[A new model for the study of filarial physiopathology: Molinema dessetae in its definitive natural host, Proechimys oris. 1].

The filarial rodent model Molinema dessetae/Proechimys oris, recently adapted in the laboratory allows studies on the host/parasite relationships. Development of filarial worm was described elsewhere, and the model standardized. Biological, parasitological data and antifilarial drug response were determined. Natural models can seldom be used in laboratory; in non natural models many informations on the host-parasite relationships are lost and pathological studies can only be fragmentary and punctual. With inbred Proechimys oris we have the possibility to investigate with a natural filarial model. Three rodent groups have been studied for over a period of one year. The first group comprises eleven parasite free animals; the second one, eight rodents infected once by L3, and the last with eight rodents regularly re-infected during the period of experiment. Several biological parameters were considered: weight, total red and white blood cell counts, haemoglobinemia, mean cell volume, differential leucocyte count, blood urea nitrogen, total serum proteins and electrophoretic pattern, endogenous creatinine clearance, circulating immune complexes. On the whole, more than 19,700 biological data were obtained and several multivariate statistical analysis were necessary for a valid interpretation. The Principal Component Analysis (ACP) shows in each infected rodent distinct trajectories related either with the age of the host or with the filarial infection itself. Three graphic methods were used: individual graphics of each rodent, graphics of each rodent group and, individual and group statistical center of gravity. At the end of the experiments, the rodents were autopsied and a detailed histological study of the whole body was made. Different lesions and stages of inflammatory processes found were analysed and classified as follows: granulomatous nodule with eosinophilic and neutrophilic polymorphs; foreign-body granulomatous nodule; sclerocicatricial nodule; mononucleate cell infiltrate. Secondary pathological alterations, such as irritative lesions and blocage of lymph and blood vessels, were found. A comprehensive study of all our qualitative histological results was performed by a second multivariate analysis: the Correspondence Analysis (AFC). This analysis confirmed the heterogeneity of each Proechimys infected and multi-infected groups. The cross checking between the ACP and AFC allows the separation of two physiopathological filarial groups; the first group (A) is characterized by moderate biological variations and the absence of hepatosplenic lesions.(ABSTRACT TRUNCATED AT 400 WORDS)