J Arthropod-Borne Dis, June 2013, 7(1): 90–93 H Albayrak , E Ozan: Seroepidemiological Study of... http://jad.tums.ac.ir Published Online: April 10, 2013 Short Communication Seroepidemiological Study of West Nile Virus and Rift Valley Fever Virus in Some of Mammalian Species (Herbivores) in Northern Turkey *Harun Albayrak1, Emre Ozan 2 1Department of Virology, Faculty of Veterinary Medicine, Ondokuz Mayis University, Samsun, Turkey 2Virology Laboratory, Veterinary Control Institute, Samsun, Turkey (Received 23 Nov 2011; accepted 24 Oct 2012) Abstract Background: West Nile virus (WNV) and Rift Valley fever virus (RVFV) are mosquito-borne viral diseases. The objective of this study was to investigate the RVFV and WNV infections as serologically in different mammalian species (cattle, horse, goat, sheep and water buffalo) in the northern Turkey. Methods: Blood samples randomly collected from 70 each cattle, horse, sheep, goat and water buffalo were ana- lyzed for the presence of antibodies to RVFV and WNV using an competitive enzyme-linked immunosorbent assay (C-ELISA) in northern Turkey. Results: None of the animals were positive for antibodies to RVFV. In contrast, WNV antibodies were found in two of 350 samples (0.57%). Conclusion: This may suggest that the RVFV disease is not present in northern Turkey.This is the first serological study on RVFV in Turkey. Keywords: ELISA, Herbivore, RVFV, Turkey, WNV Introduction West Nile virus (WNV) is a member of the Japanese encephalitis virus complex of the family Flaviviridae, genus Flavivirus, which also includes Japanese encephalitis virus, St. Louis encephalitis virus (SLEV), Murray Va- lley encephalitis virus (MVEV), and others. These viruses are mosquito borne, primarily transmitted by Culex spp, and have wide, over- lapping distributions throughout the world (Mackenzie et al. 2002). The diagnosis of WNV infection is commonly achieved using serological assays (Castillo-Olivares and Wood 2004). While plaque reduction neutralization tests are still considered the gold standard for specific diagnosis, ELISA is now routinely used (Dauphin and Zientara 2007), as it is less laborious and more suited to high- throughput screening. Rift valley fever virus (RVFV), family Bunyaviridae is an emerging epidemic disease of humans and livestock, as well as an im- portant endemic problem in sub-Saharan Af- rica. The virus is transmitted to livestock and humans by the bite of infected mosquitoes or exposure to tissues or blood of infected ani- mals. Massive epizootics are typically obser- ved in livestock during times of unusually high and sustained rainfall because of the presence of breeding sites and overabun- dance of adult competent mosquito vectors. Infections caused by RVFV are character- ized by severe disease and abortion in live- stock, particularly sheep and cattle (Lin- thicum et al. 1999). The recent RVF out- breaks in the Arabian Peninsula (Shoemaker et al. 2002), the first outbreaks outside Af- *Corresponding author: Dr Harun Albayrak, E- mail: harunalbayrak55@msn.com 90 J Arthropod-Borne Dis, June 2013, 7(1): 90–93 H Albayrak , E Ozan: Seroepidemiological Study of... http://jad.tums.ac.ir Published Online: April 10, 2013 rica, have the implication that it is likely that RVFV will now spread further into non-en- demic RVF areas since it is capable of uti- lizing a wide range of mosquito vectors (Turrel et al. 1998). The objective of this study was to inves- tigate the RVFV and WNV infections as se- rologically in different mammalian species (cattle, horse, goat, sheep and water buffalo) in the northern Turkey. Materials and Methods Blood samples were collected from se- venty each cattle, horse, sheep, goat and wa- ter buffalo, without clinical signs of the dis- eases in the northern part of Turkey between May and October 2010 (Fig. 1). The age of the animals varied from 2 to 17 years. Blood sam- ples were taken from the jugular veins of the animals. Blood tubes were centrifuged at 3, 000×g for 10 min, and the samples were trans- ferred to sterile tubes and stored in -20 °C un- til used. The commercial C-ELISA kits were obtained from ID.VET, Montpellier, France, and the test was performed according to the producer’s description. Plates were read with an ELISA reader at 450 nm and results were calculated. Suspected samples were retested by C-ELISA. Results A total of 350 animals (70 each cattle, horses, sheep, goats and water buffaloes) were tested by C-ELISA. All animals were negative for antibodies against RVFV. Al- though no WNV antibodies were detected from cattle, horse, sheep and water buffalo samples, out of 70 goats, 2 (2.85%) were found to be seropositive for WNV (Table 1). Table 1. Seroepidemiology of West Nile fever and Rift Valley fever in north of Turkey Animals Number of samples Positivity (%) for WNV Positivity (%) for RVFV Buffalo 70 0 (-) 0 (-) Cattle 70 0 (-) 0 (-) Goat 70 2 (2.85) 0 (-) Horse 70 0 (-) 0 (-) Sheep 70 0 (-) 0 (-) Total 350 2 (0.57) 0 (-) Fig. 1. Areas of sample collection 91 J Arthropod-Borne Dis, June 2013, 7(1): 90–93 H Albayrak , E Ozan: Seroepidemiological Study of... http://jad.tums.ac.ir Published Online: April 10, 2013 Discussion West Nile virus has a wide geographical range that includes portions of Europe, Asia, Africa, Australia and America (Fauquet et al. 2005). Many serological test methods were used in the diagnosis of WNV such as plaque reduction neutralization test (PRNT) and ELISA. While PRNT is still considered the gold standard for specific diagnosis, ELISA is now routinely used (Dauphin and Zientara 2007). The C-ELISA has a higher specificity (99.4%) and sensitivity (84.9%) for WNV infection (Padilla et al. 2009). West Nile virus antibodies have been de- tected in humans and animals in Turkey (Ozkul et al. 2006, Ergunay et al. 2007a, 2007b) and antibodies and viruses have been detected among mammals and vectors in the neigh- bouring countries of Balkan Peninsula (Hu- balek and Halouzka 1999). In addition, mos- quito species know to transmit mosquito-borne diseases have been observed in Tur-key (Dik et al. 2006). However, except three human West Nile cases in 2010, there has been no report of acutely infected humans and animals in Turkey. All human cases were detected in Aegean region of western border of Turkey. This region is also border bet-ween Turkey and Greece where West Nile hu-man cases were observed in 2010 and eigh-teen people died in Greece. Only one sero-logic study has been performed in the cent-ral, southern and western parts of Turkey for WNV. Ozkul et al. (2005) were carried out a serosurvey in mammalian species. Positivity rates for the animals varied and were as fol-lows: Ass-mules 2.5%, cattle 4%, dogs 37.7%, horses 13.5%; sheep 1% and humans 20.4%. There is no study on the seroprevalence of WNV infection in buffaloes and goats in Tur-key. The determined positivity in goats in this study (2.85%) was found to be very low comparing to the reported value in dogs, hu-mans and horses. Albayrak and Ozan (2010) performed a molecular study about presence of WNV in wild bird samples in the same re-gion, but they did not detect any WNV nuc-leic acid from these samples. Re- servoir-vec-tor-climate trio was very im-portant at the ep-idemiology for the all mosquito-borne virus-es. Given are average annual values of heat, humidity, and rainfall of Aegean region (west-ern) [16.3 °C (6.4–26.8 °C), 63.2%, 725.9 mm3] and Black Sea region (northern) [13.0 (4.2–22.1), 71%, 842.6 mm3]; additio- nally, an-nual heat changes are more dramatic in Black Sea region (TSMS 2010). Higher vector acti-vity cause to increase in vector- dependent di-seases. Climate conditions of western, cent-ral and southern parts of Tur- key were more suitable for mosquitoes than northern part of Turkey. It is commonplace knowledge that the result of the seropre- valance studies are influ-enced by many fac- tors such as the number of sampled animals, the age of the animals, the time of sampling, the conditions of care and feeding, indivi- dual differences and so on. There has been no report of presence of RVFV in Turkey. No antibody response was detected against RVFV in northern Turkey. Although mosquito species known to trans- mit RVFV have been observed (Dik et al. 2006), there has been no report of acutely in- fected humans and animals in Turkey. This may suggest that the disease is not present in northern Turkey. In addition, the vectors in this area may not carry RVFV. The present study indicated that RVFV might not be- come a risk potential for animals in northern Turkey. To beter understand RVFV transmi- ssion in Turkey, additional studies focusing on major vectors (eg mosquitoes) are needed. The existent data in Turkey is not enough to de- termine regional based profile of the WNV and RVFV infections. Beside, further studies are necessary to understanding of vector dy- namics, interactions among different sensi- tive species and risk factors of exposure. 92 J Arthropod-Borne Dis, June 2013, 7(1): 90–93 H Albayrak , E Ozan: Seroepidemiological Study of... http://jad.tums.ac.ir Published Online: April 10, 2013 Acknowledgements The authors declare that there is no conflict of interest. References Albayrak H, Ozan E (2010) Molecular de- tection of avian influenza virus but not West Nile virus in wild birds in north- ern Turkey. Zoonoses Public Health. 57: 71–75. Castillo-Olivares J, Wood J (2004) West Nile virus infection of horses. Vet Res. 35: 467–483. Dauphin G, Zientara S (2007) West Nile vi-rus: recent trends in diagnosis and vac-cine development Vaccine. 25: 5563–5576. Dik B, Yagcı S, Linton YM (2006) A review of species diversity and distribution of Culicoides Latreille, 1809 (Diptera: Cera- topogonidae) in Turkey. J Nat Hist. 40: 1947–1967. Ergunay K, Saygan MB, Aydogan S, Mene- menlioglu D, Turan HM, Ozkul A, Us D (2007a) West Nile virus seropreva- lance in blood donors from central Ana- tolia, Turkey. Vector Borne Zoonot Dis. 7: 157–161. Ergunay K, Ozer N, Us D, Ozkul A, Simsek F, Kaynas S, Ustacelebi S (2007b) Seroprevalance of West Nile virus and tick-borne encephalitis virus in south- eastern Turkey: First evidence for tick- borne encephalitis virus infections. Vec- tor Borne Zoonot Dis. 10: 771–775. Fauquet CM, Mayo MA, Maniloff J, Dessel- berger U, Ball LA (2005) Family Fla- viviridae. In: Fauquet CM, Mayo MA, Maniloff J, Desselberger U, Ball LA (Eds) Virus Taxonomy-Classification and Nomenclature of Viruses. Eighth re- port of the International Committee on the Taxonomy of Viruses. Elsevier Aca- demic Press, San Diego. Hubalek Z, Halouzka J (1999) West Nile fever- a reemerging mosquito-borne viral disease in Europe. Emerg Infect Dis. 5: 643–650. Linthicum KJ, Anyamba A, Tucker CJ, Kelley PW, Myers MF, Peters CJ (1999) Climate and satellite indicators to forecast Rift Valley fever epidemics in Kenya. Science. 285: 397–400. Mackenzie JS, Barrett ADT, Deubel V (2002) The Japanese encephalitis sero- logical group of flaviviruses: a brief in- troduction to the group. Curr Top Mic- robiol. 267: 1–10. Ozkul A, Yıldırım Y, Pinar D, Akcali A, Yilmaz V, Colak D (2006) Serological evidence of West Nile virus (WNV) in mammalian species in Turkey. Epide- miol Infect. 134: 826–829. Padilla JA, Rubio EL, Romero EE, Cordoba L, Cuevas S, Mejia F, Calderon R, Milian F, Rosa ATD, Weaver SC, Franco JGE, Saiz JC (2009) The conti- nous spread of west nile virus (WNV): seroprevalance in asymptomatic hor- ses. Epidemiol Infect. 137: 1163–1168. Shoemaker T, Boulianne C, Vincent MJ, Pezzanite L, Al-Qahtani MM, Al-Maz- rou Y, Khan AS, Rollin PE, Swane- poel R, Ksiazek TG, Nichol ST (2002) Genetic analysis of viruses associated with emergence of Rift Valley fever in Saudi Arabia and Yemen, 2000–2001. Emerg Infect Dis. 8: 1415–1420. Turkish state meteorological service (TSMS) (2010) Update on average annual va- lues of heat, humidity, and rainfall. Available at: http//www.dmi.gov.tr/ tahmin/il-ve- ilceler.aspx. Turrel MJ, Bailey CL, Beaman JR (1998) Vec- tor competence of a Houston, Tex-as strain of Aedes albopictus for Rift Val- ley fever virus. J Am Mosq Cont Assoc. 4: 94–98. 93