I have got a widal test report negative for O and H but positive for AH till 1 in 320 titer and BH till 1 in 160 titer. Does it signify paratyphoid fever or it is just due to a cross-reacting antigen? Sometimes, I also get only H positive till 1 in 320 titer with O negative.

How to interpret that? Actually, I am a bit confused about the whole interpretation of widal test. Please recommend the ideal guidelines.