infectious diseases
Scrub Typhus
Symptoms and Signs of Scrub Typhus
After an incubation period of 6 to 21 days (mean 10 to 12 days), symptoms of scrub typhus start suddenly and include fever, chills, headache, and generalized lymphadenopathy. At onset of fever, an eschar often develops at the site of the chigger bite. The typical lesion of scrub typhus begins as a red, indurated lesion about 1 cm in diameter; it eventually vesiculates, ruptures, and becomes covered with a black scab. The capacity of different strains ofO. tsutsugamushito result in an eschar varies, and an eschar is easier to detect in light-skinned people. Regional lymph nodes enlarge. Fever rises during the first week, often to 40 to 40.5°C. Headache is severe and common, as is conjunctival injection. A macular rash develops on the trunk during the 5th to 8th day of fever, often extending to the arms and legs. It may disappear rapidly or become maculopapular and intensely colored. Cough is present during the first week of fever, and pneumonitis may develop during the second week. In severe cases, pulse rate increases; blood pressure drops; and delirium, stupor, and muscular twitching develop. Splenomegaly may be present, and interstitial myocarditis is more common than in other rickettsial diseases. In untreated patients, high fever may persist≥2 weeks, then falls gradually over several days. With therapy, defervescence usually begins within 36 hours. Recovery is prompt and uneventful. 