No abstract

This study investigated the frequency of oocysts of Cryptosporidium spp. in feces from dogs and cats in five municipalities in the southern region of the state of Rio Grande do Sul. The risk factors associated with infection were also investigated. Feces samples from 110 dogs and 18 cats were stained using the auramine method. At the time of feces sampling, a questionnaire with semi-open-ended questions was applied to the animal guardians and all data obtained underwent statistical analysis. The real frequency of oocysts of Cryptosporidium spp. was 24.63% (27 dogs and two cats). Only four samples of dog feces were diarrheic and no presence of oocysts was observed in any of them. Variables that represented risk factors for infection were: homemade food, untreated water, circulation of animals on grassy terrain and living in the same environment as other animals (cattle). The results made it possible to inferring that within the population studied, the frequency of parasitism due to Cryptosporidium spp. in dogs was relevant and emphasize the asymptomatic nature of this infection. The adopting control measures are highlighted, particularly in relation to variables that represent risk factors for this infection.

Pythium insidiosum belongs to the phylum Oomycota. It is capable of infecting mammals causing a serious condition called pythiosis, which affects mainly horses in Brazil and humans in Thailand. The objective of the present study was to verify the in vitro anti-P. insidiosum activity of a biogenic silver nanoparticle (bio-AgNP) formulation. The in vitro assays were evaluated on P. insidiosum isolates (n = 38) following the M38-A2 protocol. Damage to the P. insidiosum hyphae ultrastructure was verified by means of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Bio-AgNP inhibition concentrations on P. insidiosum isolates ranged from 0.06 to 0.47 μg/ml. It was observed through SEM that P. insidiosum hyphae treated showed surface roughness, as well as cell walls with multiple retraction areas, loss of continuity, and rupture in some areas. The TEM of treated hyphae did not differentiate organelle structures; also, the cellular wall was rarefied, showing wrinkled and partly ruptured borders. The bio-AgNP evaluated has excellent in vitro anti-P. insidiosum activity. However, further studies on its in vivo action are necessary as so to determine the possibility of its use in the treatment of the disease in affected hosts.

Pythium insidiosum is the etiologic agent of pythiosis, a severe and emerging disease that affects mammals. Failure of conventional antifungal therapies is partially justified by the absence of ergosterol in the plasma membrane of this oomycete. Despite research advancement, the treatment of pythiosis has not been not fully established. The present study investigated the in vitro susceptibility profile of Brazilian isolates of P. insidiosum (n = 20) against Melaleuca alternifolia, Mentha piperita and Origanum vulgare essential oils, and their combinations. Susceptibility tests were performed according to CLSI M38-A2 protocol, and combinations were evaluated by the microdilution cherkerboard method. All tested essential oils showed antimicrobial activity against P. insidiosum, and the greatest activity of O. vulgare was highlighted. Synergistic and/or indifferent effect was observed for all combinations evaluated, especially the M. piperita and O. vulgare combination, which showed 65 % synergism. This is the first study to report in vitro combinations of essential oils against P. insidiosum indicating the susceptibility of this oomycete to M. alternifolia, M. piperita and O. vulgare essential oils, as well as their combinations.

Purpureocillium lilacinum is a nematophagous fungus used in biological control against some parasites, including Toxocara canis. This study researched the infectivity of embryonated T. canis eggs after exposure to the fungus P. lilacinum. T. canis eggs were exposed to P. lilacinum for 15 or 30 days and subsequently administered to Swiss mice (n=20). Control group consisted of mice who received T. canis embryonated eggs without fungal exposure. Forty-eight hours after infection, heart, lung, and liver from animals of each group were collected to assess larval recovery. The organs of mice that received embryonated eggs exposed to the fungus showed a lower average larval recovery (P<0.05) suggesting that exposure of T. canis eggs to P. lilacinum was able to reduce experimental infection. Under the evaluated conditions, the interaction time between the fungus and the parasite eggs was not a significant factor in larvae recovery. P. lilacinum may be considered a promising T. canis biological control agent. However, further studies are needed to determine a protocol for the use of this fungus as a biological control agent.

Neste estudo realizou-se a comparação e análise de concordância entre técnicas de concentração por sedimentação usando acetato de etila e formalina-éter, bem como avaliou-se os métodos de Kinyoun, Ziehl-Neelsen e Safranina para detecção de oocistos de Cryptosporidium spp. em fezes de animais de companhia. A técnica de Auramina foi empregada como método de triagem. De 136 amostras de fezes analisadas, 23,52% (n=32) apresentaram oocistos de Cryptosporidium spp. detectados pelo método de Auramina, sendo que 21,33% das amostras (29/136) e 14,7% (20/136) resultaram positivas quando utilizou-se, respectivamente, acetato de etila e formalina-éter como método de concentração. O teste Kappa evidenciou nível de concordância bom entre os métodos de concentração para a técnica de Auramina e concordância excelente para os métodos de Kinyoun, Ziehl-Neelsen e Safranina. A concordância entre os métodos Kinyoun e Ziehl-Neelsen foi fraca e não houve concordância com Safranina. É possível inferir que o emprego de acetato de etila ou formalina-éter não influencia os resultados para os métodos de coloração, embora oocistos mais íntegros tenham sido observados quando utilizado acetato de etila. Na impossibilidade de uso do método de auramina, Kinyoun deve ser empregado, seguido de Ziehl-Neelsen.

The study evaluated the ovicidal activity of enzymatic extracts of Purpureocillium lilacinum and Trichoderma virens against trichostrongylid eggs from sheep. Filtered extract (FE) and macerated crude extract (MCE) were prepared from fungal cultures in minimal broth. In the experiment, 100 trichostrongylid eggs, obtained from the feces of naturally infected sheep, were exposed to fungal extracts for 24 and 48 hours/25°C. In the control group, eggs were incubated in minimal broth. The number of L1 larvae was ascertained. Each treatment consisted of four repetitions and the experiment was repeated five times. It was observed that the effect of FE and MCE of P. lilacinum and T. virens on egg hatchability differed from that of the control group. MCE of T. virens and P. lilacinum showed higher ovicidal activity than FE over both periods and at 48 hours of exposure, respectively. From the percentage reductions in hatchability of the eggs, MCE was shown to be superior to FE for both fungi. This study demonstrated the ovicidal potential of these fungi against trichostrongylid eggs. However, further studies are needed in order to identify the molecules responsible for the ovicidal effects, and to evaluate the behavior of fungal extracts in biotic and abiotic interactions.