Risk factors for acquisition of scrub typhus in children admitted to a tertiary centre and its surrounding districts in South India: a case control study.

BACKGROUND: Scrub typhus is a mite borne zoonosis common in the tropics with no good preventive strategy. Children are also affected leading to considerable morbidity and mortality. We conducted a case control study and a vector survey to determine the risk factors for acquisition of scrub typhus. METHODS: A case control study with a 1:2 case control ratio was conducted over a 2 year period at a tertiary care centre and its surrounding districts in South India. Cases were children < 15 years with confirmed scrub typhus. Controls were age and locality matched community controls without fever. Demographic, environmental and behavioural risk factors were obtained in cases and controls by an interview and an environmental survey. A vector survey was also undertaken in the immediate vicinity of the cases. RESULTS: Case Control study: 101 cases and 167 controls were analysed. On multivariate analysis, significant association was observed with environmental factors such as the presence of a water body within 100 m of the house (OR 3.56(1.36,9.75); p 0.011), cooking outside the house (OR 5.61 (1.51,23.01); p 0.011), owning pets (OR 3.33(1.16,9.09); p 0.031), and the presence of bushes within 5 m of the house (OR 2.78 (1.11,7.69); p 0.033). Of the behavioural factors, the child going to school by a vehicle (OR 3.12 (2.29,8.37); p 0.006) was associated with an increased risk. Drying clothes on a clothesline showed a trend towards protection from acquiring scrub typhus (OR 0.31 (0.08, 1.08); p 0.077). Vector survey:26 rodents were trapped in as many houses. Trombiculid mites were isolated in 24 houses with 9(34.6%) being able to transmit scrub typhus. 254 trombiculid mites belonging to four species and two genera were collected. Leptotrombidium deliense, (33.5%). Schoengastiella ligula, (11.0%) of the total mite specimens collected. S. ligula always co-existed with L. deliense. The estimated Chigger index for Leptotrombidium deliense and Schoengastiella ligula was 3.27and 1.08 per animal respectively. CONCLUSIONS: Our study highlights risk factors for scrub typhus, some of which may be modifiable. A clean peri-domestic environment free of vegetation, drying clothes on a clothesline and cooking indoors may decrease the risk of scrub typhus.

Comparison of Scrub Typhus With and Without Meningitis.

OBJECTIVE: To compare the children admitted with scrub typhus with and without meningitis. METHODS: All children admitted with scrub typhus over a 62 mo period were reviewed. Statistical analysis was performed to compare those with and without meningitis for demographic, clinical, investigations and outcome parameters. RESULTS: Four hundred twenty seven children were admitted with scrub typhus and 63 (14.8%) had meningitis. The mean cerebrospinal fluid white blood cell (CSF WBC) count was 71 cells/cu.mm. with mean lymphocyte proportion of 92%. The mean CSF protein was 67 mg/dl and mean CSF glucose, 55 mg/dl. Of those who had meningitis, 24 (38.1%) had seizures, 17 (27%) had altered sensorium and 37 (58.7%) had nuchal rigidity. Finding an eschar, being male, breathing difficulty, and hepatomegaly were significantly more common in those without meningitis. Children with meningitis also had shorter duration of fever at presentation (median [IQR] 7 [3] days vs. 10 [4] days; p = 0.028). Headache and vomiting were significantly more common in those with meningitis. Hemoglobin and platelet were significantly lower in those without meningitis. Duration of hospitalization was significantly longer in those with meningitis, whereas acute respiratory distress syndrome (ARDS) was significantly more common in those without meningitis. There was no neurological deficit in both the groups. There was no mortality in the meningitis group compared to 3.6% mortality in the non-meningitis group (p = 0.213). CONCLUSIONS: Meningitis occurs in 15% of those with scrub typhus; those with meningitis have good neurological outcome with little mortality; those without meningitis have more complications and poorer outcome.