Salivary IgA against sporozoite-specific embryogenesis-related protein (TgERP) in the study of horizontally transmitted toxoplasmosis via T. gondii oocysts in endemic settings

Abstract

The aim of this study was to contribute to the better understanding of the relative epidemiological importance of different modes of infection with respect to horizontal transmission of Toxoplasma gondii in endemic settings. We investigated the prevalence of salivary IgA against a sporozoite-specific embryogenesis-related protein (TgERP) in a highly endemic area for toxoplasmosis in Brazil in order to pinpoint parasite transmission via oocysts. Prevalence calculated by salivary IgA specific to TgERP was compared to the prevalence calculated by serum IgG against both TgERP and tachyzoites (in conventional serological tests). Prevalence calculated by different serological and salivary parameters varied in the studied age groups. However, for the 15-21 years age group, values for T. gondii prevalence estimated by conventional serological tests and by anti-TgERP salivary IgA were similar; i.e. 68·7% and 66·6% or 66·7%, respectively, using two different cut-off parameters for salivary IgA anti-TgERP. Furthermore, salivary IgA anti-TgERP for this age group presented the highest specificity (93·33%), sensitivity (93·94%), and likelihood (14·09) compared to all the other age groups. These data demonstrate the importance of age for salivary IgA investigation against TgERP to estimate the mode of T. gondii transmission in endemic settings.

Infectious Causation of Abnormal Host Behavior: Toxoplasma gondii and Its Potential Association With Dopey Fox Syndrome

“…Wild foxes often have high seroprevalences of T. gondii with for example, 35% seroprevalence found in populations in Austria (52) and 100% in Czech Republic (53). This is consistent with high levels of exposure to the parasite often seen in human populations: for example in Brazil, human population seroprevalence can reach up to 80-90% (54,55), in France 89% (56) and in Northern Ireland 85% (57). Wild foxes also have longer lifespans relative to the commonly studied rodent animal models, allowing time for the accumulation of by-product effects of neurotropic infection that are seen in humans.…”

Toxoplasma gondii: An Underestimated Threat?

“…While in domestic cats, oocyst shedding occurs for only 1-3 weeks after initial infection, in wild feline species shedding may potentially continue intermittently for life [3]. Ingestion of these sporulated oocysts, which contaminate crops, soil, and water sources [4,5], or consumption of bradyzoites from raw or undercooked meat comprise the two major horizontal routes of transmission. Indeed, these parasite stages are responsible for a substantial burden of postnatally acquired infections, causing both sporadic outbreaks of acute, symptomatic disease in immunocompetent adults [6] and severe toxoplasmosis in immunocompromised individuals including HIV/AIDS patients (following reactivation of bradyzoites into disseminating tachyzoites) [7].…”

Identification of Oocyst-Driven Toxoplasma gondii Infections in Humans and Animals through Stage-Specific Serology—Current Status and Future Perspectives

“…The authors suggested ERP to be an early infection marker (despite its recognition by chronically infected humans) due to a unique exposure of the immune system to sporozoites vs. a permanent exposure to tachyzoite or bradyzoite stages. In further studies higher detection rates of ERP by human sera derived from settings with possibly high environmental oocysts contamination were described [50,75], compared to sera from areas where infection by the meat route was considered predominant [74]. Vieira et al reported the detection of anti-ERP antibodies in chickens and a high prevalence of anti-ERP antibodies in humans, providing evidence for the relevance of environmental oocysts contamination due to underground water contamination [50].…”

“…Over the last decade, three distinct proteins specifically expressed by T. gondii sporozoites, namely ERP, SporoSAG and CCp5A, have been reported to be able to detect oocystdriven infections by serological tests (Tables 2 and 3). The ERP protein, which was employed in several seroepidemiological studies [50,62,74,75], is part of a group of four molecules annotated as 'late embryogenesis abundant domaincontaining proteins' (LEAs). They are potentially involved in conferring stress resistance to the oocyst [77,78], and the encoding genes are significantly upregulated in this parasite stage.…”