Population dynamics of Libyostrongylus dentatus and L. douglassii of ostriches raised in the Northern Rio de Janeiro State, Brazil.

Libyostrongylus genus contains three species of gastrointestinal nematodes that infect ostriches. Of these, only Libyostrongylus douglassii has been implicated in diseases and lower productivity. A morphological diagnosis method allowing the discrimination of infective larvae of L. douglassii and Libyostrongylus dentatus and the evaluation of eggs per gram of feces (EPG) was used to determine the population dynamics of both species from two ostrich farms located in the northern region of the state of Rio de Janeiro, Brazil. The presence of these nematodes was monitored every 15 days for two years. The average EPG was 4631 and 587 on farms 1 and 2, respectively. Overall, the highest values of EPG were associated with the rainy season on both farms. However, only on farm 1 the rainy season correlated statistically with EPG. Both species of Libyostrongylus occurred on both farms with a higher predominance (86%) of L. douglassii on farm 1, whereas the distribution of infection on farm 2 was more heterogeneous with a slight predominance of L. douglassii. The infection and the prevalence of these species may vary considerably according to the farm facilities, management adopted, and season.