Mosquito Vectors of West Nile Fever in Israel

Orshan, Laor; Bin, Hanna; Schnur, Heather; Kaufman, Andrew R.; Valinsky, A.; Shulman, Lester M.; Weiss, Leah; Mendelson, Ella; Pener, Hedva

doi:10.1603/0022-2585(2008)45[939:mvownf]2.0.co;2

Cited by 33 publications

(24 citation statements)

References 40 publications

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“…Although laboratory experiments showed a low vector competence of Oc. caspius for WNV [12], infected pools of this species have been found recently in Israel and in Italy [10,50], increasing the interest in investigating its role as a potential WNV vector. Given that natural populations of this species can reach very high numbers (being the most important nuisance mosquito species in northern Italy), their potential role as amplifying vectors in eastern Piedmont cannot be ruled out.…”

Section: Discussionmentioning

confidence: 99%

Spatio-temporal patterns of distribution of West Nile virus vectors in eastern Piedmont Region, Italy

et al. 2011

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BackgroundWest Nile Virus (WNV) transmission in Italy was first reported in 1998 as an equine outbreak near the swamps of Padule di Fucecchio, Tuscany. No other cases were identified during the following decade until 2008, when horse and human outbreaks were reported in Emilia Romagna, North Italy. Since then, WNV outbreaks have occurred annually, spreading from their initial northern foci throughout the country. Following the outbreak in 1998 the Italian public health authority defined a surveillance plan to detect WNV circulation in birds, horses and mosquitoes. By applying spatial statistical analysis (spatial point pattern analysis) and models (Bayesian GLMM models) to a longitudinal dataset on the abundance of the three putative WNV vectors [Ochlerotatus caspius (Pallas 1771), Culex pipiens (Linnaeus 1758) and Culex modestus (Ficalbi 1890)] in eastern Piedmont, we quantified their abundance and distribution in space and time and generated prediction maps outlining the areas with the highest vector productivity and potential for WNV introduction and amplification.ResultsThe highest abundance and significant spatial clusters of Oc. caspius and Cx. modestus were in proximity to rice fields, and for Cx. pipiens, in proximity to highly populated urban areas. The GLMM model showed the importance of weather conditions and environmental factors in predicting mosquito abundance. Distance from the preferential breeding sites and elevation were negatively associated with the number of collected mosquitoes. The Normalized Difference Vegetation Index (NDVI) was positively correlated with mosquito abundance in rice fields (Oc. caspius and Cx. modestus). Based on the best models, we developed prediction maps for the year 2010 outlining the areas where high abundance of vectors could favour the introduction and amplification of WNV.ConclusionsOur findings provide useful information for surveillance activities aiming to identify locations where the potential for WNV introduction and local transmission are highest. Such information can be used by vector control offices to stratify control interventions in areas prone to the invasion of WNV and other mosquito-transmitted pathogens.

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Section: Discussionmentioning

confidence: 99%

Spatio-temporal patterns of distribution of West Nile virus vectors in eastern Piedmont Region, Italy

et al. 2011

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“…This is the most basic method for analyses of pooled samples where one assumes that a positive pool is infected by a single individual [36-38]. The assumption that each pool has only one positive cannot be proven and the method is too imprecise unless the prevalence is extremely low, e.g.…”

Section: Methodsmentioning

confidence: 99%

Prevalence of tick borne encephalitis virus in tick nymphs in relation to climatic factors on the southern coast of Norway

et al. 2012

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BackgroundTick-borne encephalitis (TBE) is among the most important vector borne diseases of humans in Europe and is currently identified as a major health problem in many countries. TBE endemic zones have expanded over the past two decades, as well as the number of reported cases within endemic areas. Multiple factors are ascribed for the increased incidence of TBE, including climatic change. The number of TBE cases has also increased in Norway over the past decade, and the human cases cluster along the southern coast of Norway. In Norway the distribution and prevalence of TBE virus (TBEV) in tick populations is largely unknown. The objectives of this study were to estimate the TBEV prevalence in Ixodes ricinus from seven locations and to assess the relationship between the TBEV prevalence and site-specific climatic variables.MethodsA total of 5630 questing nymphs were collected and analyzed in pools of ten. All pools were screened with an in-house real-time RT-PCR, and the positive pools were pyrosequenced. Two methods, minimum infection rate (MIR) and a frequentist method (EPP) for pooled prevalence estimations were calculated and compared. Climatic data were descriptively compared to the corresponding EPP of each location in order to explain variations in TBEV prevalence.ResultsThe seven foci of TBEV had an estimated overall prevalence (EPP) in pools of nymphs combined, of 0.53% with 95% CI (0.35–0.75), with point prevalence ranging between 0.11%–1.22%. The sites with the highest point prevalences were within the municipalities which had the highest numbers of registered TBE cases. The results indicate that the location with highest point prevalence had the highest relative mean humidity and lowest mean saturation deficit and vice versa for the lowest EPP.ConclusionOur study confirms the existence of TBEV endemic foci in Norway. These results are of importance to increase the awareness of TBEV infections in Norway and could be used for public information and recommendations of TBE vaccination. EPP is the method of choice for pooled prevalence calculations, since it provides estimated prevalences with confidence intervals. Our findings emphasise the possible importance of microclimatic conditions regarding the TBEV prevalence in ticks.

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“…In a laboratory experiment, S. aegypti mosquitoes were shown to be polymerase chain reaction (PCR)‐positive to the virus at 6 days after infection and were capable of infecting naïve cattle. This mosquito, however, does not occur in Israel, and its previous anecdotal finding was attributed to an escape from an intensive breeding programme in a research institute in the country (Orshan et al ., ). Other dipterans tested for transmission were not able to infect naïve cattle.…”

Section: Introductionmentioning

confidence: 97%

High relative abundance of the stable fly Stomoxys calcitrans is associated with lumpy skin disease outbreaks in Israeli dairy farms

Kahana-Sutin

Klement

Lensky

et al. 2016

Medical Vet Entomology

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The vector of lumpy skin disease (LSD), a viral disease affecting Bovidae, is currently unknown. To evaluate the possible vector of LSD virus (LSDV) under field conditions, a yearlong trapping of dipterans was conducted in dairy farms that had been affected by LSD, 1-2 years previously. This was done in order to calculate monthly relative abundances of each dipteran in each farm throughout the year. The relative abundances of Stomoxys calcitrans (Diptera: Muscidae) in the months parallel to the outbreaks (December and April) were significantly higher than those of other dipterans. A stable fly population model based on weather parameters for the affected area was used to validate these findings. Its results were significantly correlated with S. calcitrans abundance. This model, based on weather parameters during the epidemic years showed that S. calcitrans populations peaked in the months of LSD onset in the studied farms. These observations and model predictions revealed a lower abundance of stable flies during October and November, when LSD affected adjacent grazing beef herds. These findings therefore suggest that S. calcitrans is a potential vector of LSD in dairy farms and that another vector is probably involved in LSDV transmission in grazing herds. These findings should be followed up with vector competence studies.

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Mosquito Vectors of West Nile Fever in Israel

Cited by 33 publications

References 40 publications

Spatio-temporal patterns of distribution of West Nile virus vectors in eastern Piedmont Region, Italy

Spatio-temporal patterns of distribution of West Nile virus vectors in eastern Piedmont Region, Italy

Prevalence of tick borne encephalitis virus in tick nymphs in relation to climatic factors on the southern coast of Norway

High relative abundance of the stable fly Stomoxys calcitrans is associated with lumpy skin disease outbreaks in Israeli dairy farms

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