Prophylactic immunisation against traveller's diarrhoea caused by enterotoxin-forming strains of Escherichia coli and against cholera: does it make sense and for whom?

Immunogenicity of cholera vaccination in children with inflammatory bowel disease

The cholera vaccine can protect patients with inflammatory bowel disease (IBD) against both cholera and travelers' diarrhea. However, both immunosuppressive treatment and IBD can affect its vaccine immunogenicity. The aim of this study was to assess the immunogenicity and safety of the cholera vaccine in children with IBD. Children older than 6 years with diagnosed IBD were enrolled in this multicenter study. All patients were administered two doses of the oral cholera vaccine (Dukoral®). Anti-cholera toxin B subunit IgA and IgG seroconversion rates were evaluated in a group with immunosuppressive (IS) treatment and a group without IS treatment (NIS). Immunogenicity was assessed in 70 children, 79% of whom received IS treatment. Post-vaccination seroconversion was displayed by 33% of children, for IgA, and 70% of children, for IgG. No statistically significant differences were found in the immune responses between the IS and NIS groups: 35% vs. 27% (p = .90), for IgA, and 68% vs. 80.0% (p = .16), for IgG, respectively. One case of IBD exacerbation after vaccination was reported. The oral cholera vaccine is safe. The immunogenicity of the oral cholera vaccine in children with IBD was lower than previously observed in healthy ones. The treatment type does not seem to affect the vaccine immunogenicity.

Comparison of the immunogenicity of Dukoral® oral cholera vaccine between renal transplant recipients on either a calcineurin inhibitor or mycophenolate - A controlled trial

BACKGROUND

The evidence for recommendations regarding vaccination in solid organ transplant recipients is sparse. There is little data comparing vaccine responses between groups on different immunosuppressive drugs. This study was conducted to evaluate the antibody response to Dukoral® oral cholera vaccine in renal transplant recipients (RTR).

METHODS

In a single-center non-randomized controlled clinical trial, healthy volunteers (n = 21) and renal transplant recipients (n = 30) were vaccinated with the oral whole cell/recombinant B subunit cholera vaccine Dukoral® (Valneva Inc., Vienna, Austria). The RTR were stratified according to their maintenance immunosuppressive therapy: either prednisone and a calcineurin inhibitor (cyclosporine A or tacrolimus; P/CNI group; n = 15) or prednisone and mycophenolate (P/MMF group; n = 15). All volunteers ingested Dukoral® at baseline and at day 14. Serum samples were drawn at day 0 and day 21. The primary outcome was seroconversion, defined as either a 3-fold IgA serum titer increase in anti-cholera toxin B antibodies and/or a 4-fold rise in the serum vibriocidal titer.

RESULTS

Follow-up was complete. Seroconversion after vaccination was 57% (standard error, SE 9%) in RTR and 81% (SE 9%) in healthy controls (Relative Risk, RR 0.70; 95% CI 0.48-1.02). When stratified according to maintenance immunosuppression, the seroconversion rate was 67% (SE 12%) in the P/CNI group (RR compared with controls 0.82; 95% CI 0.55-1.25) and 47% (SE 13%) in the P/MMF group (RR compared with controls 0.58; 95% CI 0.32-1.03).

CONCLUSION

Adverse events were mild to moderate and transient. The response to Dukoral was weaker and the seroconversion rate was lower in renal transplant recipients than in healthy controls. In particular, those using mycophenolate had a poor response. Nevertheless, more than half of the transplant recipients seroconverted. Therefore oral vaccines should not be discarded as a potential tool for protection of solid organ transplant recipients. This trial is registered in clinicaltrials.gov under NCT01109914.

A cluster of acute diarrhea suspected to be cholera in French travelers in Haiti, December 2010

A cluster of 21 cases of watery diarrhea suspected to be cholera that involved French military policemen and young volunteers occurring in the context of the Haiti cholera outbreak is described. The attack rate (AR) was higher among young volunteers (71.4%) than among policemen (15.3%) (p < 0.0001). There was a significant association between raw vegetables consumption and watery diarrhea in the young volunteer group. If we consider the raw vegetables consumers only, AR was lower among doxycycline-exposed subjects (relative risk: 0.2; 95% confidence interval: 0.1-0.4). The main aspect that is of scientific interest is the potential prophylactic effect of doxycycline used for malaria prophylaxis on the watery diarrhea AR.

Vaccination strategies to combat an infectious globe: oral cholera vaccines

Cholera is a substantial health burden in many countries in Africa and Asia, where it is endemic. It is as well responsible for ongoing epidemics in sub-Saharan Africa which are becoming greater in terms of frequency, extension, and duration. Given the availability of two oral cholera vaccines and the new data on their efficacy, field effectiveness, feasibility, and acceptance in cholera-affected populations and in travelers, these vaccines should be used in endemic areas, in travelers for these areas and should be considered in areas at risk for outbreaks. The two vaccines currently available in worldwide are: (1) The killed oral vaccine (Dukoral, licensed by SBL–Sweden to Crucell–Holland) is recommended since 1999 by WHO and consists of a mixture of four preparations of heat or formalin killed whole cell Vibrio cholera O1 (Inaba and Ogaba serotypes, and classical and El Tor biotypes) that are then added with purified recombinant cholera toxin (CT) B subunit. Because CT cross-reacts with Escherichia coli LT the vaccine also provides short-term protection against ETEC (enterotoxigenic E. coli) which is of added benefit for travelers. It is available in more than 60 countries. (2) A bivalent O1 and O139 whole cell oral vaccine without CT B subunit (Shanchol) has been lately developed in Vietnam (licensed by VaBiotech–Viet Nam to Shantha Biotechnics–India. It is available in India and Indonesia. A structured search of papers in PubMed and reports on cholera vaccines by WHO and CDC, as well as critical reading and synthesis of the information was accomplished. Inclusion criteria were defined according to reports quality and relevance.

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.