Indian Journal of Animal Research

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Indian Journal of Animal Research, volume 57 issue 11 (november 2023) : 1556-1560

Epidemiological Aspects of Equine Herpes Virus Infection in South Gujarat, India

J.A. Vala1,*, M.D. Patel2, S.M. Parmar2, S.V. Mavadiya2, S.A. Mehta2, D.R. Patel2
1Teaching Veterinary Clinical Complex College of Veterinary Science and Animal Husbandry, Navsari Agricultural University, Navsari-396 450, Gujarat, India.
2Department of Veterinary Medicine College of Veterinary Science and Animal Husbandry, Navsari Agricultural University, Navsari-396 450, Gujarat, India.
Cite article:- Vala J.A., Patel M.D., Parmar S.M., Mavadiya S.V., Mehta S.A., Patel D.R. (2023). Epidemiological Aspects of Equine Herpes Virus Infection in South Gujarat, India . Indian Journal of Animal Research. 57(11): 1556-1560. doi: 10.18805/IJAR.B-4393.
Background: The equine herpes viruses (EHV) are highly infective pathogens of all members of the Equidae family worldwide. EHV-1 predominantly associated with the abortion, neonatal death, neurological diseases, whereas, EHV-4 is mostly associated with the respiratory disease, generally termed as equine rhinopneumonitis. This present investigation was planned to study sero-prevalence of EHV-1/4 infections in horses of south Gujarat, India. 

Methods: A total of 253 horses showing symptoms of respiratory illness or having history were screened by indirect ELISA test. While, blood samples were analysed for various haematological parameters. Effects of risk factors were studied and statistical analysis of data was done. 

Result: Over all prevalence of EHV-1/4 infection was 16.60% in South Gujarat, India. Effects of various risk factors (age, sex, breed, and locality) were non-significant. Means of all haematological parameters were in normal range and significant difference was not observed between sero-positive and sero-negative horses. Population of mid cells (monocytes) was found significantly higher (p<0.05 in sero-positive horses as compare to sero-negative horses.
Horses (Equuscaballus) have been used since old times by humans as a mean of transportation before invention of mechanical transport vehicles. Efficient performance of equines for transportation and other functions require a sound health and freedom from various ailments including infectious diseases. Respiratory diseases are major cause of morbidity and mortality in foals and adult horses. The equine herpes viruses (EHV) are highly infective pathogens of all members of the Equidae family worldwide (Patel and Heldens, 2005). EHV-1 and EHV-4 are respiratory pathogens of domestic horses associated with outbreaks of respiratory disease. EHV-1 predominantly associated with the abortion, neonatal death, neurological diseases, whereas, EHV-4 is mostly associated with the respiratory disease, generally termed as equine rhino-pneumonitis (Matsumara et al., 1992). Both, EHV-1 and 4 are enzootic in most domestic horse populations and majority of horses show serological evidence of exposure to these viruses (van Mannen, 2002). The spread of virus among susceptible population occurs by means of direct contact, inhalation of aerosols, nasal secretion and ingestion of contaminated feed (Garre et al., 2009). Both, EHV-1 and 4 are also capable to establish latent subclinical infections in horses which dynamically act as carriers for lifetime (Foote et al., 2004). Early epidemiological studies were not able to differentiate between EHV-1 and 4 infections as EHV-1 and 4 share most of the external glycoproteins as well as type specific epitopes (Crabb and Studdert, 1993). Development of type specific ELISA gave ability to differentiate antibodies of EHV-1 and EHV-4 and facilitated to diagnose specific infection with these viruses which allowing additional insight in to their epidemiology (Crabb and Studdert, 1995). Nowadays, serological techniques especially ELISA has been demonstrated as an important tool in epidemiological investigations of equine herpes virus infections (Ataseven et al., 2009). Considering the importance of EHV-1 and 4 as important respiratory tract pathogens and under the paucity of epidemiological study in India especially in Gujarat, the present study was carried out to study the sero-prevalence of EHV-1 and EHV-4 infections in horses of south Gujarat, India.
Generally equine herpes viruses cause respiratory disorder along with pyrexia, unthriftyness and in some cases abortion and neurological disorder. Total 253 horses showing any of above symptoms or having history was included in the present study. Sample collection detail is given in (Table 1).

Table 1: Prevalence of EHV-1/4 infection in different age, sex and breed of horses.


 
Collection and preservation of samples
 
The blood samples were collected aseptically by jugular venipucture in vacutainer with clot activator for serum and in EDTA vacutainer for haematological parameters. Blood sample  were allowed to clot at room temperature for 15-30 min and centrifuge at 1500 rpm at 4°C for 10 min. The separated serum was carefully harvested and stored at -20°C until further use. The whole blood samples in EDTA vacutainer were immediately subjected to complete blood count in automated blood analyzer (Nihon-Kohden, Japan).
 
ELISA
 
A commercial indirect IgG confirmation ELISA assay (IngezimRinoneumonitis 14.HVE.K1, Ingenasa) was used following the manufacturer’s instructions to detect antibodies to EHV-1 and/or EHV-4.
 
Haematological analysis
 
The whole blood samples in EDTA vacutainer were subject to complete blood count in automated blood analyzer (Nihon-Kohden, Japan). Various haematological parameters viz. haemoglobin (Hb), packed cell volume (PCV), total erythrocyte count (TEC), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC), total leukocyte count (TLC), differentiate leukocyte count (DLC), platelet count and mean platelet volume (MPV) were estimated.
 
Statistical analysis
 
Data pertaining to sero-diagnosis of equine herpes viruses’ infection was analyzed using Chi-square test (probability at 5% and confidence interval at 95% level) using online statistical tool available at https://www.socscistatistics.com. The findings of various haematological parameters of sero-positive and sero-negative were compared by using ‘t’ test.
Overall prevalence of EHV-1/4 infection
 
Out of 253 serum samples analyzed, 42 serum samples were found positive for presence of antibodies against EHV-1/4, which gave 16.60% overall prevalence among the horses of south Gujarat, India.
 
Risk factor analysis of EHV-1/4 infection
 
Various risk factors viz. spatial distribution of infected horses, age, sex and breed were statistically analyzed to view any significant importance of these factors in prevalence of disease. The results are shown in below (Table 1).
 
Spatial distribution of disease
 
The district-wise sero-prevalence of equine herpes virus infection in Navsari, Surat and other districts of south Gujarat was 15.60% (22/141), 17.48% (18/103) and 22.22% (02/09), respectively (Fig 1). No significant effect of geographical area on sero-positivity was observed.

Fig 1: Spatial distribution of cases.


 
Sex wise distribution of disease
 
Prevalence of equine herpes virus infection in males and female was 16.15% (26/161) and 17.39% (16/92), respectively. Similar to the geographical area wise prevalence, effect of sex on sero-prevalence of equine herpes virus infection was non-significant.

Age wise distribution of disease
 
During present study, sero-prevalence of equine herpes virus infections was 17.07% (7/41) and 16.51% (35/212) in horses aged <2 years and >2 years, respectively. The effect of age on sero-prevalence was also found non-significant.
 
Breed wise distribution of disease
 
Sero-prevalence of equine herpes virus infection in Sindhi breed, Kathiawari breed, Marwadi breed and Non-descript breeds was 18.02% (20/111), 16.67% (2/12), 20.69% (6/29) and 13.86% (14/101), respectively. The effect of breeds on sero-prevalence of equine herpes virus infection was also non-significant.
 
Haematological analysis of sero-positive and sero-negative horses
 
The mean values of all haematological parameter under study were within the normal range. Similarly, the difference between various haematological parameters of sero-positive and sero-negative horses was non-significant except mid cell percentage which was noted significantly higher (p<0.05) in sero-positive horses. The values of various haematological parameters are given in (Table 2).

Table 2: Comparison of haematological parameters of sero-positive and sero-negative horses.



In this study, sero-prevalence of EHV-1/4 infection was measured in horses using indirect ELISA. The samples were taken largely from unregistered animals in small private ownerships. These types of equids are traditionally used as transport and pack animals in the rural areas or as status symbol and hobby in urban areas. The study revealed overall sero-prevalence of EHV-1/4 infection as 16.60% in region under study. Several epidemiological investigations have been performed for the prevalence of EHV-1 and EHV-4 infections. Previously, 1.64% - 38.12% sero-prevalence of EHV-1 was recorded in different states of India (Anonymous, 2019). The sero-prevalence rate of EHV-1 and EHV-4 infection was reported within 8% to 85.2% across various countries of world (Ata et al., 2020; Ataseven et al., 2009; Avci et al., 2019; Mohamed et al., 2017; Singh, 1999; Yildrim et al., 2015). The difference in sero-prevalence may be attributed to many factors including the difference in the epidemiology of EHV-1/4 among different horse populations, the difference in the testing methods, and the antibody titre could be under the detection limit especially in latently infected animals (Dunowska et al., 2015). The present findings indicated the presence of natural infection with the virus and/or latent cases reactivation as vaccination against EHVs in the study region is not in practice.

As per findings of present study, effect of risk factors viz. geographical location, age, sex and breed on occurrence of disease were non-significant. Sex may not considered as an influential factor on occurrence of disease (Hafshejani et al., 2015). On contrary to findings of present study, in certain studies higher sero-prevalence of EHV-1 was found in females than in males (Ata et al., 2020; Senthil and Parameswaran, 2014). This might be due to unequal gender wise sample collection. Moreover, in urban areas people kept mostly male horses as status symbol and hobby purpose. Similarly, on contrary to present study, some studies found age as an important factor that can influence the occurrence of disease (Ata et al., 2020; Hafshejani et al., 2015). Standardbred and thoroughbred horses have higher susceptibility than local Arabian and Turkoman breeds (Hafshejani et al., 2015). Certain horse breeds have slight higher susceptibility to equine herpes virus infection than others, but variation in immune status and rate of infection should be taken into consideration before establishing the facts (Lunn et al., 2009). Presently, in region under study, most of reared horses are lineage of Arabian horses and non-descript horses are mostly cross over off-springs in between this breeds. This might be the reason behind equal distribution of disease among different breeds under study.

Haematological as well as serum biochemical examinations are neither specific nor diagnostically significant, as major detectable variations in both examinations are not present in EHV-1 and 4 infected horses (Constable et al., 2017). In agreement to this, mean values of all haematological parameters under study were within the normal range. The mean values of mid cells in sero-positive horses were found significantly higher than the values of sero-negative horses. Similarly, two studies found increased monocyte count in EHV-1 infected working horses (Mason et al., 1989; Fararh et al., 2016). Correct timing of sample collection during specific phase of disease is immensely important, even though it only indicates non specific viral infection (Slater, 2014).
EHV-1/4 infection is endemic among horse population of south Gujarat, India and constituteshealth risk factors for other healthy horses. Further structured serological or molecular investigations are required to study the epidemiological aspect of disease like role of mules and donkey as well as other unknown live carriers. These surveys could also look for different risk factors for spreading of disease among different populations.
The authors would like to acknowledge Dr. I.H. Kalyani, Professor and Head, Department of Veterinary Microbiology, Veterinary College, Navsari Agricultural University for giving permission and providing facility to carry out ELISA test and Dr. V.B. Kharadi, Dean and Principal, Veterinary College, Navsari Agricultural University for sparing grant for this study.
No competing interest by authors.

  1. Anonymous (2019). National Research Centre on Equines: Annual Report 2018-19. Retrieved from http://nrce.gov.in/downloads/.

  2. Ata, E., Salama, A., Zaghawa A., Ghazy, A., Elsify, A., Naye, A., Hegazy, Y., Abdel-Rehman, E. and Warda, S. (2020). Seroprevalence of equine herpes virus-1 in endemic area of Egypt with risk factor assessment. Bulgarian Journal of Veterinary Medicine. 23(1): 102-111.

  3. Ataseven, V., Dagalp, S., Guze, M., Baºaran, Z., Tan, M. and Geraghty, B. (2009). Prevalence of equine herpes virus-1 and equine herpes virus-4 infections in equidae species in Turkey as determined by ELISA and multiplex nested PCR. Research in Veterinary Science. 86: 339-344.

  4. Avci, O., Yapici, O., Bulut, O., Kale, M. and Atli, K. (2019). Detection of equine herpes virus 1, equine herpes virus 4 and equine arteritis virus antibodies in Kyrgyzstan by ELISA. Bionature. 38(3): 219-224.

  5. Constable, P., Hinchcliff, K., Done, S. and Gruenberg, W. (2017). A textbook of diseases of cattle, horse, sheep, pigs and goat. 11th Edition. Elseveir Health Sciences, London, United Kingdom. pp. 1040.

  6. Crabb, B. and Studdert, M. (1993). Epitopes of glycoprotein G of equine herpes viruses-4 and 1 located near the C termini elicit type-specific antibody responses in the natural host. J Virol. 67(10): 6332-6338.

  7. Crabb, B. and Studdert, M. (1995). - Equine herpes viruses-4 (equine rhinopneumonitis virus) and 1 (equine abortion virus). Advances in Virus Research. 45: 153-190.

  8. Dunowska, M., Gopakumar, G., Perrot, M., Kendall, A., Waropastrakul, S., Hartley, C. and Carslake, H. (2015). Virological and serological investigation of equid herpes virus-1 infection in New Zealand. Veterinary Microbiology. 176: 219-228. 

  9. Fararh, K., Kandil, O., Add-Allah, O. and Thabet, N. (2016). Clinicopathological changes in equine herpes virus type-1 (EHV-1) infection in Arabian foals. International Journal of Pharm Tech Research. 9(3): 138-149.

  10. Foote, C., Love, D., Gilkerson, J. and Whalley, J. (2004). Detection of EHV-1 and 4 DNA in unweaned thoroughbred foals from vaccinated mares on a large stud farm. Equine Veterinary Journal. 36(4): 341-345. 

  11. Garre, B, Gryspeerdt, A, Croubels, S, De Backer, P and Nauwynck, H. (2009). Evaluation of orally administered valacyclovir in experimentally EHV-1 infected ponies. Veterinary Microbiology. 135(3-4): 214-221.

  12. Hafshejani, T., Nekoei, S., Vazirian, B., Doosti, A., Khameshipour, F. and Anyanwu, M. (2015). Molecular detection of equine herpes virus types 1 and 4 infection in healthy horses in Ishafan Central and Shahrekord Southwest regions,Iran. BioMed Research International. doi.org/ 10.1155/ 2015/ 917854.

  13. Lunn, D., Horohov, D., Osterrieder, K. and Pusterla, N. (2009). EHV-1 consensus statement. Journal of Veterinary Internal Medicine. 23: 450-461.

  14. Mason, D., Watkins, K. and Luk, C. (1989). Haematological changes in two thoroughbred horses in training with confirmed equine herpes virus-1 infections. Veterinary Record. 124(19): 503-504.

  15. Matsumara, T., Sugiura, T., Imagava, H., Fukunaga, Y. and Kamada, M. (1992). Epizootiological aspect of type-1 and type-4 equine herpes virus infections among horse population. Journal of Veterinary Medical Science. 54: 207-211.

  16. Mohamed, S., Mohamed, A., El Deeb, A. and Salem, S. (2017). Prevalence of equine herpes viruses-1 and 4 in Arabian horses’ population in Egypt. Journal of Virological Science. 2: 1-9.

  17. Patel, J. and Heldens, J. (2005). Equine herpes viruses 1 (EHV-1) and 4 (EHV-4) Epidemiology, disease and immunopro-phylaxis: a brief review. The Veterinary Journal. 170: 14-23.

  18. Senthil, N. and Parameswaran, T. (2014). Seroprevalance of equine herpes virus (EHV–1) in equide using serum neutra-lization test. Journal of Research Agrilcultural and Animal Science. 2(5): 4-6.

  19. Singh, B. (1999). National assessment of equine herpes virus-1 infection amongst equidae in India. In Equine Infectious Diseases VIII, Proceedings of the Eighth International Conference (U. Wernery, J. Wade, J. Mumford and O. Kaaden, eds), RandW Publications: Newmarket. pp. 578.

  20. Slater, J. (2014). Equine herpes viruses, In Equine Infectious Diseases (D. Sellon and M. Long eds), Elsevier Health Sciences, London, United Kingdom. pp. 151.

  21. van Mannen, C. (2002). Equine Herpes virus-1 and 4 infections: an update. Veterinary Quarterly. 24(2): 57-78.

  22. Yildrim, Y., Yilmaz, V. and Kirmizigul, A. (2015). - Equine herpes virus type-1 (EHV-1) and 4 (EHV-4) infections in horses and donkeys in northeastern Turkey. Iranian Journal of Veterinary Research. 16(4): 341-344. 

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