ABSTRACT School-age children are a social group in which blood collection for laboratory testing can be perceived as an invasive procedure, with low acceptance and tolerance of stakeholders. This problem could be circumvented by replacing serum samples with saliva. For this purpose, and to make the collection of saliva samples playful and instructive for children, educational activities on hygiene and toxoplasmosis transmission and prevention were performed using toys and audiovisual tools. The target audience consisted of 7-10 year-old children from low-income families who attended public schools in the city of São Paulo. Saliva samples were used in a previously described in-house Enzyme-Linked Immunosorbent Assays (ELISA) to detect anti- Toxoplasma gondii IgG antibodies and establish the immunological status of each of the participants. One year later, children’s memory and fixation of concepts regarding hygiene habits, as well as transmission and prevention of toxoplasmosis were tested in the same schools, by means of a questionnaire application, using students who did not participate in the first intervention as controls. The prevalence of positive anti- T. gondii IgG among students was 50% (82/164). One year later, 45 children had more knowledge on toxoplasmosis (28/45 vs 29/147) and they drew the cat’s involvement in the transmission of toxoplasmosis more often than controls (28/45 vs 29/147). Sorted according to the presence of specific IgG in saliva, recovered positive students presented worse memory of the above cited knowledge as did saliva-negative IgG students, but both groups had isolated higher frequency of fixed knowledge than non-intervened students. Our data show that there is a high prevalence of T. gondii infection in school-children from low-income areas; saliva is an alternative to blood for anti- T. gondii IgG detection; and a one-day educational intervention in school-children was effective in promoting knowledge fixation on hygiene and toxoplasmosis transmission and prevention after one year.
Toxoplasma gondii causes severe fetal disease during acute infection in pregnant women, thus demanding early diagnosis for effective treatment and fetus preservation. Fetal tests are inefficient and risky, and diagnosis is based on maternal IgM serology, which had weak screening ability due to increased sensitivity, with alternative IgG avidity tests. Here, we performed ELISA and avidity assays using a recombinant T. gondii antigen, rROP2, in samples from 160 pregnant women screened from a large public hospital who were referred due to positive IgM assays. IgG serology and avidity assays were compared using whole T. gondii extract or rROP2. ELISA IgG detection with rROP2 showed good agreement with assays performed with T. gondii extract, but rROP2 IgG avidity assays were unrelated to whole extract antigen IgG avidity, regardless of the chaotrope used. These data show that avidity maturation is specific to individual antigen prevalence and immune response during infection. ELISA rROP2 IgG assays may be an alternative serological test for the diagnosis of toxoplasmosis during pregnancy, although our data do not support their use in avidity assays.
A toxoplasmose causa grave doença fetal durante a infecção aguda da gestante, assim demanda diagnóstico precoce para tratamento efetivo e preservação fetal. Os testes fetais são de baixa eficiência e o diagnóstico é baseado na sorologia para IgM materna, que tem fraca capacidade de triagem devido a sensibilidade crescente dos testes, sendo uma alternativa os testes de avidez de IgG. Apresentamos aqui um ELISA e ensaio de avidez de IgG usando antígeno recombinante de T. gondii, rROP2, em amostras de 162 gestantes triadas para um grande hospital público por uma sorologia positiva para IgM. O ELISA IgG e o ensaio de avidez de IgG foram comparados usando o antígeno rROP2 ou extrato total de T. gondii. O ELISA usando rROP2 mostrou excelente concordância com os ensaios usando extrato de T. gondii, mas nos ensaios de avidez usando rROP2, os valores encontrados não se relacionaram com os encontrados na avidez com extrato de T. gondii, independente do tipo de caotrópico utilizado. Estes dados mostram que a maturação da avidez é especifica para a resposta imune ou a prevalência de um antígeno durante a infecção. Os ELISA para IgG anti rROP2 podem ser teste sorológico alternativo para o diagnóstico da toxoplasmose durante a gravidez, embora nossos dados não apóiem seu uso em ensaios de avidez de IgG