NCT04506944

The Epidemiology of Rickettsial Infections in South India: Cohort Study

Completed Last updated 5 October 2023

What this trial tests

trial testing No intervention in Scrub Typhus in 32,566 participants. Completed in 31 July 2023.

Timeline

1 August 2020

Primary endpoint
5 August 2022

31 July 2023

Quick facts

Lead sponsor	London School of Hygiene and Tropical Medicine
Status	Completed
Study type	OBSERVATIONAL
Enrollment	32,566
Start date	1 August 2020
Primary completion	5 August 2022
Estimated completion	31 July 2023
Sites	1 location across India

Drugs / interventions tested

• No intervention

Conditions studied

• Scrub Typhus — all drugs for Scrub Typhus →
• Spotted Fever; India — all drugs for Spotted Fever; India →
• Murine Typhus — all drugs for Murine Typhus →

Sponsor

London School of Hygiene and Tropical Medicine

Who can join

Eligibility, any sex, with Scrub Typhus or Spotted Fever; India. Patients with the condition only — healthy volunteers not accepted.

Sponsor's own description

There is enough evidence to suggest that scrub typhus and spotted fever group rickettsioses are common causes of febrile illness in India. Serological evidence also exists for murine typhus, but is rarely tested for. Incidence, risk factors, clinical features and molecular epidemiology of these three infections are poorly understood. Delays in disease recognition and treatment may cause thousands of preventable deaths across India.

The objectives of the research are to determine the incidence and risk factors of scrub typhus, spotted fever and murine typhus by severity, to determine clinical features of these neglected and often unrecognized infections. Further to study the effect of previous infection on incidence and severity of subsequent infections. Finally to study the association between vector parameters and scrub typhus risk.

Enrolled will be 30,000 individuals who will be followed up for the development of fever using active and passive surveillance. Active surveillance will include household screening every 3-6 weeks. Fever cases occuring in the past two months will be tested for Scrub typhus, murine typhus and spotted fever IgG/IgM. 4000 individuals will be followed up by annual serological testing to identify asymptomatic infections. Participants notifying the study team with ongoing fever will undergo blood testing for acute diagnosis of rickettsial infection (IgM, PCR). In addition, we will enroll fever cases at study clinics who are not part of the main cohort. The research includes spatial and socio-economic risk factor analysis. Rodents carrying mite larvae will be trapped to compare the intensity of mite infestation between areas of high and low risk for human scrub typhus.

The data on incidence, burden of disease and environmental determinants of scrub typhus, spotted fever and murine typhus will be used for health care planning and information campaigns for the public and medical professionals.

Publications & conference data

3 peer-reviewed publications reference this trial (live from Europe PMC):

1. Incidence of Scrub Typhus in Rural South India.
   Devamani C, Alexander N, Chandramohan D, Stenos J, et al · · 2025 · cited 9× · PMID 40073309 · DOI 10.1056/nejmoa2408645
2. Risk factors for scrub typhus infection in South India: population-based cohort study.
   Schmidt WP, Alexander N, Rose W, Chandramohan D, et al · · 2025 · cited 1× · PMID 40855461 · DOI 10.1017/s0950268825100484
3. Cost of illness of scrub typhus in South India - a population-based, mixed-methods study.
   Devamani C, Biran A, Ariyoshi K, John KR, et al · · 2026 · PMID 41628250 · DOI 10.1371/journal.pntd.0013960