Abstract
Female mosquitoes “sting” humans or animals in order to suck the blood and have their eggs matured. First, they thrust their mouth needle (proboscis) into the skin of the victim animal (or human) and inject the salivary fluid and then suck the blood. This saliva causes various skin reactions. At least, two types of skin reactions have been discriminated; the early reaction (erythema and wheal reaction) and the late reaction (papule reaction). Most people show the following lifetime course of the skin reactivity; no reaction—late reaction appears—early reaction appears—late reaction wanes—early reaction wanes—no reaction. It has been speculated that the saliva substances function as the allergens, although the primary toxic stimulation theory has not been positively denied. As to the physicochemical and biological characteristics of the saliva substances, very limited informations are available so far. Several investigations showed that the mosquito saliva contains non-dialyzable peptides which function as the allergens. These studies employed homogenates of the whole mosquito bodies as the analysis materials. However, the mosquito salivary gland is extremely small, usually less than one-thousandth of the whole body, and these homogenate contains too much contaminating materials to analyze the exact nature of the salivary gland substances. This has been in fact the biggest obstruction for these kind of investigations. Recently a new experimental trial was reported in Japan. Namely, salivary glands were separated individually under the stereoscopic microscope observation and then analyzed. Various substances were detected in the salivary gland including histamine, polyamines, esterases and peptides. Although this study itself gave only a preliminary information as to the nature of the salivary gland substances, their sample preparation method of individual salivary gland dissection would be obviously the method of choice for further studies of the mosquito sting allergens.
