreased after the occurrence of ASF (OR = 7.679, 2015–2017 vs. 2019–2020). In general, the proportion of seropositive animals increased with the age of the swine, indicating post-natal transmission of T. gondii. Furthermore, there was a significant difference in seroprevalence between suckling pigs and weaned pigs (p < 0.05). This is the first large-scale investigation of T. gondii infection in swine after an ASF outbreak in China. The lower seroprevalence of T. gondii in swine after ASF may be due to stricter biosecurity measures on the farms, but results indicated swine exposure to zoonotic parasites despite these measures. This highlights that pigs must be considered a potential source of human T. gondii infections.

Additional evidence of tigers (Panthera tigris altaica) as intermediate hosts for Toxoplasma gondii through the isolation of viable strains

“…The clinical manifestation of anorexia and paralysis in Tiger#12 is compatible with cats, however, the clinical toxoplasmosis in tigers is unknown. The seroprevalence of T. gondii in cattle, swine and sheep from China was 9.1%, 1.42% and 11.8%, respectively ( Dong et al, 2018 ; Xie et al, 2021 ). Although it is difficult to determine how and when T. gondii infection occurred for these tigers, raw beef and pork might contain viable cysts, which is a possible source of T. gondii infection.…”