[The occurrence of Babesia divergens in the Freiburg i. Br. district and piroplasmosis prevention trials in cattle]. / Zum Vorkommen von Babesia divergens im Bezirk Freiburg i. Br. und Versuche zur Piroplasmoseprophylaxe beim Rind.

The occurrence of Babesia divergens in the Freiburg i. Br. district is reported. By interviewing farmers and by serological investigations, three valleys where located in which bovine piroplasmosis occurs since many years. Main objective of this study was to strategically control the vector ticks, Ixodes ricinus with the synthetic pyrethroid flumethrin, in order to prevent clinical piroplasmosis after turnout to pastures in spring, without interfering with protective immunity against Babesia divergens. A total of 200 cattle were used for trials in the period 1990-92. Three pour-on treatments of fortnightly intervals provided best results. Only 4.3% of 163 treated cattle contracted piroplasmosis, in contrast to 19% of 37 untreated cattle. All cattle were sero-negative at the time of turnout. At the end of pasture periods 1990 and 1991 82.4 and 79.6% respectively of treated cattle were sero-positive.

Production and consumption of T cell growth factor by peripheral blood lymphocytes of cattle infected with Taenia saginata.

Calves were infected with 25,000 or 50,000 viable eggs of Taenia saginata. Larval numbers ranged between 2077 and 6005. During infection the animals developed leucocytosis, which was mainly due to lymphocytosis. An apparently positive correlation was observed between the lymphocytosis and the in vitro proliferative response of the lymphocytes to antigen prepared from proglottids. Maximal in vitro blast transformation of the cells stimulated with antigen occurred on Days 12 and 32 post-infection (p.i.). Specific antibodies to T. saginata were demonstrated on Day 14 p.i. At that time, the proliferative response of the cells paralleled the formation of specific antibodies, particularly of the IgG class. The stimulated cells produced a lymphokine showing interleukin 2 (IL 2)-like activity, since the addition of supernatant of such cells to IL 2-dependent concanavalin A (Con A)-blast cells supported the in vitro growth of the cells. In addition, peripheral blood lymphocytes (PBL) specific for T. saginata could be maintained in long-term cultures when they were cultured in medium containing supernatants of MLA-144 cell lines. The data presented in this study indicate that cells specific for T. saginata produced and consumed T cell growth factor (TCGF).

Enhancement of neutrophil adherence to Toxocara canis larvae by the C3 component of complement and IgG antibodies.

In the present study, the binding human neutrophils to Toxocara canis larvae was examined in vitro. It was found that IgG and/or the C3 component of complement were able to enhance the attachment of the cells to the parasites. This was associated with the generation of strong chemiluminescence reactions. Despite the binding of the cells, the larvae were able to escape and to maintain their infectivity. This was apparent, since the parasites could survive and migrate into different organs including the brain after having been inoculated into mice.