Increase in cellular immune responses in Onchocerca-infected cattle after treatment with the microfilaricide, milbemycin.

Lymphocytes from Onchocerca-infected steers treated with the microfilaricide, milbemycin showed increased proliferation when challenged with antigen from Dirofilaria immitis, concanavalin A, tuberculin and tetanus toxoid, compared with untreated animals. This paper confirms that Onchocerca infection induces immunosuppression to filarial and non-filarial antigens. It raises the possibility that filarial-induced immunosuppression may increase the susceptibility to mycobacterial infections and reduce the efficacy of vaccinations and strongly indicates that further research is required.