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| Year : 1990 | Volume
: 34
| Issue : 1 | Page : 20-34 |
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The current status of diarrhoea related vaccines.
SK Sarkar, SC Pal
National Institute of Cholera and Enteric Diseases, Calcutta
Correspondence Address:
S K Sarkar
National Institute of Cholera and Enteric Diseases, Calcutta
 Source of Support: None, Conflict of Interest: None  | Check |
PMID: 1966245 
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Since diarrhea is responsible for considerable morbidity and mortality in India as well as in developing and developed countries, public health specialists strive to develop vaccines against various pathogens which cause diarrhea. Rotavirus (RV) causes 20-40% of severe diarrhea among 6-24 month olds. So they hope for a single dose vaccine against all 4 RV serotypes which can be administered to newborns, but such a vaccine does not yet exist. The bovine and rhesus vaccines are the only heterologous candidate vaccines available, (as of the end of 1989). Another candidate vaccine is the human-animal reassortant RV vaccine where scientists incorporate the VP7 surface protein of human RV into animal RV. The 3rd type of RV candidate vaccine include the naturally attenuated human RV (nursery strains). Vibrio cholerae also causes significant diarrhea in India. Researchers have conducted field trials of many cholera vaccines since the mid 1990s, but they could not find a vaccine which could be used for mass vaccination against cholera. In fact, the cholera vaccine currently used only provides 50% protection, lasts 3-6 months, does not affect carriers, and does not protect against all strains. Salmonella typhi also causes diarrhea, especially among school age children and young adults. The results of large scale field trials in the 1960s reveal that 2 doses of the acetone inactivated typhoid vaccine performed the best of the injectable killed whole cell vaccines. In fact, it provides 79-93% protection and lasts 3-4 years. Further the live oral Ty21a lyophilized vaccine reconstituted in a liquid form and given in multiple doses provides comparable protection (71-96%) against typhoid as well as some protection against paratyphoid. Moreover they induce no side effects. Shigella species also cause diarrhea, especially in children. Various candidate vaccines against shigellosis include the spontaneously attenuated vaccines, streptomycin dependent vaccines, toxoid against exotoxins, and mutant hybrid strains. |
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