The relationship between equine and human West Nile virus disease occurrence

doi:10.1016/j.vetmic.2007.11.022

Veterinary Microbiology

Volume 129, Issues 3–4, 22 June 2008, Pages 378-383

https://doi.org/10.1016/j.vetmic.2007.11.022 Get rights and content

Abstract

Cases of human and equine West Nile virus (WNV) disease reported in Texas in 2002 were analyzed to assess their temporal relationship. For each human case with a known residential location, the closest equine case (within a 5 km radius) was selected. A total of 80 human–equine case pairs were identified, 51 (64%) of which were located in urban areas. Dates-of-onset of human and equine cases were positively correlated (r_SP = 0.494, P < 0.001). Although overall there was no significant (P = 0.207) difference between the dates-of-onset of human and equine cases, in urban areas of Texas equine cases were reported significantly (P = 0.011) earlier (August 7) than corresponding human cases (August 19). Monitoring equine populations that are susceptible to WNV disease within close proximity to urban human populations might be useful for predicting disease risk in human populations.

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Acknowledgement

Dawn Hesalroad, Texas Department of State Health Services Zoonoses Control Branch is thanked for assistance in database management and processing.

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Breaking the chain of zoonoses through biosecurity in livestock
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Citation Excerpt :
Interestingly, the number of WNV humans cases declined in the US from 2003 following the availability of the equine WNV vaccine [65]. Although it is difficult to determine if this is a causal relationship, it has been demonstrated that human infections can be directly linked to equine infections [66]. The recent outbreak of human WNV infection in Greece emphasizes the need for new primary prevention strategies to limit the spread and occurrence of WNV outbreaks in the future [25].
Increases in global travel, trade and urbanisation are leading to greater incidence of zoonotic disease, and livestock are often a key link in the spread of disease to humans. As such, livestock vaccination strategies, as a part of broader biosecurity solutions, are critical to both animal and human health. Importantly, approaches that restrict infectious agents in livestock, not only protects their economic value but should reduce the potential for spill over infections in humans. Biosecurity solutions to livestock health can take a number of different forms and are generally heavily weighted towards prevention of infection rather than treatment. Therefore, vaccination can provide an effective component of a strategic approach, particularly as production economics dictate the use of cost effective solutions. Furthermore, in an evolving global environment there is a need for vaccines that accommodate for lower socioeconomic and rapidly emerging zoonotics.
West Nile viral infection of equids
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Licensure of a killed WNV vaccine in late 2002 (Ng et al., 2003) resulted in a dramatic reduction in the subsequent number of equine encephalitis cases reported in 2003 despite the large increase in human cases that year (United States Department of Agriculture, 2012), indicating the efficacy of equine vaccination. In some instances in Europe, equine cases have been observed without substantial human disease being reported, such as in Tuscany, Italy (1998) (Autorino et al., 2002) and Camargue (Pantheir et al., 1966), France (2000); however, in North America equine and human cases have demonstrated similar incidence patterns, both before and after widespread vaccination of horses (Ward and Scheurmann, 2008). Since 2010, WNV infections among horses repeatedly were reported in the Mediterranean basin and other European countries, namely in Bulgaria, Croatia, Greece, Italy, Macedonia, Morocco, Portugal, Romania and Spain (Barros et al., 2011; Garcia-Bocanegra et al., 2011; OIE, 2012).
West Nile virus (WNV) is a flavivirus transmitted between certain species of birds and mosquito vectors. Tangential infections of equids and subsequent equine epizootics have occurred historically. Although the attack rate has been estimated to be below 10%, mortality rates can approach 50% in horses that present clinical disease. Symptoms are most commonly presenting in the form of encephalitis with ataxia as well as limb weakness, recumbency and muscle fasciculation. The most effective strategy for prevention of equine disease is proper vaccination with one of the numerous commercially available vaccines available in North America or the European Union. Recently, WNV has been increasingly associated with equine epizootics resulting from novel non-lineage-1a viruses in expanding geographic areas. However, specific experimental data on the virulence of these novel virus strains is lacking and questions remain as to the etiology of the expanded epizootics: whether it be a function of inherent virulence or ecological and/or climactic factors that could precipitate the altered epidemiological patterns observed.
Spreading of West Nile virus infection in Croatia
2012, Veterinary Microbiology
Citation Excerpt :
Chickens and horses are commonly used as sentinel animals (Seidowski et al., 2010; Angelini et al., 2010). Because of their relatively high susceptibility to WNV infection (Castillo-Olivares and Wood, 2004), reports of equine cases might potentially provide early warning of corresponding WNV transmission in human population (Ward and Scheurmann, 2008; Laperriere et al., 2011). In the last decade many serological surveys have included cattle.
West Nile virus (WNV) is an emerging zoonotic pathogen with rapid global expansion. The virus circulation is confirmed in many countries of Mediterranean Basin and Southern and Central Europe. In our study detection of specific WNV antibodies was performed in horses and cattle sera samples collected from October 2010 to April 2011. Serum samples were randomly taken from different parts of Croatia and tested by IgG and IgM ELISA. Positive serological results were confirmed by virus neutralization assay (VN-assay) and plaque reduction neutralization test (PRNT). Results showed that WNV antibodies were present in 72 out of 2098 horse sera (3.43%) and 3 of 2695 cattle sera (0.11%). The highest seroprevalence was found in Eastern Croatia in counties next to Hungarian, Serbian and Bosnia and Herzegovinian state borders. In Adriatic part of Croatia positive animals were found only in the westernmost county, near Slovenian and Italian borders. Geographic distribution and number of positive horses indicated that WNV is highly present in Croatia and spreading from East to West. However, positive horses in westernmost part of country indicate possible second origin of spreading. Location of serological positive cattle supports the hypothesis that seropositive cattle could be indicators of high WNV activity in the respective geographic regions.
Identification of suitable areas for West Nile virus outbreaks in equid populations for application in surveillance plans: The example of the Castile and Leon region of Spain
2012, Epidemiology and Infection
European College of Equine Internal Medicine consensus statement on equine flaviviridae infections in Europe
2022, Journal of Veterinary Internal Medicine
Mapping the Risk for West Nile Virus Transmission, Africa
2022, Emerging Infectious Diseases

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Short communicationThe relationship between equine and human West Nile virus disease occurrence

Abstract

Section snippets

Acknowledgement

Prev. Vet. Med.

Vet. Microbiol.

California State Mosquito-Borne Virus Surveillance and Response Plan: a retrospective evaluation using conditional simulations

Am. J. Trop. Med. Hyg.

West Nile virus in host-seeking mosquitoes within a residential neighborhood in Grand Forks, North Dakota

Vector-Borne Zoonotic Dis.

Surveillance results from the first West Nile virus transmission season in Florida, 2001

Am. J. Trop. Med. Hyg.

Enhancing West Nile virus surveillance, United States

Emerg. Infect. Dis.

Clinical and neuropathological features of West Nile virus equine encephalomyelitis in Italy

Equine Vet. J.

“Neon needles” in a haystack: the advantages of passive surveillance for West Nile virus

Ann. N.Y. Acad. Sci.

Early-season avian deaths from West Nile virus as warnings of human infection

Emerg. Infect. Dis.

Epidemiology and transmission dynamics of West Nile virus disease

Emerg. Infect. Dis.

Early season mortality as a sentinel for West Nile Virus disease in humans, northeastern United States

Vector-Borne Zoonotic Dis.

Short communication
The relationship between equine and human West Nile virus disease occurrence