SUMMARY Giardia duodenalis is an enteric parasite that has distinct genetic groups. Human infections are mainly caused by assemblages A and B, although sporadic infections by assemblages C and D have also been reported. Animals can be infected by a wide range of assemblages (A to H). The aim of this study is to identify the assemblages and sub-assemblages of G. duodenalis with zoonotic features in fecal samples of school-aged children, and in dogs that coexist in the same households in Lages, Santa Catarina, Brazil. Fecal samples of 91 children and 108 dogs were obtained and G. duodenalis cysts were detected in samples from 11 (12.08%) children and 10 (9.25%) dogs. DNA extracted from the 21 positive samples was analyzed by PCR-RFLP, using the gdh gene. Results showed the presence of sub-assemblages AI (2/11), AII (4/11), BIII (2/11), and BIV(3/11) among children and AI (5/10) and BIV(3/10) in dogs, with zoonotic characteristics, and the carnivore specific assemblage C (2/10). G. duodenalis was found to infect both children and dogs living in the same household, with the same sub-assemblage (BIV) indicating that pet dogs are a potential risk of transmission of G. duodenalis to humans.
Context The effect of heat stress on the production and physiology of lactating dairy cows is well documented in literature. However, little is known about the effect of the provision of shade on DNA damage. Aims The present study aimed to evaluate the effects of shade provision on physiological, oxidative-stress, and DNA-strand damage in dairy cows exposed to mild heat stress. Methods The study was conducted at Lages, SC, Brazil, during 15 days in a southern hemisphere summer (January and February), with 14 lactating Holstein (n = 10) and Holstein × Jersey crossbreed (n = 4) dairy cows. Animals were randomly allocated to two groups of seven animals each (named as shaded and unshaded). These two groups were evaluated in the following three different periods: pre-stress period (5-day duration), stress period (4-day duration) and post-stress period (6-day duration). Shaded cows had free access to shade throughout the study; unshaded cows were prevented from accessing shade only in the stress period. Physiological (rectal temperature, heart and respiratory frequencies and panting score) and DNA-damage parameters (through Comet assay), as well as oxidative stress (in blood: carbonyl content, nitrite:nitrate ratio, thiobarbituric acid-reactive substances, TBARS) were evaluated. Key results In the stress period, shade deprivation resulted in higher values of respiratory rate, indicating that cows were under heat stress. In addition, DNA-damage levels were higher in this circumstance, probably due to inhibition of the DNA-repair systems by the thermal stress as well as thermal stress acting as a DNA-damage agent. Conclusions In a high-altitude subtropical region, during the hot season, shade provision decreases solar radiation heating effects and, thus, reduces DNA damage and the negative effects on cow metabolism and cell structure. Implications Shade effects on cow metabolism and cell structure must be taken into consideration in the planning of dairy farms and our results suggest that shade availability must not be disregarded, even in situations of mild heat stress.
The knowledge of the epidemiology of parasitic infections in stray and domestic animals, especially of its incidence and prevalence, is fundamental to adopting effective prophylactic measures. Stray dogs play an important role in environmental contamination favoring the transmission cycle of zoonotic agents. Among the parasitic infections that affect humans, Giardia duodenalis is the most common intestinal protozoa and was designated as a re-emerging infectious disease. This study aimed to determine the prevalence of G. duodenalis in dogs siezed by the Center for Control of Zoonoses (CCZ) of the city of Lages, Santa Catarina, Brazil using two diagnostic techniques. In 357 stool samples analysed, the prevalence of G. duodenalis cysts was 5.3% (19/357) and 4.8% (17/357) detected by floatation and sedimentation techniques, respectively. No correspondence between gender and age was found among the methods used for analyzing the infected dogs in this study. Our data suggested that two diagnostic techniques should be used in a complementary way to ensure that false negatives are not neglected.
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