FACTORS AFFECTING THE DEVELOPMENT OF DIROFILARIASIS PATHOGENS IN INTERMEDIATE HOSTS, BLOOD-SUCKING MOSQUITOES (REVIEW)

Abstract

Dirofilariasis is a transmissible parasitic disease caused by helminths Dirofilaria repens and D. immitis. Vectors of pathogens are blood-sucking mosquitoes (Diptera, Culicidae). Climate change, urbanization, and importation of exotic mosquito species into the territory of Russia lead to the expansion of the Dirofilaria vector range and, consequently, an increase in the incidence of the disease among the population and animals. The purpose of this research was to study the literature data on factors of the dirofilariasis pathogen development in blood-sucking mosquitoes. An important factor in the development of Dirofilaria from the larval stage to the invasive stage is an optimal environmental temperature, the average daily value of which should not be less than 130. This number is referred to as the "Dirofilaria Development Unit (DDU)". The immune response of the insect plays an important role in the helminth development in the intermediate host. Melanin, which is produced by mosquito hemocytes, forms a capsule around the larvae thus preventing their maturation. However, the extent of this response depends on the phenoloxidase enzyme and the age of the mosquito. The symbiotic intracellular Wolbachia bacteria found in Dirofilaria are essential for the helminth development in mosquitoes. But no information has currently been found on interaction between mosquito immunity and these bacteria in the literature; although a correlation has been found between the mosquito infected with the bacteria and the probability of infection transmitted by them.