Scrub Typhus

Ira Shah
Consultant Pediatrician and Pediatric Infectious Diseases, Nanavati Hospital, Mumbai, India
First Created: 01/02/2013 

Introduction

Scrub typhus, also called Tsutsugamushi disease, is an acute infectious disease that is transmitted to humans by certain mites (chiggers). Recent outbreaks have been seen in India. The causative organism is Orientia (formerly Rickettsia) tsutsugamushi. Trombiculid mites (Leptotrombidium delinese & L. Akamushi) serve as both reservoirs and vectors.

Pathology

The basic pathologic process of scrub typhus is a perivasculitis of the small blood vessels analogous to the other rickettsial diseases. In addition, an eschar or necrotic inflammatory lesion develops at the site of the mite bite, with subsequent regional lymphadenopathy. General lymphadenopathy occurs commonly in scrub typhus but rarely or not at all in all other rickettsial diseases.

Presentation

The chigger bite results in a papule, enlarging to a bulla that rapidly sloughs, leaving a shallow ulcer. A black crust surrounded by a 1-2 cm erythematous raised circle then forms (Figure 1). Within 5 days, an unremitting fever to 40 degrees C accompanied by a severe headache is seen in virtually all patients. Generalized lymphadenopathy is the most consistent physical finding, The characteristic rash of scrub typhus is maculopapular & generalized & most prominent on non - exposed skin surfaces. Hepatosplenomegaly and conjunctival injection are common; deafness and tinnitus occur less commonly. Myocarditis and disseminated intravascular coagulation also have been reported.

Figure 1: Rickettsial rash with eschar (arrow)


Scrub Typhus

Diagnosis

The Weil-Felix OX-K strain agglutination reaction may be the only serologic test available in less developed countries. However, it is not very sensitive; OX-K agglutinins develop in only a little more than 50 percent of scrub typhus patients. Moreover, OX-K agglutinins are also produced by relapsing fever. A fourfold rise in agglutinin titres in paired sera or a high cut-off titre (>1:320) in single samples is diagnostic for skin infection. Immunofluorescent tests are much more diagnostic and reliable.

Treatment

Tetracycline is the drug of choice. In younger children, chloramphenicol or quinolone group of antibiotics is used.


1. McIntosh N et al. Forfar & Arneil's Textbook of Pediatrics. Geographic spread of scrub typhus. Vol 6. 2003; 1441-1442.
2. Park K, Park's textbook of preventive & social medicine. Epidemiology of communicable diseases. Agent Factors. 2009; 20: 262.
3. Rudolph CD et al, Rudolph's textbook of pediatrics. Typhus. 2001; 21:1016-1017.
4. Shirai A, Brown GW, Gan E, et al. Rickettsia tsutsugamushi antibody in mother cord pairs of sera. Jpn J Med Sci Biol. 1981; 34: 37-39.
5. Jin-ju W, Gui-zhong T, Shi-feng S. Study on Leptotrombidium gaohuensis sp. nov.: Newly discovered vectors of tsutsugamushi disease. Chin Med J. 1987; 100: 590-594.
6. Chayakul P, Panich V, Silpapojakul K. Scrub typhus pneumonitis: An entity which is frequently missed. Q J Med. 1988. 68: 591H302.
7. Ognibene AJ, O'Leary DS, Czarnecki SW et al. Myocarditis and disseminated intravascular coagulation in scrub typhus. Am J Med Sci. 1971; 262: 233-239.
8. Kelly DJ, Wong PW, Gan E, et al. Comparative evaluation of the indirect immunoperoxidase test for the serodiagnosis of rickettsial disease. Am J Trop Med Hyg. 1988; 38: 400-406.
9. Watt G, Kantipong P, Jongsakul K et al. Doxycycline and rifampin for mild scrub-typhus infections in northern Thailand: A randomised trial. Lancet. 2000; 356: 1057-1061.
10. Agarwal M, Textbook of Pediatrics. Treatment of scrub typhus. 2008: 158-159.
11. Twartz JC, Shirai A, Selvaraju G et al. Doxycycline prophylaxis for human scrub typhus. J Infect Dis. 1982; 146: 811-818.
12. Batra HV. Spotted fevers & typhus fever in Tamil Nadu. Indian J Med Res. 2007; 126: 101-103.
13. Lee N, Ip M, Wong B, Lui G, Tsang OT, Lai JY, et al. Risk factors associated with life-threatening rickettsial infections. Am J Trop Med Hyg. 2008; 78: 973-978.
14. Song SW, Kim KT, Ku YM, et al. Clinical role of interstitial pneumonia in patients with scrub typhus: a possible marker of disease severity. J Korean Med Sci. 2004; 19: 668-673.


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