Comparative Medicine: investigations into the fields of infectious and zoonotic disease research, and population-level epidemiology

R Medicine (General);Q Science (General)

Walls, Claire Elizabeth ; Mellor, Dominic J.

University:University of Glasgow

Department:School of Veterinary Medicine

关键词: cardiology, Trypanosomiasis, zoonotic, equine, disease, Africa, epidemiology, infectious disease, population;   

Others  :  http://theses.gla.ac.uk/2187/1/2010wallsmsc.pdf

来源: University of Glasgow

【 摘 要 】

Project 1: Human African Trypanosomiasis causes cardiac rhythm disturbances through hitherto unknown mechanisms.It is known that the presence of such protozoan parasites or simply their supernatant has excitatory effects on isolated cardiomyocytes, seen as increased Ca2+ wave occurrence.We investigated the theory that the protozoa are able to release a cathepsin L-like product into solution which is the initiator of such waves.Adult rat left ventricular cardiomyocytes were isolated in solution before [Ca2+] was raised to physiological extracellular concentration.The cells were then exposed to pH controlled samples of supernatant, with or without a known cathepsin L-like protease inhibitor (K11777), and all were subjected to population studies of wave incidence over 60 second timeframes.Baseline percentage of spontaneously waving cells in mock extracellular solution was found to be significantly lower than with the presence of Trypanosome supernatant.Addition of K11777 led to a significant reduction in spontaneity toward baseline.These results suggest that T. b. brucei produces a cathepsin L-like cysteine protease which causes increased incidence of Ca2+ waves.Project 2: Two survey-based studies of equine disease in the UK gathered thirty years apart were compared on the basis of disease category prevalence.The first study, published in 1965, was conducted by the British Equine Veterinary Association and covered the whole of mainland UK and Ireland.The second dataset was obtained from The Home of Rest for Horses Study, which surveyed Scotland and northern England in the mid-1990s.Musculoskeletal and alimentary diseases were the most important categories of disease in both studies, but there were significant differences seen in both the composition of the horse population in terms of breed type, and the profile of disease between the studies.The predominant horse type in the BEVA study was the pony, whereas the HRH study reported a more even distribution of ponies, hunter-type horses and racehorses within the population.Disease categories which were more commonly diagnosed in the HRH versus the BEVA study included musculoskeletal and systemic disease.Those categories which had were less commonly diagnosed comprised alimentary and respiratory disease.Project 3: Diarrhoea is the second most common cause of death of children under 5 years of age in the developing world, and accounts for more child deaths than measles, malaria and HIV combined.An important cause of such enteric disturbances is infection with pathogenic organisms, many of which may be acquired through zoonotic transmission from domestic animal species.Detailed epidemiological information regarding the causative agents implicated in diarrhoeic disease in western Kenya is lacking.The Kenyan Medical Research Institute (KEMRI) in collaboration with the Centres for Disease Control and Prevention (CDC) began conducting a case-control study of diarrhoeic children in western Kenya in 2008.Ninety seven and a half percent of compounds housed chickens, 75.9% housed dogs and 74.7% kept cattle, other species were less common.Two point four percent of pooled animal faecal samples were classified as diarrhoeic faeces, 66.7% of which were from young animals.The following pathogens were found in animal faecal samples at the stated prevalences (all animal species sample results combined); E. coli 99.3%, Salmonella enterica 6.6%, Campylobacter jejuni 1.8%, Campylobacter coli 0.7%, Salmonella typhi 0.2%, Giardia spp. 10.2% and Cryptosporidium spp. 2.5%.In stool samples from children, the following pathogens were found to be marginally more prevalent in cases versus than controls; C. jejuni, C. coli, S. enterica, and Cryptosporidium.Giardia spp. were more prevalent among control children than cases.No statistically significant associations were found between the presence of any of the identified pathogens in the animal population of a compound with its presence in the child samples of the same compound.