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Perumalsamy N, Sharma R, Subramanian M, Nagarajan SA. Hard Ticks as Vectors: The Emerging Threat of Tick-Borne Diseases in India. Pathogens 2024; 13:556. [PMID: 39057783 PMCID: PMC11279560 DOI: 10.3390/pathogens13070556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Revised: 05/06/2024] [Accepted: 05/07/2024] [Indexed: 07/28/2024] Open
Abstract
Hard ticks (Ixodidae) play a critical role in transmitting various tick-borne diseases (TBDs), posing significant global threats to human and animal health. Climatic factors influence the abundance, diversity, and vectorial capacity of tick vectors. It is imperative to have a comprehensive understanding of hard ticks, pathogens, eco-epidemiology, and the impact of climatic changes on the transmission dynamics of TBDs. The distribution and life cycle patterns of hard ticks are influenced by diverse ecological factors that, in turn, can be impacted by changes in climate, leading to the expansion of the tick vector's range and geographical distribution. Vector competence, a pivotal aspect of vectorial capacity, involves the tick's ability to acquire, maintain, and transmit pathogens. Hard ticks, by efficiently feeding on diverse hosts and manipulating their immunity through their saliva, emerge as competent vectors for various pathogens, such as viruses, parasites and bacteria. This ability significantly influences the success of pathogen transmission. Further exploration of genetic diversity, population structure, and hybrid tick vectors is crucial, as they play a substantial role in influencing vector competence and complicating the dynamics of TBDs. This comprehensive review deals with important TBDs in India and delves into a profound understanding of hard ticks as vectors, their biology, and the factors influencing their vector competence. Given that TBDs continue to pose a substantial threat to global health, the review emphasizes the urgency of investigating tick control strategies and advancing vaccine development. Special attention is given to the pivotal role of population genetics in comprehending the genetic diversity of tick populations and providing essential insights into their adaptability to environmental changes.
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Affiliation(s)
| | | | | | - Shriram Ananganallur Nagarajan
- Division of Vector Biology and Control, Indian Council of Medical Research—Vector Control Research Centre (ICMR-VCRC), Puducherry 605006, India; (N.P.); (R.S.); (M.S.)
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Blacksell SD, Le KK, Rungrojn A, Wongsantichon J, Stenos J, Graves SR, Day NPJ. Gaps and inconsistencies in the current knowledge and implementation of biosafety and biosecurity practices for rickettsial pathogens. BMC Infect Dis 2024; 24:268. [PMID: 38424500 PMCID: PMC10905923 DOI: 10.1186/s12879-024-09151-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Accepted: 02/19/2024] [Indexed: 03/02/2024] Open
Abstract
INTRODUCTION Rickettsia spp. and Orientia spp. are the causes of neglected infections that can lead to severe febrile and systemic illnesses in humans. Implementing proper biosafety practices when handling these pathogens is crucial to ensure a safe and sustainable work environment. It is essential to assess the current knowledge and identify any potential gaps to develop effective measures that minimise the risk of exposure to these pathogens. By doing so, we can establish a comprehensive framework that promotes safety, mitigates hazards, and safeguards the well-being of personnel and the surrounding community. METHODS AND RESULTS This review aimed to synthesise and determine the evidence base for biosafety precautions for Rickettsia spp. and Orientia spp. pathogens. Enhancing our understanding of the relative infectious risk associated with different strains of Rickettsia and Orientia spp. requires identifying the infectious dose of these pathogens that can cause human disease. The application of risk groups for Rickettsia and Orientia spp. is inconsistent across jurisdictions. There is also incomplete evidence regarding decontamination methods for these pathogens. With regards to Orientia spp. most of the available information is derived from experiments conducted with Rickettsia spp. CONCLUSIONS Rickettsia and Orientia spp. are neglected diseases, as demonstrated by the lack of evidence-based and specific biosafety information about these pathogens. In the case of Orientia spp., most of the available information is derived from Rickettsia spp., which may not be appropriate and overstate the risks of working with this pathogen. The advent of effective antibiotic therapy and a better understanding of the true hazards and risks associated with pathogen manipulation should inform decisions, allowing a sustainable and safe work environment.
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Affiliation(s)
- Stuart D Blacksell
- Mahidol-Oxford Tropical Research Medicine Unit, Faculty of Tropical Medicine, Mahidol University, 10400, Bangkok, Thailand.
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, Department of Medicine Research Building, University of Oxford, Nuffield, Oxford, UK.
| | - Khanh Kim Le
- Mahidol-Oxford Tropical Research Medicine Unit, Faculty of Tropical Medicine, Mahidol University, 10400, Bangkok, Thailand
| | - Artharee Rungrojn
- Mahidol-Oxford Tropical Research Medicine Unit, Faculty of Tropical Medicine, Mahidol University, 10400, Bangkok, Thailand
| | - Jantana Wongsantichon
- Mahidol-Oxford Tropical Research Medicine Unit, Faculty of Tropical Medicine, Mahidol University, 10400, Bangkok, Thailand
| | - John Stenos
- Australian Rickettsial Reference Laboratory, University Hospital Geelong, Geelong, VIC, Australia
| | - Stephen R Graves
- Australian Rickettsial Reference Laboratory, University Hospital Geelong, Geelong, VIC, Australia
| | - Nicholas P J Day
- Mahidol-Oxford Tropical Research Medicine Unit, Faculty of Tropical Medicine, Mahidol University, 10400, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, Department of Medicine Research Building, University of Oxford, Nuffield, Oxford, UK
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Ragini G, Raju HK, Krishnamoorthi R, Elango A, Muthukumaravel S, Kumar A. The Molecular Detection of Bacterial Infections of Public Health Importance in Hard Tick ( Ixodidae) Nymphs Collected from the Forest Fringes of Western Ghats in the Goa, Karnataka and Maharashtra States of India. Microorganisms 2023; 12:52. [PMID: 38257879 PMCID: PMC10819270 DOI: 10.3390/microorganisms12010052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 12/14/2023] [Accepted: 12/18/2023] [Indexed: 01/24/2024] Open
Abstract
A survey was conducted to determine the human tick-borne bacterial infections in the nymphs which were collected from Western Ghats' fringe forest areas. Tick nymphs were collected using the flagging method from the villages where cases Kyasanur Forest Disease (KFD) were previously reported in the states of Goa, Karnataka and Maharashtra. A total of 200 tick pools consisting of 4587 nymphs were tested by PCR for the detection of bacteria of public health importance, such as Coxiella burnetii and Rickettsia spp. Of these, four pools (4.8%) in Karnataka and three pools (4.4%) in Maharashtra were positive for Coxiella burnetii, while none of the samples from Goa state were positive. Rickettsia spp. were positively obtained from Maharashtra (51.5%), Goa (35.42%) and Karnataka (26.19%). The sequence results of Rickettsia spp. showed similarity to the spotted fever group Candidatus Rickettsia shennongii, Rickettsia conorii subsp. heilongjiangensis and Rickettsia spp. strain koreansis. Individuals are entering into the forest areas for various reasons are more likely to infect with Coxiella burnetii. and Rickettsia spp.
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Affiliation(s)
- Gnanasekar Ragini
- Climate Change, GIS and VBD Stratification/Mapping, ICMR-Vector Control Research Centre, Department of Health Research, Ministry of Health & Family Welfare, GOI, Medical Complex, Indira Nagar, Puducherry 605 006, India; (G.R.); (R.K.)
| | - Hari Kishan Raju
- Climate Change, GIS and VBD Stratification/Mapping, ICMR-Vector Control Research Centre, Department of Health Research, Ministry of Health & Family Welfare, GOI, Medical Complex, Indira Nagar, Puducherry 605 006, India; (G.R.); (R.K.)
| | - Ranganathan Krishnamoorthi
- Climate Change, GIS and VBD Stratification/Mapping, ICMR-Vector Control Research Centre, Department of Health Research, Ministry of Health & Family Welfare, GOI, Medical Complex, Indira Nagar, Puducherry 605 006, India; (G.R.); (R.K.)
| | - Ayyanar Elango
- Division of Vector Biology and Control, ICMR-Vector Control Research Centre, Department of Health Research, Ministry of Health & Family Welfare, GOI, Medical Complex, Indira Nagar, Puducherry 605 006, India;
| | - Subramanian Muthukumaravel
- Molecular Epidemiology, ICMR-Vector Control Research Centre, Department of Health Research, Ministry of Health & Family Welfare, GOI, Medical Complex, Indira Nagar, Puducherry 605 006, India;
| | - Ashwani Kumar
- Centre for Global Health Research, Saveetha Medical College and Hospital, Saveetha Institute of Medical and Technical Sciences, Saveetha University, Chennai 605102, India;
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Nallan K, Ayyavu V, Ayyanar E, Thirupathi B, Gupta B, Devaraju P, Kumar A, Rajaiah P. Molecular Evidence of Rickettsia conorii subsp. raoultii and Rickettsia felis in Haemaphysalis intermedia Ticks in Sirumalai, Eastern Ghats, Tamil Nadu, South India. Microorganisms 2023; 11:1713. [PMID: 37512886 PMCID: PMC10384621 DOI: 10.3390/microorganisms11071713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 06/21/2023] [Accepted: 06/22/2023] [Indexed: 07/30/2023] Open
Abstract
Rickettsia is an important pathogenic entity among tick-borne diseases (TBD), which are considered serious emerging public health problems globally. In India, though the widespread distribution of ticks and TBD has been documented, its real burden remains underreported. In a preliminary attempt, rickettsial surveillance was carried out in ticks collected from Sirumalai, Eastern Ghats in Tamil Nadu, India by using pathogen genome-based phylogenetic inferences generated through multi-locus sequence typing (MLST), targeting the genes 16s rRNA, OmpA, OmpB, and gltA by nested PCR. The laboratory evidence confirms the circulation of Rickettsia in Haemaphysalis intermedia species collected from this area. Analysis of the four gene sequences detected demonstrates their closest identity to the spotted fever group (SFG) available in the GenBank database. Further, multiple sequence alignment with other sequences derived from the GenBank database showed close relatedness to Rickettsia conorii subsp. raoultii (16s rDNA-99.32%, OmpA-93.38%, OmpB-97.39%, and gltA-98.57%) and Rickettsia felis (16s rDNA 99.54%, OmpA-100%, OmpB-100% and gltA-99.41%). With this genomic evidence, the circulation of rickettsial pathogens in the pools of H. intermedia ticks infesting livestock in the Sirumalai foothill area has been demonstrated and to complement the microscopic identification of the tick species, DNA barcodes were generated for H. intermedia using the mitochondrial cytochrome c oxidase subunit I gene (COI). Nevertheless, R. raoultii and R. felis were found to be the aetiological agents of tick-borne lymphadenopathy and flea-borne spotted fever in human cases, respectively, further study on the determination of their diversity, distribution, clinical relevance, and potential risk to the local community in these areas is highly warranted.
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Affiliation(s)
- Krishnamoorthy Nallan
- ICMR-Vector Control Research Centre, Field Unit, 4. Sarojini Street, Madurai 625002, India
| | - Veerapathiran Ayyavu
- ICMR-Vector Control Research Centre, Field Unit, 4. Sarojini Street, Madurai 625002, India
| | - Elango Ayyanar
- ICMR-Vector Control Research Centre, Puducherry 605006, India
| | - Balaji Thirupathi
- ICMR-Vector Control Research Centre, Field Unit, 4. Sarojini Street, Madurai 625002, India
| | - Bhavna Gupta
- ICMR-Vector Control Research Centre, Field Unit, 4. Sarojini Street, Madurai 625002, India
| | | | - Ashwani Kumar
- ICMR-Vector Control Research Centre, Puducherry 605006, India
| | - Paramasivan Rajaiah
- ICMR-Vector Control Research Centre, Field Unit, 4. Sarojini Street, Madurai 625002, India
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