DIAGNOSIS AND TREATMENT OF SCRUB THYPUS

Derm

1. DIAGNOSIS AND TREATMENT OF SCRUB T Y P H US. NETHAJI

2. CASE DISCUSSION: A 73 year old female admitted with complaints of fever x 5 days,vomiting x 2 episodes for 2 days.No other complaints. past hx:DM X 10 years taking reg medicines and HTN x 10 years. On examination:Bp:110/70mmhg HR:92bpm.RR:24min.Temp:101 f. PICCL- B/L pitting pedal edema present till knee. Eschar noted on left side of the neck. Investigations showed platelet count :1,61,0000. Dengue was negative, scrub typhus negative, blood culture shows coagulase negative staphylococcus. How we will diagnosis? How will you manage?

3. INTRODUCTION: S crub typhus infection is an aetiology of acute undifferentiated fever in Indi a. It is a zoonotic rickettsial illness caused by Orientia tsutsugamushi . R eservoirs are chiggers (larva of trombiculid mite) and rats and humans are accidentally infected. T ransmitted by trombiculid mites in long grasses and in dirt-floor homes .

4. Epidemiology O. tsutsugamushi is maintained by transovarial transmission in trombiculid mites. After hatching, infected larval mites inoculate organisms into the skin. Infected chiggers to be found in areas of heavy scrub vegetation during the wet season. in some areas, >3% of the population is infected or reinfected each month.

5. PATHOPHYSIOLOGY Chigger inoculates O.tsutsugamushi pathogens. Bacteria multiply at the inoculation site,and a papule forms the ulcerates and becomes nectroic,evolving into an eschar ,with regional lymohadenopathy that may progress to generalized lymphyadnopathy within a few days . O.Tsutsugamushi stimulates phagocytosis by the immune cells,and then escapes the phagosome.it replicates in the cytoplasm and then buds fromthe cell.

6. CLINICAL MANIFESTATIONS: COURSE OF ILLNESS Mild and s e lf-limiting to fatal. Incubation period of 6-21 days. Scrub thypus lasts for 14 to 21 days without treatment. Death may occur end of 2nd week due to complications.

7. Clinical symptoms: Fever is high grade(>104 f) Severe headache,profuse sweating,conjunctival injection. Myalgia,cough,and gastrointestional symptoms(nausea,vomiting,diarrhea) Fever lasts for long periods in untreated patients.

8. SYMPTOMS AND SIGNS: The classic case includes 1) eschar present , 2)regional lymphadenopathy, 3)transient maculopapular rash. - 40%develop a rash(on day 4-6 of illness) -comprises 5 to 40 macular,then papular and vesicular spots. -Non-pruritic..

9. ESCHAR Painless papule often at the site of the infecting chigger bite. Subsequent central necorsis then occurs forming eschar with black crust.

10. SIGNS: Relative bradycardia. Lymphadenopathy-Tender lymph node. Hepatomegaly anad splenomegaly can be observed.

11. Respiratory : cough ARDS Pathogenesis of ARDS in scrub typhus not known, immunological response of the lung to the infection without direct invasion of the organism and diffuse alveolar damage without evidence of vasculitis. NEUROLOGICAL: Involvement of bood vessels in the CNS may produce meningitis . Mental changes from slight intellecutal blunting to coma or delirium. In severe cases,to a multiple organ dysfunction syndrome.

12. COMPLICATIONS: -Over whelming pneumonia with ARDS. -Acute kindy injury. -Atypical pneumonia. -Myocarditis,CHF. -Pulmonary edema. -Circulatory collapse -Disseminated intravascular coagulation.

13. DIFFERENTIAL DIAGNOSIS: The most common signs are similar to a variety of the other infectious diseases. Typhoid fever. Malaria. Leptospirosis. Dengue fever. Brucelosis. Chickungunya.

14. Lab parameters Leucocytosis or leucopenia may be present,but mostly normal wbc count. Liver enzymes levels are increased in 60% of cases. Thrombocytopenia may be sufficient to cause bleeding. Hyperbilirubinemia and increased creatinine.

15. Diagnosis evalution: Serologic assays - Indirect fluorescent antibody(gold standard) -indirect immunoperoxidase. -enzyme immunoassays. -Serological methods are reliable when a four-fold rise in antibody titre is looked. -When a single measurement is performed,the most common cut off titre is 1:50 -PCR amplificatiton of orientia genes from eschar,lymphnodes and blood.

16. WEIL FELIX TEST: The weil-felix test detects cross-reacting antibodies to proteus mirabilius OX-K. The weil-felix test its a low cost. Fifty percent of patient have a positive test result during the second week. Weil felix test is based on cross reactons which occur between antibodies peoduced in acute rickettsial infecttions with antigens of OX(OX19, OX 2 and OX K)

17. Biospy of an eschar or generalized rash. -pathological hallmark-lymphohistiocytic vasculitis. -Endothelial injury causes loss of vasular integrity.Egress of plasma and plasma proteins and microscopic and macroscopic hemorrhages. -Histologic change in biopsies of eschars shows focal intense vasculitis with perivascular collection of lymphocytes and macrophages.

18. Isolation of O.tsutsugamushi can be done in cell culture or in inoculated mice. Chest radiography may reveal pneumonitis especially in the lower lung fields. In meningitis,there is apredominant mononuclear response.

19. TREATMENT: ADULT TREATMENT: Doxycycline (100mg bd orally for 7-15 days) -but can also be given in a single dose or short periods (3 to 7 days)although relapse can occur. -Azithromycin (500mg orally for 3 days) especially for the pregnant patients.

20. PROPHYLAXIS: Single oral dose of chloramphenicol or tetracycline given every five days for a total of 35 days,with 5-day non-treatment intervals(for endemic regions). No vaccine is available for scrub typhus.

21. PREVENTION: Protective clothing. Insect repellents containing dibutyl phthalate,benzyl benzoate,diethyl toluamide etc applied to the skin and clothing to prevent chigger bits. Do not sit or lie on bare ground or grass. Clearing of vegetation and chemical treatment of the soil may help to break up the cycle of transmission from chiggers to humans to other chiggers.

22. TAKE HOME MESSAGE: Scrub typhus is a re-emerging disease in india. An important cause of community acquired undifferntiated febrile illness in india. It has to be considered in the differential diagnosis of sepsis and multi organ dysfunction syndrome. Failure of early diagnosis is associated with significant mortality and morbidity . Search for an eschar in hidden areas of body. Screening by weil felix and diagnosis is done by IgM scrub typhus ELISA. DOC: Doxycycline.

23. REFERENCE: PMC ARTICLE Indian J Dermatol. 2017 Sep-Oct; 62(5): 478–485. Sayantani Chakraborty and Nilendu Sarma1 From the Department of Dermatology, R. G. Kar Medical College, Kolkata, West Bengal, India Harrison’s principles of internal medicine 21st edition.

24. THANKYOU.