Formal Name
Widal Test
This article was last reviewed on
This article waslast modified on
January 15, 2018.

The Widal test is one method that may be used to help make a presumptive diagnosis of enteric fever, also known as typhoid fever. Although the test is no longer commonly performed in the United States or other developed countries, it is still in use in many developing countries where enteric fever is endemic and limited resources require the use of rapid, affordable testing alternatives.

Enteric fever is a life-threatening illness caused by infection with the bacterium Salmonella enterica serotype Typhi (S. typhi), usually transmitted through food and drinks contaminated with fecal matter. It is associated with symptoms that include high fever, fatigue, headache, abdominal pain, diarrhea or constipation, weight loss, and a rash known as "rose spots." Early diagnosis and treatment are important because serious complications, including severe intestinal bleeding or perforation, can develop within a few weeks.

The infection is rare in the U.S. and other industrialized nations but is more common in developing countries, including India, parts of South, East and Southeast Asia, and countries in Africa, the Caribbean, Central and South America, and Eastern Europe. Cases of enteric fever in the U.S. are usually attributed to travelers to these endemic areas.

Developed in 1896 and named after Georges Ferdinand Widal, who introduced it, the method relies on a reaction in a test tube or on a slide between antibodies present in the infected person's blood sample and specific antigens of S. typhi, which produces clumping (agglutination) that is visible to the naked eye. While the method is easy to perform, concerns remain about the reliability of the Widal test and studies of the assay's sensitivity and other measures of reliability have been disappointing. Besides cross-reactivity with other Salmonella species, the test cannot distinguish between a current infection and a previous infection or vaccination against typhoid.

In the U.S. and other industrialized nations, testing for enteric fever usually involves a blood culture to detect the bacteria during the first week of fever. A stool, urine or bone marrow culture may also be performed. A blood culture, however, can be labor- and time-intensive in areas of the world that lack the resources for automated equipment. In developing countries, such as those in Africa, the Widal test continues to be used instead of cultures because it is quicker, simpler, and less costly to perform.

The World Health Organization (WHO) has said that due to the various factors that can influence the results of a Widal test, it is best not to rely too much on this test. WHO instead recommends the use of cultures, whenever possible. Until another simple, inexpensive, and reliable option becomes available, however, use of the Widal test will probably persist in those countries with limited resources. There are newer rapid antibody tests for typhoid fever commercially available, several of which have been included in comparative studies of their reliability, for example in India and Africa. Findings seem to vary as to whether any are as reliable as blood culture for diagnosing this infection.

Related Pages

On This Site
Conditions: Travelers' Diseases

Elsewhere On The Web
CDC: Travelers' Health, 2014 Yellow Book: Typhoid and Paratyphoid Fever
CDC: Typhoid Fever General Information 
Mayo Clinic: Typhoid fever
MedlinePlus Medical Encyclopedia: Typhoid fever 

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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.

Sources Used in Current Review

Centers for Disease Control and Prevention. Travelers' Health. Typhoid & Paratyphoid Fever. Chapter 3. 2014 Yellow Book. Available online at http://wwwnc.cdc.gov/travel/yellowbook/2014/chapter-3-infectious-diseases-related-to-travel/typhoid-and-paratyphoid-fever through http://wwwnc.cdc.gov. Accessed September 2013.

MayoClinic.com. Typhoid fever: Symptoms Available online at http://www.mayoclinic.com/health/typhoid-fever/DS00538/DSECTION=symptoms through http://www.mayoclinic.com. Accessed September 2013.

Keddy, KH et al. Sensitivity and specificity of typhoid fever rapid antibody tests for laboratory diagnosis at two sub-Saharan African sites. Bulletin of the World Health Organization 2011;89:640-647. Available online at http://www.who.int/bulletin/volumes/89/9/11-087627/en/ through http://www.who.int. Accessed September 2013.

Krishna S, Desai S, Anjana V K, Paranthaaman R G. Typhidot (IgM) as a reliable and rapid diagnostic test for typhoid fever. Ann Trop Med Public Health 2011;4:42-4. Available online at http://www.atmph.org/article.asp?issn=1755-6783;year=2011;volume=4;issue=1;spage=42;epage=44;aulast=Krishna through http://www.atmph.org. Accessed September 2013.

Sources Used in Previous Reviews

Willke A, Ergonul O and Bayar B. Widal Test in Diagnosis of Typhoid Fever in Turkey. Clin Diagn Lab Immunol. 2002 July; 9(4): 938–941. Available online at http://www.ncbi.nlm.nih.gov/pmc/articles/PMC120044/ through http://www.ncbi.nlm.nih.gov. Accessed August 2010.

Saudi Society of Medical Microbiology and Infectious Diseases. Widal Test. Available online at http://ssmmid.org/widal-test/ through http://ssmmid.org. Accessed August 2010.

Omuse G, Kohli R and Revathi G. Diagnostic utility of a single Widal test in the diagnosis of typhoid fever at Aga Khan University Hospital (AKUH), Nairobi, Kenya. Version published on 1 January 2010. Trop Doct 2010;40:43-44. © 2010 Royal Society of Medicine Press. Available online at http://td.rsmjournals.com/cgi/content/abstract/40/1/43 through http://td.rsmjournals.com. Accessed August 2010.

Ley B et al. Evaluation of the Widal tube agglutination test for the diagnosis of typhoid fever among children admitted to a rural hospital in Tanzania and a comparison with previous studies. BMC Infectious Diseases 2010, 10:180. Available online at http://www.biomedcentral.com/1471-2334/10/180 through http://www.biomedcentral.com. Accessed August 2010.

MedlinePlus Medical Encyclopedia. Typhoid Fever. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/001332.htm. Accessed August 2010.

Begum Z et al. Comparison between DOT EIA IgM and Widal Test as early diagnosis of typhoid fever. Mymensingh Med J. 2009 Jan;18(1):13-7. Available online at http://www.ncbi.nlm.nih.gov/pubmed/19182742 through http://www.ncbi.nlm.nih.gov. Accessed August 2010.

Narayanappa D et al. Comparative study of dot enzyme immunoassay (Typhidot-M) and Widal test in the diagnosis of typhoid fever. Indian Pediatr. 2010 Apr 7;47(4):331-3. Epub 2009 Apr 15. Available online at http://www.ncbi.nlm.nih.gov/pubmed/19430063 through http://www.ncbi.nlm.nih.gov. Accessed August 2010.

World Health Organization. Guidelines on Standard Operating Procedures for MICROBIOLOGY: Enteric Fever. Available online at http://www.searo.who.int/EN/Section10/Section17/Section53/Section482_1794.htm through http://www.searo.who.int. Accessed August 2010.

Centers for Disease Control and Prevention. Travelers' Health, 2010 Yellow Book: Typhoid and Paratyphoid Fever. Available online at http://wwwnc.cdc.gov/travel/yellowbook/2010/chapter-2/typhoid-paratyphoid-fever.aspx through http://wwwnc.cdc.gov. Accessed August 2010.

MayoClinic.com. Typhoid Fever. Available online at http://www.mayoclinic.com/health/typhoid-fever/DS00538 through http://www.mayoclinic.com. Accessed August 2010.

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