Serological Diagnosis for Infectious Diseases: Not As Easy as It Appears ! / Lao Medical Journal

Serological diagnoses for infectious diseases such as those based on disease¬specific IgM antibody detection often confuse clinicians and therefore make treatment decisions difficult. This is due to the relatively long persistence of IgM in the blood circulation following exposure to the organism or nonspecific polyclonal activation of memory cells. We report a Lao patient diagnosed as having scrub typhus on admission based on detection of IgM to Orientia tsutsugamushi and initially treated with Doxycycline. The patient became afebrile but had severe pulmonary involvement. The blood culture was subsequently positive for Leptospira spp. which is the cause of leptospirosis. The admission blood sample of the patient was negative for Orientia tsutsugamushi, Rickettsia typhi, and Rickettsia spp. DNA targets, by PCR, suggesting that the patient did not have scrub typhus, murine typhus or Spotted Fever. After one week of IV ceftriaxone treatment, the patient improved and was discharged well. The positive IgM to scrub typhus detected on admission was probably due to previous exposure to O. tsutusgamushi, and scrub typhus was not the cause of her presenting illness. Fortunately, Doxycycline, given to the patient for scrub typhus treatment, is also effective for leptospirosis preventing death. However, the patient required intravenous ceftriaxone (which would not have been effective for scrub typhus) when she developed severe disease. This patient’s illness is a reminder that clinicians should be cautious about serological diagnosis. At present, laboratory diagnosis of leptospirosis remains a big challenge for the clinicians because the existing gold standard test such as Microscopic Agglutination Test (MAT) and culture are labour intensive, expensive and seldom available. Until the development of the simple, rapid, and more reliable tests, the empirical treatment of patients with suspected leptospirosis with doxycycline, penicillins or ceftriaxone are strategies to reduce severe complications and death although it should be born in mind that penicillins and ceftriaxone will not be effective against rickettsial organisms.

TB Meningitis (TBM): An Important Problem Which Should Not be Neglected in Laos! / Lao Medical Journal

Tuberculosis (TB) is an infectious disease commonly found in both developing and developed countries. Tuberculosis meningitis (TBM) is a serious central nervous system infection with a high mortality rate despite anti-TB drug treatment and is associated with HIV/AIDS. The diagnosis of TBM is difficult since the clinical aspects of the disease are similar to other central nervous system infections, examination for AFB in cerebrospinal fluid (CSF) stained with Ziehl-Neelsen is not sensitive and culture of Mycobacterium tuberculosis from CSF takes too long to influence initial therapy. Delayed diagnosis and treatment of TBM results in high mortality and disability. We report a Lao patient who had pulmonary TB in combination with TBM (confirmed by positive AFB in a sputum examination and a positive culture of Mycobacterium tuberculosis in the CSF) whose diagnosis and treatment were delayed resulting in serious nervous system sequelae and disability which may not be easily reversible. We discuss TBM diagnosis and use of simple clinical and laboratory features and suggest a low threshold for empirical treatment with anti-TB drug in case of suspected TBM.