Vaccines against traveler's diarrhoea and rotavirus disease - a review

Real-time multiplex PCR assay reveals the increased prevalence of Campylobacter spp and diarrhoeagenic Escherichia coli in humans from Vellore, South India

Introduction. Bacterial dysentery is one of the greatest causes of morbidity and mortality worldwide. Campylobacter spp. and diarrhoeagenic Escherichia coli (DEC) are recognised as the most common causes of bacterial enteritis in developing countries including India.Hypothesis/Gap statement. Rapid and accurate identification of dysentery causing organisms using molecular methods is essential for better disease management, epidemiology and outbreak investigations.Aim. In view of the limited information available on the dysentery causing agents like Campylobacter spp., enterohemorrhagic E. coli (EHEC)/enteropathogenic E. coli (EPEC) and enteroinvasive E. coli (EIEC)/Shigella in India, this study was undertaken to investigate the presence of these pathogens in human and poultry stool samples by molecular methods.Methodology. In total, 400 human stool samples and 128 poultry samples were studied. Microaerophilic culture along with real-time multiplex PCR with the targets specific to the genus Campylobacter, Campylobacter jejuni, Campylobacter coli, EHEC, EPEC and EIEC/Shigella was performed. Further species confirmation was done using MALDI-TOF MS.Results. On microaerophilic culture, C. coli was isolated in one human sample and two C. jejuni and one C. fetus in poultry samples. On PCR analysis, among human stool samples, typical EPEC (42%) was predominantly seen followed by Campylobacter spp. (19%) and EIEC/Shigella (10%). In contrast, Campylobacter spp. (41%) was predominant in poultry samples, followed by typical EPEC (26%) and EIEC/Shigella (9%). Poly-infections with Campylobacter spp. and DEC were also observed among both sources.Conclusion. The present study documented the increased prevalence of Campylobacter spp. in humans compared with the results of previous studies from India. Typical EPEC was found to be predominant in children less than 5 years of age in this study. The high prevalence of coinfections in the current study indicates that a multiple aetiology of diarrhoea is common in our settings.

An outbreak of acute gastroenteritis associated with group A Rotavirus in long-term care facility in Slovenia

BACKGROUND

In April 2013, an outbreak of acute gastroenteritis was reported in a residential long-term care facility (LTCF) in Ljubljana. We carried out an outbreak investigation to describe the outbreak, identify factors associated with contracting infection and to recommend control measures.

METHODS

We conducted descriptive epidemiology of the outbreak and a case-control study among residents; a case was a resident or staff member of the LTCF with acute diarrhoea and at least one of the following symptoms: fever, vomiting, nausea, fatigue, headache and abdominal pain between 11 and 23 April 2013. Controls had no gastrointestinal symptoms during the outbreak period. Stool specimens were tested for enteric pathogens, including Rotavirus.

RESULTS

Of 244, 33 (13.5 %) and 4 of 106 staff (3.8 %) were affected. Twenty-eight (84.8 %; median age 85 years; range 71-95 years) among affected residents and four (100 %; median age 35 years; range 30-45 years) among affected staff were women. The main symptoms besides acute diarrhoea were fatigue (54.1 %) and nausea (45.9 %). The average duration of gastroenteritis symptoms was 3.6 days in residents and 1.3 days in staff. None of the affected persons was hospitalized. Rotavirus group A was detected in a single stool specimen. In the multivariable analysis, being ambulant (aOR = 12.3; 95 % CI: 1.14-133.1), and having more than two comorbidities (aOR = 4.7; 95 % CI: 1.14-19.0) were significantly associated with acute gastroenterocolitis.

CONCLUSIONS

Contact precautions of affected persons and controlled staff interactions between outbreak ward and unaffected ward are recommended in times of outbreak, with additional effort in targeting mobile residents and those with comorbidities.

The suppressive activities of six sources of medicinal ferns known as gusuibu on heat-labile enterotoxin-induced diarrhea

Diarrheal disease is one of the most important worldwide health problems. Enterotoxigenic Escherichia coli (ETEC) is the most frequently isolated enteropathogen in diarrheal diseases. In developing countries, a very large number of people, especially children, suffer from diarrhea. To combat this problem, World Health Organization has constituted the Diarrhea Diseases Control Program which guides studies on traditional medicinal practices and preventive measures. Gusuibu, a traditional folk medicine, has been claimed to heal certain types of diarrhea. However, so far no scientific study has been carried out on the anti-diarrheal mechanism of Gusiubu. The present study was performed to examine the suppressive activities of ethanol extracts of six sources of folk medicinal ferns used as Gusuibu on heat-labile enterotoxin (LT)-induced diarrhea. Inhibitory effects of six sources were evaluated on the ETEC LT subunit B (LTB) and monosialotetrahexosylganglioside (GMI) interaction by GM1-enzyme linked immunosorbent assay and patent mouse gut assay. Our results indicated that Drynaria fortunei had no anti-diarrheal effect, while, among the remaining five folk medicinal ferns, four belonging to family Davalliaceae had significant abilities on both the blocking of LTB and GM1 interaction and the inhibition of LT-induced diarrhea. In conclusion, these findings suggested the potential application of Gusuibu as an anti-diarrheal remedy.

Exploiting mucosal surfaces for the development of mucosal vaccines

Mucosal immunity covers a variety of mucosal surfaces susceptible to different pathogens. This review highlights the diversity of mucosal tissues and the unique microenvironments in which an immune response is generated. It argues that tissue-specific factors present throughout mucosal tissues and lymph nodes determine the differentiation into IgA-producing B cells, which in turn determines their migration patterns. Mucosal immunity can therefore be induced when antigen is delivered at any mucosal tissue without the need for specific 'mucosal adjuvants' or targeting to specialised lymphoid structures. Non-oral vaccination strategies directed at alternative and more accessible mucosal tissue sites, may provide new avenues for both mucosal and systemic immunization, and will be greatly facilitated by the use of large animal models.

Travellers' diarrhoea - pros and cons of different prophylactic measures

Travellers' diarrhoea is the most likely cause for disturbing travel arrangements. At an average, 30-40% of tourists are concerned, depending on the travel destination. Due to the high impact on the travellers' health this topic is still of utmost importance in travel medicine. A wide spectrum of enteropathogens can be accountable, with enterotoxigenic Escherichia coli being the major causing pathogen among other bacteria, parasites and viruses. Here we discuss advantages and disadvantages of different prophylactic measures against travellers' diarrhoea. The effectiveness but also the relevance of hygiene education, vaccination and antibiotic or probiotic application will be discussed in the context of the travellers' different risk profiles.

Effectiveness and economic analysis of the whole cell/recombinant B subunit (WC/rbs) inactivated oral cholera vaccine in the prevention of traveller's diarrhoea

BACKGROUND

Nowadays there is a debate about the indication of the oral whole-cell/recombinant B-subunit cholera vaccine (WC/rBS) in traveller's diarrhoea. However, a cost-benefit analysis based on real data has not been published.

METHODS

A cost-effectiveness and cost-benefit study of the oral cholera vaccine (WC/rBS), Dukoral for the prevention of traveller's diarrhoea (TD) was performed in subjects travelling to cholera risk areas. The effectiveness of WC/rBS vaccine in the prevention of TD was analyzed in 362 travellers attending two International Vaccination Centres in Spain between May and September 2005.

RESULTS

The overall vaccine efficacy against TD was 42,6%. Direct healthcare-related costs as well as indirect costs (lost vacation days) subsequent to the disease were considered. Preventive vaccination against TD resulted in a mean saving of 79.26 euro per traveller.

CONCLUSION

According to the cost-benefit analysis performed, the recommendation for WC/rBS vaccination in subjects travelling to zones at risk of TD is beneficial for the traveller, regardless of trip duration and visited continent.

Pyrosequencing analysis of the gyrB gene to differentiate bacteria responsible for diarrheal diseases

Pathogens causing acute diarrhea include a large variety of species from Enterobacteriaceae and Vibrionaceae. A method based on pyrosequencing was used here to differentiate bacteria commonly associated with diarrhea in China; the method is targeted to a partial amplicon of the gyrB gene, which encodes the B subunit of DNA gyrase. Twenty-eight specific polymorphic positions were identified from sequence alignment of a large sequence dataset and targeted using 17 sequencing primers. Of 95 isolates tested, belonging to 13 species within 7 genera, most could be identified to the species level; O157 type could be differentiated from other E. coli types; Salmonella enterica subsp. enterica could be identified at the serotype level; the genus Shigella, except for S. boydii and S. dysenteriae, could also be identified. All these isolates were also subjected to conventional sequencing of a relatively long ( approximately1.2 kb) region of gyrB DNA; these results confirmed those with pyrosequencing. Twenty-two fecal samples were surveyed, the results of which were concordant with culture-based bacterial identification, and the pathogen detection limit with simulated stool specimens was 10(4) CFU/ml. DNA from different pathogens was also mixed to simulate a case of multibacterial infection, and the generated signals correlated well with the mix ratio. In summary, the gyrB-based pyrosequencing approach proved to have significant reliability and discriminatory power for enteropathogenic bacterial identification and provided a fast and effective method for clinical diagnosis.