Scrub Typhus （恙虫病） Department of Infectious Diseases, the Third Affiliated Hospital Li Gang,Definition,Acute febrile infectious diseaseCaused by Rickettsia tsutsugamushiTransmitted by the bite of chiggersSource of infection: RatsCharacterized by fever, eschar, rash,and lymphadenopathy,Etiology,Intracellular organism Propagated in mice, some cells Antigenically diverse microorganism Common antigen with Proteus OX-K Low resistance,Epidemiology, Source of infection: Rats Vector: Mite The life cycle: ovum, larva, pupa, naiad and imago Only its larva (chigger) feeding on humans,imago,larva,rat,pupa,naiad,imago,ovum,larva,rat,pupa,naiad,第一代,第二代,(遗传、传染),The life cycle of mite,bite,ovum,Epidemiology,Proliferate in warm, wet environments Both a vector and a reservoir Route of transmission: bite of chigger Susceptibility: universal Immunity: long-lasting immunity against the homologous strains; Partial immunity against the other heterologous strains,Epidemiology, Other epidemiological features: Geographic distribution:Asian-pacific region Sporadic Seasonal distribution: rainy seasonsbetween May and November,Pathogenesis,human body,rickettsemia,eschar,local site,rickettsia,mite,vasculitis,rats,Pathology Basic lesion: inflammation of the walls of the small blood vessels Pathologic findings:eschar, lymphadenopathy, rash, enlargement of spleen and liver Serious pathologic manifestations:myocarditis, meningoencephalitis, pneumonia, interstitial nephritis,Clinical manifestations Incubation period: 421 days Sudden onset, High fever: remittent fever accompanied by chill, headache, malaise, prostration, poor appetite.,Clinical manifestations Signs of multiorgan damage: Meningoencephalitis: delirium, convulsion, coma, and neck stiffness.Interstitial pneumonia: cough, chest pain, breathlessness.,Clinical manifestations Signs of multiorgan damage: Myocarditis: gallop rhythm, poor quality heart sounds, systolic murmurs.Hepatitis: jaundice, hemorrhage. Natural course: 23 weeks.,Characteristic manifestations Eschar and ulceration: Characteristic sign. Seen in 36.998 of patients. Generally located in warm, wet, intense smelled areas.,eschar,eschar,ulceration,Characteristic manifestations2. Lymphadenopathy: Enlarged markedly regional lymph nodes near the eschar. Generalized lymphadenopathy. Painful, movable, not purulent.,Characteristic manifestations3. Rash: Appears on the 4th to the 6th day. Beginning on the trunk, spread to the extremities. Maculopapular, congestive, no itching. Lasting 37 days. Seen in 35100 of patients.,Characteristic manifestations4. Splenomegaly and hepatomegalySplenomegaly : 3050 of patients.Hepatomegaly: 1020 of patients.,Complications Pneumonia, myocarditis, hepatitis, DIC.,Diagnosis, Epidemiologic dataHistory of exposure to endemic areas.Rainy season.,Diagnosis,2. Clinical features Abrupt onset of fever. Accompanied with chill, lymphadenopathy, rash, enlargement of spleen and liver. Most characteristic sign: eschar. Therapeutic diagnosis.,Diagnosis,3. Lab findingsA. Routine lab data: WBC liver enzyme values proteinuria.B. Serological tests Weil-Felix reaction,Diagnosis, Weil-Felix reaction: Positive result obtained from the 4th day. Higher than 1:160 is suggestive. Available and inexpensive. About 50 of patients have diagnostic titers.,Diagnosis, Complement fixation test and indirect immunofluorescent antibody test: More sensitive and specific than Weil- Felix reaction. Fourfold or greater increase in convalescence. Rarely used because of the difficult in preparing antigens.,Diagnosis,C. Isolation of organismBlood inoculating into mice.Organism found in mononuclear cells.Specific test to confirm the diagnosis.Cant give a rapid diagnosis.,Diagnosis,D. Molecular biologic assaysNucleic acid hybridization and PCR.Great potential for sensitive and specific detection of nucleic acid.Being evaluated.Limitation of technique and facilities conditions.,Differential Diagnosis,Other rickettsial diseases, typhoid fever, leptospirosis, malaria, dengue, septicemia, influenza PrognosisFatality rate: 960 without treatment. 5 effective treatment.,Treatment,Chloramphenicol, tetracycline, doxycyclineChloramphenicol: 1.52g daily, divided into 34 aliquots.Fever abates within 48 hours.Total course: 1014 days.Side effects: suppression of bone marrow and aplastic anemia.,Prevention, Exterminating the source of infection. Reducing and controlling the vectors. Individual protection: Avoiding contact with mites: the best method.,Cysticercosis （囊尾蚴病）, Definition and introduction One of parasitic diseases. Caused by the infection with the tissue larvae of Taenia solium. Acquired by ingestion of Taenia solium eggs in contaminated foods. Humans: definite host and intermediate host.,Definition and Introduction,Human infected with Taenia solium in two forms: intestinal Taenia solium and cysticercosis. Cysticercosis has greater clinical significance. Cysticercosis: human tissue infection with theintermediate cyst forms of pork tapeworm. Cysticercus located in the subcutaneous tissue, muscle, brain.,