A PRELIMINARY ENTOMOLOGICAL STUDY IN RESURGENCE MALARI FOCUS, KHOJIR REGION, TEHRAN PROVINCE

Background: Re-emerging of vector-borne diseases {VBDs) which were controlled due to long efforts is one of the very important health issues. They usually reappeared with the new characteristics in epidemiological, entomological and immunological aspects. Malaria is one of the most important diseases which have been re-emerged in different parts of the world during the recent decade. Although importation of index case from Afghanistan was the main factor of this re-emerging of malaria in north-east of Tehran but still shows importance the risk of malaria reintroduction in such cleared up foci. This return has been associated with different factors including population movement, changes in the behavioral patterns of the vectors, drug resistance to malaria parasites, insecticide resistance of vectors, environmental changes and interventions have been led to a new situation in VBD epidemiology. Malaria occurrence at new parts became double problems.Objectives: To study of some bioecological features of Anopheles species in the area.Material and Methods: Since August 2017, a new malaria re-emerging focus has been occurred in the Khojir region, the north eastern part of capital city Tehran. The most positive cases were originated from the Afghan refugees. Three introduced cases were also detected using the RDT kit. Also, the thick and thin of blood smears were prepared from suspected cases and their relatives and searched for malaria parasites by direct microscopy method. The population of the region will be followed up on a monthly basis during the receptive seasons for three years. Different malaria entomological methods were employed in indoors and outdoors as well as the larval survey carried out by dipping assay.Results and Discussion: The entomological studies in indoor and outdoor shelters as well as in the natural and artificial habitats of larvae revealed the activity of two species, Anopheles maculipennis complex and An. claviger in the region. At present, by improving and modernization of house constructions and increasing the socio-economic of the residents in the region, the behavioral changes of An. maculipenns complex were considered as a diversion from animals to the humans for blood feeding as well as resting at special shelters. The high density of An. maculipennis complex were observed in the places such as baths, toilets, storerooms, poultry houses, sub-dwellings, inside water wells, cement pipes, and dark damp roofed places, whereas the mosquitoes rarely found in the sitting rooms. The focal residual spraying was carried out using deltamethrin WG 25% at 25 mg/m2 in such mentioned shelters in the houses having the positive malaria cases and some houses around them under supervision of the School of Public Health, Tehran University of Medical Sciences.Conclusion: The sole species of malaria vector is An. maculipennis complex. Due to lack of livestock breeding places in the studied villages, the mosquitoes often showed a tendency for blood-feeding on the human who are at open area. A research project has been approved for further bioecological studies on malaria vectors in the Khojir region, Tehran province.

Keywords:

Malaria , resurgence , Anopheles maculipennis complex , Tehran