Spatial changes in the distribution of malaria vectors during the past 5 decades in Iran.

BACKGROUND: Global warming and climate change affect various aspects of mankind, including public health. Anopheles mosquitoes are of Public Health importance and can be affected by global warming and other environmental variables. Here, we studied the distribution of Anopheles vectors of malaria in relation to environmental variables in Iran. METHODS: Long-term meteorological and entomological data of about 50 years in retrospect were collected and arranged in a geo-database and analyzed using ArcGIS ver. 9.3 and exported to SPSS ver. 20 for statistical analysis. RESULTS: Distribution maps have been updated for seven species of Anopheles vectors of malaria which involved Anopheles culicifacies s.l., An. fluviatilis s.l., An. stephensi, An. dthali, An. sacharovi, An. maculipennis.l. and An. superpictus in Iran. Distribution maps of vectors were made based on district areas using Kriging model. Historical and recent records were demonstrated for each Anopheles based on climatic factors in the distribution areas of each Anopheles vectors. DISCUSSION: Iran, like other parts of the world is faced with warming and this probably affected the distribution of Anopheles vectors. Despite the warming phenomenon, the country's climate had changed during the cold season as temperatures became colder or cooler. This study shows that some vectors had migrated from the central part of Iran with dry and sunny landscape, moved towards the mountainous areas of the north or the warm and humid areas of the south. Historical records show that these anophelines have previously been distributed in lowland areas. If this process continues in the future, Anopheles mosquitoes may be seen in low lands with cold areas in central and northern parts of the country or will occupy humid and warm climates in the southern parts of the country where water is more available.

Anopheles culicifacies in Baluchistan, Iran.

Anopheles culicifacies (probably species A) is the main vector of malaria in Baluchistan, southeastern Iran. Adult mosquitoes were collected during 1990-92 by five methods of sampling: knock-down pyrethrum space-spray indoors, human and animal bait (18.00-05.00 hours), pit shelters and CDC light traps, yielding 62%, 3%, 6%, 4% and 25% of specimens, respectively. Whereas spray-catches comprised c. 70% gravid and semi-gravid females, light trap catches were mostly (c. 60%) unfed females, while females from pit shelters comprised all abdominal stages more equally (13-36%). An.culicifacies populations peaked in April-May and rose again during August-November. Densities of indoor-resting mosquitoes were consistently greater in an unsprayed village than in villages subjected to residual house-spraying with propoxur, malathion or pirimiphos-methyl. Monthly malaria incidence generally followed fluctuations of An.culicifacies density, usually with a peak in May-June.