Date of Award

2006

Document Type

Doctoral Thesis

Degree Name

Doctor of Philosophy

Department

Biological Sciences

First Advisor

Dr. Helen O'Shea

Abstract

On average more than 3,000 cases of rotavirus diarrhea are detected annually amongst Irish children less than 3 years of age. Rotavirus disease occurs mainly during the winter months, with peak infections detected from February to April. The symptoms of disease are diarrhea and dehydration, with 80% of patients requiring hospitalisation, The mean duration of hospitalisation is 3-4 days, with an average cost per day of €409. Eighteen percent of infections were detected in infants less than 6 months of age, suggesting inadequate maternal derived protection from existing strains, or the existence of novel strains in Ireland with little or no immunity in the population to such strains. The most efficient method of rotavirus control would be the implementation of a suitable vaccination programme. Prior to the introduction of a vaccine however, the epidemiology of strains in circulation needs to be determined to monitor the wild-type rotavirus population and to detect novel strains.

Four hundred and twenty-two rotavirus positive stool samples were isolated from Irish children presenting with confirmed diarrhea, admitted to four major hospitals in the southern region of Ireland from 2001-2004. The strains were characterised using polyacrylamide gel electrophoresis and nested reverse transcriptase polymerase chain reaction (nRT-PCR) mediated-typing.

The predominant G-types over the three-year period were G1, G9, G3 and G4. Mixed infections, with more than one G-type involved accounted for a large percentage of the collection. G3 and G9 were novel strains not previously detected in Ireland. G8 and G9 strains, recovered from Irish children, are normally associated with infections in animals.

To date, no data describing the epidemiology of animal rotavirus strains exists. Substantial economic loss occurs, due to increased morbidity and mortality and treatment costs in dairy and beef calves. An effective vaccine would be useful for cattle herds experiencing problems relating to calf diarrhea, minimising economic losses to the herd owners.

One hundred and two faecal samples were collected from calves showing clinical signs of neo-natal diarrhea, in the southern region of Ireland, from 2002-2004. Ninety-three were confirmed positive for rotavirus, using an enzyme-linked immunosorbent assay. The strains were characterised as for the human samples. The bovine rotavirus G-types in circulation were G6, G10 and mixed infections with G6 and G10.

Norovirus causes gastroenteritis in all age groups, and normally occurs during the winter months, hence termed, “Winter Vomiting Disease”. The onset of disease is usually sudden with projectile vomiting and often occurs where there are large gatherings of people e.g. schools, creches, hospitals and hotels. It results in huge economic losses with shut down of schools, hotels, hospital wards and procedures. The transmission routes are mainly person to person and through food and waterborne sources.

Norovirus is confirmed by electron microscopy in most medical laboratories in Ireland, as to date there is no rapid sensitive screening method available. For PCR mediated technology, there is also a lack of a consensus set of primers to detect all strains of Norovirus in circulation, with many research institutions using an array of primer pairs to detect Norovirus.

Fifty-three stool samples were collected from patients suffering from disease symptoms of Norovirus gastroenteritis in 2002. Thirty-four water samples were collected in February and July of 2003 and analysed for the presence of Norovirus. Both the clinical and water samples were tested for Norovirus using enzyme immunoassay and nested reverse transcriptase polymerase chain reaction methods. Forty-eight of the clinical samples were positive for Noroviruses using the enzyme immunoassay method, while only seventeen were positive using PCR methods. After concentration of the water samples, six were positive by the enzyme immunoassay method, PCR was unsuccessful for determining the presence of Norovirus in the water samples.

Access Level

info:eu-repo/semantics/openAccess

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