West nile virus in horses 2013

Demographic variables that were shown to associate with seroprevalence to WNV were age and breed of the horses. Previous studies demonstrated the association of age with seroprevalence to WNV in endemic areas.

Prior to the WNF human epidemic in Israel, seroprevalence was shown to increase with age, as in healthy soldiers aged 18—20 years a lower seroprevalence was noted 7. This increase in seroprevalence with age was also observed in Iran, another WNV endemic region, in which a difference of 5 years in horses' age corresponded to a change of seropositivity odds by a factor of 1.

Surprisingly, in the current study, when we divided the horses into age groups in the two sampling periods in this study i. In , the very high overall seroprevlance and FOI could have masked differences between groups as from a very young age horses were largely exposed to the virus.

In addition, the great outbreak that occurred in hit all age groups equally and therefore in no differences were found between the different age groups, except for the youngest age group 1—3 yr , which include foals that were not yet born during the outbreak and therefore the seroprevalence of that group was significantly lower. The reason for the lower WNV seroprevalence found in our study among Ponies and Warmblood horses, as compared to other breeds, is unknown and might indicate different preference of mosquitoes to different breeds of horses, due to variables such as density of hair and differences in sweat composition.

In addition, grooming and anti-pesticides regimes are most likely stricter in the Warmblood breeds since they are mostly used for competitions in Israel while the Quarter horses and cross breeds are used mostly for pleasure riding. The higher seroprevalence detected in the Quarter horses in our study is in accordance with a study performed in Florida, USA, in which Quarter horses were the most commonly affected breed [13] , and with a study performed in Saskatchewan, Canada, which indicated that most of the WNV clinical cases were light horse breeds and most were used for pleasure riding [54].

Though, since these results were not repeated in the logistic regression model, the above findings might be due to association between colour and breed. The extensive serological survey in horses, throughout duration of more than a decade, covering periods before and after , the largest documented WNF outbreak in Israel , permitted the investigation of the spatio-temporal dynamics of WNV in a longstanding endemic region such as Israel.

Demographic variables such as age and breed were found to significantly associate with seroprevalence to WNV. But more prominently, environmental factors geographical location and precipitation amounts , and more specifically the geographical location of the horse along the Great Rift Valley, the main route of birds migration in Israel, was found to be of great impact on the likelihood of WNV exposure throughout the years investigated.

Humans, similar to horses, serve as incidental hosts to WNV and therefore may share common epidemiological aspects regarding disease occurrence and spread. Interestingly, weather conditions, and more specifically rainfall conditions, such as periods of spring drought, together with lower incidence rate in the population, were shown to precede transition from endemic state to epidemic state of WNV observed in humans in Israel during the years and Analyzed the data: KA EK. Wrote the paper: KA AS.

Browse Subject Areas? Click through the PLOS taxonomy to find articles in your field. Abstract With the rapid global spread of West Nile virus WNV and the endemic state it has acquired in new geographical areas, we hereby bring a thorough serological investigation of WNV in horses in a longstanding endemic region, such as Israel.

Funding: The authors have no support or funding to report. Materials and Methods Blood samples Blood samples were collected from clinically healthy horses distributed throughout Israel, in order to determine seroprevalence of WNV in the years , and Serum preparation, serum neutralization test SN and competitive enzyme-linked immunosorbent assay cELISA Blood samples were collected from the jugular vein of each horse into sterile serum-separating tubes and centrifuged at rpm for 8 minutes.

Collection of demographic and environmental data During blood collections information on age, gender, colour, breed and geographical location was recorded for every subject. Download: PPT. Figure 1. Spatial distribution of WNV seroprevalence in horses in Israel during , and Precipitation levels in epidemic vs.

Statistical analyses An interrater reliability analysis using the Kappa statistic was performed to determine consistency among the ELISA and the Serum Neutralization results of the samples. Figure 2. The association of WNV seroprevalence with age in and Table 1.

Table 2. Demographic risk factors for WNV in In the univariate analysis, significant association was detected between WNV seroprevalence and age, colour, gender and breed of the horses. Table 3. Figure 3. Discussion Seroprevalence, force of infection and factors associated with transition from endemic to epidemic state Although WNV was shown to circulate in Israel since the 's, it has been receiving growing attention only in the last decade since the WNF outbreak among humans and horses.

Conclusions The extensive serological survey in horses, throughout duration of more than a decade, covering periods before and after , the largest documented WNF outbreak in Israel , permitted the investigation of the spatio-temporal dynamics of WNV in a longstanding endemic region such as Israel. References 1. View Article Google Scholar 2. Am J Trop Med — View Article Google Scholar 3. Ann N Y Acad Sci — View Article Google Scholar 4. Ann Trop Med Parasitol — View Article Google Scholar 5.

Bull World Health Organ — View Article Google Scholar 6. Equine Vet J 31— Some horses may need clinical care while others can receive treatment at home. Usually, horses with WNV are given anti-inflammatory and pain medications to help relieve their symptoms. All rights reserved. For that, serum samples from horses, collected between September and November in central Spain, were analysed by ELISA blocking and IgM and confirmed by virus neutralization, proving its specificity using parallel titration with another flavivirus Usutu virus.

As a result, 10 of horse serum samples analysed gave positive results by competitive ELISA, 5 of which were confirmed as positive to WNV by virus neutralization seropositivity rate: 1. Bti can be purchased in small, donut-shaped form, often called "mosquito dunks", which are useful in small areas of standing water, such as a birdbath or small puddle of water that may gather in a low spot on your property.

A granular form of Bti is available, and effective for larger areas, such as backyard ponds. Bti can be purchased in many lawn and garden, outdoor supply, and home improvement stores. The great thing about this bacteria is that it kills only mosquito and black fly larvae. It is not harmful to people, pets, aquatic life such as fish or plants. The best way to control mosquitoes is still to get rid of standing water on your property. And, make sure you follow all label instructions carefully if you use Bti at home.

The virus is transmitted from avian reservoir hosts by mosquitoes and infrequently by other bloodsucking insects to horses, humans and a number of other mammals. Horses and humans are considered to be dead-end hosts for WNV; the virus is not directly contagious from horse to horse or horse to human.

Thus vaccination for West Nile virus is recommended as a core vaccine and is an essential standard of care for all horses in North America. Authors Ann M. Why do we need this? Entering your postal code will help us provide news or event updates for your area. Related Products.

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