Middle East DVEP - Armed Forces Pest Management Board

Scabies mites are very small, about 0.2 to 0.4 mm. Both sexes burrow in the horny layerof the skin, but only the female makes permanent winding burrows parallel to the skinsurface. The female lays a few eggs in the burrows. The six-legged larvae that hatchfrom the eggs leave the burrow and move to the hair follicles. Two nymphal stages thatprecede the adult are also found in the hair follicles. The entire life cycle takes 10 to 14days. Scabies is transmitted from person to person only by close prolonged personalcontact. Transmission is common in dormitories, barracks and medical facilities. Mitesdie rapidly away from the human body.Most mite burrows occur in the interdigital and elbow skin, but skin of the scrotum,breasts, knees and buttocks is also affected. The face and scalp are rarely involved. Innewly infested persons, a period of 3 to 4 weeks usually elapses before sensitization tomites and mite excretions develops. Itching is not experienced during this period, andinfestations may progress extensively before being noticed. However, fewer than 20mites are enough to produce intense itching, particularly at night. The burrows oftenbecome secondarily infected with bacteria. In infested persons, an extensive rash cancover areas where there are no mites. In immunocompromised individuals, who do notrespond to infestation by itching and scratching, mites can reach very high populationsand produce a scaly, crusted skin known as Norwegian scabies.Scabies is the most important disease caused by mite infestation. It is cosmopolitan andcommon in the Middle East. Persons of all ages are affected. In developing countries,infestation is highest in poor communities and in children. Scabies is not a reportabledisease in most countries; thus, estimated rates of infestation are usually inaccurate.Scabies is usually only reported when large outbreaks occur. Increases in the incidence ofscabies appear to occur in 15 to 20 year cycles that are related to fluctuating levels ofimmunity to S. scabiei. In the Israel Defense Force, compulsory reporting of scabies hasbeen required since 1968. There was a 13-year period of quiescence from theimplementation of reporting until 1981. This period was followed by an epidemic of 15years, peaking in 1985 and 1986, and a return to the baseline rates of the quiescent periodby 1996.2. Araneae (spiders). More than 34,000 species of spiders have been describedworldwide. All spiders, with the exception of the family Uloboridae, are venomous anduse their venom to immobilize or kill prey. Most spiders are harmless because theirchelicerae cannot penetrate human skin, or they have venom of low toxicity to humans.Those that can bite humans are rarely seen or recovered for identification, so physiciansneed to be able to recognize signs and symptoms of common venomous spider bites inorder to administer appropriate therapy. In the Middle East the widow spiders,Lactrodectus spp., and the violin (brown recluse) spiders, Loxosceles spp., are responsiblefor significant local or systemic effects from envenomization.The adult brown recluse or fiddleback spider (Loxosceles spp.) is medium-sized with a 2to 4 cm legspan. Distinguishing characteristics include six eyes arranged in a semicircleof three pairs on the top of the head and a violin-shaped marking extending from the areaof the eyes to the beginning of the abdomen. The violin-shaped marking may not alwaysbe apparent. The brown recluse is nocturnal in its feeding habits and is most frequently133