Juraj Peško

West Nile virus lineage 2 isolated from Culex modestus mosquitoes in the Czech Republic, 2013: expansion of the European WNV endemic area to the North?

We report the detection and isolation of four almost identical strains of West Nile virus (WNV) lineage 2from Culex modestus mosquitoes collected at three fish ponds in South Moravia, Czech Republic, during August 2013. Phylogenetic analysis demonstrated that the Czech WNV strains isolated are closely related to Austrian, Italian and Serbian strains reported in 2008,2011 and 2012, respectively. Our findings show the current northernmost range of lineage 2 WNV in Europe.

Co-circulation of Usutu virus and West Nile virus in a reed bed ecosystem

BackgroundMosquito-borne flaviviruses are a major public health threat in many countries worldwide. In Central Europe, West Nile virus (WNV) and Usutu virus (USUV), both belonging to the Japanese encephalitis virus group (Flaviviridae) have emerged in the last decennium. Surveillance of mosquito vectors for arboviruses is a sensitive tool to evaluate virus circulation and consequently to estimate the public health risk.MethodsMosquitoes (Culicidae) were collected at South-Moravian (Czech Republic) fishponds between 2010 and 2014. A total of 61,770 female Culex modestus Ficalbi mosquitoes, pooled to 1,243 samples, were examined for flaviviruses by RT-PCR.ResultsOne pool proved positive for USUV RNA. Phylogenetic analysis demonstrated that this Czech USUV strain is closely related to Austrian and other Central European strains of the virus. In addition, nine strains of WNV lineage 2 were detected in Cx. modestus collected in the same reed bed ecosystem.ConclusionsThis is the first detection of USUV in Cx. modestus. The results indicate that USUV and WNV may co-circulate in a sylvatic cycle in the same habitat, characterised by the presence of water birds and Cx. modestus mosquitoes, serving as hosts and vectors, respectively, for both viruses.

Daily and seasonal variation in the activity of potential vector mosquitoes

In the course of season 2010 (May–September), three 2-day trappings of female mosquitoes were carried out at two sites in order to determine the daily activity of the common mosquito species (e.g. species from genus Culex, Aedes, Ochlerotatus, Anopheles, etc.) in the area. CDC light traps filled with CO2 and placed at a height of 1 m were used to trap individuals, and were sampled every 2 h. A total of 19,604 female mosquitoes from 20 identifiable species were trapped: 7,549 at Sedlec and 12,055 at Kančí obora. The activity of the major species of mosquitoes in South Moravia differed throughout the course of the day. Calamity species of the genus Aedes and Ochlerotatus remained active throughout the day and night, but with different course. Aedes vexans, Ae. cinereus, and Ae. rossicus were most active in the late afternoon and highly active for most of the night. Ochlerotatus sticticus was captured most often in the afternoon, and its abundance decreased rapidly before sunset. The activity of Oc. cantans s.l. (Oc. cantans + Oc. annulipes) females varied little during the day and night. The daily activity for the main vectors of West Nile virus, Culex pipiens and Cx. modestus, were totally different from that of other species. Cx. pipiens females showed significant night activity, while Cx. modestus was most active in the evening. Nighttime activity was also observed in female mosquitoes of the genus Anopheles.

Emmonsiosis of subterranean rodents (Bathyergidae, Spalacidae) in Africa and Israel

The presence of adiaspores of the fungal genus Emmonsia was examined in the lungs of 85 mole rats representing 3 subterranean genera: blind mole rats (Spalax galili and S. golani) from Israel, Ansells mole-rats (Cryptomys anselli) from Zambia, and silvery mole-rats (Heliophobius argenteocinereus) from Malawi and Zambia. Emmonsiosis was found in 28% of the blind mole rats, 100% of the Ansells mole-rats, but in none of the silvery mole-rats. Infection in African mole-rats was caused by Emmonsia parva, and infection in Israeli blind mole rats was caused by E. parva and E. crescens. The study indicates that the perennial burrow system of the Ansells mole-rat forms an appropriate microhabitat for the saprophytic growth of E. parva in Lusaka region, Zambia. We suggest that factors contributing to the striking difference in prevalence of emmonsiosis between the two African mole-rat genera (Cryptomys, Heliophobius) may be their differing burrow types, burrow longevity, and social lives.

Isolation of Tahyna Virus (California Encephalitis Group) From Anopheles hyrcanus (Diptera, Culicidae), a Mosquito Species New to, and Expanding in, Central Europe.

ABSTRACT Two strains of Tahyna virus (TAHV; Orthobunyavirus, Bunyaviridae) were isolated from 4,568 (92 pools) female Anopheles hyrcanus Pallas (Diptera, Culicidae) mosquitoes collected on the fishponds in South Moravia (Czechland, central Europe) during July–August 2013. This is the first isolation of TAHV from An. hyrcanus in Europe. An. hyrcanus is a species new to Czechland since 2007; its population density was very high in the year 2013 at these ponds. The virus isolation procedure was based on intracerebral inoculation of newborn mice; moreover, the positive pools were also tested by polymerase chain reaction and found to contain TAHV RNA. An. hyrcanus, feeding preferentially on mammals including humans, may be a new potential vector for TAHV in Europe.

Seasonal dynamics of mosquito occurrence in the Lower Dyje River Basin at the Czech-Slovak-Austrian border

Abstract During 2009–2011, a total of 45 two-day captures of mosquitoes (Insecta: Diptera: Culicidae) were made at six sites in the Lower Dyje River Basin. Trapping was performed from early April through the end of October using Centers for Disease Control and Prevention (CDC) miniature light traps baited with carbon dioxide (CO2). In total, 415,218 female mosquitoes belonging to six genera and 30 species were captured. In early April, only small numbers of wintering species females (Culex pipiens s.l., Culiseta annulata and Anopheles maculipennis s.l.) were detected. From mid-April, there was a sharp increase in the occurrence of snow-melt species (Aedes cataphylla, Ae. intrudens and, sporadically, Ae. communis and Ae. leucomelas, totalling 2090 females). Their occurrence peaked in early May, but they gradually ceased flying in during June. Ae. sticticus females also became active starting in late April, while Ae. cantans s.l., Ae. vexans, Ae. rossicus and other species were active from early May. The greatest occurrence of mosquitoes was recorded in summer months (from mid-June through the end of August). In this period, the dominant species were Ae. vexans (49.70–80.20%) and Ae. sticticus (6.14–25.62%). The species Ae. rossicus, Ae. cantans s.l., Cx. pipiens s.l. and Cx. modestus also were very abundant from mid-June to late July. The occurrence of mosquitoes decreased rapidly during September. In the second half of October, only small numbers of Ae. vexans, An. claviger and Cx. pipiens s.l. females were captured, while Ae. cinereus s.l., Ae. rossicus, Ae. sticticus, Cx. modestus, An. maculipennis s.l. and An. plumbeus were seen only very sporadically.

Cryptic species Anopheles daciae (Diptera: Culicidae) found in the Czech Republic and Slovakia

We report the distribution of mosquitoes of the maculipennis complex in two distinct areas of the Czech Republic (Bohemia and South Moravia) and in one locality of neighbouring Slovakia with emphasis on the detection of the newly described cryptic species Anopheles daciae (Linton, Nicolescu & Harbach, 2004). A total of 691 mosquitoes were analysed using a species-specific multiplex PCR assay to differentiate between the members of the maculipennis complex. In the Czech Republic, we found Anopheles maculipennis (with a prevalence rate of 1.4%), Anopheles messeae (49.0%) and Anopheles daciae (49.6%). In Slovakia, only An. messeae (52.1%) and An. daciae (47.9%) were detected. In this study, An. daciae was documented for the first time in the two countries where it represented a markedly higher proportion of maculipennis complex species (with an overall prevalence almost reaching 50%) in comparison to previous reports from Germany, Romania and Poland. The determination of the differential distribution of maculipennis complex species will contribute to assessing risks of mosquito-borne diseases such as malaria or dirofilariasis.

The invasive Asian tiger mosquito Aedes albopictus (Diptera: Culicidae) in the Czech Republic: Repetitive introduction events highlight the need for extended entomological surveillance

In the framework of a regional collaborative project between authorities and scientists, evidence was found of repeated introduction of Aedes (Stegomyia) albopictus (Skuse) alongside the main road entrances (E461 and E65) connecting Austria and the Slovak Republic with the Czech Republic. In comparison to data from 2012 (17 specimens collected on three occasions), the seasons 2016 (66 specimens on ten occasions) and 2017 (90 specimens on eight occasions) show an apparent increase of introduction events as well as of mosquito numbers and underline the need for more intense surveillance activities.