Typhoid vaccine (GlaxoSmithKline)

Access to safe and nutritious food is key to promoting good health. An estimated 600 million fall ill after eating contaminated food, for which food handlers may constitute a common source of contamination. In addition to unhealthy food handlers, disease carriers handling the food play an equally important role in transmitting these diseases and pose a significant threat to public health. This study, therefore, aimed to know the morbidity profile among the food handlers employed in various food establishments in Panaji city.

Using stratified sampling techniques, we conducted a cross-sectional study among 227 participants selected from 12 food establishments. We did three visits to each food establishment. We excluded food handlers who were unavailable despite three visits at fortnightly intervals and those who did not consent to the study. We administered a pre-designed and pre-structured questionnaire to each participant. A general examination and laboratory investigations, including stool and urine routine, were performed on all participants. We performed descriptive and analytical statistics by using SPSS version 14

Out of the 227 study participants, 79 (34.8%) had at least one morbidity at the time of examination. None of the food handlers had received a single dose of typhoid, hepatitis A, or cholera vaccines. Most (74.4%) study participants did not administer deworming tablets

We found that the health status of the study participants was substandard. Food safety may be in peril among food handlers with lower education backgrounds with morbidities as they may have little understanding of the risk of microbial contamination of food. Therefore, it is essential to create awareness among them.

Many bacterial polysaccharide vaccines, including the typhoid Vi polysaccharide (ViPS) and tetravalent meningococcal polysaccharide conjugate (MCV4) vaccines, do not incorporate adjuvants and are not highly immunogenic, particularly in infants. I found that endotoxin, a TLR4 ligand in ViPS, contributes to the immunogenicity of typhoid vaccines. Because endotoxin is pyrogenic, and its levels are highly variable in vaccines, I developed monophosphoryl lipid A, a nontoxic TLR4 ligand–based adjuvant named Turbo. Admixing Turbo with ViPS and MCV4 vaccines improved their immunogenicity across all ages and eliminated booster requirement. To understand the characteristics of this adjuvanticity, I compared Turbo with alum. Unlike alum, which polarizes the response toward the IgG1 isotype, Turbo promoted Ab class switching to all IgG isotypes with affinity maturation; the magnitude of this IgG response is durable and accompanied by the presence of long-lived plasma cells in the mouse bone marrow. In striking contrast with the pathways employed by alum, Turbo adjuvanticity is independent of NLPR3, pyroptotic cell death effector Gasdermin D, and canonical and noncanonical inflammasome activation mediated by Caspase-1 and Caspase-11, respectively. Turbo adjuvanticity is primarily dependent on the MyD88 axis and is lost in mice deficient in costimulatory molecules CD86 and CD40, indicating that Turbo adjuvanticity includes activation of these pathways. Because Turbo formulations containing either monophosphoryl lipid A or TLR2 ligands, Pam2CysSerLys4, and Pam3CysSerLys4 help generate Ab response of all IgG isotypes, as an adjuvant Turbo can improve the immunogenicity of glycoconjugate vaccines against a wide range of bacterial pathogens whose elimination requires appropriate IgG isotypes.