Quantitative analysis of microfilarial periodicity of Dirofilaria immitis in cats

Microfilarial periodicity of Dirofilaria immitis in the venous blood of inf ected cats was analyzed by a trigonometric model. Cats were infected by sub cutaneous transplantation with 120-day-old juvenile D, immitis. Microfilari ae in the blood were first observed 98 days after transplantation. Blood wa s collected at 4 h intervals for a 24 h period, and examinations were repea ted five times in two cats. The calculated periodicity index was 75.1 and 5 0.3 in these two cats. The estimated hour of peak microfilarial density ran ged from 1.00 to 2.84 h. Thus, the periodicity of microfilariae of D. immit is in the blood of cats was characterized as nocturnally sub-periodic. (C) 2000 Elsevier Science B.V. All rights reserved.