NEW FEATURES ON THE MOLTS AND MORPHOGENESIS OF THE HUMAN FILARIA LOA LOA BY USING RODENT HOSTS - CONSEQUENCES

The development of the human filaria Loa Loa (Dirofilariinae, Onchocer cidae), previously studied in monkeys, was studied using the non permi ssive hosts-mice and jirds. The development proved to be rapid: moult 3 occurred on day 8 post-inoculation, the adult stage was reached on d ay 25 and measured al that lime 3-3.5 mm in length. As in the other fi larioids, the female genital apparatus developed during the fourth sta ge. A critical analysis of the studies on the development of Onchocerc id species was made. The optimal duration of the sieges (i.g. the shor test time) was chosen for the comparison. it appeared thai the duratio n of the stage 3 was a constant character in a given species whatever the experimental conditions, whereas moult 4 might be retarded in a no n susceptible host. Comparison between the 18 developmental cycles of Onchocercidae in the vertebrate host was made. Two biological types co uld be distinguished: either the moult 3 occurred on day 2-3 and was f ollowed apparently by a late moult 4 (greater than or equal to 50 days ), or the moult 3 occurred after about one week oi development and ii was associated with a less long stage 4 (20-40 days). The first group includes Dirofilaria and Onchocerca, the second group brings together mainly Loa and the Onchocercinae of the Dipetalonema line and related genera (Acanthocheilonema, Brugia, Litomosoides, etc.). The groups thu s formed suggest real relationships as they fit with the morphology of the infective stage and the results of a recent molecular analysis of the 5S DNA.