ИСТИНА

The reintroduction of vivax malaria remains possible in temperate regions that had been freed from it. This is why the question of determinants and drivers of malaria re-emergence does not lose its relevance and requires new approaches. Between 1999 and 2008 Russia experienced a flareup of transmission of vivax malaria following its massive importation. More than 500 autochthonous cases occurred in European Russia , the Moscow region being the most affected. The study aimed to identify geographical determinants of autochthonous transmission. The degree of favourability of climate for vivax malaria was assessed using data from 22 weather stations. For geospatial analysis, the locations of each of 405 autochthonous cases detected in the Moscow region have been ascertained. A MaxEnt method was used for modelling the territorial differentiation of Moscow region according to the suitability of infection re-emergence. We calculated the key indicators of climate favorability for malaria transmission, viz. the sum of effective temperatures, the duration of the season of effective infectiveness, and a new integral index of climate favorability. A dramatic increase of all three indicators, which accelerated after 1984, and high spatial heterogeneity among them were demonstrated. Meteorological conditions were extremely favourable for malaria in 1999, 2001 and 2002. Most likely, the urban heat island additionally amplified malaria re-introduction: the degree of climatic favorability is especially high in the densely urbanized areas of Moscow megacity compared with the suburban and rural areas. The greatest number of cases occurred at the northwestern periphery of the city and in the adjoining rural areas. A significant role was played by rural construction activities attracting migrant labour, vegetation density and landscape division. A cut-off altitude of 200 m was observed, though this factor did not play a significant role at lower altitudes. The malariogenic potential in relation to vivax malaria was high in Moscow region, albeit heterogeneous in this regard. This recent event of large-scale reintroduction of vivax malaria in a temperate area can serve as a case study for further research. This research was funded by the Russian Science Foundation (Grant 17-77-20070 Assessment and Forecast of the Bioclimatic Comfort of Russian Cities under Climate Change in the 21st Century)