Hi and thanks for the query, Typhoid fever for sure could be very challenging to treat. This is usually for three main reasons: Firstly, the inappropriate drug for the particular germ can be used, secondly, treating for a shorter during of time the required and thirdly, using an antibiotic to which the germ is already resistant to. It is not rare however to mistake a different infectious process for typhoid fever. Concerning the blood tests, persistence of antibodies or positivity of the test after treatment does not mean that the treatment was not effective. It might take some time for these antibodies to be cleared from the system. It might be interesting however to get samples of blood and stool, to carry out a stool culture and antibiotic sensitivity test and also a blood culture. the germ could be specifically identified and the antibiotic capable for curing it appropriately administered. Simple blood test to check for hemoglobin levels to be sure its not anemia should not be undermined. Persistence of these symptoms after all these could at some point necessitate the opinion of an infectious disease specialist (infectiologist). It is rare however not to get children treated after following the above mentioned recommendations, especially from my experience. thanks and hope this helps as I wish you the best of health. Kind regards, Bain LE, MD.