The aim of this study was to investigate the occurrence of Cryptosporidium in cattle and sheep from the North Pioneer mesoregion of the state of Paraná. For this, 317 stool samples were collected from cattle and sheep on 16 properties in six municipalities in the North Pioneer mesoregion of Paraná. For detection of Cryptosporidium species, molecular analysis was performed using nested-PCR techniques targeting the 18S rRNA gene. Of the 37 beef cows and 115 calves analyzed, four (10.8%) and 14 (12.2%), respectively, were positive for Cryptosporidium. Of the 12 cows and 52 calves, one (8.3%) and 14 (26.9%), respectively, were positive for Cryptosporidium; and of the 42 ewes and 59 lambs, six (14.3%) and 12 (20.3%), respectively were positive for Cryptosporidium. Cattle (15.3%) and sheep (17.8%) were both susceptible to infection. All the properties of the municipalities of Assaí, Ibaiti and, Leópolis presented infected animals. The study showed that Cryptosporidium occurs in most municipalities assessed, that dairy calves had a higher risk (Odds Ratio=2,66, p-value=0,018) for infection than beef calves, and that sheep are just as susceptible to infection as are cattle, and that further Cryptosporidium studies are developed.

The objective of this study was to analyze the effect of ivermectin (3.15%) on gastrointestinal nematodes found in calves through the fecal egg count reduction test (FECRT), and larval culture in 16 animals from a school farm at the Universidade Estadual do Norte do Paraná. The animals were divided into two experimental groups: animals treated with ivermectin 3.15% (G1 group) and control animals (G2 group). Stool samples were collected from the animals twice i.e., on days 0 and 10 for fecal examinations. There was no significant change in the egg count per gram of feces (EPG) in both the groups. Helminths were found to be resistant to ivermectin (3.15%), due to the observed 5.62% FECRT rate. Cooperia was found to be the dominant nematode larvae present (53% on day 10 day and 8% in day 0), while Trichostrongylus was detected in small numbers (0% on day 0 to 1 % on day 10). The drug was found to be effective only in Trichuris, while the same was inefficient against Haemonchus and Cooperia, although Trichostrongylus and Oesophagostomum were found to be 100 % resistant. Therefore, the findings of this study suggest that ivermectin 3.15% should not be used for the control of nematodes in calves, since most of the parasites demonstrated drug resistance. This is the first report on the resistance of Haemonchus, Cooperia, Trichostrongylus, and Oesophagostomum in cattle to ivermectin 3.15% in the state of Paraná. Key words: Anthelmintic resistance, bovine, macrocyclic lactone ResumoObjetivou-se, neste estudo, analisar o efeito da ivermectina (3,15%) sobre nematódeos gastrointestinais de bezerros com aptidão leiteira por meio do Teste de Redução na Contagem de Ovos nas Fezes (RCOF) e da cultura de larvas em 16 animais da Fazenda Escola da Universidade Estadual do Norte do Paraná. Para tanto, dois grupos experimentais foram formados: animais tratados com ivermectina 3,15% (grupo G1) e grupo controle (Grupo G2). Foram coletadas amostras de fezes dos animais em dois momentos, ou seja, nos dias 0 e 10 para realização dos exames coproparasitológicos. Não houve alteração significativa na contagem de ovos nas fezes (OPG) em ambos os grupos. Os helmintos foram considerados resistentes à ivermectina 3,15%, já que a taxa de RCOF foi de 5,62%. O gênero de nematódeo mais observado na cultura de larvas foi Cooperia (53% no dia 10 a 88% no dia zero) e o menos foi Trichostrongylus (0% no dia zero a 1% no dia 10). Observou-se eficiência apenas sobre o gênero Trichuris e ineficiência sobre os gêneros Haemonchus e Cooperia e ainda 100% de resistência dos gêneros Oesophagostomum e Trichostrongylus. Concluiu-se neste estudo que a ivermectina 3,15% não deve ser indicada no controle de