title: Salmonella enterica serovar Typhi-specific immunoglobulin A antibody responses in plasma and antibody in lymphocyte supernatant specimens in Bangladeshi patients with suspected typhoid fever.
abstract: Many currently available diagnostic tests for typhoid fever lack sensitivity and/or specificity, especially in areas of the world where the disease is endemic. In order to identify a diagnostic test that better correlates with typhoid fever, we evaluated immune responses to Salmonella enterica serovar Typhi (serovar Typhi) in individuals with suspected typhoid fever in Dhaka, Bangladesh. We enrolled 112 individuals with suspected typhoid fever, cultured day 0 blood for serovar Typhi organisms, and performed Widal assays on days 0, 5, and 20. We harvested peripheral blood lymphocytes and analyzed antibody levels in supernatants collected on days 0, 5, and 20 (using an antibody-in-lymphocyte-supernatant [ALS] assay), as well as in plasma on these days. We measured ALS reactivity to a serovar Typhi membrane preparation (MP), a formalin-inactivated whole-cell preparation, and serovar Typhi lipopolysaccharide. We measured responses in healthy Bangladeshi, as well as in Bangladeshi febrile patients with confirmed dengue fever or leptospirosis. We categorized suspected typhoid fever individuals into different groups (groups I to V) based on blood culture results, Widal titer, and clinical features. Responses to MP antigen in the immunoglobulin A isotype were detectable at the time of presentation in the plasma of 81% of patients. The ALS assay, however, tested positive in all patients with documented or highly suspicious typhoid, suggesting that such a response could be the basis of improved diagnostic point-of-care-assay for serovar Typhi infection. It can be important for use in epidemiological studies, as well as in difficult cases involving fevers of unknown origin.
authors.affiliation: International Centre for Diarrhoeal Disease Research, Bangladesh (ICDDR,B), Dhaka, Bangladesh.
authors.forename: Alaullah
authors.initials: A
authors.lastname: Sheikh
authors.forename: M Saruar
authors.initials: MS
authors.lastname: Bhuiyan
authors.forename: Farhana
authors.initials: F
authors.lastname: Khanam
authors.forename: Fahima
authors.initials: F
authors.lastname: Chowdhury
authors.forename: Amit
authors.initials: A
authors.lastname: Saha
authors.forename: Dilruba
authors.initials: D
authors.lastname: Ahmed
authors.forename: K M A
authors.initials: KM
authors.lastname: Jamil
authors.forename: Regina C
authors.initials: RC
authors.lastname: LaRocque
authors.forename: Jason B
authors.initials: JB
authors.lastname: Harris
authors.forename: Mian Mashhud
authors.initials: MM
authors.lastname: Ahmad
authors.forename: Richelle
authors.initials: R
authors.lastname: Charles
authors.forename: W Abdullah
authors.initials: WA
authors.lastname: Brooks
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Calderwood
authors.forename: Alejandro
authors.initials: A
authors.lastname: Cravioto
authors.forename: Edward T
authors.initials: ET
authors.lastname: Ryan
authors.forename: Firdausi
authors.initials: F
authors.lastname: Qadri
mesh_terms: D000293:Adolescent; D000328:Adult; D000907:Antibodies, Bacterial / Q000032:analysis* / Q000097:blood*; D001459:Bangladesh; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood*; D008214:Lymphocytes / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D012485:Salmonella typhi / Q000276:immunology*; D014435:Typhoid Fever / Q000175:diagnosis* / Q000276:immunology*; D055815:Young Adult
chemical_list: D000907:Antibodies, Bacterial; D007070:Immunoglobulin A