Evaluation of new-generation serologic tests for the diagnosis of typhoid fever: data from a community-based surveillance in Calcutta, India.
Although typhoid fever is confirmed by culture of Salmonella enterica serotype Typhi, rapid and simple diagnostic serologic tests would be useful in developing countries. We examined the performance of Widal test in a community field site and compared it with Typhidot and Tubex tests for diagnosis of typhoid fever. Blood samples were collected from 6697 patients with fever for > or =3 days for microscopy, culture, and serologic testing and from randomly selected 172 consenting healthy individuals to assess the baseline Widal anti-Typhi O lipopolysaccharide antibody (anti-TO) and anti-Typhi H flagellar antibody (anti-TH) titers. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the 3 serologic tests were calculated using culture-confirmed typhoid fever cases as "true positives" and paratyphoid fever and malaria cases as "true negatives". Comparing cutoff values for the Widal test, an anti-TO titer of 1/80 was optimal with 58% sensitivity, 85% specificity, 69% PPV, and 77% NPV. Sensitivity was increased to 67% when the Widal test was done on the 5th day of illness and thereafter. The sensitivity, specificity, PPV, and NPV of Typhidot and Tubex were not better than Widal test. There is a need for more efficient rapid diagnostic test for typhoid fever especially during the acute stage of the disease. Until then, culture remains the method of choice.
Dutta
Shanta
S
National Institute of Cholera and Enteric Diseases, P-33 CIT Road, Scheme XM, Beliaghata, P.O. Box 177, Calcutta 700010, India.
Sur
Dipika
D
Manna
Byomkesh
B
Sen
Bhaswati
B
Deb
Alok Kumar
AK
Deen
Jacqueline L
JL
Wain
John
J
Von Seidlein
Lorenz
L
Ochiai
Leon
L
Clemens
John D
JD
Kumar Bhattacharya
Sujit
S
D000907:Antibodies, Bacterial / Q000097:blood*; D005407:Flagella / Q000276:immunology; D006801:Humans; D007194:India; D019081:O Antigens / Q000276:immunology*; D011159:Population Surveillance; D012485:Salmonella typhi / Q000276:immunology*; D012680:Sensitivity and Specificity; D012698:Serologic Tests; D013997:Time Factors; D014435:Typhoid Fever / Q000097:blood / Q000175:diagnosis*; D014505:Urban Population
D000907:Antibodies, Bacterial; D019081:O Antigens