Detection by PCR of eight groups of enteric pathogens in 4,627 faecal samples: re-examination of the English case-control Infectious Intestinal Disease Study (1993–1996)

Abstract

The English case-control Infectious Intestinal Disease Study (1993-1996) failed to detect an enteric pathogen or toxin in 49% of cases of gastroenteritis. In the present study, polymerase chain reaction (PCR) assays were applied to DNA and cDNA generated from 4,627 faecal samples from cases and controls archived during the original study for the detection of norovirus, rotavirus, sapovirus, Campylobacter spp., Salmonella spp., enteroaggregative Escherichia coli, Cryptosporidium spp., and Giardia spp. The percentage of archived samples from cases and from controls in which at least one agent (or toxin) was detected increased from 53% in the original study to 75% and from 19 to 42%, respectively, after the application of PCR assays. Among cases, the following percentages of enteric pathogens were detected: norovirus 36%, rotavirus A 31%, sapovirus 4%, Salmonella spp. 6%, Campylobacter jejuni 13%, Campylobacter coli 2%, other Campylobacter spp. 8%, enteroaggregative E. coli 6%, Giardia spp. 2%, and Cryptosporidium spp. 2%. The present study provides additional insight into the aetiology of infectious intestinal disease in England and highlights the occurrence of viral infections in cases as well as in asymptomatic individuals. Other notable findings include the frequent presence of Campylobacter spp. other than C. jejuni or C. coli, the high frequency of multiple agents in 41% of cases and in 13% of controls, and the variation in the aetiology and rate of infection found for different age groups. The results demonstrate the greater sensitivity of PCR-based methods compared to current conventional methods.

Molecular epidemiology of rotaviruses in Bulgaria: annual shift of the predominant genotype

“…However, cases of rotavirus diarrhea were identified among older children and adults with an incidence of 15.4%. This is similar to recent reports from the United Kingdom, where rotavirus infections, both symptomatic and asymptomatic, were detected across the age groups [42]. Secondly, we observed year-round circulation of rotaviruses in the country, with increased incidence in the winter season and unexpected peaks preceding the rotavirus seasons.…”

Prevalence and characteristics of asymptomatic norovirus infection in the community in England

“…Further work is needed to validate the use of a cycle threshold value cutoff for use in studies without a control group. Asymptomatic norovirus infection is very common (1,16,21,(33)(34)(35). Therefore, this quantitative approach provides the most rigorous estimate of norovirus disease burden.…”

“…All specimens, including those previously positive by electron microscopy, were later retested for norovirus using a more sensitive RT-PCR assay. All norovirus RT-PCR-positive specimens were retested by using a semiquantitative RT-PCR assay (run for 40 cycles) (16). Recruitment and stool testing in IID cases are summarized in Table 1.…”

Risk factors for symptomatic and asymptomatic norovirus infection in the community

“…previously positive by electron microscopy, were subsequently retested for norovirus using a more sensitive semi-quantitative real-time reverse transcriptionpolymerase chain reaction (RT-PCR) [13].…”

“…The specimens from the IID study were archived and have been retested using more sensitive molecular methods to detect norovirus [13][14][15]. We used the results from this retesting to identify cases of norovirus-associated IID and asymptomatic norovirus infections, and looked for risk factors for both symptomatic and asymptomatic norovirus infection, across all age groups.…”