Cholera vaccines: the current status and problems

Kabir, Shahjahan

doi:10.1097/01.revmedmi.0000174307.33651.81

Cited by 25 publications

(17 citation statements)

References 124 publications

(161 reference statements)

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“…[47]. Duration of immunity after cholera infection is controversial [33]. 3 Assumed as the actual value is unknown; we assume the same value as previous studies.…”

Section: Examplesmentioning

confidence: 99%

Reproduction numbers for infections with free-living pathogens growing in the environment

Bani-Yaghoub

Gautam

Shuai

et al. 2012

Journal of Biological Dynamics

110

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The basic reproduction number R 0 for a compartmental disease model is often calculated by the next generation matrix (NGM) approach. When the interactions within and between disease compartments are interpreted differently, the NGM approach may lead to different R 0 expressions. This is demonstrated by considering a susceptible-infectious-recovered-susceptible model with free-living pathogen (FLP) growing in the environment. Although the environment could play different roles in the disease transmission process, leading to different R 0 expressions, there is a unique type reproduction number when control strategies are applied to the host population. All R 0 expressions agree on the threshold value 1 and preserve their order of magnitude. However, using data for salmonellosis and cholera, it is shown that the estimated R 0 values are substantially different. This study highlights the utility and limitations of reproduction numbers to accurately quantify the effects of control strategies for infections with FLPs growing in the environment.

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“…[47]. Duration of immunity after cholera infection is controversial [33]. 3 Assumed as the actual value is unknown; we assume the same value as previous studies.…”

Section: Examplesmentioning

confidence: 99%

Reproduction numbers for infections with free-living pathogens growing in the environment

Bani-Yaghoub

Gautam

Shuai

et al. 2012

Journal of Biological Dynamics

110

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“…Although these studies were carried out with Dukoral (WC-rCTB), it is likely that similar observations may emerge with the other killed oral vaccine, Shanchol, as protective immunity against cholera is predominantly antibacterial (86,99). The major difference between Dukoral and Shanchol is that the former contains additional rCTB (60) and the latter has additional V. cholerae O139 cells (32).…”

Section: Concluding Remarks On the Killed Ocvs Shanchol And Dukoralmentioning

confidence: 99%

“…The substitution of rCTB for CTB can potentially weaken the vaccine. Some reports have correctly distinguished between WC-CTB and WC-rCTB (85,86); however, the purity of chemically isolated products can vary from lot to lot, further confusing comparisons. Although a rise in serum antitoxin and vibriocidal antibody titers after oral immunization with WC-rCTB and WC-CTB was detected in a few Swedish volunteers, the mean vibriocidal antibody titer increase was greater in those who received WC-CTB (87).…”

Section: On the Questionable Biological Similarity Between Ctb And Rctbmentioning

confidence: 99%

Critical Analysis of Compositions and Protective Efficacies of Oral Killed Cholera Vaccines

Kabir

2014

Clin. Vaccine Immunol.

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Two cholera vaccines, sold as Shanchol and Dukoral, are currently available. This review presents a critical analysis of the protective efficacies of these vaccines. Children under 5 years of age are very vulnerable to cholera and account for the highest incidence of cholera cases and more than half of the resulting deaths. Both Shanchol and Dukoral are two-spaced-dose oral vaccines comprising large numbers of killed cholera bacteria. The former contains Vibrio cholerae O1 and O139 cells, and the latter contains V. cholerae O1 cells with the recombinant B subunit of cholera toxin. In a field trial in Kolkata (India), Shanchol, the preferred vaccine, protected 45% of the test subjects in all of the age groups and only 17% of the children under 5 years of age during the first year of surveillance. In a field trial in Peru, two spaced doses of Dukoral offered negative protection in children under 5 years of age and little protection (15%) in vaccinees over 6 years of age during the first year of surveillance. Little is known about Dukoral's long-term protective efficacy. Both of these vaccines have questionable compositions, using V. cholerae O1 strains isolated in 1947 that have been inactivated by heat and formalin treatments that may denature protein. Immunological studies revealed Dukoral's reduced and short-lived efficacy, as measured by several immunological endpoints. Various factors, such as the necessity for multiple doses, poor protection of children under 5 years of age, the requirement of a cold supply chain, production costs, and complex logistics of vaccine delivery, greatly reduce the suitability of either of these vaccines for endemic or epidemic cholera control in resource-poor settings.

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“…Even though epidemics have ceased and severe diarrheal cases have been limited to sporadic cases since 2008, it is possible that another epidemic could easily reoccur in Lao PDR because people's natural immunity to the cholera vibrios is limited to O1 serotype Ogawa, biotype El Tor and, as such, this immunity will not be very long lasting (Kabir, 2005). Moreover, in some local areas, people were indifferent about the cholera disease itself (Midorikawa et al, 2010).…”

Section: Cholera Epidemics In Lao Pdr From 1993 To the Presentmentioning

confidence: 99%