The adult female lays no eggs but produces microfilariae that circulate in the blood, completing the cycle. In areas where dog-heartworm infection is prevalent, dog owners should provide mosquito-proof sleeping quarters for their animals. Culex tarsalis and Oc. melanimon are the most important vectors throughout the western U.S., and birds are the major host. Aching in the lower back and headaches around the head and eyes will often occur.
The fact is, there is little that can be done by anyone but a physician with experience in handling cases of delusory parasitosis. Be honest in answering questions, do not agree to see pests that are not there, and do not apply pesticides in these situations. Several ticks are responsible for this malady in the U.S., including D. andersoni, D. variabilis, A. americanum, A. maculatum and I. scapularis. Periodic outbreaks among nonvaccinated equines also provide evidence of local EEE viral activity. The disease persists in the ticks, and the rodents serve as a natural source of infection. Neither epidemic typhus nor louse-borne relapsing fever are found in the U.S., so these diseases are not addressed further in this manual.
However, LAC virus also seems to be associated with container-breeding mosquitoes, such as Oc. triseriatus, that readily maintain it in a transovarial transmission cycle. When cercariae accidentally come in contact with an unsuitable host, such as humans, they may penetrate into, but not through, the skin. As the cercariae enter the skin a temporary, prickly, itching sensation occurs, sometimes followed by a general inflammation of the area affected. Within the arthropod, the pathogen may or may not multiply. If the pathogen or parasite that causes the disease undergoes the sexual portion of its life cycle in a host, that host is the primary or definitive host, as in the mosquito that harbors malaria. They are found in every type of habitat and in all regions of the world. Infected wild birds infect the mosquitoes that feed on them, but the WEE virus is present in the infected bird’s blood for only three to four days in the amounts needed to infect feeding mosquitoes. The contaminated blood is then regurgitated into the wound caused by the flea bite.