It is well known that eosinophilia is a key pathogenetic component of toxocariasis. The objective of the present study was to determine if there is an association between peritoneal and blood eosinophil influx, mast cell hyperplasia and leukotriene B4 (LTB4) production after Toxocara canis infection. Oral inoculation of 56-day-old Wistar rats (N = 5-7 per group) with 1000 embryonated eggs containing third-stage (L3) T. canis larvae led to a robust accumulation of total leukocytes in blood beginning on day 3 and peaking on day 18, mainly characterized by eosinophils and accompanied by higher serum LTB4 levels. At that time, we also noted increased eosinophil numbers in the peritoneal cavity. In addition, we observed increased peritoneal mast cell number in the peritoneal cavity, which correlated with the time course of eosinophilia during toxocariasis. We also demonstrated that mast cell hyperplasia in the intestines and lungs began soon after the T. canis larvae migrated to these compartments, reaching maximal levels on day 24, which correlated with the complete elimination of the parasite. Therefore, mast cells appear to be involved in peritoneal and blood eosinophil infiltration through an LTB4-dependent mechanism following T. canis infection in rats. Our data also demonstrate a tight association between larval migratory stages and intestinal and pulmonary mast cell hyperplasia in the toxocariasis model.

Foram examinados exsudatos peritoneais e órgãos (cérebro, coração, pulmão e músculo estriado) de 53 camundongos infectados experimentalmente pelo Toxoplasma gondii, sendo 21 na fase aguda e 32 na crônica. Camundongos albinos, machos, de cerca de 25 g e 2 meses de idade foram inoculados, por via intraperitoneal, com 0,5 ml de exsudato peritoneal (taquizoitas) ou macerado de cérebro (cistos) de camundongos previamente infectados. O exame a fresco foi feito no exsudato peritoneal, entre 3 e 12 dias após inoculação e no cérebro, após 10 dias. Foram realizadas inoculações de macerados de órgãos em novos camundongos (repiques) para a recuperação do parasita no exsudato ou no cérebro. Na infecção aguda as positividades foram, ao exame a fresco: exsudato peritoneal 19/19, pulmão 12/14, músculo 6/9, coração 4/9 e cérebro 1/3. Após inoculação: exsudato peritoneal 5/5, cérebro 2/2, coração 19/19, pulmão 13/13 e músculo 14/17. Após estes últimos resultados foram registrados 9 novos órgãos positivos. A positividade final (igual à recuperação do parasita) foi: exsudato peritoneal 19/19 (100%), coração 15/17 (88,5%), músculo 12/14 (85,7%), pulmão 14/14 (100%) e cérebro 2/3 (66,6%). Na infecção crônica, que transcorreu entre 10 e 495 dias, as positividades foram, ao exame a fresco: cérebro 28/32, coração 0/4 e músculo 0/4. Após repique: cérebro 6/6, coração 14/29 e músculo 16/26. Neste exame foi revelado um novo camundongo positivo elevando para 29 o total de camundongos positivos ou 90,6%. O resultado final foi: cérebro 28/32 (87,5%), músculo 16/28 (57,15%) e coração 14/31 (45,1%). No fim da pesquisa, aos 495 dias, o cérebro apresentava grandes cistos ao exame a fresco e coração e músculo mostravam-se positivos através da inoculação. Conclusões: 1º) nos camundongos o toxoplasma persistiu por 495 dias no cérebro, coração e músculo estriado; 2º) o exame a fresco do pulmão pode substituir ou confirmar o do exsudato peritoneal; 3º) a inoculação de órgãos é necessária pois pode revelar novos casos positivos; 4º) a atividade dos cistos foi demonstrada pelo aumento gradual do seu tamanho e pela recuperação do toxoplasma no cérebro, coração e músculo, após o longo tempo de infecção.

Peritoneal exsudates and organs from 53 male albino mice, experimentally infected by Toxoplasma gondii were studied, 21 at the acute phase of infection, and 32 at the chronic phase. Peritoneal inoculations were made with 0,5 ml of peritoneal exsudates (tachyzoites), or brain macerates (cysts) of previously infected mice. Direct examinations of peritoneal exsudates (tachyzoites) were realized between 3 to 12 days post-inoculation, and in brain (cysts) after 10 days post-inoculation. Organs macerates were inoculated in new mice, for the parasite recovering, from exsudates or from brains. At the acute infection (3 to 12 days) the positivity at the direct examination was: peritoneal exsudate 19/19, lung 12/14, muscle 6/9, heart 4/9 and brain 1/3. After inoculation: peritoneal exsudate 5/5, heart 9/9, lung 13/13, muscles 14/17 and brain 2/2. Then, there were 9 new positive organs. At the chronic infection, between 10 and 495 days, the positivity was, at direct examination: brain 28/32, heart 0/4 and muscle 0/4. After inoculation: brain 6/6, heart 14/29 and muscle 16/26. After that a new positive mouse was detected, which leads to 29 the positivity for all mice, or 90,6%. Finally the positivity for the acute phase was: peritoneal exsudate 19/19 (100%), heart 15/17 (88,5%), muscle 12/14 (85,7%), lung 14/14 (100%) and brain 2/3 (66,6%). For the chronic phase: brain 28/32 (87,5%), muscle 16/28 (57,1%) and heart 14/31 (45,1%). At the end of experience, at the 495th day, the brain still presented large cysts by direct examination and also the heart and muscle were positives after inoculation. Conclusions: 1st) on mice the Toxoplasma gondii remained for 495 days, mainly on the brain, but also on heart and muscle; 2nd) the lungs direct examination could be useful as substitute of the peritoneal exsudate examination; 3th) organs inoculations are necessary for the discovery of new infected mice; 4th) the cyst activity was demonstrated by its gradative increase during the chronic infection, and by its recovery in tissues after a long time.

O baixo resultado encontrado por nós no isolamento do Toxoplasma gondii de embutidos de carne de porco procedentes de Erechim (RS) (uma positiva em 40 amostras) levou-nos a pesquisar a ação do sal de cozinha, presente nesses embutidos, sobre taquizoitas e cistos do parasita. Foram obtidos exsudatos peritoneais (taquizoitas) e macerados de cérebros (cistos) de camundongos previamente inoculados com cepas de Toxoplasma gondii isoladas do material de Erechim. A este inóculo foi acrescentado sal de cozinha refinado, comum, nas concentrações de 2,2%, 2,5% e 3,0% habitualmente usadas no preparo dos embutidos. O tempo de exposição ao sal foi de 24 e 48 horas, 3-5 e 7 dias, a 4ºC, após o qual, camundongos albinos, machos, foram inoculados, por via intraperitoneal, com 0,5 ml desses inóculos, padronizados quanto ao número de parasitas. Os resultados mostraram que, nas concentrações de sal a 2,2%, 2,5% e 3,0% e exposições de 24 e 48 horas, todos os camundongos inoculados com taquizoitas mais sal morreram, menos um, provavelmente não infectado, (um sobrevivente em 28 inoculados). Na concentração de 3,0% e exposição durante 3-5 e 7 dias houve 10 sobreviventes em 37 animais inoculados (27%), sendo que com 5 e 7 dias, 7 de 15 camundongos sobreviveram (46,6%). Nos camundongos inoculados com cistos mais sal a 3,0% e exposições de 24, 48 e 72 horas, faltam anotações dos resultados; com exposições de 5 e 7 dias houve 17 sobreviventes e 3 mortos (85%). Camundongos-controles para cada grupo foram inoculados nas mesmas condições, porem sem o sal. A morte destes ocorreu em 100%, sempre, mais cedo do que a dos camundongos-testes. O toxoplasma foi recuperado do exsudato peritoneal e do cérebro dos camundongos recém-mortos e moribundos, mas nunca dos sobreviventes. Estes resultados evidenciam a ação inativante do sal de cozinha sobre o Toxoplasma gondii, na concentração de 3%, durante um mínimo de 3 dias e, possivelmente, explicam a raridade do isolamento do parasita nos embutidos de carne de porco salgada do inquérito de Erechim.

Results of our inquiry on Toxoplasma gondii frequency in pork sausages from Erechim (RS, Brazil), where the incidence of toxoplasmotic chorioretinitis is high (9% according SILVEIRA, 1987)9, revealed only one isolation of the parasite among 40 sausage samples. (MARTINS, 1989)5,6. The sausages were prepared with pork and common table salt, and were ingested, frequently, in raw stale, during its preparation. In this experiment, table salt action on tachyzoites and cysts of Toxoplasma gondii, was investigated. Albino male mice were intraperitoneally inoculated with 0,5 ml of peritoneal exsudates (tachyzoites) or brain macerates (cysts) from previously infected mice. Some strains were isolated from pork and pork sausages from Erechim. Refined common table salt was added to the inocula at 2,2%, 2,5% and 3,0% concentrations, during 24 and 48 hours, 3-5 and 7 days of exposition time, at 4º C. The results demonstrated that at 2,2%, 2,5% and 3,0% salt concentrations and 24 and 48 hours of time exposition all mice inoculated with tachyzoites were dead, except one, probably not infected. At 3,0% and 3-5 and 7 days of contact, 10 in 37 inoculated mice survived (27%). Of the mice inoculated with cysts plus salt at 3,0%, at 5 and 7 days exposition, 85%; survived (17 in 20). All the controls mice inoculated with the same inocula without salt, at the same conditions, died earlier than the test mice. The Toxoplasma was recovered from peritoneal exsudates and brains of recently dead and diyng mice, but not from the survivors. Conclusion: the table salt has an inactive action on Toxoplasma gondii in 3,0% concentration and at 3 to 7 days exposition. Possibly this may explain the rare isolation of the parasite in pork sausages of Erechim inquiry.