scrub typhus.pptx dr.ramjiban yadav nepal

ppt

1. Scrub typhus Dr Santosh Karki FCPS RESIDENT

2. INTRODUCTION Scrub typhus is a mite-borne infectious disease caused by  Orientia tsutsugamushi  (previously called  Rickettsia tsutsugamushi ). Scrub typhus is of greatest public health importance in the rural Asian tropics .  Scrub typhus is manifested clinically by high fever, cough, intense generalized headache, diffuse myalgias , and, in many patients, rash and an eschar at the site of the insect bite

3. MICROBIOLOGY O. tsutsugamushi  is an obligate intracellular, gram-negative coccobacillus that infects a range of host cell types including endothelial cells, monocytes, macrophages, and dendritic cells . Like all rickettsiae ,  O. tsutsugamushi  cannot be propagated in cell-free media   It is unique in that it is released from infected cells by budding from the plasma membrane of host cells

4. EPIDEMIOLOGY

5. EPIDEMIOLOGY in Nepal

6. TRANSMISSION

7. CLINICAL MANIFESTATIONS C linical manifestations can range from mild signs and symptoms to multiorgan failure and death Acute febrile illness  — Infection commonly presents as an acute febrile illness about a week after the bite of an infected mite, although clinical onset can range from 6 to 21 days after exposure Scrub typhus may begin insidiously with headache, anorexia, and malaise, or start abruptly with chills and fever. As the illness evolves, most patients develop the following symptoms: ●Fever, which typically lasts for long periods in untreated patients (median 14.4 days; range 9 to 19) [ 8 ] ●Intense generalized headache ●Diffuse myalgias Rash, eschar , and other signs and symptoms may also be present

8. Other signs and symptoms Lymphadenopathy Localized, and subsequent generalized lymphadenopathy, occurs in the majority of patients and may be accompanied by inflammation of the lymphatic sinuses, splenomegaly, and portal triaditis . Gastrointestinal Nausea, vomiting, and/or diarrhea are prominent findings in approximately one-fourth of patients Respiratory Respiratory complaints occur in up to two-thirds of cases, with symptoms ranging from mild cough to overt acute respiratory distress syndrome (ARDS)  Cardiovascular  Relative bradycardia occurs commonly in patients with scrub typhus . Relative bradycardia has been defined as a median increase in heart rate <10 beats/min per 1ºC increase in temperature Central nervous system Meningitis , meningoencephalitis , seizures, and strokes, especially in children and older adults  Altered sensorium is particularly common in older patient Renal   Acute kidney injury has been reported in those with severe disease

9. Laboratory findings   Most patients with severe illness develop thrombocytopenia. Elevations in hepatic enzymes, bilirubin, and creatinine may also be present Leukopenia or leukocytosis can occur, but most have a normal white blood cell count

10. DIAGNOSIS   Initial diagnosis of scrub typhus is made presumptively, based on compatible clinical signs, symptoms, and laboratory features as well as epidemiologic clues  Treatment should be initiated immediately when the diagnosis is suspected A rapid response to empiric treatment can also be used to support the diagnosis, although response times >48 hours have been reported

11. Diagnostic tests DIAGNOSTIC TEST REMARKS SEROLOGY Indirect fluorescent antibody (IFA) test remains the mainstay of serologic diagnosis.  Detectable IgM antibodies when combined with an appropriate clinical syndrome and epidemiology A dot blot immunoassay dipstick, which is undergoing clinical evaluation, may permit rapid diagnosis of scrub typhus Biopsy of an eschar or generalized rash  In challenging cases pathological hallmark of scrub typhus is a lymphohistiocytic vasculitis Polymerase chain reaction  PCR testing of blood samples even in the minority of patients who lack IgM antibodies early in the course of infection  PCR assays on blood have demonstrated lower sensitivity than specificity Culture  Culture of this organism is available in only a few specialized laboratory centers with rigorous quality control and appropriate laboratory safety measures.

12. Differential diagnosis Malaria and dengue Leptospirosis   Salmonella   Typhi   Rickettsial diseases

13. TREATMENT Indications  All patients with suspected or confirmed scrub typhus should be treated with antimicrobial therapy . Treatment should be initiated as soon as possible . Delayed administration of antibiotics has been independently associated with the development of major organ dysfunction and hospitalization for >10 days

14. Determining disease severity Types Clinical Features Mild Patients with mild to moderate disease typically present with fever, myalgia, and headache Moderate Patients with mild to moderate disease typically present with fever, myalgia, and headache  as well as a rash (with or without eschar ) and/or cough. Severe Combination with clinical or laboratory manifestations that indicate end-organ damage. These include hyperbilirubinemia , renal failure, cardiovascular collapse (hypotension/shock), acute respiratory distress syndrome (ARDS), and meningoencephalitis .

15. Preferred antimicrobial regimens   For patients with presumed mild to moderate scrub typhus, we suggest monotherapy with  doxycycline  or  azithromycin . Persons with severe disease   M onotherapy with  doxycycline is standard care 200 mg of doxycycline twice daily on day one, followed by 100 mg twice daily for a total duration of seven days However, combination therapy with  doxycycline  and  azithromycin  may be considered on a case-by-case basis . Duration : doxycycline -7 days , azithromycin 5-7 days

16. Alternate antimicrobial regimens   Rifampin C ontraindications to  doxycycline  and  azithromycin  (the preferred agents) rifampin creates challenges with its many drug-drug interactions rifampin  (600 mg once daily for five days) Combination therapy with  doxycycline  plus  rifampin is rarely indicated Fluoroquinolones  particularly in mild/moderate disease associated with delayed time to resolution and higher mortality compared to  doxycycline  or  minocycline Chloramphenicol first drug  no significant differences in time to resolution of fever and incidence of relapse in patients treated with  doxycycline  or chloramphenicol  toxicity of this drug and difficulty obtaining it in most countries, chloramphenicol should be reserved for situations when other options are not available.

17. Considerations during pregnancy Scrub typhus may cause spontaneous abortions or stillbirths in pregnant persons   T ypically administer  azithromycin  (500 mg daily) for seven days

18. PREVENTION Prevention of scrub typhus consists of avoiding exposure to mites No vaccine is available to prevent the transmission of scrub typhus

19. Reference: Up To date Harrison 21 edition Thank you