Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 11

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych:  zespoly chorobowe
help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
Two groups of swine diseases were presented depending on their etiology. The first one included diseases caused, in each case independently, by one pathogenic microorganism and the second one contained diseases primarily caused by unfavorable environmental conditions. In this group as a consequence of the lowering of resistance against infection pathological action by facultatively pathogenic microorganisms took place. The paper concentrates on the two syndromes belonging to the second group of diseases: porcine post-weaning diarrhea (PPWD) and porcine respiratory disease syndrome (PRDS). In relation to PPWD, predisposing environmental factors connected with intensive technologies of swine production were presented. These were the following: a short period of lactation, too low temperatures in the weaning house, particularly during the two first weeks after weaning, and improper ventilation. As a consequence of these predisposing environmental conditions facultatively pathogenic E. coli strains proliferate in the intestine. Their pathogenic factors, special adhesions and enterotoxins participating in the pathogenesis of diarrhea were characterized. The role of rotaviruses as additional etiological agents of PPWD was also mentioned. Vaccination and antibiotic therapy were evaluated. As the next multifactorial disease, PRDS was characterized. Environmental factors contributing to lowering the resistance of the respiratory system to infection were noted. Some other contributing factors were: inadequate gilt replacement programs, large populations and too high a density of pigs, wide ranges of weaning ages, co-mingling pigs with mixed health status. Mycoplasma hyopneumoniae and PCV2 were mentioned as the main microorganisms participating in the etiology of the syndrome the PRRS virus, followed by other facultatively pathogenic microorganisms contributing to the development of the disease. Suggestions for general prophylactic measures were mentioned. Vaccination, particularly against PCV2, but also the two other noted microorganisms, was recommended. A figure containing general indications of potential risk factors in relation to both described syndromes was included in the paper.
Losses in animal production caused by unfavourable environmental conditions and facultatively pathogenic bacteria, occurring relatively often as commensals in cattle, swine and poultry, are believed to be higher than those related to pathogens causing diseases irrespectively of environmental conditions, even if these conditions are favourable. Stress plays an essential role in the transition of commensals into pathogens. This review presents up-to-date definitions of stress and mechanisms leading as a consequence of stressors in relation to the microorganisms and the host. Stress thus suppresses the immune system and increases the susceptibility of the animal to infection by releasing neurotransmitters, cytokines and hormones into the circulation or tissues. The most important role is played by catecholamines (epinephrine and norepinephrine) and by glucocorticoids (cortisol and corticosterone). Additionally a new perspective is presented, indicating that stress-related hormones directly affect the microorganism or the hostpathogen interaction. As a result of stress, which causes neuroendocrine changes, commensals grow faster and generate pathogenic processes. This effect of stress stimulates the development of multifactorial syndromes with symptoms from the intestinal tract or the respiratory system. The above-mentioned examples refer to infections caused by certain serotypes of Escherichia coli, serovars of Salmonella enterica and Campylobacter jejuni. In conclusion, stress may influence the outcome of common bacterial infections. Since stress leads to serious losses in animal production, the implementation of procedures for preventing stress and ensuring the welfare of food animals from birth to slaughter should be a priority for animal breeders and veterinarians.
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.