What is Typhoid and Paratyphoid Fever?

Typhoid and paratyphoid (enteric) fever are systemic infections caused by Salmonella enterica serovars Typhi and Paratyphi, characterised by prolonged fever and bacteraemia.

Spread is faecal-oral through contaminated water and food. The Vi capsular polysaccharide and O/H antigens underpin serology and Vi-conjugate vaccine research, supported by ELISA and antigens.

Transmission & symptoms

Enteric fever is caused by Salmonella enterica serovars Typhi and Paratyphi, spread faecal-orally via contaminated water and food. It presents as sustained fever with systemic symptoms and bacteraemia rather than prominent diarrhoea.

Diagnosis & serology

Diagnosis is by blood/stool culture; serology historically used the Widal test, and the Vi capsular polysaccharide and O/H antigens underpin modern assays and Vi-conjugate vaccine research.

Research applications

Research tools cover Salmonella antigens (Vi, O, H/flagellin), innate recognition (TLR4, TLR5) and mucosal inflammatory responses (IL-8) relevant to pathogenesis and vaccines.