Dr. Murai Éva szerk.: Parasitologia Hungarica 22. (Budapest, 1989)

Computer simulation of the role of the face fly, Musca autumnalis, in spreading and causing infectious bovine keratoconjunctivitis (IBK), based on field data Dr. Gábor LŐRINCZ, Dr. László PAPP and Dr. Judit KOZMA* Zoological Department, Hungarian Natural History Museum, Budapest, Hungary "Computer simulation of the role of the face fly, Musca autumnalis, In spreading and causing infectious bovine keratoconjunctivitis (IBK), based on field data" - Lorincz, G. - Papp, L. - Kozma, J. - Parasit. hung.. 22: 75-85.1989. ABSTRACT. Face fly counts were made in three lowland pastures of Hungary on the whole body and on the eyes of cattle and also the duration of face fly visits on eyes were measured. As a mean, 13.6 face flies per body and 2.63 face flies per head were found with 21.9% c*

7 flies on the eyes. Half of the face fly visits is of short duration (less than 10 seconds) but one-third of the visits is longer than one minute. Flies of this latter category may be Involved in causing mechanical damage to bovine eyes. A stochastic computer simulation was made modeling the pasture situation with host changes, based on our field data. Simulation results suggest that the activity of face flies can alone maintain complete infestation in a herd by their host changes with infective agents. The most important simulation result is that long ( > 60 seconds) fly visits (i.e. mechanical damage to eyes) with evening mean values may have extremely high individual values. KEY WORDS: Diptera, face fly, Musca autumnalis, IBK, transmission, computer simulation. Infectious bovine keratoconjunctivitis (IBK, pinkeye, keratitis contagiosa, New Forest disease, infectious ophthalmia, infectious keratitis etc.) occurs wherever cattle are present. A vast amount of papers including reviews are available in the world literature; here we mention an excellent and rather recent review of PUNCH and SLATTER (1984), who summarized the relevant literature on its prevalence and economic importance, etiology, clinical siems, predisposing factors (incl. face flies), pathology and Immunology and the current treatment regimes. As they say, IBK has been regarded as a syndrome rather than a specific disease. Various bacteria and mycoplasmas, rickettslae, viruses and nematode parasite species of the genus Thelazia had been reported as etiological agents but they conclude (see also HALL, 1984) that Moraxella bovis Hauduroy is the true etiological agent. In the same year HALL (1984) published a concise review on the relationships of the face fly, Musca autumnalis * At the time of the studies a veterinary student preparing her thesis work.