Satellite-derived estimation of environmental suitability for malaria vector development in Portugal

Abstract

Malaria was endemic in Europe for more than two millennia until its eradication in the 1970s. Recent autochthonous cases registered in Greece have increased the awareness regarding the threat of malaria re-emergence in Southern Europe. Currently, the presence of competent vectors, suitable environmental conditions and the evidences of a changing climate may increase the widespread re-emergence of malaria in Southern Europe. This work focused on determining the current relationships between environmental factors and the density of the former malaria vector Anopheles atroparvus in Portugal, a previously endemic country. Adult females were sampled and vector density was estimated in 22 sites in Southern Portugal between 2001 and 2010 and related with land cover and satellite-derived air temperature and vegetation indices. The relationship between vector density and local larval habitat, temperature and, in a broader sense, to environmental suitability, was assessed using a statistical modelling approach. Results showed that present environmental conditions are suitable for vector development at high densities and the spatial and temporal patterns closely resemble the ones registered in the past endemic period. The use of satellite-derived data, together with statistical models, allowed the extrapolation of suitable environmental conditions for vector development from site-level to the Portuguese mainland territory. This work also improved the baseline knowledge needed to understand the potential impacts of future environmental changes on vector density and, indirectly, on the risk of malaria re-emergence.

The Health Effects of Climate Change in the WHO European Region

“…In France and the Netherlands, a few malaria cases without recent travel history were reported [87,88]. The observed and projected risk of malaria was explored for Portugal [89], Turkey [90], Spain [91], and Germany [92]. Although transmission risk may theoretically increase with warming temperatures and provided that suitable mosquito breeding grounds are available, other factors (health system functionality, building and development regulations, and patterns of land use) make the reemergence of malaria in most countries in Europe unlikely [84] (see also Table 7).…”

“…Observed and Projected Effects (6) Malaria in Portugal [89] Malaria in Germany [92] Malaria in Turkey [90] Aedes albopictus in Europe [98] Malaria in Spain [91] Recent and future Aedes albopictus suitability [99] WNF in Israel [93] Dengue in Europe [100] WNF in Hungary and Austria [94] Dengue in Europe [103] Chikungunya in Italy [96] Dengue and Chikungunya in Europe [101] Dengue in Madeira 2012 [102] Ticks transmit climate-sensitive infectious diseases including Crimean Congo hemorrhagic fever [108,109], Lyme borreliosis [110][111][112], tick-borne encephalitis [113][114][115][116][117][118][119][120] and Tularemia [121]. Several studies identified in the literature review do not report on climate change and tick-transmitted diseases, but instead describe changes in tick distribution, specifically in the United Kingdom [122], Slovenia [123], and the Czech Republic [124].…”

Satellite Earth Observation Data in Epidemiological Modeling of Malaria, Dengue and West Nile Virus: A Scoping Review

“…The mosquitoes' collection was implemented by ovitraps, classical dipping techniques [41,42] or by recording indices, like the Breteau Index (BI) [33,43], House Index (HI) or Container Index (CI) [33,43,44], and the Entomological Inoculation Rate (EIR) [45,46] indices, the latter being a commonly used measure that estimates the number of infected bites per person and per unit time (usually year) [47]. Different kinds of traps (e.g., light traps, magnet traps baited with octenol, CO 2 baited traps, odour-baited MM-X) were used by the various studies [41,45,46,[48][49][50][51][52] as a method to capture mosquitoes, and produce the vectors' density assessments and its status as infected or not. It is worth noting that there is only one study [53] that used crowdsourced data, providing information on both the vector (% of mosquito bites, % of mosquito Larvae) and human cases (% of known human dengue cases) in the area.…”

Using hand-draw maps of residential neighbourhood to compute level of circularity and investigate its predictors

“…Studies over a wide variety of disciplines have used Geographic Information System (GIS) software to estimate circular spatial buffers to study: air pollutants (Ross et al, 2013); political elections (Linke, 2013); neighbourhood walkability (Duncan et al, 2013); mammalian behavior in suburban yards (Kays & Parsons, 2014); adolescent sexual behaviors (Bersamin, Todd, & Remer, 2011); gas shale exploration effects on housing prices (Gopalakrishnan & Klaiber, 2014); body mass index (Lear et al, 2011); remote sensing and malaria (Benali et al, 2014); vehicle trafc patterns (Pulugartha & Kusam, 2012); toxic release effects (Conley, 2011); adverse birth outcomes (Meng et al, 2013); physical activity (Colabianchi et al, 2014); and many others. A complete review of the literature using circular spatial buffers would include thousands of publications extending back decades.…”