Search

Shiga toxin-producing Escherichia coli (STEC) O157:H7 is a food and waterborne pathogen with severe public health implications. We report the first-time isolation of this pathogen in the Central Highlands of Peru through standardized culture procedures and polymerase chain reaction (PCR). Escherichia coli strains were cultured from rectal-anal swabs from dairy calves and beef from food markets. The latex agglutination test was used to detect O157 and H7 antigens, and multiplex real-time PCR was carried out to detect virulence-related genes. The STEC O157:H7 strains were isolated from 3.5% (1/28) of beef samples and from 6.0% (3/50) of dairy calves that also carried both eaeA and stx1 genes. Therefore, this pathogen is a potential cause of food/waterborne disease in the region, and its surveillance in both livestock and their products should be improved to characterize the impact of its zoonotic transmission. From 2010 to 2020, E. coli was suspected in 10 outbreaks reported to the Peruvian Ministry of Health. Isolates from future outbreaks should be characterized to assess the burden posed by STEC O157:H7 in Peru.

A comparison was made between the reinforcing properties of a purposive attack provoked by stimulation of the hypothalamus and those of natural behaviour based on a certain motivation and exteroceptive stimuli. A model of an experiment with two cats has been evolved which made it possible to study simultaneously their behaviour in response to one and the same indifferent stimulus, reinforced in one cat by stimulation of the hypothalamus, while for the other, the stimulus acted as a signal of the attack on the part of the stimulated cat. It was shown that conditioned reflexes were not elaborated on the basis of reinforcement of the indifferent stimulus with behavioral effects of the purposive attack, produced by stimulation of the hypothalamus. It is assumed that conditioned reproduction of the purposive attack is impossible due to the absence of natural motivation; hence behavioral acts imposed by stimulation of the brain are not fixed in the memory.