An epidemiological surveillance of asymptomatic typhoid carriers associated in respect to socioeconomic status in India

Abstract

The term ‘enteric fever’ was coined to embrace both typhoid and paratyphoid. It was known as a generalized infection of the reticuloendothelial system and intestinal lymphoid tissue accompanied by sustained fever and bacteraemia. Typhoid has remained a major public health issue in many tropical countries and the highest burden of the disease is in Asia (Pang et al. 1998). The global burden of typhoid was estimated as 16,000,000 cases and 600,000 deaths per year (Pang and Puthucheary 1983; Pang and Bhutta 1995). Currently global pandemics are being caused by the less common serovar of S. typhi (Miko et al. 2002). The asymptomatic carrier state in humans has had serious consequences on public health and the exclusive source for typhoid bacillus was asymptomatic typhoid carriers. An individual could asymptomatically carry the typhoid bacilli for days to years without any symptoms of typhoid fever (Bigelow and Anderson 1933: White and Parry 1996; Senthilkumar and Prabakaran 2005). They usually excrete as many as 10 virulent typhoid bacilli per gram of faeces. These organisms reside in the scarred foci of the biliary tract, migrate through the bile ducts and over the vast surface area of intestinal epithelium; however, they did not cause typhoid fever in the carrier (Hornick et al. 1970). S. typhi usually possesses a polysaccharide Vi (virulence) surface antigen that was associated with enhanced capacity to invade the host. Vi antigen of S. typhi and its relation with high serum titres of S. typhi carrier state, reports about the usefulness of Vi serology in the detection of the carrier state (Felix and Pitt 1934; Felix 1938; Lanata et al. 1983) and establishes a chronic asymptomatic infection in the gall bladder (Kauffmann 1954; Prouty et al. 2002). Asymptomatic typhoid carriers were deficient in IgM and anatomical alterations in the biliary tract lead to prolong bacterial persistence (Cheronokhvostova et al. 1969). The carrier state occurred disproportionately often following infection not only in women but also in older patients, with biliary carriage rather than the urinary carriage (Hornick 1985). Identification of asymptomatic typhoid carriers as the source of an outbreak usually required multiple cultures for several weeks (Engleberg et al. 1983). Positive asymptomatic carriers from food handlers significantly contributed to the spread of S. typhi, S. paratyphi A and S. paratyphi B. Therefore, a periodic assay of Salmonella spp in foodstuffs and food handlers could help in the control of food borne diseases (Sasikumar et al. 2005).