False-positive widal in melioidosis

Enteric fever is endemic in this part of the world, and Widal test is one of the time-honored laboratory tests that are being used for years to diagnose the disease. On the other hand, melioidosis is a newly emerging disease from this region, which is most often misdiagnosed or underdiagnosed by clinicians. It is well accepted that false-positive Widal reactions following certain non-typhoid Salmonella infections may occur commonly. Three cases of high titers of Widal test are described, where melioidosis was the actual diagnosis in every occasion and was never suspected until diagnosed microbiologically. All the patients had shown a partial response to ceftriaxone. Blood and pus cultures grew Burkholderia pseudomallei, whereas Salmonella typhi was not isolated from blood in any patient. With appropriate antibiotics, the patients showed clinical and microbiological improvement with lowering of Widal titers. These 3 cases show that high Widal titer in any patient may mislead the diagnosis of melioidosis, and further laboratory workup should always be done to rule out melioidosis, especially in cases with nonresponsiveness to treatment.