Q: I am a 25 years old boy who suffered from typhoid 2 months back. I took treatment for 14 days. Now again I am feeling pain in my joints with chills. I took a widal test and the result was positive - salmonella O - 1:40 and H - 1:80, white blood cell (WBC) count - 7300, lymphocytes - 32%. Also, I feel malaise and stomach burning and neck stiffness. Why I am getting recurrent typhoid or is this some other disease? I feel throat pain too. Please advise.
A:You have not mentioned what were your symptoms when you were diagnosed with typhoid 2 months back. Usually, fever is a prominent symptom, but you have not mentioned that in your query.
Let me provide you some details about the Widal test. Widal is a blood test, though widely used for serological diagnosis of enteric fever (typhoid / paratyphoid fever), which has poor clinical diagnostic utility.
It measures the titre (level) of antibodies (in blood of patients) against salmonella antigens:
- TO – Somatic (O) antigen of Salmonella enterica serovar Typhi.
- TH – Flagellar (H) antigen of Salmonella enterica serovar Typhi.
- AH – Flagellar (H) antigen of Salmonella enterica serovar Paratyphi A.
- BH - Flagellar (H) antigen of Salmonella enterica serovar Paratyphi B.
The antibodies against O antigen of only Salmonella typhi are measured, since all Salmonella have similar O antigens. An increasing O antibody level signifies acute infection, whilst a raised H antibody level may indicate the serotype of the infecting organism, or an earlier infection.
However, as with many other serological tests, it has many limitations as a diagnostic tool, since it provides indirect evidence (as a surrogate marker) for infection. Also, the rise in antibody levels, needed to make the diagnosis, takes 7-14 days, which limits its use.
The interpretation of the serology thus requires consideration of factors such as previous immunisation, the stage of the illness and the effect of any antibiotic treatment, infection with any other gram-negative bacteria, etc.
Ideally, Widal test must be done on paired serum samples for diagnosis. The first sample is taken early in the disease and the second sample at least 2 weeks later. A four-fold rise in antibodies in the paired samples is significant and diagnoses acute recent infections.
Widal test can also be used in carrying out serological surveys in a community to know the prevalence (and endemicity in an area) of enteric fever and determine the cut off titre for interpretation in that population. However, the isolation of Salmonella bacteria in the blood (by blood culture) is the gold standard for diagnosing enteric fever.
In your case, the Widal report may indicate an earlier infection, but the current problem - with symptoms of bodyache / headache / joint pains are non-specific and in the absence of fever are not indicative of typhoid.