# Cost of illness of scrub typhus in South India – a population-based, mixed-methods study

## TL;DR

This study estimates the financial burden of scrub typhus in South India and finds that hospitalization is a major cost driver, especially for severe cases.

## Contribution

The study provides novel population-based cost-of-illness data for scrub typhus in rural South India, including insights into treatment-seeking behavior.

## Key findings

- The mean overall cost of illness was USD 189, with severe cases costing USD 1,321 and non-severe cases USD 86.
- Hospitalization was common and significantly increased costs, often exceeding average monthly household income.
- Treatment-seeking behavior included use of traditional healers and pharmacies for mild symptoms, with higher demand for diagnostics and care when symptoms worsened.

## Abstract

Scrub typhus is a potentially life-threatening acute febrile illness found in many parts of Asia. This study aimed to estimate the cost of illness among scrub typhus cases in Tamil Nadu, South India and explore treatment-seeking behaviour.

Cases were enrolled from a population-based cohort study on scrub typhus in 32,279 individuals living in rural villages. Data on direct and indirect costs were collected using structured questionnaires from 311 scrub typhus cases of which 26 were severe. Thirteen cases with severe infections (or their relatives) underwent in-depth interviews to understand treatment-seeking pathways.

The mean age of cases was 41.1 years, and 64% were female. The average monthly household income was USD 236 (standard deviation, SD 155). The average number of workdays missed in severe infection was 18 days per episode (SD 22.2) compared to 4 days (SD 11.6) in non-severe illness. The mean overall cost of illness was USD 189 (SD 495), disaggregating to USD 1,321 (SD 1045) for severe cases and USD 86 (SD 209) for non-severe. In both severe and non-severe cases, hospital admission was common (69/311) and was associated with a cost increase of over USD 400. Costs were almost twice as high in males compared to females. Catastrophic health expenditure exceeding 25% of annual income occurred in 10% of cases. Treatment by traditional healers, untrained practitioners, pharmacies and local clinics was sought even for mild fever of short duration. In-depth interviews revealed that patients preferred to have a one-off treatment enabling them to return to daily routines with little demand for fever diagnostics. There was demand for higher level of care and diagnostic procedures only when symptoms became severe or the case was a child or a pregnant woman.

Hospitalisation, common in both severe and non-severe patients, was the driving factor for high costs. Early case recognition may reduce hospitalisations and health expenditure in highly endemic settings.

Scrub typhus is an important cause of fever in many Asian countries, including China, India, Vietnam and Japan. It is caused by the intra-cellular bacteria Orientia (mostly O. tsutsugamushi) and transmitted to humans by trombiculid mite larvae (“chiggers”). Scrub typhus is potentially life-threatening, but treatable with cheap antibiotics such as doxycycline and azithromycin. In this study, the cost of illness was determined in 311 cases identified as part of a cohort study on the incidence of scrub typhus in a rural setting in South India. In-depth interviews were conducted to determine treatment seeking behaviour. The mean overall cost of illness per case was USD 189, disaggregating to USD 1,321 for severe cases and USD 86 for non-severe cases. Hospitalisations were found to be the driving factor for high costs in both mild and severe cases, often leading to health expenditures exceeding the average monthly household income of USD 236.