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Updated: Dec 19, 2025
Extraction of Saliva, Haemolymph, Salivary Glands, and Midgut from Individual Ticks (Acari: Ixodidae)
Published on: October 31, 2025
Detection of African genotype in Hyalomma tick pools during Crimean Congo hemorrhagic fever outbreak, Rajasthan,
Rima R Sahay1, Suhas Dhandore2, Pragya D Yadav1
1ICMR-National Institute of Virology, Microbial Containment Complex, Sus-Pashan Road, Pune, Maharashtra, India.
Insights
Crimean-Congo hemorrhagic fever (CCHF) outbreaks in Rajasthan, India, reveal co-circulating Asian and African CCHFV lineages in Hyalomma ticks. This highlights the need for enhanced surveillance and biosafety measures to manage the zoonotic disease.
Area of Science:
- Virology
- Epidemiology
- Public Health
Background:
- Crimean-Congo hemorrhagic fever (CCHF) is a severe zoonotic viral disease with significant hemorrhagic manifestations in humans.
- Previous CCHF outbreaks were reported in Gujarat (2011-2019) and Rajasthan (2014-2015), indicating endemicity in India.
- A recent CCHF outbreak in Rajasthan (August-November 2019) necessitated further investigation into the circulating viral strains and vectors.
Purpose of the Study:
- To investigate the genetic diversity of Crimean-Congo hemorrhagic fever virus (CCHFV) strains involved in a recent outbreak in Rajasthan, India.
- To identify the tick species and lineages responsible for CCHF transmission in the affected districts.
- To assess the implications of identified CCHFV lineages for disease surveillance and management strategies.
Main Methods:
- Collection and analysis of human blood and Hyalomma tick samples from affected districts in Rajasthan.
- Detection of CCHFV IgG antibodies in livestock animal samples.
- Next-generation sequencing (NGS) of CCHFV positive human blood and tick pool samples to determine viral genotypes and lineages.
Main Results:
- Five human CCHF cases were reported across three districts in Rajasthan between August and November 2019.
- High CCHFV IgG antibody positivity was observed in livestock samples.
- NGS analysis identified two distinct CCHFV M segment genotypes in Hyalomma tick pools: one Asian and one African lineage. The L and S genes clustered within the Asian lineage.
- A 3.56% amino acid variation was noted in the M gene between fatal and survived CCHF cases.
Conclusions:
- The study confirms the circulation of at least two distinct CCHFV lineages (Asian and African) within Hyalomma tick populations in Rajasthan, India.
- The genetic diversity of CCHFV underscores the importance of robust surveillance systems for ticks, livestock, and humans in Rajasthan and neighboring states.
- Enhanced biosafety measures, including personal protective equipment, barrier nursing, and availability of ribavirin, are crucial for preventing nosocomial infections and managing CCHF cases effectively.
Abstract:
Crimean Congo hemorrhagic fever (CCHF) is a zoonotic viral disease presenting with fever and hemorrhagic manifestations in humans. After several outbreaks of CCHF being reported from Gujarat since 2011 till 2019 and from Rajasthan in 2014 and 2015, the present study reports the CCHF outbreak which was recorded from five human cases in three districts Jodhpur, Jaisalmer, and Sirohi of Rajasthan state since August 2019 till November 2019. A high percent of positivity was recorded in livestock animal samples for the CCHFV IgG antibody. CCHF virus (CCHFV) positive human blood samples and Hyalomma tick pool samples were sequenced using next-generation sequencing method. Two different M segment genotypes, encoding glycoprotein precursor, were identified from tick pools in the study: first from Asian and second from African lineage. The L gene (polymerase) and the S gene (nucleocapsid) clustered in the Asian lineage. The present study illustrates the existence of two different CCHFV lineages being circulating within the Hyalomma tick pools in the Rajasthan state, India. We also observed 3.56% amino acid changes between the death and the survived case of CCHFV in the M gene. This report also sets an alarm to enhance human, tick and livestock surveillance in other districts of Rajasthan and nearby states of India. Biosafety measures, barrier nursing along with the availability of personal protective equipment and ribavirin drug will always be a mainstay in preventing nosocomial infection for proper case management.
