Indian Journal of Pediatrics, Volume 75—September, 2008 947 Clinical Brief Correspondence and Reprint requests : Dr. Sanjay K. Mahajan, 25/3, US Club, Shimla-171001, Himachal Pradesh, India. [Received July 20, 2007; Accepted February 18, 2008] Pediatric Scrub Typhus in Indian Himalayas Sanjay K. Mahajan, Jean-Marc Rolain 1 , Naveen Sankhyan, Ram Krishan Kaushal and Didier Raoult 1 Department of Pediatrics, IG Medical College, Shimla, H.P., India; 1URMITE UMR 6236, CNRS-IRD, Faculte de Medecine et de Pharmacie, Marseille, France ABSTRACT To retrospectively confirm the suspected rickettsial disease (Scrub typhus) using a gold standard diagnostic test i.e. microimmunofluorescence in pediatric patients with acute febrile illness of unknown etiology. Two serological tests, Weil-Felix and Microimmunofluorescence were used to confirm infection. All five children had fever, vomiting and generalized lymphadenopathy, but none had eschar or rash. One was cured with doxycycline, remaining four patients treated with azithromycin and one died despite treatment. Scrub typhus is a cause of fever of unknown origin in Himalayan region of India and azithromycin is an effective alternative to doxycycline in treating this disease. [Indian J Pediatr 2008; 75 (9) : 947-949] E-mail: sanjay_mahajan64@rediffmail.com Key words : Rickettsia; Orientia tsutsugamushi; Eschar; Himachal Pradesh; Azithromycin Scrub typhus is a zoonosis caused by Orientia tsutsugamushi and is transmitted through the bite of larval mites (chiggers) of the Trombiculidae family. The disease has been reported from many regions of Asia and the Pacific islands .1, 2 Fever, headache, and myalgias are common but nonspecific initial symptoms. Manifestations such as pneumonitis, meningoencephalitis, jaundice, renal failure, and myocarditis can develop in severely affected patients. Weil-Felix test detects agglutinating antibodies by 5-10 days following onset of symptoms but is insensitive. Immunofluorescence assay (IFA) is “gold standard” technique and is used as a reference technique in most laboratories. 3 Clinical suspicion may be delayed or absent in areas where the disease has not been documented or in regions lacking diagnostic facilities. Suspecting the diagnosis and initiating prompt antimicrobial drug therapy are important to prevent mortality. We present, possibly the first account of childhood scrub typhus diagnosed using a gold standard diagnostic test i.e. microimmunofluorescence (MIF) from this region. MATERIAL AND METHODS Scrub typhus was suspected clinically in febrile children without obvious focus. After taking informed consent, blood samples were taken from patients for total blood cell count, biochemistry analysis, serologic diagnosis and molecular biology. Patients with clinical features suggestive of scrub typhus received anti-rickettsial drug (doxycyclin/azithromycin) empirically. Two serological tests were used to confirm infections. The Weil-Felix Proteus agglutination assay with P. vulgaris OX-19, OX-2 and P. mirabilis OX-K strains (Wellcome Diagnostics, Dartford, England) was performed on each sample and a titer 1: ≥ 80 was considered as positive results. In MIF, serum specimens were tested by using a panel of eleven rickettsial antigens, including SFG rickettsiae (R. japonica, R. helvetica, R. slovaca, R. conorii subsp.indica, R. honeï, R. heilongjangensis, and R. felis), R.typhi and O. tsutsugamushi (Gilliam, Karp, Kato and Kawasaki strains). The MIF assay was considered positive at a cut off antibody titers of 1/128 for IgG and 1/64 for IgM. Eight sera showed titers 1: > 80-320 to Proteus OXK antigen on Weil-Felix test. In MIF, 5 of these 8 patients showed significant antibody titers (both IgG and IgM) to O. tsutsugamushi (Gilliam, Karp, Kato and Kawasaki strains). RESULTS There were four boys and one girl among five children with serologically confirmed scrub typhus. All had fever, vomiting and generalized lymphadenopathy (Table 1). None had either eschar or rash. Among these five patients, one was cured and mortality was seen in a 5