Abstract
Background:
West Nile virus (WNV) is a mosquito-borne virus that causes a febrile disease and may cause a fatal neurological illness in humans. We aimed to investigate the geographic distribution of Culicinae mosquitoes and their possible infection with WNV in Hormozgan Province, southern Iran.
Methods:
Field studies were carried out from June 2017 to May 2019. Different mosquito sampling methods were used monthly to collect mosquitoes from 22 sites. The Real-Time PCR technique was used to detect the virus infection in the mosquitoes.
Results:
Overall, 6165 mosquitoes were caught. The species were Culex theileri (33.25%), Cx. pipiens (20.45%), Cx. quinquefasciatus (10.51%), Aedes caspius (6.33%), Cx. tritaeniorhynchus (5.82%), Ae. vexans (4.10%), Cx. sinaiticus (3.62%), Cx. antennatus (3.29%), Culiseta longiareolata (2.81%), Cx. perexiguus (2.03%), Cs. subochrea (1.95%), Cx. mimeticus (1.49%), Cx. pusillus (1.38%), Cx. univittatus (1.27%), Cx. modestus (1.14%), and Cx. sitiens (0.57%). The molecular detection of virus infection in mosquitoes found to be negative for WNV.
Conclusion:
The presence of many species of mosquito vectors and high population traffic increase the risk of disease transmission is very high. Therefore, the way to restrict WNV infection factors is increasing the knowledge for personal protection measures to prevent mosquito bites.
Keywords: West Nile virus, Culicidae mosquitoes, Iran
Introduction
The Culicinae is the subfamily of Culicidae (Diptera: Culicidae). So far, more than 3,500 species of Culicidae mosquitoes have been identified in 43 genera (1). A wide range of important arbovirus diseases is transmitted by Culicinae mosquitoes, including yellow fever, dengue fever, chikungunya, encephalitis as well as West Nile fever. Aedes and Culex species play an important role in the transmission of these diseases (2–3).
West Nile virus (WNV) is a common arbovirus disease between humans and some animals, especially birds. About 300 species are known as the reservoir host of WNV. Corvus and Cyanocitta crows are considered as important reservoirs of the disease (4). Migratory birds play a very important role in transmission of the virus in world (5). Hormozgan, due to its numerous wetlands and mangrove forests, hosts a variety of birds every year from October to the end of May. Culex mosquitoes due to their ornithophilic feature are considered important vectors of WNV (6–7). Recently the presence of WNV was reported in mosquitoes in the northwestern (8) and southern part of Iran in Hormozgan Province. The finding indicated that WNV genome was present in Culex pipiens complex, (9).
We aimed to determine the species composition and geographical distribution of potential Culicines vectors as well as their possible infection with WNV in Hormozgan Province, an area with a high risk of WNV transmission in the south of Iran.
Materials and methods
Ethics approval
This study was approved by the Ethics Committee of the Tehran University of Medical Sciences IR.TUMS.SPH.REC.1397.
Study area
Hormozgan Province is located in the south of Iran bordering the Persian Gulf, with an approximate population of 1,776,000. the province with 71,000 km2 located between latitude 25° 24′–28°53′N and longitude 52°44′–59°14′ E (10). Out of 13 counties of the province, 8 cities and regions were selected, and entomological studies conducted monthly from June 2017 to June 2019 (Fig. 1).
Fig. 1:
Selected areas for entomological survey in Hormozgan Province, Southern Iran
Mosquito collection
Mosquitos’ larvae were collected from the different natural and artificial larval habitats by dipper method collection. The breeding sites were categorized as temporary or permanent breeding places, vegetated water bodies, larval habitats with substrate of mud, stone, cement and sand bottom, water quality such as opacity or transparency and light status (sunny, partial shade, shade).
Adult mosquitoes were collected by different methods including CDC light traps, human baited trap net, animal baited trap net, birds baited trap net, mosquito trap net with CO2, hand catch method from indoor places, and collecting mosquitoes from shelter pits. Finally, the collected mosquito species were identified using valid keys (11, 12).
Molecular assays for detection of West Nile Virus (WNV)
To extract RNA from mosquitoes’ specimens, each separated pool that prepared from mono species was homogenized in 300 μl of PBS buffer using the pestle, then 200 μl of mosquito homogenates were added to a new tube consisting of 600 μl of RLT buffer, and then the samples were mixed using a vortex for 15 seconds. Mosquito homogenates were centrifuged at 1300rpm. Total RNA extraction was purified according to the manufacturer’s kit by the use of the RNeasy mini kit (QIAGEN) and stored at −70 °C until needed for WNV detection. For detection and amplifying of WNV genomes in the mosquitoes, One-Step Real-Time PCR Kit (QIAGEN) was used. Briefly, RT-PCR reaction was carried out in a final 20µl volume (5 μl of 5X QIAGEN One-Step RT-PCR Buffer, 1μl of dNTP, 1µl of QIAGEN One-Step RT-PCR Enzyme,1 μl of Primer F(CAGACCACGCTACGGCG), 1 μl of Primer R (CTAGGGCCGCGTGGG), 5.5 μl of RNase free water, 0.5 μl of probe and 5µl of extracted RNA as a template). The cycling conditions consisted of one cycle at 50°C for 30 min, one cycle at 95°C for 5 min, and 45 cycles at 95°C for 10 s and 60°C for 1 min (13).
Results
Culicinae species
During the current study, 6165 female culicine mosquitoes were collected included 3 genera and 16 species. The species were Culex theileri, Cx. pipiens, Cx. quinquefasciatus, Cx. tritaeniorhynchus, Cx. antennatus, Cx. perexiguus, Cx. mimeticus, Cx. pusillus, Cx. univittatus, Cx. modestus, Cx. sitiens, Cx. sinaiticus, Aedes caspius, Ae. vexans, Culiseta longiareolata and Cs. subochrea. Culex theileri with 33.25% and Cx. pipiens with 20.45% were dominant species (Table 1). The predominant species based on the collected site is summarized in Table 1. Totally, 2377 mosquitoes were collected in Bandar Abbas County; the most abundant species was Cx. pipiens (22.09%). Aedes mosquitoes were collected only in certain months of the year during the rainy season. The number of collected female mosquitoes in Minab County was 1180, and the dominant species was Cx. theileri species (30.34%). In Hajiabad County, 473 mosquitoes were collected and the most abundant species was Cx. theileri (53.49%). In Parsian County, 473 mosquitoes were collected and the most abundance was related to Cx. theileri (76.92%). In Bandar Lengeh County, the most abundant species was Cx. theileri (40.40%). In Rudan County, the most abundant species was Cx. theileri (45.75%). In Jask County, the most abundant mosquito was Cx. theileri (31.41%). In Qeshm County, the dominant species was Cx. pipiens 180 (39.91%).
Table 1:
Distribution of female Culicinae mosquitoes in study area in Hormozgan, Southern Iran during June 2017 to May 2019
| City & Collection Site | Species & Nomber of Female Mosquitoes | Nomber of female mosquitos | ||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
| ||||||||||||||||||
| City | Collection sites | Cx. pipiens | Cx. theileri | Cx. titaeniorhynchus | Cx. quinquefasciatus | Cx. perexiguus | Cx. modestus | Cx. pusillus | Cx. mimeticus | Cx. sitiens | Cx. univittatus | Cx. antennatus | Cx. sinaiticus | Ae. caspius | Ae. vexans | Cs. subochrea | Cs. longiareolata | |
| Bandar Abbas | Daneshkadeh Behdasht | 32 | 75 | 8 | 10 | 0 | 0 | 0 | 3 | 2 | 5 | 3 | 10 | 12 | 6 | 0 | 6 | 172 |
| Mahaleh sang kan | 70 | 110 | 18 | 80 | 21 | 15 | 15 | 1 | 3 | 12 | 12 | 16 | 35 | 29 | 18 | 19 | 474 | |
| Khour shilat | 85 | 80 | 17 | 55 | 25 | 21 | 22 | 5 | 2 | 17 | 9 | 17 | 36 | 27 | 37 | 17 | 472 | |
| Mohaleh posht shahr | 69 | 35 | 16 | 28 | 0 | 2 | 14 | 6 | 2 | 6 | 12 | 16 | 35 | 25 | 31 | 16 | 313 | |
| hormoudar Rural | 45 | 150 | 30 | 32 | 14 | 15 | 12 | 10 | 0 | 20 | 10 | 20 | 64 | 30 | 18 | 26 | 496 | |
| khorgoo Rural | 49 | 75 | 16 | 48 | 21 | 17 | 22 | 12 | 6 | 18 | 11 | 26 | 68 | 25 | 16 | 20 | 450 | |
| Minab | City of Minab | 96 | 108 | 23 | 57 | 12 | 0 | 0 | 7 | 3 | 0 | 15 | 36 | 0 | 33 | 0 | 0 | 390 |
| Haji balouchi | 88 | 150 | 25 | 71 | 6 | 0 | 0 | 9 | 4 | 0 | 17 | 30 | 0 | 38 | 0 | 0 | 438 | |
| Bolboli | 75 | 100 | 35 | 44 | 10 | 0 | 0 | 7 | 5 | 0 | 11 | 25 | 0 | 40 | 0 | 0 | 352 | |
| Hajiabad | Haji Abad City | 65 | 150 | 10 | 28 | 0 | 0 | 0 | 0 | 0 | 0 | 12 | 0 | 0 | 0 | 0 | 0 | 265 |
| Tejerj | 35 | 103 | 25 | 32 | 0 | 0 | 0 | 0 | 0 | 0 | 13 | 0 | 0 | 0 | 0 | 0 | 208 | |
| Parsian | Parsian | 20 | 220 | 8 | 7 | 0 | 0 | 0 | 0 | 0 | 0 | 7 | 0 | 0 | 0 | 0 | 6 | 268 |
| ziyarat | 45 | 200 | 9 | 7 | 0 | 0 | 0 | 0 | 0 | 0 | 8 | 0 | 0 | 0 | 0 | 9 | 278 | |
| Bandar Lengeh | Bandar Kong | 72 | 120 | 27 | 12 | 0 | 0 | 0 | 0 | 0 | 0 | 12 | 0 | 0 | 0 | 0 | 54 | 297 |
| Rudan | roudan | 45 | 98 | 10 | 17 | 0 | 0 | 0 | 10 | 3 | 0 | 12 | 14 | 0 | 0 | 0 | 0 | 209 |
| ziyarat ali | 75 | 112 | 18 | 5 | 0 | 0 | 0 | 12 | 5 | 0 | 10 | 13 | 0 | 0 | 0 | 0 | 250 | |
| Bandar Jask | bahmadi | 68 | 73 | 12 | 40 | 0 | 0 | 0 | 0 | 0 | 0 | 6 | 0 | 0 | 0 | 0 | 0 | 199 |
| zar abad | 47 | 47 | 33 | 42 | 5 | 0 | 0 | 0 | 0 | 0 | 9 | 0 | 0 | 0 | 0 | 0 | 183 | |
| Qeshm | Mesen | 58 | 15 | 7 | 10 | 2 | 0 | 0 | 2 | 0 | 0 | 8 | 0 | 62 | 0 | 0 | 0 | 164 |
| Direstan | 74 | 10 | 10 | 15 | 9 | 0 | 0 | 4 | 0 | 0 | 2 | 0 | 40 | 0 | 0 | 0 | 164 | |
| Shib Draz | 48 | 19 | 2 | 8 | 0 | 0 | 0 | 4 | 0 | 0 | 4 | 0 | 38 | 0 | 0 | 0 | 123 | |
| Nomber of female mosquitos | 1261 | 2050 | 359 | 648 | 125 | 70 | 85 | 92 | 35 | 78 | 203 | 223 | 390 | 253 | 120 | 173 | 6165 | |
| Abundance (%) | 20.45 | 33.25 | 5.82 | 10.51 | 2.03 | 1.14 | 1.38 | 1.49 | 0.57 | 1.27 | 3.29 | 3.62 | 6.33 | 4.1 | 1.95 | 2.81 | 100 | |
Sampling female mosquitoes
The number of collected mosquito species based on different sampling methods was represented in Table 2. The majority mosquitoes were collected by hand catch method (43.70%), followed by animal bait (13.12%) and exit traps were placed over the air vents of septic tanks (12.68%). The light trap (0.92%) collected the lowest number of mosquitoes. The most abundant species collected by hand catch method was Cx. theileri (35.89%), but no Aedes and Culiseta species captured. The number of mosquitoes captured by the human baited trap was 360, and with dominancy of Cx. pipiens (34.72%). Furthermore, 809 Culicinae mosquitoes collected using animal baited trap nets, the dominant species was Cx. pipiens (49.69%). The number of mosquitoes captured by the CDC light traps method was relatively very low and only 57 mosquitoes were captured and mostly Cx. theileri (78.94%).
Table 2:
Abundance of Culicinae species collected with different methods in study area in Hormozgan Province, Southern Iran during June 2017 to May 2019
| Species | Cx. Pipiens | Cx. theileri | Cx. Tritaeniorhynchus | Cx. quinquefasciatus | Cx. perexiguus | Cx. modestus | Cx. pusillus | Cx. mimeticus | Cx. sitiens | Cx. univittatus | Cx. antennatus | Cx. sinaiticus | Ae. caspius | Ae. vexans | Cs. subochrea | Cs. longiareolata |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
| ||||||||||||||||
| Collection methods | Number & (Percentage) | Number & (Percentage) | Number & (Percentage) | Number & (Percentage) | Number & (Percentage) | Number & (Percentage) | Number & (Percentage) | Number & (Percentage) | Number & (Percentage) | Number & (Percentage) | Number & (Percentage) | Number & (Percentage) | Number & (Percentage) | Number & (Percentage) | Number & (Percentage) | Number & (Percentage) |
| Hand catch | 449 (35.61) | 967 (47.17) | 242 (67.41) | 475 (73.30) | 74 (59.20) | 43 (61.43) | 53 (62.35) | 30 (32.61) | 22 (62.86) | 46 (58.97) | 166 (81.77) | 127 (56.95) | 0 (0.00) | 0 (0.00) | 0 (0.00) | 0 (0.00) |
| Human bait | 125 (9.91) | 120 (5.85) | 15 (4.18) | 10 (1.54) | 0 (0.00) | 0 (0.00) | 0 (0.00) | 0 (0.00) | 0 (0.00) | 0 (0.00) | 0 (0.00) | 0 (0.00) | 75 (19.23) | 15 (5.93) | 0 (0.00) | 0 (0.00) |
| Animal bait | 402 (31.88) | 352 (17.17) | 20 (5.57) | 35 (5.40) | 0 (0.00) | 0 (0.00) | 0 (0.00) | 0 (0.00) | 0 (0.00) | 0 (0.00) | 0 (0.00) | 0 (0.00) | 0 (0.00) | 0 (0.00) | 0 (0.00) | 0 (0.00) |
| Light trap | 10 (0.79) | 45 (2.20) | 0 (0.00) | 2 (0.31) | 0 (0.00) | 0 (0.00) | 0 (0.00) | 0 (0.00) | 0 (0.00) | 0 (0.00) | 0 (0.00) | 0 (0.00) | 0 (0.00) | 0 (0.00) | 0 (0.00) | 0 (0.00) |
| Adult collection of artificial ponds | 67 (5.31) | 158 (7.71) | 18 (5.01) | 15 (2.31) | 0 (0.00) | 12 (17.14) | 10 (11.76) | 5 (5.43) | 0 (0.00) | 10 (12.82) | 0 (0.00) | 26 (11.66) | 75 (19.23) | 62 (24.51) | 0 (0.00) | 0 (0.00) |
| Adult collection from Septic tank | 85 (6.74) | 298 (14.54) | 35 (9.75) | 96 (14.81) | 51 (40.80) | 15 (21.43) | 22 (25.88) | 52 (56.52) | 13 (37.14) | 22 (28.21) | 37 (18.23) | 56 (25.11) | 0 (0.00) | 0 (0.00) | 0 (0.00) | 0 (0.00) |
| By collecting larvae | 123 (9.75) | 110 (5.37) | 29 (8.08) | 15 (2.31) | 0 (0.00) | 0 (0.00) | 0 (0.00) | 5 (5.43) | 0 (0.00) | 0 (0.00) | 0 (0.00) | 14 (6.28) | 240 (61.54) | 176 (69.57) | 120 (100) | 173 (100) |
| Total & Percentage | 1261 (20.45) | 2050 (33.25) | 359 (5.82) | 648 (10.51) | 125 (2.03) | 70 (1.14) | 85 (1.38) | 92 (1.49) | 35 (0.57) | 78 (1.27) | 203 (3.29) | 223 (3.62) | 390 (6.33) | 253 (4.10) | 120 (1.95) | 173 (2.81) |
The diversity of collected species from artificial ponds was more than other methods and totally 458 adult mosquitoes was captured while the dominant species was Cx. theileri (34.49%). By replacing window exit-traps over the air vents of septic tanks, 782 mosquitoes were captured. The dominant species was Cx. theileri, but no any Aedes and Culiseta species were not collected from these places.
Larval habitats
Totally three genera of Aedes, Culex, and Culiseta larvae were collected from different breeding places which included 10 (Table 3). Culex pipiens was the dominant species collected from running water while Ae. caspius was dominant in stagnant water. In temporary running water, Cs. longiareolata was the most frequent. However, these three species were found in temporary stagnant water. Culex pipiens was found in non-vegetated habitats while in vegetated habitats, Ae. caspius was the most frequent species.
Table 3:
Culicinae larval habitats by species in the study areas of Hormozgan Province, Southern Iran during June 2017 to May 2019
| Species | Cx. pipiens | Cx. theileri | Cx. tritaeniorhynchus | Cx. quinquefasciatus | Cx. mimeticus | Cx. Sinaiticus | Ae. caspius | Ae. vexans | Cs. subochrea | Cs. longiareolata | Total | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Total number of collected larvae water | 123 | 110 | 29 | 15 | 5 | 14 | 240 | 176 | 120 | 173 | 1005 | |
| Habitat type | Permanent with running water | 33 | 20 | 0 | 0 | 0 | 0 | 0 | 11 | 6 | 4 | 74 |
| Permanent with stagnant water | 50 | 59 | 0 | 0 | 0 | 0 | 84 | 45 | 10 | 15 | 263 | |
| Temporary with running water | 15 | 3 | 0 | 0 | 0 | 0 | 0 | 0 | 25 | 64 | 107 | |
| Temporary with static water | 25 | 28 | 4 | 15 | 5 | 14 | 156 | 120 | 79 | 90 | 536 | |
| Vegetation status | non-vegetated habitats | 43 | 20 | 4 | 0 | 0 | 0 | 0 | 0 | 0 | 30 | 97 |
| vegetated habitats | 80 | 90 | 0 | 15 | 5 | 14 | 240 | 176 | 120 | 143 | 883 | |
| Floor type | mud | 85 | 65 | 4 | 15 | 0 | 14 | 240 | 150 | 98 | 108 | 779 |
| Sand | 38 | 30 | 0 | 0 | 0 | 0 | 0 | 26 | 22 | 65 | 181 | |
| Stone or cement | 0 | 15 | 0 | 0 | 5 | 0 | 0 | 0 | 0 | 0 | 20 | |
| Water condition | non-clear water clear water | 108 | 95 | 4 | 15 | 5 | 14 | 30 | 10 | 15 | 25 | 321 |
| 15 | 15 | 0 | 0 | 0 | 0 | 210 | 166 | 105 | 148 | 659 | ||
| The state of sunlight | sunny | 0 | 15 | 4 | 0 | 0 | 0 | 30 | 8 | 6 | 20 | 83 |
| semi-shady | 91 | 73 | 0 | 15 | 0 | 14 | 125 | 99 | 99 | 118 | 634 | |
| shady | 32 | 22 | 0 | 0 | 5 | 0 | 85 | 69 | 15 | 35 | 263 | |
| Habitat type | natural | 88 | 90 | 4 | 15 | 0 | 14 | 205 | 141 | 95 | 141 | 793 |
| artificial | 35 | 20 | 0 | 0 | 5 | 0 | 35 | 35 | 25 | 32 | 187 | |
The largest number of Culicinae larvae were collected in mud-bottomed habitats and less in rock or cement bottom. The greatest number of larvae collected in habitats with sandy floor was Cs. longiareolata. Ae. caspius was the most frequent in clear water habitats and Cx. pipiens dominantly found in non-clear water. In sunny, semi-shady, shady habitats, different larval species of all three genera were collected in the areas. In the semi-shady larval habitats, all species has been collected except Cx. tritaeniorhynchus and Cx. mimeticus. In natural habitats, all species were collected except Cx. mimeticus, Aedes while Culiseta were the more abundant in natural habitats.
Determination of West Nile Virus (WNV)
A total of 145 pools of mosquito species collected in the study areas were subjected to RT-PCR molecular tests to determine WNV infection (Table 4). Examinations on all samples (female and male mosquitoes) from different regions showed that the samples were not infection with WNV.
Table 4:
Number of pools prepared for molecular assays in the study areas of Hormozgan Province, southern Iran during June 2017 to May 2019
| Mosquitoes species | Number of pools provided by County | Total | |||||||
|---|---|---|---|---|---|---|---|---|---|
|
| |||||||||
| Bandar Abbas | Minab | Hajiabad | Parsian | Bandar Lengeh | Rudan | Bandar Jask | Qeshm | ||
| Cx. pipiens | 7 | 5 | 2 | 2 | 2 | 3 | 3 | 4 | 28 |
| Cx. theileri | 10 | 7 | 5 | 8 | 2 | 4 | 3 | 1 | 40 |
| Cx. tritaeniorhynchus | 2 | 2 | 1 | 1 | 1 | 1 | 1 | 1 | 10 |
| Cx. quinquefasciatus | 5 | 3 | 3 | 1 | 1 | 1 | 1 | 1 | 15 |
| Cx. perexiguus | 1 | 1 | 0 | 0 | 0 | 0 | 1 | 1 | 4 |
| Cx. modestus | 2 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 2 |
| Cx. pusillus | 2 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 2 |
| Cx. mimeticus | 1 | 1 | 0 | 0 | 0 | 1 | 0 | 1 | 4 |
| Cx. sitiens | 1 | 1 | 0 | 0 | 0 | 1 | 0 | 0 | 3 |
| Cx. univittatus | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 |
| Cx. antennatus | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 8 |
| Cx. sinaiticus | 2 | 2 | 0 | 0 | 0 | 1 | 0 | 0 | 5 |
| Ae. caspius | 5 | 0 | 0 | 0 | 0 | 0 | 0 | 3 | 8 |
| Ae. vexans | 3 | 3 | 0 | 0 | 0 | 0 | 0 | 0 | 6 |
| Cs. subochrea | 3 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 3 |
| Cs. longiareolata | 3 | 0 | 0 | 1 | 2 | 0 | 0 | 0 | 6 |
| Total | 49 | 26 | 11 | 14 | 9 | 13 | 10 | 13 | 145 |
Discussion
In the current investigation, the highest number of mosquito species belonged to Cx. theileri (33.25%) and Cx. pipiens (20.45%). Cx. theileri and Cx. pipiens are dominantly present in all the study areas. Other species such as Cx. pusillus, Cx. univittatus, Ae. caspius, Ae. vexans and Cs. subochrea either did not exist or had a very low distribution. In a study conducted in Sistan-Baluchestan Province, Cx. pipiens complex was one of the most collected species (14). Based on the study conducted in Isfahan Province, it was one of the most frequent species (15). Furthermore, Azari Hamidian et al showed that this species is one of the most abundant Culicinae mosquitoes in Guilan Province (16).
In addition, in Kurdistan and Kermanshah (17), and Mazandaran provinces (18), Cx. pipiens is considered one of the most frequently collected samples. Cx. pipiens complex has a worldwide distribution and is also well adapted to different types of breeding site, including stagnant water and even sewage system of the houses (3, 19, 20). Cx. pipiens can be dominant and abundant in different breeding places. Investigation of Cx. pipiens larval habitats and their characteristics can make it clear that a very high compromise of this species with different types of larvae habitats and different degrees of contamination is the reason for the high distribution and abundance of this species in Iran. In the current study except Culex genus were the most abundant species and a few numbers of Cs. longiareolata and Cs. subochrea mosquitoes were collected. In contrast, in East Azerbaijan (21), Kurdistan and Kermanshah (17) provinces. Cs. longiareolata is one of the most abundant species in Northwestern Iran. In our study, all three genera of collected mosquitoes were found in natural larval habitats having some vegetation. Among three genera, Culex species approximately were collected from different types of larval habitats and this finding was similar to study conducted in Northwestern Iran (21). Cx. pipiens complex e.g., Cx. quinquefasciatus and Cx. pipiens are important vectors to transmit some arboviral diseases mainly WNV to humans in many areas. Moreover, Cx. quinquefasciatus plays a major role in virus transmission among birds (6–7,19,22,23).
Although, our molecular detection of WNV infection among the collected mosquitoes from Hormozgan Province was negative, but in a previous study, Cx. pipiens was found infected with the virus from different areas of this province (9) and in the equine population (24). Thus, WNV should be more considered as an important mosquito-borne disease.
In addition, Cx. theileri and Cx. pipiens were positive to WNV in Lorestan Province (25). WNV was detected in Ae. caspius, collected from West Azerbaijan Province (8). However, we could not detect WNV among 6165 collected mosquitoes. It seems that the circulation of WNV between vectors and reservoir occurs every few years, not seasonally or annually. Therefore, it is possible we done the present survey during the time which WNV circulation was silence. However, Cx. pipiens mosquitoes was found positive to WNV in Morocco (26) Bulgaria (27) Greece and the other countries (28).
Conclusion
Although detection of WNV genome was not confirmed in our study due to circulation of WNV in Hormozgan Province, more studies and regular checking of mosquitos is recommended for accurate monitoring of the disease in future.
Journalism Ethics considerations
Ethical issues (Including plagiarism, informed consent, misconduct, data fabrication and/or falsification, double publication and/or submission, redundancy, etc.) have been completely observed by the authors.
Acknowledgements
The authors would like to thank the School of Public Health, Tehran University of Medical Sciences, for their support in carrying out this research. This study was financially supported by the Deputy of Research of International Campus, Tehran University of Medical Sciences, with Grant No. 37360. In addition, the authors would like to appreciate the collaboration received from Dr. Alireza Sanei Dehkordi, and Abdolrasool Mojahedi and Masood Yerian of Hormozgan Health to provide required data for this study.
Footnotes
Conflict of Interest
The authors declare that there is no conflict of interest.
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