[Tsutusgamushi fever after travel to Southeast Asia]. / Tsutsugamushi-Fieber nach Südostasienreise.

HISTORY AND CLINICAL FINDINGS: A 49-year-old travel guide fell ill during his return from a 6-week-stay in Vietnam, Myanmar and Thailand. He developed high fever and severe headache. On admission, the body temperature was at 39.5 degrees C with relative bradycardia. A black, crusted skin lesion of approximately 5 mm diameter was noted on the chest wall and was interpreted as an insect bite. INVESTIGATIONS: CRP and liver enzymes were elevated. Total leucocyte count was normal but the differential count showed a left shift and aneosinophilia. Imaging procedures revealed splenomegaly and small pleural effusions on both sides. TREATMENT AND COURSE: The patient was treated with a parenteral quinolone based on the initial suspicion of typhoid fever. Failure of this treatment and negative blood cultures raised concerns about the possibility of Tsutsugamushi fever, based on travel history and a re-evaluation of the skin lesion as an eschar. Tsutsugamushi fever was suspected on epidemiological and clinical grounds and was confirmed by the detection of specific IgM to Orienta tsutsugamushi and by seroconversion of IgG antibodies during follow-up. Even before immunodiagnostic confirmation was available, a course of doxycycline was started. This led to rapid improvement of the patient's condition. CONCLUSION: In febrile travellers returning from Southeast Asia, Tsutsugamushi fever has to be considered in the differential diagnosis. The causative agent, Orienta tsutsugamushi is transmitted by larvae of trombiculid mites (chiggers). Leading symptoms are fever continua, cephalgia, and a primary lesion (eschar) at the site of cutaneous inoculation. The Eschar is easily overlooked and has to be searched carefully. Diagnosis is confirmed by the detection of specific antibodies. However, serology may be negative in the beginning. Therefore, treatment with doxycycline should be initiated on clinical grounds.

Kinetic characterization of glutathione reductase from the malarial parasite Plasmodium falciparum. Comparison with the human enzyme.

The homodimeric flavoenzyme glutathione reductase (GR) maintains high intracellular concentrations of the antioxidant glutathione (GSSG + NADPH + H(+) <--> 2 GSH + NADP(+)). Due to its central function in cellular redox metabolism, inhibition of GR from the malarial parasite Plasmodium falciparum represents an important approach to antimalarial drug development; therefore, the catalytic mechanism of GR from P. falciparum has been analyzed and compared with the human host enzyme. The reductive half-reaction is similar to the analogous reaction with GR from other species. The oxidative half-reaction is biphasic, reflecting formation and breakdown of a mixed disulfide between the interchange thiol and GSH. The equilibrium between the E(ox)-EH(2) and GSSG-GSH couples has been modeled showing that the Michaelis complex, mixed disulfide-GSH, is the predominant enzyme form as the oxidative half-reaction progresses; rate constants used in modeling allow calculation of an K(eq) from the Haldane relationship, 0.075, very similar to the K(eq) of the same reaction for the yeast enzyme (0.085) (Arscott, L. D., Veine, D. M., and Williams, C. H., Jr. (2000) Biochemistry 39, 4711-4721). Enzyme-monitored turnover indicates that E(FADH(-))(S-S). NADP(+) and E(FAD)(SH)(2).NADPH are dominant enzyme species in turnover. Since the individual forms of the enzyme differ in their susceptibility to inhibitors, the prevailing states of GR in the cell are of practical relevance.