Species composition, geographical distribution and seasonal abundance of the Anopheles maculipennis complex along the Upper Rhine, Germany

Between May and September 2016, mosquitoes were collected on a biweekly basis at 55 locations with CO₂-baited encephalitis vector surveillance traps along the Upper Rhine, Germany, to evaluate the species composition, geographical distribution and abundance of the Anopheles maculipennis complex, some members of this complex being considered vectors of historical malaria in Germany. A total of 2115 Anopheles maculipennis complex specimens were collected during the season, of which a sample of 1252 individuals was determined to species level by amplification of species-specific internal transcribed spacer 2 (ITS2) sequences. A total of 856 individuals of Anopheles daciae (68.37%), 394 Anopheles messeae (31.47%) and 2 Anopheles maculipennis s.s. (0.16%) were recorded. The number and proportion of A. daciae was remarkably higher in the northern meandering zone of the Upper Rhine (843 specimens, 79.90%), than in the more canalised southern furcation zone where A. messeae with 183 collected specimens represented 92.89% of 197 classified individuals. The average number of collected A. maculipennis s.l. individuals per trapping site was 38.45, equalling 0.64% of the total mosquito collection. Despite an increase in imported malaria cases, this comparatively low abundance of A. maculipennis s.l. may indicate a low risk of endemic malaria transmission by members of the A. maculipennis complex today. The proportionally dominance of A. daciae suggests that this species could be suspected the main historical vector of malaria in the Upper Rhine region. Sequence analyses of the ITS2 fragment revealed intraindividual polymorphisms within 3 of 5 diagnostic nucleotides in all specimens of A. daciae, raising the question if additional loci should be considered, to gain further insight into the taxonomical relation to A. messeae.

Spatial modelling of the potential temperature-dependent transmission of vector-associated diseases in the face of climate change: main results and recommendations from a pilot study in Lower Saxony (Germany)

The sustained climate change is going to modify the geographic distribution, the seasonal transmission gate and the intensity of the transmission of vector-borne diseases such as malaria or the bluetongue disease. These diseases occur nowadays at higher latitudes or altitudes. A further rise in ambient temperature and rainfall will extend the duration of the season in which mosquito vectors are transmitting pathogens. The parasites transmitted by the vectors also benefit from increasing temperatures, as both their reproduction and development are then accelerated, too. Thus, it seemed prudent to examine potential effects on the seasonal transmission gate due to the ongoing and predicted climate changes. Lower Saxony (northwest Germany) is a former malaria region with highest incidences of Anopheles atroparvus and tertian malaria along the coastal zones before malaria had finally become extinct in the early 1950s. Nevertheless, the Anopheles mosquitoes which transmit the malaria pathogens have still been present in Lower Saxony up to now. This together with the climate change-related implications gave reason to investigate whether a new autochthonous transmission could take place if the malaria pathogen is introduced again in Lower Saxony. Thus, the potential spatial and temporal structure of temperature-driven malaria transmissions was mapped using the basic reproduction rate (R (0)) and measured and predicted air temperatures (1947-1960, 1961-1990, 1985-2004, 2020, 2060, 2100, each best case and worst case scenario). This paper focuses on both the summarizing of the results from this risk modelling approach and on the conclusions to be drawn. The recommendations highlight the need to link vector monitoring as one of the key elements of an epidemiological monitoring with the environmental monitoring.