Evidence map›Paper›PMID 39825388›Full record

ArticleParasites & vectors2025

First evidence of transovarial transmission of Kyasanur Forest disease virus in Haemaphysalis and Rhipicephalus ticks in the wild.

Sarah J Burthe, Bhimanagoud Kumbar, Stefanie M Schäfer, Bethan V Purse, Abi T Vanak, Natrajan Balakrishnan, Richard Hassall, Subhash L Hoti, Darshan Narayanaswamy, Santoshkumar Potadar and 2 more

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Article in Parasites & vectors, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 3 papers, 1 of them a synthesis that pooled it.

0numbers the graph read from it
0cells of the map it votes in
3citing papers in PubMed, 1 pooled it
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

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3 · Its place in the literature

Who cites it

3 citing papers in PubMed, 1 synthesis or guideline pooled it.

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4 · The record

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5 · Who and what money

Authors and funding

12 authors.

Sarah J Burthe *UK Centre for Ecology & Hydrology, Penicuik, EH26 0QB, UK. sburthe@ceh.ac.uk.
Bhimanagoud Kumbar *ICAR-National Institute of Veterinary Epidemiology and Disease Informatics, Bengaluru, India.
Stefanie M SchäferUK Centre for Ecology & Hydrology, Wallingford, OX10 8BB, UK.
Bethan V PurseUK Centre for Ecology & Hydrology, Wallingford, OX10 8BB, UK.
Abi T VanakAshoka Trust for Research in Ecology and the Environment, Bengaluru, India.
Natrajan BalakrishnanICAR-National Institute of Veterinary Epidemiology and Disease Informatics, Bengaluru, India.
Richard HassallUK Centre for Ecology & Hydrology, Wallingford, OX10 8BB, UK.
Subhash L HotiICMR-Vector Control Research Centre, Puducherry, India.
Darshan NarayanaswamyVirus Diagnostic Laboratory, Department of Health and Family Welfare Services, Government of Karnataka, Shimoga, India.
Santoshkumar PotadarICMR-National Institute of Traditional Medicine, Belgaum, India.
Mujeeb RahmanAshoka Trust for Research in Ecology and the Environment, Bengaluru, India.
Mohammed Mudassar ChandaICAR-National Institute of Veterinary Epidemiology and Disease Informatics, Bengaluru, India. chandamudassar@gmail.com.

Funding

Global Challenges Research Fund MR/P024335/1Global Challenges Research Fund MR/T029846/1
6 · The paper itself

Abstract

backgroundKyasanur forest disease virus (KFDV) is a tick-borne flavivirus causing debilitating and potentially fatal disease in people in the Western Ghats region of India. The transmission cycle is complex, involving multiple vector and host species, but there are significant gaps in ecological knowledge. Empirical data on pathogen-vector-host interactions and incrimination have not been updated since the last century, despite significant local changes in land use and the expansion of KFD to new areas. Mathematical models predict that transovarial transmission, whereby adult female ticks pass KFDV infections to their offspring, plays an important role in the persistence of KFD, but this has not been shown in the wild. Here we set out to establish whether transovarial transmission of KFDV was occurring under natural field conditions by assessing whether host-seeking larvae were positive for KFDV.

methodsTicks were sampled by dragging and flagging across a broad range of habitats within the agro-forest matrix at 49 sites in two districts: Shivamogga, Karnataka and Wayanad, Kerala (September 2018-March 2019), and larvae were tested for KFDV by PCR.

resultsIn total, larval ticks from 7 of the 49 sites sampled tested positive for KFDV, indicating that transovarial transmission is occurring. Of the 13 KFDV-positive larval samples, 3 came from around houses and gardens, 5 from crops (3 from harvested rice paddy and 2 from areca plantation), 1 from teak plantation and 4 (2 from 1 transect) from forests. Five different tick species were found to have KFDV-positive larvae: Haemaphysalis spinigera, H. bispinosa, Rhipicephalus annulatus, R. microplus and an unidentifiable species of Haemaphysalis (no close match in GenBank).

conclusionsOur empirical confirmation of transovarial transmission has important implications for understanding and predicting KFD dynamics, suggesting that ticks may act as a reservoir for KFDV. Moreover, small mammals and cattle may play crucial roles in transmission if small mammals are the main hosts for larvae infected via transovarial transmission, and cattle support large numbers of infected female adult ticks. This first report of transovarial transmission of KFDV, and within a hitherto undescribed range of vectors and habitats, will help disease managers improve KFD surveillance and mitigation strategies, ultimately leading to communities becoming more resilient to the risk of this tick-transmitted disease.

Indexed as

Arachnid VectorsEncephalitis Viruses, Tick-BorneIxodidaeKyasanur Forest DiseaseRhipicephalusAnimalsAnimals, WildFemaleIndiaLarvaEmerging infectionMonkey FeverTick-borne pathogenZoonotic diseases

Identifiers

PMID39825388
PMCPMC11740564

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.