SPREAD OF CANINE DIROFILARIASIS IN THE SO UTH OF SWITZERLAND

Microfilarial infections could be detected by the Difil Test in 11 (2. 2%) of 479 blood samples of clinically asymptomatic dogs from the Sout h of Switzerland. Dirofilaria repens and D. immitis were identified in 3 (0.6%) and 8 dogs (1.6%), respectively, by the acid phosphatase act ivity of the microfilariae. 10 dogs with microfilaremia had been abroa d or a stay outside Switzerland could not be excluded. One dog diagnos ed with D. immitis could have had acquired the infection in the canton Tessin according to information given by the owner. Dogs with microfi laremia are a potential source of infection for mosquitoes. An indigen ous cycle of infection in the South of Switzerland is possible since t he mean average temperature in summer is above 18 degrees C which is n ecessary for opitmal parasite development in the vector. A strict cont rol of imported dogs or animals exposed to the disease in endemic regi ons as well as the therapy of infected dogs in the South of Switzerlan d is advisable.