First report on the molecular phylogenetics and population genetics of Aedes aegypti in Iran

BACKGROUND

Aedes aegypti, the primary vector of various human arboviral diseases, is a significant public health threat. Aedes aegypti was detected in Iran in 2018, in Hormozgan province, but comprehensive information regarding its genetic diversity and origin within the country remains scarce. This study aimed to determine the origin and genetic diversity of Ae. aegypti in southern Iran.

METHODS

Aedes aegypti mosquitoes were collected from Bandar Abbas City, Hormozgan Province, southern Iran, between May and July 2022. Specimens were morphologically identified. Origin and assess genetic diversity were assessed based on the mitochondrial DNA-encoded cytochrome c oxidase subunit I (mtDNA-COI) gene.

RESULTS

BLAST (basic local alignment search tool) analysis confirmed the accuracy of the morphological identification of all specimens as Ae. aegypti, with 100% similarity to GenBank sequences. Calculated variance and haplotype diversity were 0.502 and 0.00157, respectively. Among the 604 examined nucleotide sequences, only a single site was non-synonymous. Total nucleotide diversity and average pairwise nucleotides were determined as 0.00083 and 0.502, respectively. Fu and Li's D test values were not statistically significant. Strobeck's S statistic value was 0.487, and Tajima's D value was 1.53395; both were not statistically significant (P > 0.10).

CONCLUSIONS

Phylogenetic analysis revealed two distinct clades with minimal nucleotide differences and low haplotype diversity, suggesting the recent establishment of Ae. Aegypti in the southern region of Iran. The phylogenetic analysis also indicated an association between Ae. aegypti populations and mosquitoes from Saudi Arabia and Pakistan.

Medically Significant Vector-Borne Viral Diseases in Iran

Vector-borne viral diseases (VBVDs) continue to pose a considerable public health risk to animals and humans globally. Vectors have integral roles in autochthonous circulation and dissemination of VBVDs worldwide. The interplay of agricultural activities, population expansion, urbanization, host/pathogen evolution, and climate change, all contribute to the continual flux in shaping the epidemiology of VBVDs. In recent decades, VBVDs, once endemic to particular countries, have expanded into new regions such as Iran and its neighbors, increasing the risk of outbreaks and other public health concerns. Both Iran and its neighboring countries are known to host a number of VBVDs that are endemic to these countries or newly circulating. The proximity of Iran to countries hosting regional diseases, along with increased global socioeconomic activities, e.g., international trade and travel, potentially increases the risk for introduction of new VBVDs into Iran. In this review, we examined the epidemiology of numerous VBVDs circulating in Iran, such as Chikungunya virus, Dengue virus, Sindbis virus, West Nile virus, Crimean-Congo hemorrhagic fever virus, Sandfly-borne phleboviruses, and Hantavirus, in relation to their vectors, specifically mosquitoes, ticks, sandflies, and rodents. In addition, we discussed the interplay of factors, e.g., urbanization and climate change on VBVD dissemination patterns and the consequent public health risks in Iran, highlighting the importance of a One Health approach to further surveil and to evolve mitigation strategies.

Entomological surveillance of invasive Aedes mosquitoes in Mazandaran Province, northern Iran from 2014 to 2020

Mosquitoes are the most important vectors of serious infectious diseases in the world. Dengue, Zika, chikungunya and yellow fever are emerging and re-emerging infectious diseases, associated with the distribution of two key vectors i.e. Aedes aegypti and Aedes albopictus throughout the world including countries neighbouring Iran. Entomological surveillance was planned and performed monthly from May to December during 2014-2020 in selected counties of Mazandaran Province, North of Iran, by ovitrap, larval collection, hand catch and human baited trap. Overall, 4410 Aedes specimens including 2376 larvae (53.9%) and 2034 (46.1%) adults belonging to six species, namely Aedes vexans, Aedes geniculatus, Aedes caspius, Aedes echinus, Aedes pulcritarsis and Aedes flavescence were collected and morphologically identified. Over the seven years of surveillance, Ae. aegypti and Ae. albopictus were not found by any sampling method. Aedes vexans and Ae. geniculatus were the most abundant species, their populations peaked in October and November and was positively correlated with precipitation and relative humidity. Aedes flavescence was a new species record for the province. A flowchart for planning and implementation of invasive mosquito surveillance for provincial health authorities in the country is proposed. These surveillance efforts provide basic and timely information for the health system to act promptly on integrated and intensified surveillance and control programs should Ae. aegypti and Ae. albopictus detected in the province.

West Nile virus: The current situation in Egypt

Background and Aim

Due to climatic changes, arthropod-borne viruses have become a global health concern. In Egypt, West Nile virus (WNV) was initially detected in humans in 1950 and then in 1951, 1954, 1968, and 1989. Although WNV infection has been recorded in numerous Middle Eastern countries, its prevalence among the equine population in Egypt is unknown. This study aimed to investigate the current situation of vector-borne WNV in Egypt, estimate its seroprevalence, and assess the associated risk factors.

Materials and Methods

We screened 1100 sera samples and nasal swabs from the same equids, 156 mosquito pools, and 336 oropharyngeal and cloacal swabs from migratory birds for WNV. The sera were investigated for the presence of immunoglobulin G (IgG) and immunoglobulin M (IgM) against WNV-prE. Real-time reverse transcription-polymerase chain reaction was used to detect WNV RNA in the nasal swab samples, mosquito pools, and migratory birds' oropharyngeal and cloacal swabs.

Results

The seroprevalence showed positive IgG in sera samples collected from different districts. The data showed that horses were 1.65-fold more susceptible than donkeys, with male being 1.45 times more susceptible than females. Moreover, the tested equids samples were divided into three groups based on their age: <5 years, 5-10 years, and >10 years. The 5-10-year group was 1.1 and 1.61 times more vulnerable to infection than the <5- and >10 year groups. All the sera samples were negative for IgM. The nasal swabs from equids, oropharyngeal and cloacal swabs from migratory birds, and mosquito samples tested negative for WNV by molecular detection.

Conclusion

Based on the obtained data, we recommend that effective control programs should be implemented to enable epidemiological investigations and understand the current situation of WNV in Egypt.

West Nile, Sindbis and Usutu Viruses: Evidence of Circulation in Mosquitoes and Horses in Tunisia

Mosquito-borne diseases have a significant impact on humans and animals and this impact is exacerbated by environmental changes. However, in Tunisia, surveillance of the West Nile virus (WNV) is based solely on the surveillance of human neuroinvasive infections and no study has reported mosquito-borne viruses (MBVs), nor has there been any thorough serological investigation of anti-MBV antibodies in horses. This study therefore sought to investigate the presence of MBVs in Tunisia. Among tested mosquito pools, infections by WNV, Usutu virus (USUV), and Sindbis virus (SINV) were identified in Cx. perexiguus. The serosurvey showed that 146 of 369 surveyed horses were positive for flavivirus antibodies using the cELISA test. The microsphere immunoassay (MIA) showed that 74 of 104 flavivirus cELISA-positive horses were positive for WNV, 8 were positive for USUV, 7 were positive for undetermined flaviviruses, and 2 were positive for tick-borne encephalitis virus (TBEV). Virus neutralization tests and MIA results correlated well. This study is the first to report the detection of WNV, USUV and SINV in Cx. perexiguus in Tunisia. Besides, it has shown that there is a significant circulation of WNV and USUV among horses, which is likely to cause future sporadic outbreaks. An integrated arbovirus surveillance system that includes entomological surveillance as an early alert system is of major epidemiological importance.

Population Fluctuations and Abundance Indices of Mosquitoes (Diptera: Culicid), as the Potential Bridge Vectors of Pathogens to Humans and Animals in Mazandaran Province, Northern Iran

Background

Seasonal activity patterns of mosquitoes are essential as baseline knowledge to understand the transmission dynamics of vector-borne diseases. This study was conducted to evaluate the monthly dynamics of the mosquito populations and their relation to meteorological factors in Mazandaran Province, north of Iran.

Methods

Mosquito adults and larvae were collected from 16 counties of Mazandaran Province using different sampling techniques, once a month from May to December 2014. "Index of Species Abundance" (ISA) along with "Standardized ISA" (SISA) was used for assessing the most abundant species of mosquitoes based on the explanations of Robert and Hsi. Pearson's correlation coefficient (R) was used to assess the relationships between the monthly population fluctuations and meteorological variables.

Results

Overall, 23750 mosquitoes belonging to four genera and nineteen species were collected and identified. The highest population density of mosquitoes was in July and the lowest in May. The ISA/SISA indices for Culex pipiens were both 1 for larvae and 1.25/0.973 for adults in total catch performed in human dwellings. For Cx. tritaeniorhynchus, the ISA/SISA were 1.68/0.938 in pit shelter method. A significant positive correlation was observed between population fluctuations of Cx. tritaeniorhynchus and mean temperature (R: 0.766, P< 0.027).

Conclusion

The results indicated that the mosquitoes are more active in July, and Cx. pipiens and Cx. tritaeniorhynchus were the most abundant species. Considering the potential of these species as vectors of numerous pathogens, control programs can be planed based on their monthly activity pattern in the area.

Epidemiological Evidence of Mosquito-Borne Viruses among Persons and Vectors in Iran: A Study from North to South

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The overall seroprevalence of DENV, WNV and CHIKV in Iran were 5.9%, 18.8% and 1.8% between 2017 and 2018.

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No proof of viral RNAs was presence in vectors.

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Gilan and Hormozgan were high risk regions and the elderlies were at higher risk of infection by WNV and CHIKV.

Vector-borne diseases in Iran: epidemiology and key challenges

Vector-borne diseases have become a global health concern in recent decades as a result of global warming, globalization, growth in international trade and travel, use of insecticide and drug resistance. This review study addressed the key vector-borne diseases and their current status in Iran to emphasize the requirements for further research on vector-borne diseases. The dispersion patterns of these diseases differ in various regions. Some of them such as Crimean-Congo hemorrhagic fever, and Q fever are distributed all across Iran, whereas some others such as plague, leishmaniasis, tularemia, and malaria are restricted to specific areas. The high prevalence of vectors throughout the country necessitates enhancing the monitoring and surveillance of emerging and reemerging vector-borne diseases and their potential vectors.

Modeling host-feeding preference and molecular systematics of mosquitoes in different ecological niches in Canada

Several mosquito-borne viruses (mobovirus) cause infections in Canada. Ecological data on mosquito species and host range in Canada remains elusive. The main aim of the current study is to determine the host range and molecular systematics of mosquito species in Canada. Mosquitoes were collected using BG-Sentinel traps and aspirators at 10 trapping sites in Canada during 2018 and 2019. Mosquitoes collected were identified via morphology and molecular techniques. Mosquito sequences were aligned by MUSCLE algorithm and evolutionary systematics were drawn using MEGA and SDT software. Moreover, the source of blood meals was identified using a DNA barcoding technique. A total of 5,708 female mosquitoes over 34 different taxa were collected. DNA barcodes and evolutionary tree analysis confirmed the identification of mosquito species in Canada. Of the total collected samples, 201 specimens were blood-fed female mosquitoes in 20 different taxa. Four mosquito species represented about half (51.47%) of all collected blood-fed specimens: Aede cinereus (39 specimens, 19.11%), Aedes triseriatus (23, 11.27%), Culex pipiens (22, 10.78%), and Anopheles punctipennis (21, 10.29%). The most common blood meal sources were humans (49 mosquito specimens, 24% of all blood-fed mosquito specimen), pigs (44, 21.5%), American red squirrels (28, 13.7%), white-tailed deers (28, 13.7%), and American crows (16, 7.8%). Here, we present the first analysis of the host-feeding preference of different mosquito species in Canada via molecular techniques. Our results on mosquito distribution and behavior will aid in the development of effective mitigation and control strategies to prevent or reduce human/animal health issues in regards to moboviruses.

Computational genomics of Torque teno sus virus and Porcine circovirus in swine samples from Canada

Emerging viral diseases include pathogens that can threaten the health of the Canadian swineherd. Anelloviruses and Circoviruses comprise of pathogens with veterinary significance. The aim of this study was to determine the genomic organization and phylogenetic relationships of Torque teno sus virus (TTsusV) and Porcine circovirus (PCV) from Canadian pig samples. Fecal and tissue specimens were collected during the winter, spring and summer of 2018. We utilized either virus- or genus-specific PCR assays to characterize the occurrence and genetic diversity of TTsusV and PCV in Canadian pigs. Pairwise comparison of all partial sequences and identity calculation was performed using MAFFT algorithm implemented in Sequence Demarcation Tool (SDT). The obtained full-length sequences were aligned using ClustalW, and phylogeny was inferred using a Maximum likelihood (ML) method by Geneious software. The PCR detection results revealed that the overall positive rate of TTsusV type-1 and type-2 was 45.6% and 32.6%, respectively. The TTsusV isolate MK990454 from Canada clustered in the subtype TTsusV1b, while the TTsusV isolate MK872392 fell in the subtype TTsusV2c, and all showed similarity to known American and Chinese isolates. In addition, our screening PCR showed that 2.7% of stool samples were positive for PCV1. Phylogenetic analysis using the full-length sequence demonstrated that PCV1 (MK872393) isolated from Quebec clustered with other Chinese PCV1 strains. Despite the far geographical distance between Canada and China, the close similarity between Canadian and Chinese TTsusV1 and 2, and PCV1 sequences may be explained by a considerable amount of pig trade between these two nations.

Autochthonous Transmission of West Nile Virus by a New Vector in Iran, Vector-Host Interaction Modeling and Virulence Gene Determinants

Using molecular techniques and bioinformatics tools, we studied the vector-host interactions and the molecular epidemiology of West Nile virus (WNV) in western Iran. Mosquitoes were collected during 2017 and 2018. DNA typing assays were used to study vector-host interactions. Mosquitoes were screened by RT-PCR for the genomes of five virus families. WNV-positive samples were fully sequenced and evolutionary tree and molecular architecture were constructed by Geneious software and SWISS-MODEL workspace, respectively. A total of 5028 mosquito specimens were collected and identified. The most prevalent species was Culex (Cx.) pipiens complex (57.3%). Analysis of the blood-feeding preferences of blood-fed mosquitoes revealed six mammalian and one bird species as hosts. One mosquito pool containing non-blood-fed Cx. theileri and one blood-fed Culex pipiens pipiens (Cpp.) biotype pipiens were positive for WNV. A phylogram indicated that the obtained WNV sequences belonged to lineage 2, subclade 2 g. Several amino acid substitutions suspected as virulence markers were observed in the Iranian WNV strains. The three-dimensional structural homology model of the E-protein identified hot spot domains known to facilitate virus invasion and neurotropism. The recent detection of WNV lineage 2 in mosquitoes from several regions of Iran in consecutive years suggests that the virus is established in the country.

Serological evidence of West Nile virus infection among birds and horses in some geographical locations of Iran

Recent expansion of arboviruses such as West Nile (WNV), Usutu (USUV), and tick‐borne encephalitis (TBEV) over their natural range of distribution needs strengthening their surveillance. As common viral vertebrate hosts, birds and horses deserve special attention with routine serological surveillance. Here, we estimated the seroprevalence of WNV, USUV and TBEV in 160 migrating/resident birds and 60 horses sampled in Mazandaran, Golestan, North Khorasan, Kordestan provinces and Golestan province of Iran respectively. ELISA results showed that of 220 collected samples, 32 samples (14.54%), including 22 birds and 10 horses, were positive. Microsphere immunoassay results showed that 16.7% (10/60) of horse blood samples collected in Golestan province were seropositive against WNV (7; 11.7%), Flavivirus (2; 3.3%) and seropositive for USUV or WNV (1; 1.7%). Furthermore, micro virus neutralization tests revealed that four of seven ELISA‐positive bird blood samples were seropositive against WNV: two Egyptian vultures, and one long‐legged buzzard collected in Golestan province as well as a golden eagle collected in North Khorasan province. No evidence of seropositivity with TBEV was observed in collected samples. We showed that WNV, responsible for neuroinvasive infection in vertebrates, is circulating among birds and horses in Iran, recommending a sustained surveillance of viral infections in animals, and anticipating future infections in humans.

Morphological and molecular identification of Culicidae mosquitoes (Diptera: Culicidae) in Lorestan province, Western Iran

Culicidae mosquitoes are main vectors of arboviruses that cause arboviral diseases in humans. Studies on fauna, ecology, biology, resting behaviors of Culicidae mosquitoes are important and greatly impacts the control of arboviral diseases that are transmitted by vectors. The aim of the present study was to determine fauna of mosquitoes (Diptera: Culicidae) based on morphological and molecular (genomic) identification and their habitats in Lorestan province, Western Iran. Meanwhile mosquito samples were examined for arbovirus infection.

Culicidae mosquitoes were caught in 2015 and 2016 from human homes, animal dwellings, storehouses and pit shelters in Lorestan province, Western Iran, using an oral aspirator (hand catch), total catch, human and animal bait and light trap methods. The samples were identified on the genus and species. Six species of Culex and eight species of Anopheles were caught. One complex species (Cx. pipiens complex) and a hybrid between Cx. pipiens pipiens biotype pipiens and Cx. pipiens pipiens biotype molestus were identified. Among all of the trapped mosquitoes (4211), 94.68% were from genus Culex mosquitoes (3987), which indicate that this genus is the dominant in Lorestan province, Western Iran. Anopheles comprised of 201 individuals out of the total catch. Arboviruses were not detected in these samples.

Mosquito Species Composition and Abundance in Quebec, Eastern Canada

Given current and projected changes in the climate, the composition of mosquito species is predicted to shift geographically with implications for the transmission dynamics of vector-borne pathogens. Many mosquito species are rarely collected in Canada and their history is poorly understood; thus assessing their potential role as vectors for pathogenesis is difficult. Mosquitoes were collected from four trapping sites in Quebec Province, Canada, from June to September during 2018 and 2019 using BG sentinel traps. From all morphologically identified female mosquitoes, at least one specimen was selected for identification confirmation using the DNA-barcoding technique. Sequences were subjected to alignment and a Neighbor-Joining (NJ) tree was created using Geneious software. In total, 2,752 female mosquitoes belonging to 20 species over five genera: including Aedes (Ae.), Anopheles (An.), Culex (Cx.), Culiseta (Cu.), Coquillettidia (Cq.) were collected. The predominant mosquito was found to be Ae. cinereus. The highest number of mosquito species was captured in July, followed by August, September, and then June. Five genera were characterized by a distinctive set of cytochrome oxidase I (COI) sequences that formed well-supported clusters in the NJ-tree. The presence of Ae.japonicus in Quebec provides an initial look at the distribution of mosquito species in eastern Canada, which may put Canadians at risk of a wider range of arboviruses.

Detection of arboviruses in mosquitoes: Evidence of circulation of chikungunya virus in Iran

Mosquitoes are vectors of viruses affecting animal and human health. In Iran, the prevalence of mosquito-borne viruses remains poorly investigated. Once infected, mosquito females remain infected for all their life making virus detections possible at early steps before infections are reported in vertebrate hosts. In this study, we used a recently developed high-throughput chip based on the BioMark Dynamic arrays system capable of detecting 37 arboviruses in a single experiment. A total of 1,212 mosquitoes collected in Mazandaran, North-Khorasan, and Fars provinces of Iran were analyzed. Eighteen species were identified, belonging to five genera; the most prevalent species were Anopheles maculipennis s.l. (42.41%), Culex pipiens (19.39%), An. superpictus (11.72%), and Cx. tritaeniorhynchus (10.64%). We detected chikungunya virus (CHIKV) of the Asian genotype in six mosquito pools collected in North Khorasan and Mazandaran provinces. To our knowledge, this is the first report of mosquitoes infected with CHIKV in Iran. Our high-throughput screening method can be proposed as a novel epidemiological surveillance tool to identify circulating arboviruses and to support preparedness to an epidemic in animals and humans.

High Transmission Potential of West Nile Virus Lineage 1 for Cx. pipiens s.l. of Iran

: Vector competence is an important parameter in evaluating whether a species plays a role in transmission of an arbovirus. Although the protocols are similar, interpretation of results is unique given the specific interactions that exist between a mosquito population and a viral genotype. Here, we assessed the infection (IR), dissemination (DR), and transmission (TR) rates of Cx. pipiens s.l., collected from Iran, for West Nile virus (WNV) lineage 1a. We showed that Cx. pipiens s.l. mosquitoes in Iran were susceptible to WNV with IR up to 89.7%, 93.6%, and 83.9% at 7, 14, and 21 days post-infection (dpi) respectively. In addition, DR and TR reached respectively 92.3% and 75.0% at 21 dpi, and the number of viral particles delivered with saliva reached up to 1.33 × 105 particles. Therefore, an unexpected high risk of WNV dissemination in the region where Cx. pipiens s.l. mosquitoes are well established should be considered carefully and surveillance measures implemented accordingly.

Comparative Pathology of West Nile Virus in Humans and Non-Human Animals

West Nile virus (WNV) continues to be a major cause of human arboviral neuroinvasive disease. Susceptible non-human vertebrates are particularly diverse, ranging from commonly affected birds and horses to less commonly affected species such as alligators. This review summarizes the pathology caused by West Nile virus during natural infections of humans and non-human animals. While the most well-known findings in human infection involve the central nervous system, WNV can also cause significant lesions in the heart, kidneys and eyes. Time has also revealed chronic neurologic sequelae related to prior human WNV infection. Similarly, neurologic disease is a prominent manifestation of WNV infection in most non-human non-host animals. However, in some avian species, which serve as the vertebrate host for WNV maintenance in nature, severe systemic disease can occur, with neurologic, cardiac, intestinal and renal injury leading to death. The pathology seen in experimental animal models of West Nile virus infection and knowledge gains on viral pathogenesis derived from these animal models are also briefly discussed. A gap in the current literature exists regarding the relationship between the neurotropic nature of WNV in vertebrates, virus propagation and transmission in nature. This and other knowledge gaps, and future directions for research into WNV pathology, are addressed.

A detailed review of the mosquitoes (Diptera: Culicidae) of Iran and their medical and veterinary importance

Mosquitoes (Diptera: Culicidae) are the most significant arthropods of medical importance because of the burden of diseases, such as malaria, encephalitis and filariasis, which are caused by pathogens and parasites they transmit to humans. In 2007, the most recently published checklist of Iranian mosquitoes included 64 species representing seven genera. Public databases were searched to the end of August 2018 for publications concerning the diseases in Iran caused by mosquito-borne pathogens. Pertinent information was extracted and analyzed, and the checklist of Iranian mosquitoes was updated. Six arboviral diseases, two bacterial diseases, four helminthic diseases and two protozoal diseases occur in Iran. The agents of these diseases are biologically or mechanically known or assumed to be transmitted by mosquitoes. The updated checklist of Iranian mosquitoes includes 69 species representing seven or 11 genera depending on the generic classification of aedines. There is no published information about the role of mosquitoes in the transmission of the causal agents of avian malaria, avian pox, bovine ephemeral fever, dengue fever, Rift Valley fever, Sindbis fever, Deraiophoronema evansi infection, lymphatic filariasis, anthrax and tularemia in Iran. There is just one imported case of lymphatic filariasis, which is not endemic in the country. It seems arthropods do not play an important role in the epidemiology of anthrax and ixodid ticks are the main vectors of the tularemia bacterium. In view of the recent finding of only a few adults and larvae of Aedes albopictus in southeastern Iran and the absence of Ae. aegypti, it is not possible to infer the indigenous transmission of the dengue fever virus in Iran. Considering the importance of mosquito-borne diseases in the country, it is necessary to improve vector and vector-borne disease surveillance in order to apply the best integrated vector management interventions as a part of the One Health concept.

Epidemiology of West Nile Virus in the Eastern Mediterranean region: A systematic review

Background

West Nile Virus (WNV), a member of the genus Flavivirus, is one of the most widely distributed arboviruses in the world. Despite some evidence for circulation of WNV in countries summarized by the World Health Organization as the Eastern Mediterrian Regional Office (EMRO), comprehensive knowledge about its epidemiology remains largely unknown. This study aims to provide a concise review of the published literature on WNV infections in the Eastern Mediterranean Regional Office of WHO (EMRO).

Methodology/principal findings

A systematic review of WNV prevalence studies on humans, animals and vectors in the EMRO region was performed by searching: Web of Science, Science Direct, Scopus, PubMed, Embase and Google Scholar. Finally, 77 citations were included, comprising 35 seroprevalence studies on general population (24460 individuals), 15 prevalence studies among patients (3439 individuals), 22 seroprevalence studies among animals (10309 animals), and 9 studies on vectors (184242 vector species). Of the 22 countries in this region, five had no data on WNV infection among different populations. These countries include Kuwait, Bahrain, Oman, Syria and Somalia. On the other hand, among countries with available data, WNV-specific antibodies were detected in the general population of all investigated countries including Djibouti (0.3–60%), Egypt (1–61%), Iran (0–30%), Iraq (11.6–15.1%), Jordan (8%), Lebanon (0.5–1%), Libya (2.3%), Morocco (0–18.8%), Pakistan (0.6–65.0%), Sudan (2.2–47%), and Tunisia (4.3–31.1%). WNV RNA were also detected in patient populations of Iran (1.2%), Pakistan (33.3%), and Tunisia (5.3% –15.9%). WNV-specific antibodies were also detected in a wide range of animal species. The highest seropositivity rate was observed among equids (100% in Morocco) and dogs (96% in Morocco). The highest seroprevalence among birds was seen in Tunisia (23%). In addition, WNV infection was detected in mosquitoes (Culex, and Aedes) and ticks (Argas reflexus hermanni). The primary vector of WNV (Culex pipiens s.l.) was detected in Djibouti, Egypt, Iran and Tunisia, and in mosquitoes of all these countries, WNV was demonstrated.

Conclusions

This first systematic regional assessment of WNV prevalence provides evidence to support the circulation of WNV in the EMRO region as nearly all studies showed evidence of WNV infection in human as well as animal/vector populations. These findings highlight the need for continued prevention and control strategies and the collection of epidemiologic data for WNV epidemic status, especially in countries that lack reliable surveillance systems.

West Nile Virus (WNV) is a mosquito-borne Flavivirus belonging to the Flaviviridae family, which is endemic in a vast geographical area, including the EMRO region. However, the epidemiology of WNV in the EMRO region remains poorly understood. To address this gap, we performed a systematic review on WNV prevalence studies conducted on human populations, animals and vectors across Eastern Mediterranean countries. Our review indicated the infection of most investigated human, animal and vector populations with WNV; however, the paucity of epidemiological data underline the need for integrated surveillance programs as well as continued deployment of prevention and control strategies.

Host-feeding patterns of Culex mosquitoes in Iran

Background

Different mosquito-borne pathogens are circulating in Iran including Sindbis virus, West Nile virus, filarioid worms and malaria parasites. However, the local transmission cycles of these pathogenic agents are poorly understood, especially because ecological data on vector species are scarce and there is limited knowledge about the host range; this understanding could help to direct species-specific vector control measurements or to prioritize research.

Methods

In the summers of 2015 and 2016, blood-fed mosquitoes were collected at 13 trapping sites on the coast of the Caspian Sea in northern Iran and at an additional trapping site in western Iran. Mosquitoes were generally collected with either a Biogents Sentinel trap or a Heavy Duty Encephalitis Vector Survey trap installed outside. A handheld aspirator was used at the trapping site in western Iran, in addition to a few samplings around the other trapping sites. On average, eight trapping periods were conducted per trapping site. The sources of blood meals were identified using a DNA barcoding approach targeting the cytochrome b or 16S rRNA gene fragment.

Results

The source of blood meals for 580 blood-fed mosquito specimens of 20 different taxa were determined, resulting in the identification of 13 different host species (9 mammals including humans, 3 birds and 1 reptile), whereby no mixed blood meals were detected. Five mosquito species represented more than 85.8% of all collected blood-fed specimens: Culex pipiens pipiens form pipiens (305 specimens, 55.7% of all mosquito specimens), Cx. theileri (60, 10.9%), Cx. sitiens (51, 9.3%), Cx. perexiguus (29, 5.3%) and Anopheles superpictus (25, 4.6%). The most commonly detected hosts of the four most abundant mosquito species were humans (Homo sapiens; 224 mosquito specimens, 40.9% of all mosquito specimens), cattle (Bos taurus; 171, 31.2%) and ducks (Anas spp.; 75, 13.7%). These four mosquito species had similar host-feeding patterns. The only exceptions were a relatively high proportion of birds for Cx. pipiens pipiens f. pipiens (23.2% of detected blood meal sources) and a high proportion of non-human mammals for Cx. theileri (73.4%). Trapping month, surrounding area, or trapping method had no statistically significant impact on the observed host-feeding patterns of Cx. pipiens pipiens f. pipiens.

Conclusions

Due to the diverse and overlapping host-feeding patterns, several mosquito species must be considered as potential enzootic and bridge vectors for diverse mosquito-borne pathogens in Iran. Most species can potentially transmit pathogens between mammals as well as between mammals and birds, which might be the result of a similar host selection or a high dependence on the host availability.

Electronic supplementary material

The online version of this article (10.1186/s13071-018-3237-2) contains supplementary material, which is available to authorized users.

Widespread circulation of West Nile virus, but not Zika virus in southern Iran

West Nile virus (WNV) and Zika virus (ZIKV) are mosquito-borne viral infections. Over the past few decades, WNV has been associated with several outbreaks involving high numbers of neuroinvasive diseases among humans. The recent re-emergence of ZIKV has been associated with congenital malformation and also with Guillain-Barre syndrome in adults. The geographic range of arthropod-borne viruses has been rapidly increasing in recent years. The objectives of this study were to determine the presence of IgG specific antibodies and the genome of WNV and ZIKV in human samples, as well as WNV and ZIKV genomes in wild-caught mosquitoes in urban and rural areas of the Hormozgan province, in southern Iran. A total of 494 serum samples were tested for the presence of WNV and ZIKV IgG antibodies using ELISA assays. One hundred and two (20.6%) samples were reactive for WNV IgG antibodies. All serum samples were negative for ZIKV IgG antibodies. Using the multivariable logistic analysis, age (45+ vs. 1-25; OR = 3.4, 95% C.I.: 1.8-6.3), occupation (mostly outdoor vs. mostly indoor; OR = 2.4, 95% C.I.: 1.1-5.2), and skin type(type I/II vs. type III/IV and type V/VI; OR = 4.3, 95% C.I.: 1.7-10.8 and OR = 2.7, 95% C.I.: 1.3-5.5 respectively, skin types based on Fitzpatrick scale) showed significant association with WNV seroreactivity. We collected 2,015 mosquitoes in 136 pools belonging to 5 genera and 14 species. Three pools of Culex pipiens complex were positive for WNV RNA using real-time reverse transcription polymerase chain reaction (rtRT-PCR). ZIKV RNA was not detected in any of the pools. All WNV ELISA reactive serum samples were negative for WNV RNA. In conclusion, we provided evidence of the establishment of WNV in southern Iran and no proof of ZIKV in serum samples or in mosquito vectors. The establishment of an organized arbovirus surveillance system and active case finding strategies seems to be necessary.

Kobinger G, Moosa-Kazemi SH. DNA barcodes corroborating identification of mosquito species and multiplex real-time PCR differentiating Culex pipiens complex and Culex torrentium in Iran

Identifying mosquito species is a fundamental step in risk assessment and implementation of preventative strategies. Moreover, Culex pipiens is the most widespread mosquito vector in several regions of Iran and is the main vector for transmission of West Nile virus (WNV). Mosquitoes were collected at 14 sites in northern regions of Iran in 2015 and 2016. A subset of mosquito specimens was selected for identification confirmation using a DNA-barcoding technique. Construction of a phylogenetic tree showed clustering of mosquito sequences into three main genera: Aedes, Anopheles and Culex with individuals of a single species clustered closely together, regardless of where and when they were collected. Cx. pipiens complex and Cx. torrentium were identified and differentiated using multiplex real-time PCR targeting the gene locus for acetylcholinesterase 2 (ace2) to discriminate between Cx. pipiens pipiens and Cx. torrentium. The CQ11 microsatellite locus was used for discrimination between Cpp. biotypes. The predominant mosquito species in investigated regions were Cx. pipiens pipiens biotype pipiens, but we also detected Culex pipiens pipiens biotype molestus and hybrids of the two pipiens biotypes, as well as Cx. torrentium. The results of this study represent the first certain evidence of the presence of Cx. pipiens pipiens biotype molestus and hybrids between pipiens and molestus forms, and Cx. torrentium in Iran through a molecular identification approach. This report of a potentially important bridge vector for WNV might have key influence in the risk projections for WNV in Iran.

Co-circulation of Crimean-Congo Hemorrhagic Fever virus strains Asia 1 and 2 between the border of Iran and Pakistan

Crimean-Congo Hemorrhagic Fever (CCHF) is a tick-borne viral disease that is transmitted by numerous species of ticks, which serve both as a reservoir and vector of CCHF virus (CCHFV). Molecular and serological tests were undertaken on hard ticks (Ixodidae spp.) and samples from livestock were collected in 2015 from Chabahar County in Southeast Iran. Using RT-PCR, the ticks were tested for the presence of CCHFV. In addition, seven livestock were serologically tested for the presence of IgG antibodies using an ELISA test. IgG antibodies against CCHFV were detected in one of 7 of the livestock that were tested. In total, 49 ticks including five species: Rhipicephalus sanguineus, Hyalomma anatolicum, Hy. asiaticum, Hy. dromedarii and Hy. marginatum with a prevalence of 46.9%, 32.7%, 4.1%, 4.1% and 2.1% respectively were identified. CCHFV was detected in three ticks among 49 collected ticks. The ticks infected with CCHFV belonged to the genus Hyalomma and Rhipicephalus. Phylogenetic analysis demonstrated that two sequences clustered in clade IV (Asia-1) and one sequence was located within clade IV (Asia-2). Most of the animal and human CCHF cases of the country are reported from Sistan and Baluchistan provinces. Regular monitoring programs in the tick population and livestock are needed in the future.