A geographic study of West Nile virus in humans,dead corvids and mosquitoes in Ontario using spatial scan statistics with a survival time application

Surveillance of West Nile virus (WNv) in Ontario has included passive reporting of human cases and testing of trapped mosquitoes and dead birds found by the public. The dead bird surveillance programme was limited to testing within a public health unit (PHU) until a small number of birds test positive. These dead corvid and mosquito surveillance programmes have not been compared for their ability to provide early warning in geographic areas where human cases occur each year. Spatial scan statistics were applied to time‐to‐event survival data based on first cases of WNv in found dead corvids, mosquitoes and humans. Clusters identified using raw data were compared to clusters based on model‐adjusted survival times to evaluate whether geographic and sociodemographic factors influenced their distribution. Statistically significant (p < .05) space–time clusters of PHUs with faster time to detection were found using each surveillance data stream. During 2002–2004, the corvid surveillance programme outperformed the mosquito programme in terms of time to WNv detection, while the clusters of first‐positive mosquito pools were more spatially similar to first human cases. In 2006, a cluster of first‐positive dead corvids was located in northern PHUs and preceded a cluster of early human cases that was identified after controlling for the influence of geographic region and sociodemographic profile.     

Immunopathology of <Emphasis Type="Italic">Dirofilaria immitis</Emphasis> Infection

Heartworm disease caused by Dirofilaria immitis affects canine and feline hosts, with infections occasionally being reported in humans. Studies have shown that both dirofilarial antigens and those derived from its bacterial endosymbiont Wolbachia, interact with the host organism during canine, feline and human infections and participate in the development of the pathology and in the regulation of the host’s immune response. Both innate and acquired immune responses are observed and the development of the acquired response may depend on the host and, or on its parasitological status. This review aims at illustrating current research on the role of both D. immitis and Wolbachia, in the immunology and immunopathology of dirofilariosis.     

Moniezia infection in the dwarf breeds of small ruminants in Southern Nigeria

A survey of Moniezia infection was conducted among two groups of sheep and goats, of dwarf breeds, in Nigeria: a. those being reared under a traditional, extensive husbandry system in groups of rural villages situated in two different ecological zones; and

b. those reared under an intensive system on experimental stations in two ecological zones of Nigeria.

Moniezia expansa was the predominant species encountered in the animals. The incidence of Moniezia infection was higher in sheep than in goats. The highest infection rates were found in kids and lambs younger than eight months old.

The clinical significance of the infection and some of the highlights of the results are discussed. It is concluded that Moniezia infection in small ruminants can pose a problem deserving of more attention and a suggestion is made for studies on the bionomics of the mite forming the intermediate host in Nigeria.     

Preliminary investigation on rodent–ectoparasite associations in the highlands of Tigray,Northern Ethiopia: implications for potential zoonoses

We studied associations between rodents and their arthropod ectoparasites in crop fields and household compounds in the highlands of Tigray, Northern Ethiopia. Ectoparasite infestation indices, such as percent infestation, mean abundance, prevalence and host preferences, were calculated for each taxon. In total, 172 rodents from crop fields and 97 from household compounds were trapped. Rodent species and numbers trapped from the crop fields and household compounds were Mastomys awashensis (Lavrenchenko, Likhnova & Baskevich, 1998) (88 and 44), Arvicanthis dembeensis (Ruppel, 1842) (63 and 37) and Acomys sp. (21 and 16), respectively. A total of 558 insects and acarids (belonging to 11 taxa) were recovered from the rodents trapped in the crop fields, and 296 insects and acarid (belonging to 6 taxa) from the rodents trapped in the household compounds. Approximately 66% of the rodents trapped from the crop fields and 47% of those trapped from the household compounds were infested with ectoparasites. Laelaps sp. (64.9%) and Xenopsylla sp. (20.6%) comprised the highest proportion of the ectoparasites recovered in the crop fields, and the same ectoparasites, but in reverse order, comprised the highest proportions in the household compounds (Xenopsylla [50.3%] and Laelaps sp. [29%]). Our study revealed that crop fields and household compounds in the highlands share similar rodents and several ectoparasites. Furthermore, at least 1 of the rodent species and some of the ectoparasites identified in this study were reported to have posed medical and veterinary threats in other parts of Ethiopia and neighboring countries.     

Ongoing Activity of Toscana Virus Genotype A and West Nile Virus Lineage 1 Strains in Turkey: A Clinical and Field Survey

Toscana virus (TOSV), West Nile virus (WNV) and tickborne encephalitis virus (TBEV) are among major viral pathogens causing febrile disease and meningitis/encephalitis. The impact of these viruses was investigated at a referral centre in Ankara Province, Central Anatolia in 2012, where previous reports suggested virus circulation but with scarce information on clinical cases and vector activity. Serum and/or cerebrospinal fluid samples from 94 individuals were evaluated, in addition to field‐collected arthropod specimens that included 767 sandflies and 239 mosquitoes. Viral nucleic acids in clinical samples and arthropods were sought via specific and generic nested/real‐time PCRs, and antibody responses in clinical samples were investigated via commercial indirect immunofluorescence tests (IIFTs) and virus neutralization. A WNV antigen assay was also employed for mosquitoes. WNV neuroinvasive disease has been identified in a 63‐year‐old male via RNA detection, and the WNV strain was characterized as lineage 1. TOSV infections were diagnosed in six individuals (6.3%) via RNA or IgM detection. Partial sequences in a 23‐year‐old female, presented with fever and transient pancytopenia, were characterized as TOSV genotype A. Febrile disease with arthralgia and/or peripheral cranial nerve involvement was noted in cases with TOSV infections. Previous WNV and TOSV exposures have been observed in 5.3% and 2.1% of the subjects, respectively. No confirmed TBEV exposure could be identified. Morphological identification of the field‐collected mosquitoes revealed Culex pipiens sensu lato (74.4%), Anopheles maculipennis (20.9%), An. claviger (2.1%) and others. Sandfly species were determined as Phlebotomus papatasi (36.2%), P. halepensis (27.3%), P. major s. l. (19.3%), P. sergenti (8.9%), P. perfiliewi (4.4%), P. simici (2.6%) and others. Viral infections in arthropods could not be demonstrated. TOSV genotype A and WNV lineage 1 activity have been demonstrated as well as serologically proven exposure in patients. Presence of sandfly and mosquito species capable of virus transmission has also been revealed.     

The epidemiology of helminthosis in small ruminants under the traditional husbandry system in eastern Nigeria

The epidemiology of helminth infections in West African dwarf sheep and goats under the traditional husbandry system prevailing in the derived savanna area of eastern Nigeria was studied for 12 months. The infections observed were due to Haemonchus contortus (87.1%), Trichostrongylus spp. (63.8%), metacestodes of Taenia hydatigena (30.2%), Oesophagostomum columbianum (22.4%), Strongyloides sp. (18.8%), Cooperia spp. (17.2%), Gaigeria pachyscelis (6.0%), Moniezia expansa (6.0%), Bunostomum trigonocephalum (4.3%), Trichuris ovis (3.5%), Capillaria sp. (0.9%) and paramphistomes (0.9%). Mixed infections were most prevalent. The endemicity of parasitic gastroenteritis in the area was indicated by the high prevalence of the helminths irrespective of the season of the year. The overall trend in helminthosis in these animals was that of an escalating worm burden during the period of confinement (April – October) and a low worm burden when animals were allowed free range (November – March), these periods corresponding to the cropping and harvest seasons respectively. A strong positive correlation (r=0.73; p<0.01) was obtained between the mean strongyle worm burden and the eggs per gram (EPG) of faeces. A single treatment with a broad spectrum anthelmintic followed by movement into clean sheds at the beginning of confinement is suggested to give control of helminthosis in small ruminants in this area.     

Culex annulirostris as a vector of Eperythrozoon ovis infection in sheep

Eperythrozoon ovis, a blood parasite of sheep, was transmitted from carrier lambs to susceptible lambs by the interrupted feeding of the mosquito Culex annulirostris. The circumstances of some of the transmissions were similar to those encountered in the field, in that carrier and susceptible lambs were exposed to a natural population of mosquitoes, while in another transmission an artificial means of containment of the mosquitoes was used. Infective E. ovis organisms were shown to be present in and/or on Cx. annulirostris for at least 14 hours by the inoculation of physiological saline-extracted material from macerated mosquitoes fed on E. ovis carrier lambs.     

West Nile Virus in North‐Eastern Italy, 2011: Entomological and Equine IgM‐Based Surveillance to Detect Active Virus Circulation

Since 2008, West Nile Virus (WNV) has expanded its range in several Italian regions, and its yearly recurrence suggests the virus may have become endemic in some areas. In 2011, a new plan based also on the detection of IgM antibodies was implemented in the north‐eastern Italian regions of Veneto and Friuli Venezia Giulia, aiming to early detect WNV infections in areas where the virus had already circulated during the previous summers, and in adjacent zones. From July to November 2011, 1880 sera from 521 equine premises were screened by a commercial IgM capture ELISA. Mosquitoes were captured by CDC‐CO₂ traps at 61 locations in the two regions. Collected mosquitoes were identified, pooled by species/date/location and examined by real‐time RT‐PCR and sequencing. Passive surveillance was carried out on clinically affected horses and non‐migratory wild birds found dead. IgM sero‐positive equines were detected in 19 holdings, five in the area with WNV circulation (AWC) and 14 in the surveillance area (SA); 10 more horse premises tested positive to further serological controls within 4 km of the positive holdings. A total of 85 398 mosquitoes of 15 species were collected and 2732 pools examined. Five Culex pipiens pools tested positive for the presence of WNV. Passive surveillance on non‐migratory wild birds allowed detection of the virus only in one found dead collared dove (Streptopelia decaocto), of 82 birds sampled. The WNV belonged to the lineage 2, which had been isolated for the first time in Italy earlier in 2011. By the first week of October, nine human cases had been confirmed in the same area. The implementation of a protocol combining IgM screening of horses with surveillance on mosquito vectors proved to be valuable for early detecting WNV circulation.     

Nucleotide Detection of Mosquito Japanese Encephalitis Virus and Sequence Analysis of PrM and E Genes in Upper Pearl River Region

This experiment was conducted to understand mosquito species, distribution of the main vector of Japanese encephalitis virus (JEV), JEV genotype and molecular characteristics in upper Pearl River region. We collected mosquito and Culicoides specimen in Shizong county, upper Pearl River region in July 2013, and these specimens were classified and identified. Meanwhile, JEV nucleotide were detected using PrM and E genes specific primers in 162 pools of mosquito and Culicoides specimen, and the positive specimens were sequencd and analyzed by bioinformatics software. Total 3 705 mosquitoes were collected from 4 collection spots, and the mosquitoes belong to 7 species in 4 generas: Culex, Anopheles, Aedes and Armigeres. In cattle pens, Anopheles Sinensis and Armigeres subalbatus were the dominant mosquito species. In sheep pens, Anopheles Sinensis and Armigeres subalbatus were the dominant mosquito species. And in pig pens, Culex tritaeniorhynchus, Anopheles Sinensis and Armigeres subalbatus were the dominant mosquito species. 4 of 162 pools mosquito and Culicoides were positive detecting by using PrM and E genes specific primers. Sequence analysis of JEV PrM and E genes results showed that 4 strains virus from Culex tritaeniorhynchus samples belonged to genotype Ⅰ JEV, and existing 15 amino acid difference sites between vaccine strain SA14-14-2 in the E gene protein, and 8 important sites which affected virus virulence did not mutant. These results suggested that there were many mosquito species in upper Pearl River region, and Culex tritaeniorhynchus, Anopheles Sinensis were dominant mosquito species in this region, and Culex tritaeniorhynchus was the main media of JEV in local region, genotypeⅠ JEV was popular in local media, and virulence of the pandemic strain did not reduce.     

Ecological Surveillance for West Nile in Catalonia (Spain), Learning from a Five‐Year Period of Follow‐up

To enhance early detection of West Nile virus (WNV) transmission, an integrated ecological surveillance system was implemented in Catalonia (north‐eastern Spain) from 2007 to 2011. This system incorporated passive and active equine surveillance, periodical testing of chicken sentinels in wetland areas, serosurveillance wild birds and testing of adult mosquitoes. Samples from 298 equines, 100 sentinel chickens, 1086 wild birds and 39 599 mosquitoes were analysed. During these 5 years, no acute WNV infection was detected in humans or domestic animal populations in Catalonia. WNV was not detected in mosquitoes either. Nevertheless, several seroconversions in resident and migrant wild birds indicate that local WNV or other closely related flaviviruses transmission was occurring among bird populations. These data indicate that bird and mosquito surveillance can detect otherwise silent transmission of flaviviruses and give some insights regarding possible avian hosts and vectors in a European setting.     

珠江上游地区蚊虫乙型脑炎病毒核酸检测及PrM和E基因序列分析

试验旨在了解珠江上游地区乙型脑炎病毒（JEV）主要传播媒介蚊虫的种类、分布及携带JEV基因型和分子特征。2013年7月在珠江上游地区师宗县采集蚊虫和库蠓标本,并对蚊虫进行分类鉴定;同时采用黄病毒属引物对采集到的蚊虫和库蠓标本进行检测,阳性标本用JEV PrM和E基因特异引物进行扩增、测序,然后采用生物信息学软件进行序列分析。在4个采集点共采集蚊虫3 705只,分别属于库蚊、按蚊、伊蚊和阿蚊4个属的7种蚊虫,牛圈以中华按蚊、骚扰阿蚊为优势蚊种,羊圈以中华按蚊、骚扰阿蚊为优势蚊种,猪圈以三带喙库蚊、中华按蚊和骚扰阿蚊为优势蚊种。采用JEV PrM和E基因特异引物对采集到蚊虫和库蠓标本分162批进行扩增、测序,采用生物信息学软件进行序列分析。结果显示,4株蚊虫携带的病毒均为基因Ⅰ型JEV,与疫苗株SA14-14-2 E蛋白存在15个氨基酸差异位点,在8个影响病毒毒力的重要位点上未发生突变。以上结果提示珠江上游地区存在多种蚊虫种类,三带喙库蚊和中华按蚊是该地区的优势蚊种,三带喙库蚊是当地JEV的主要传播媒介,在当地的媒介中存在基因Ⅰ型JEV流行,而流行株的毒力并未降低。     

Absence of Wolbachia endobacteria in Sri Lankan isolates of the nematode parasite of animals Setaria digitata

Setaria digitata is an animal filarial parasite with natural hosts of cattle and buffaloes that causes mild disease conditions. Infection of non-permissive hosts such as goats, sheep and horses, by this nematode can cause cerebrospinal nematodiasis that leads to lumbar paralysis and the eventual death of the animals and inflicts considerable economic losses on livestock farmers. Wolbachia are obligate mutualistic endosymbionts for some filarial nematodes and are currently being targeted for the control of diseases caused by these parasites. However, little is known about the occurrence of this endosymbiont in the Setariidae family. In this work, worms collected from infected cattle in Sri Lanka were morphologically identified as S. digitata and tested for the presence of Wolbachia by PCR screening using the WSP- and Wolbachia-specific 16S rRNA and multilocus sequence typing primers that were designed to amplify the gatB, coxA, hcpA, ftsZ and fbpA sequences of Wolbachia. The presence of endobacteria in S. digitata was also examined by whole-mount immunofluorescence staining of the parasites and transmission electron microscopic studies. These analyses did not produce evidence of presence of Wolbachia or any other endosymbiotic bacteria in S. digitata, whereas such evidence was found in Brugia malayi, which was used as a positive control in this study.     

新疆地区蚊类携带西尼罗病毒情况调查研究

为查明新疆地区蚊体内携带西尼罗病毒的情况,从2005年-2007年每年的7月~10月采集新疆不同地区的蚊子共计16000余只,并提取总RNA,通过RT-nest PCR的方法检测样品中西尼罗病毒。结果表明,调查样品中没有检测到西尼罗病毒,但不能就此推测新疆是否存在西尼罗病毒,至少对新疆地区和全国制定针对不同动物和人的积极防御政策有重要的公共卫生学意义。     

West Nile virus in the United States (1999-2005)

The accidental introduction of West Nile Virus into New York City from the Old World in 1999 resulted in an epidemic in humans, horses, and birds that swept to the west coast in just 3 years. The virus is transmitted by infective mosquitoes among susceptible native birds, which serve as amplifying hosts. Clinical disease occurs in humans and horses, but not enough virus is produced in their blood to infect other mosquitoes; therefore, humans and horses are considered dead-end hosts. Humans can best protect themselves by remaining indoors during periods of high mosquito activity and/or by using recommended repellents. Effective vaccines are available for horses.     

Isolation of Western Equine Encephalomyelitis (Wee) Virus From Mosquitoes In Saskatchewan, 1962

Saskatchewan, in the summer of 1962, was the scene of an extensive outbreak of western equine encephalomyelitis (WEE) in horses. The results of mosquito survey work showed Culiseta inornata and Culex tarsalis respectively to be the two most abundant mosquito species during midsummer. These species are those reported to be most commonly associated with outbreaks of WEE. Five hundred and sixty-four pools of mosquitoes were examined for the presence of WEE virus. Six pools, three of C. tarsalis and one each of C. inornata, Aedes flavescens and Aedes dorsalis, yielded WEE virus. Positive mosquitoes were from St. Walburg (C. inornata), Saskatoon (C. tarsalis — two, A. dorsalis — one), Outlook (C. tarsalis) and Kisbey (A. flavescens).     

Dirofilariasis in Argentina: historical review and first report of Dirofilaria immitis in a natural mosquito population

Argentina is one of the four South American countries where the presence of Dirofilaria immitis is currently confirmed. The objective of this study was to review information on dirofilariasis in the country, and to report our recent findings on mosquito vectors. Since the first report of dogs with unidentified microfilariae in 1926, D. immitis was found in seven provinces and canine prevalence ranged 0-71% at local scale. National prevalence was 8% by the end of the 1980s and current information is available only for Buenos Aires Province. Four pulmonary human infections of D. immitis and one subcutaneous of Dirofilaria sp. were documented. The common coati was the only wild host found, and natural infection in mosquitoes was not previously reported in the country. In our recent mosquito survey in Greater Buenos Aires, we captured and dissected 2380 mosquitoes belonging to 20 species. According to a minimum temperature of 14 degrees C, the potential transmission period (PTP) for D. immitis in Buenos Aires covers 6 months, and the most favourable period (mean temperature above 20 degrees C) takes place from the middle of November to the beginning of April. To identify potential vectors of the parasite, we assessed weekly abundances of mosquito species during those PTP estimated previously. We found two specimens of Culex pipiens and one of Aedes aegypti carrying non-infective stages of D. immitis. These two highly anthropophilic mosquitoes may enhance the role of D. immitis as zoonotic agent in temperate Argentina.     

Sequence Analysis of the Nucleoprotein Gene of Asian Lineage Peste des Petits Ruminants Vaccine Virus

The complete nucleotide sequence of the nucleocapsid (N) protein of the peste-des-petits ruminants vaccine virus (PPRV Sungri/96) belonging to the Asian lineage was determined. The gene was 1692 nucleotides in length and encoded a polypeptide of 525 amino acids. The PPRV Sungri/96 N gene has a nucleotide homology of 92% for PPRV Nigeria 75/1 to 55.5% for canine distemper virus. At amino acid level the homology was 94.1% with PPRV Nigeria 75/1, while with other morbilliviruses, PPRV Sungri/96 had only 71.4–64.9% amino acid identity. The phosphorylation prediction reveals eight conserved sites across morbilliviruses, whereas in the C-terminal portion of the protein the sites are not conserved. Phylogenetic analysis of different N proteins of morbilliviruses revealed five well-defined clusters as observed previously. To the best of our knowledge this is the first report describing the nucleocapsid gene sequence of PPRV Indian isolate. Muthuchelvan, D., Sanyal, A., Balamurugan,V., Dhar, P. and Bandyopadhyay, S.K., 2006. Sequence analysis of the nucleoprotein gene of Asian lineage peste des petits ruminants vaccine virus.Veterinary Research Communications, 30(8), 957–963     

A common conserved peptide harboring predicted T and B cell epitopes in domain III of envelope protein of Japanese Encephalitis Virus and West Nile Virus for potential use in epitope based vaccines

Japanese encephalitis virus (JEV) and West Nile virus (WNV) are two major mosquito borne flaviviruses belonging to same serocomplex. JEV is transmitted by Culex mosquitoes and the reservoir host for the virus is pigs and/or water birds. WNV is also transmitted by Culex mosquitoes and reservoir host in this case is birds. It can also be transmitted through contact with other infected animals, their blood, or other tissues. The envelope protein of these viruses is the major source of epitopes and provides protective immunity. Bioinformatics tools were used to identify conserved epitopes in the envelope protein of these viruses. A conserved peptide "TPVGRLVTVNPFV" present in both the viruses containing predicted T and B cell epitopes was found. The model of one of the predicted epitope was generated and upon docking it bound in the groove of HLA-A0201 Class I MHC molecule. Further, it was amenable to proteasomal cleavage enhancing its chances of processing by cytosolic pathway. The peptide was found to be non toxic, non allergenic and stable in mammalian cells based on database search. The population coverage was pan world and nearly 70% identity of the peptide was found in the Zika virus envelope protein. The peptide was located in the domain III of envelope protein which is the exposed domain therefore B cell receptors may recognize this peptide easily. The conserved peptide containing T and B cell epitopes can have future application for designing epitope based vaccines for both JEV and WNV.