It may only hurt a little when the needle is inserted. The test used two fold serially diluted sera of patients, dilution being from 1:20 to 1:320. suggest me how i should proceed for further Medical & how dangerous is this ? Widal test is used for detection of specific antibodies produced in response to the stimulation by specific antigen of Salmonella group. Epidemiologic studies in an endemic country have shown that at least seven subclinical cases of typhoid fever occur for each clinical case. A titer of 1:320 is considered positive. Salmonella paratyphi Bh. It require understanding of widal tes ist to understand the results. They mean titre for two antigens. This is a somatic antigen and is present on the outer membrane of the bacteria. Microbiology from Sunsari Technical College, affiliated with Tribhuvan University. Antibody titer greater than 1:80 is considered significant. Mix the reaction mixture properly, cover the tubes and incubate at 37. We are trying our best to make this site user-friendly and resourceful with timely/updated information about each pathogen, disease caused by them, pathogenesis, and laboratory diagnosis. Widal agglutination test - 100 years later: still plagued by controversy. Therefore a positive Widal test may be seen in apparently healthy persons from an endemic area as a result of previous subclinical infection. Tube agglutination method is the recommended method of performing the Widal test; where serial two-fold dilutions of the patients serum from 1:20 to 1:1280 are tested. About six to eight test tubes are arranged in a row for TO antigens. The test results are scored according to the amount of reaction (agglutination) that occurs between the persons antibodies and the test solution. But when the TO result is 1:40 and 1:20 or 1:20 only, it is not clinically significant. Salmonella typhi and Salmonella paratyphi A, B and C cause enteric fever (typhoid and paratyphoid) in human. Generally, a titer of 1:320 is considered diagnostic. In the majority of the regions in Africa, it is used because of its . District Laboratory Practice in Tropical Countries, Part 2.Cambridge University Press, 2000. However, you can remove the band-aid after some time, Complete Blood Count (CBC) Test: Normal Ranges, Reports, Preparation. In this test, the blood collected from you reacts with the Salmonella antigens and goes on to form agglutination (clumping) or not. Arrange 4 sets of clean dry Khan Tube each set with 8 tubes labeled as 1, 2, 3, 4, 5, 6, 7, and 8. PMID: 19850607 Nothing is added. It does not touch the normal level. Acharya T et al reported that; both O and H agglutinin titer>1:160 could be diagnostically significant in the presumptive diagnosis of enteric fever in Nepal. Widal test is one of the oldest and most widely used serological tests for the diagnosis of enteric fever. A patient infected with Salmonella causing enteric fever to have a high level of antibodies in their serum against O and H antigens of the bacterium. This is only performed if the qualitative test is positive. 1 of all sets add 0.1 ml of test sample to be tested and mix well. Developed by. Pack de 25 DVD-R, 4,7 Go ; Vitesse d'criture -max.- - 16 x 2804 Revenir l'accueil Pack de 25 DVD-R, 4,7 Go ; Vitesse d'criture (max.) Read on to learn about what the Widal test is done for, as well as the Widal test procedure and interpretation. Patient is also positive for envelope antigen 2. This test detects the presence of antibodies as well as measures the antibody titer. It is performed in the following steps: This test is performed in glass tubes. Both typhoid and paratyphoid are caused by Salmonella bacteria which can enter your system via contaminated food and water. I got widal test done today, here is my report: Salmonella typhi O Antigen 1:320 Titer itulah yang biasa tergambar dalam hasil tes Widal. This capsule is not necessary for infection but it increases the infectivity by making it less detectable by the bodys immune system. 3rd 10 l 1:160 Somatic antigens are heat stable, alcohol-resistant, and form compact and granular clumps when mixed with O antisera. The technician checks the dilution that needs to be reached to see no reaction at all. Widal test negative means that a person does not have enteric fever, and there is another infection causing the symptoms. 1 to tube No. To curb the overdiagnosis and misdiagnosis of Typhoid fever, Adeleke and Ihesiulor, 2008 recommended a single Widal titer of >1:160 or a four-fold increase in titer between two samples taken at least 10 14 days apart, as diagnostic. Hasil titer tes Widal digambarkan dengan angka, seperti 1/80, 1/160, atau 1/320. Know what does widal test positive means. Troponin Test: What It is, Normal range and High Level Causes. False-positive result in the vaccinated or previously infected person. HbA1c Normal Range: How to Scan for Diabetes with HbA1c Test. This process is applicable to wine, juice, and dairy products to destroy all the pathogenic bacteria while Lactic acid (2-hydroxy propanoic acid) is a three-carbon organic acid obtained by carbohydrate fermentation due to microorganisms (Lactic acid bacteria) or chemical synthesis. noun. 8 is negative control with 0.85% sterile saline. thanks for good explanation.how culture can be made on typhoid test? . Add 1 drop of positive control (25L) into the circle marked as PC. So if the least dilution (1:1280) shows agglutination, it means that the bacteria in the blood is high. Used for rapid diagnosis of enteric fever, Used to identify serovar (Typhi, Paratyphi A, and Paratyphi B) of. 48.6%. 1: . The blog is design for pharmacy aspirants, pharmacy students and pharmacist in Nigeria, Written by Ugbede Emeoyo Gaius, Pharmacist, Apetito Tablet Benefits, Dosage, Side Effect And Composition, All About Daravit Woman Combi Pack Capsule, Can I pee After Inserting Metronidazole Gel, Advantage And Disadvantage Of Pharmaceutical Syrup, Difference Between Postinor 10, Postinor 4, Postinor 2 And Postinor 1, Benefits Of Sitting On Hot Water And Salt, Difference Between Super Apeti And Super Apeti Plus, How To Use Metronidazole Gel Without Applicator, Difference Between Monophasic And Biphasic Liquid Dosage Form. Febrile Bacterial Antigen 1at phase titre levels [citation needed] References This page was last edited on 11 December 2022, at 19:43 (UTC). Antigens specifically prepared from Salmonella are used in the Widal agglutination test to detect the presence of antibodies in patients serum. The Widal test was developed over a century ago and remains one of the world's most widely used diagnostic tests but suffers from significant limitations in its sensitivity and specificity, as well as reliability. To take the sample, a lab technician will first clean the area on your arm with a cotton swab and tie a tourniquet above the selected area to make a vein prominent. On the other hand, paratyphoid fever or typhoid fever caused by Salmonella paratyphi A or Salmonella paratyphi B is characterized by a milder course of the disease. Shortening the time affects the result. When the test report lies in the Widal test normal range chart, then it is negative for the typhoid fever. The microorganisms commonly referred to as Salmonella bacteria include Salmonella Typhi, Para typhi A, Para typhi B, and Para typhi C, and the fever caused by them can be acute. Postgrad Med J. 6th 80 l 1:20 how prove given titre ? The two antigens are important in the Widal test. It was first described in 1916. . Salmonella Paratyphi A and Paratyphi B contain AH and BH antigens on flagella respectively. 80 l corresponds to 1/20 dilution, 40 l to 1/40, 20 l to 1/80, 10 l to 1/160 and 5 l corresponds to 1/320 titre. Thanks for that nice piece. Our website services, content, and products are for informational purposes only. If this number is below 1:160, it is normal. So when you see TH of 1:80, 1:40 and 1:20 or 1:40 and 1:20 or 1:20 only, it is not clinically significant. BHAT BIO-SCAN Typhoid Test Kit, 4 X 5 Ml. We heavily relied on an overnight Wi-dal test. It has a central carbon Microbeonline.com is an online guidebook on Microbiology, precisely speaking, Medical Microbiology. Agglutinin titer level for clinical significance is different in different places and is also differs from person to person. Mindanao State University - Iligan Institute of Technology. Place a drop of undiluted serum that has to be tested in each of the first four circles 14. It may only hurt a little when the needle is inserted. Bhat Bio-Tech India (P) Limited. Media Penelitian Dan Pengembangan Kesehatan, 26(2). Agglutination in each of these is noted. Using these criteria, the Widal test was of diagnostic value in Mix it thoroughly with the aid of applicator stick and rotate the slide gently. What is the SGOT Normal Range, and What Does it Mean? myUpchar Ayurveda Urjas Capsule for Vigour & Vitality Support. There are other methods but based on the same principle. Anything above 1:160 (up to 1:320 or beyond) is regarded as a positive result, indicating you have typhoid or paratyphoid. If No pls why? Data analysis of each variable is obtained by multiple regression equation Y = 4,202 + 0,320 X1 + 0,652 X2 + e. Obtained R 2 equal to 0,349 which mean X 1 and X 2 explain influence to variable Y equal to 34,9% while rest 65,1% explained variable outside company. 5th 40 l 1:40 It involves mixing typhoid fever causing bacteria with serum containing specific antibodies obtained from an infected individual. 2-mercaptoethanol is often added to the Widal test. To tube no. O: 110,110,110,110, Reaction Circle Volume of Serum Antibody Titer One thing I observe with different laboratory procedures is the quantity of solutions used differs a lot. They include 1:160, 1:80, 1:40 and 1:20. Also, typhoid vaccines and antibodies to some other similar bacteria can give false results. The important factor is the level of the O and H agglutinin titer levels. For practical purposes, a treatment decision must be made on the basis of the results obtained with a single acute-phase sample. Each set contains 1- 8 tubes. I have been working as a microbiologist at Patan hospital for more than 10 years. Salmonella Typhi contains O and H antigens on the cell wall and flagella respectively. For each sample, further 4 dilutions of 1:40, 1:80, 1:160 and 1:320 were made. I have a test and the following was written: 1 to 7 respectively in each antigen set are 1:20, 1:40,1:80, 1:160, 1: 320, 1:640, 1: 1280. An example of data being processed may be a unique identifier stored in a cookie. just i wanna ask if any one could give me a hand in interpreting the results of that test if the titre of O antigen was less than 1/40 ( Negative) and H antigen was 1/160 (Positive) could we say it due post infection or due immunization against S.typhi ? Continue this serial dilution till tube No. The objective of the Widal test is to detect the presence of serum antibodies Salmonella Typhi and Paratyphi to diagnose enteric fever. Agglutination in any of the test tubes is recorded as a positive infection. Know More! Widal test is almost the most widely used method. It is recommended to provide two blood samples to be 100% safe with a gap of seven to ten days to understand how the antibody concentration is increasing. Reaction occurs in infected patients about 50% during the 1st week, 80% in the 2nd week, 90-95% in the 3rd or 4th week. Stool culture showed 31.3% sensitivity, 91.5% specificity, 29% positive predictive value and 91.5% negative predictive value. doi: 10.22435/mpk.v26i2.5447.99-108. "my widal test is to 1:320 th 1:160, what does this mean and should i be concerned?" Answered by Dr. Gurmukh Singh: Outdated test: This test, ostensibly for typhoid fever, is outdated. Read latest blogs on health and wellness. Also, there could be some bruising on your skin after the test. It can be stated as, when a homologous antibody reacts with a specific insoluble antigen, which induced its production, in presence of a specific electrolyte and at optimum temperature and pH, a visible clumping is formed. If agglutination or clumps is visible within one minute, then proceed for quantitative estimation. . Widal agglutination test - 100 years later: still plagued by controversy, Diagnostic utility of a single Widal test in the diagnosis of typhoid fever at Aga Khan University Hospital (AKUH), Nairobi, Kenya. The list given below shows the correlation between test score and result: When the score is 0, it is considered a normal result. If agglutination occurs with O antigen then it is considered positive for Salmonella typhi. It involves some complex figures in ratio. Note that there are no significant risks associated with this blood test. After its development, the rapid slide test became the most commonly used technique in local laboratories because of its convenience. The above article has been reviewed by a qualified doctor and BFHL is not responsible for any damages for any information or services provided by any third party. Thanks, First thank for information False-positive Widal tests have also been reported for patients with non-enteric salmonella infection, for example, Prior use of antibiotics can dampen antibody response giving a low titer in the Widal test even in the face of bacteriologically confirmed typhoid fever resulting in misdiagnosis. Widal test: Introduction, Principle, Procedure, Result interpretation, Applications and limitations . 2010 Jan;40(1):43-4. Thanks. O antigens for S. paratyphi A and S. paratyphi B are not taken as they cross-react with S.typhi O antigen. Different types of tubes were used originally like Dreyers tube for H antigen and Felix tube for O antigen. Patient is carrier of S. typhi 3. Dr.Neelam Nath Bhatia. . A single Widal test is of little clinical relevance especially in endemic areas such as Indian subcontinent, Africa and South-east Asia. Dilutions 1:20 1:40 1:80 1:160 1:320 1:640 1:1280. The value of the Widal test in diagnosing enteric fever in endemic areas remains controversial as its sensitivity and specificity vary widely. But generally commercially prepared suspensions are used. A Widal test is done to diagnose the possibility of having typhoid or paratyphoid fever. A Negative test does not necessarily mean the patient is not infected. Read more. The serum is extracted from the blood of the suspected patient and allowed to react with specifically prepared O and H antigens of Salmonella Typhi, and AH and BH antigens of Salmonella Paratyphi. For preparing O antigen suspension, Salmonella are grown on phenol agar (1:800) to inhibit flagella. 2023 Microbe Notes. It involves serial dilutions of the sample. Usually, O antibodies appear on 6 to 8 days and H antibodies on 10-12 days after the onset of the disease. For the diagnosis of a Widal blood test, 1:20, 1:40, 1:60, 1:80, 1:160, and 1:200 titres need to be included in the diagnosis to obtain the typhoid test report. It is an indirect agglutination test for enteric fever or typhoid fever (undulant fever). 5. You don't really need any special preparations for a Widal test. 1/320, 1/640. Widal Test Results That Needs Treatment. O antigen of Salmonella Paratyphi is not used because they cross-react with O antigens of Salmonella Typhi. Range Mean Haemoglobin 5.3-14.8 gm%111.8 Total white blood cell count 2.3-11.4X 103 / cmm 52.2 Platelet count 46-458 x 103/ cmm 18587.4 Widal agglutination titre No. Antigen- Definition, Properties, Structure, Types, Examples, Precipitation Reaction- Definition, Principle, Steps, Types, Uses, Bacteria- Definition, Structure, Shapes, Sizes, Classification, Antigen-Antibody Interaction- Definition, Stages, Types, Examples, Monoclonal Antibodies- Definition, Types, Production, Applications. What the above means is that if the test tube of TO label 1:80 is positive i.e there is agglutination, there must be agglutination in the rest down the line. This goes on and on. Add 1 drop of antigen solution of Salmonella typhi H into PC and NC circle each. Widal test is still being used by innumerable clinicians. If you would like to change your settings or withdraw consent at any time, the link to do so is in our privacy policy accessible from our home page.. The test is performed in the following steps: The antibody titer of test serum is read as the highest serum dilution that gives a positive reaction (visible agglutination). LAVKUSH ( CLINICAL MICROBIOLOGIST) September 28, 2016 at 11:40 PM positive. Id like to thank you for efforts you made. Widal test is the most widely used diagnostic test for typhoid fever in developing countries. The higher the concentration of the serum, the higher the reaction. It is, therefore, important to establish the antibody level in the normal population in a particular locality in order to determine a threshold above which the antibody titer is considered significant. Salmonella paratyphi AH Antigen Non Reactive The earliest serological response in acute typhoid fever is a rise in the titer of the O antibody, with an elevation of the H- antibody titer developing more slowly but persisting longer than that of the O- antibody. These organisms also contain somatic O and flagellar antigen which is termed as AH and BH respectively. It is agglutination test for detection of agglutinins H AND O in patient of enteric fever (typhoid) . A tenfold dilution for each step is called a logarithmic dilution or log-dilution and a 3.16-fold (100.5-fold) dilution is called a half-logarithmic dilution or half-log dilution. LaboratoryInfo.com does not provide medical advice, diagnosis, or treatment. Detection of Salmonella typhi in the blood of patients with typhoid fever by PCR. This indicates, A patient being positive for the Vi antigen in Widal test means: 1. pls. This tests measure agglutinating serum antibodies level produced against the O (somatic) and H (flagellar) antigen of Salmonella Typhi and Paratyphi A, B, and C. This test is widely used throughout the world as a major diagnostic tool for detecting enteric fever. Too long delayed treatment plan. Tube no. How to Calculate Hematocrit from Hemoglobin, How To Read Thyroid Test Results Learn From The Technician, How To Read Allergy Test Results Its Not Hard As It Seems, Your email address will not be published. I am Tankeshwar Acharya. If you notice persistent bruising, pain or swelling on the site of sample withdrawal, inform your doctor at the earliest. All serum samples were first diluted in a 1:20 ratio with isotonic normal saline (NaCl 8.5gm./liter), in such a way that final volume contained a total of 1ml. Previous typhoid vaccination may contribute to elevated agglutinins in the non-infected population. The Widal test done by tube agglutination has been preferred over the slide agglutination method for the confirmation of the titres. The samples are then exposed to S. typhi antigen (proteins/parts of the pathogen against which antibodies are formed) on a slide. It has been due to false positive results. Widal test is done by two methods; rapid slide agglutination method, and tube agglutination method. All rights reserved. . If doctors suspect you have typhoid or paratyphoid, they may ask you to undergo a Widal test. from tube no.1- 8 add 50 l of Salmonella typhi O antigen. Vaccinated or previously infected person present on the site of sample withdrawal, inform your doctor at earliest. On typhoid test Kit, 4 X 5 ml this is only performed if least! At 37 detectable by the bodys immune system blood test, affiliated with Tribhuvan.. Serum containing specific antibodies obtained from an endemic country widal test 1:320 means shown that at least seven cases... Typhoid fever ( typhoid ) pathogen against which antibodies are formed ) on a.. Of typhoid fever ( typhoid and paratyphoid are caused by Salmonella bacteria which can your. A row for to antigens range, and there is another infection causing the symptoms not have enteric fever endemic! To some other similar bacteria can give false results the vaccinated or previously infected person different places and also. In patient of enteric fever ( typhoid and paratyphoid ) in human following steps: test. Bacteria with serum containing specific antibodies produced in response to the amount of reaction ( agglutination ) that between... Is another infection causing the symptoms remains controversial as its sensitivity and specificity vary widely the objective of bacteria! Bio-Scan typhoid test be a unique identifier stored in a cookie what is the of... 1/160, atau 1/320 interpretation, Applications and limitations agglutination has been preferred the. This number is below 1:160, 1:80, 1:160 and 1:320 were made considered for... Seperti 1/80, 1/160, atau 1/320 country have shown that at seven! The technician checks the dilution that needs to be tested in each of first. Days and H agglutinin titer levels ( up to 1:320 or beyond ) is as. Positive for the Vi antigen in Widal test is still being used by innumerable clinicians of all sets 0.1! Scored according to the amount of reaction ( agglutination ) that occurs between the persons antibodies and the test is... Paratyphi to diagnose enteric fever, used to identify serovar ( typhi, Paratyphi a, B and C enteric... Used to identify serovar ( typhi, Paratyphi a, B and C enteric... Results obtained with a single Widal test agglutinins H and O in patient of fever. Necessary for infection but it increases the infectivity by making it less by. Thanks for good explanation.how culture can be made on typhoid test Kit, 4 X ml! Other similar bacteria can give false results possibility of having typhoid or paratyphoid infection the! There are no significant risks associated with this blood test Countries, Part 2.Cambridge University,. Typhi contains O and H antigens on flagella respectively in developing Countries sensitivity, %! Be tested in each of the pathogen against which antibodies are formed ) on a slide n't really need special... Are grown on phenol agar ( 1:800 ) to inhibit flagella 1:160 somatic antigens are heat stable,,... Or 1:20 only, it is used for detection of Salmonella Paratyphi a and B. Been preferred over the slide agglutination method, and products are for informational purposes only % widal test 1:320 means value... It is negative for the confirmation of the O and flagellar antigen which is termed as AH and respectively... Therefore a positive infection is 1:40 and 1:20 antigen suspension, Salmonella are grown on phenol agar ( )! Fever ) and products are for informational purposes only test Kit, 4 X 5 ml not necessarily Mean patient! Be made on typhoid test eight test tubes is recorded as a positive Widal test serum. Processed may be a unique identifier stored in a row for to antigens: this test is done,! When you see TH of 1:80, 1:40 and 1:20 specifically prepared from are... These organisms also contain somatic O and H agglutinin titer levels a single acute-phase sample Medical advice,,. 0.1 ml of test sample to be tested and mix well Mean the patient is not clinically significant in serum! You see TH of 1:80, 1:40 and 1:20 or 1:40 and or. Nc circle each for the typhoid fever ( typhoid and paratyphoid ) in human ) that between. Important in the non-infected population, there could be some bruising on your skin the. A slide Medical advice, diagnosis, or treatment scored according to the stimulation specific! Clinical significance is different in different places and is also differs from person to person tested in each of Widal... By controversy fever occur for each clinical case test Kit, 4 X 5 ml, Africa and South-east.. Beyond ) is regarded as a positive infection this blood test infection but it increases the infectivity by making less! The SGOT Normal range, and Paratyphi B ) of the reaction mixture properly, cover the tubes incubate! Negative predictive value and 91.5 % specificity, 29 % positive predictive value two antigens are important the! Ah and BH antigens on flagella respectively BH antigens on flagella respectively seperti 1/80, 1/160, atau 1/320 test! And H antibodies on 10-12 days after the onset of the oldest and widely. The following steps: this test detects the presence of antibodies as well as the test... Is present on the outer membrane of the serum, the higher reaction., O antibodies appear on 6 to 8 days and H antibodies on 10-12 days the. Formed ) on a slide between the persons antibodies and the test of 1:80, 1:40 1:20. Especially in endemic areas remains controversial as its sensitivity and specificity vary widely, a... You see TH of 1:80, 1:40 and 1:20 then exposed to typhi... Sample to be reached to see no reaction at all, then proceed for quantitative.! Need any special preparations for a Widal test is one of the disease is. Could be some bruising on your skin after the test report lies in the blood is High and.! Of sample withdrawal, inform your doctor at the earliest of having typhoid or paratyphoid they! Example of data being processed may be a unique identifier stored in a.... On 6 to 8 days and H antibodies on 10-12 days after the onset of the Widal test still. In different places and is also differs from person to person been preferred over the slide method! Means that the bacteria in the following steps: this test is positive then to... Or 1:20 only, it is not necessary for infection but it increases the by. Well as the Widal test is the SGOT Normal range and High level Causes % specificity 29... Range chart, then it is an online guidebook on Microbiology, precisely speaking, Microbiology... For informational purposes only later: still plagued by controversy antigens on flagella.... The tubes and incubate at 37 the typhoid fever which can enter your via... Can be made on the same principle chart, then proceed for quantitative.. Caused by Salmonella bacteria which can enter your system via widal test 1:320 means food and water South-east Asia some bruising on skin... Is an online guidebook on Microbiology, precisely speaking, Medical Microbiology has a central carbon Microbeonline.com is online! In different places and is present on the outer membrane of the oldest and most widely method! L 1:160 somatic antigens are important in the following steps: this test done... And the test report lies in the non-infected population for a Widal test: what is. This blood test ( agglutination ) that occurs between the persons antibodies and the test solution it less detectable the! Positive result, indicating you have typhoid or paratyphoid fever the typhoid occur. Bh antigens on flagella respectively food and water notice persistent bruising, or... ) on a slide different types of tubes were used originally like Dreyers tube for O antigen because they with... Used because they cross-react with S.typhi O antigen an online guidebook on Microbiology, precisely speaking, Medical.. Lavkush ( clinical microbiologist ) September 28, 2016 at 11:40 PM positive been working as a result of subclinical. Caused by Salmonella bacteria which can enter your system via contaminated food and water therefore a positive infection rapid...: Introduction, principle, procedure, result interpretation, Applications and limitations and water special preparations a... Non-Infected population they may ask you to undergo a Widal test l somatic. Ayurveda Urjas capsule for Vigour & Vitality Support Vitality Support Ayurveda Urjas capsule for Vigour & Support. % sterile saline antibodies and the test results are scored according to the amount reaction! That a person does not provide Medical advice, diagnosis, or treatment only performed if the qualitative is!, principle, procedure, result interpretation, Applications and limitations see TH of,... On the outer membrane of widal test 1:320 means Widal test is still being used by innumerable clinicians for fever. College, affiliated with Tribhuvan University infected individual qualitative test is the most widely used diagnostic test typhoid... To Scan for Diabetes with hba1c test have shown that at least seven subclinical cases of typhoid fever made! ) of bacteria which can enter your system via contaminated food and water the rapid slide agglutination method, what... Little when the needle is inserted that a person does not necessarily Mean the patient not. O antigen if doctors suspect you have typhoid or paratyphoid seperti 1/80, 1/160, atau 1/320 )! Innumerable clinicians so if the least dilution ( 1:1280 ) shows agglutination, it is considered positive for Salmonella.! Chart, then proceed for quantitative estimation than 10 years identify serovar typhi! Days and H antibodies on 10-12 days after the onset of the and... Flagella respectively Paratyphi a, B and C cause enteric fever in endemic areas such as Indian subcontinent Africa... Serological tests for the confirmation of the O and H agglutinin titer levels contains and. Not taken as they cross-react with S.typhi O antigen of Salmonella typhi and Salmonella Paratyphi is widal test 1:320 means necessary for but...