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Blood test shows typhi and paratyphi positive. What does it mean?

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Posted on Sun, 30 Sep 2012
Question: Hi I am AAAA 32 yrs .I have done blooddest and it says s.typhi o positive 1/320 dil and s paratyphi A H POSITIVE Upto 1/160 dil what that means.
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Answered by Dr. Ratnakar Kini (2 hours later)
Hi XXXXXXX

I am Dr. Ratnakar Kini and I would be answering your query.
The test you have mentioned is called Widal test.

It is done to diagnose enteric fever (commonly called as typhoid fever).
The Widal test is done to diagnose infection by Salmonella typhi and Salmonella paratyphi organsims.

The test is done to detect the antibodies to the above-mentioned organisms.

If the antibodies are present, then the test is marked positive. But antibodies can be due to present infection or even a past infection.

Serial dilution of the serum is used to do the test. The dilution starts from 1 in 20 and has a series like 1 in 40, 1 in 80, 1 in 160, 1 in 320....

A person is diagnosed with enteric fever (typhoid) only if more than 1 in 100 titer is positive for O and 1in 200 titer positive of H antigens. In practice, a titer of more than 1 in 160 is taken as positive for enteric fever.

Positive tests at lower titers only, may indicate older infection with the above organisms or cross-reacting infection.

Therefore, your test report indicates you have enteric fever.

Does that answer your question? Please let me know if you have more concerns.

Regards,
Dr.Ratnakar Kini

Above answer was peer-reviewed by : Dr. Shanthi.E
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Dr. Ratnakar Kini

Gastroenterologist

Practicing since :1994

Answered : 2029 Questions

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Blood test shows typhi and paratyphi positive. What does it mean?

Hi XXXXXXX

I am Dr. Ratnakar Kini and I would be answering your query.
The test you have mentioned is called Widal test.

It is done to diagnose enteric fever (commonly called as typhoid fever).
The Widal test is done to diagnose infection by Salmonella typhi and Salmonella paratyphi organsims.

The test is done to detect the antibodies to the above-mentioned organisms.

If the antibodies are present, then the test is marked positive. But antibodies can be due to present infection or even a past infection.

Serial dilution of the serum is used to do the test. The dilution starts from 1 in 20 and has a series like 1 in 40, 1 in 80, 1 in 160, 1 in 320....

A person is diagnosed with enteric fever (typhoid) only if more than 1 in 100 titer is positive for O and 1in 200 titer positive of H antigens. In practice, a titer of more than 1 in 160 is taken as positive for enteric fever.

Positive tests at lower titers only, may indicate older infection with the above organisms or cross-reacting infection.

Therefore, your test report indicates you have enteric fever.

Does that answer your question? Please let me know if you have more concerns.

Regards,
Dr.Ratnakar Kini