Body lice

The value of insecticides in controlling human and animal diseases spread by insects has been dramatic. It has been shown that between 1942 and 1952, the use of DDT in pubHc health measures to control the mosquito vectors of malaria and the human body louse vector of typhus saved five million hves and prevented 100 million illnesses (4). Insecticides have provided the means to control such important human diseases as filariasis transmitted by Culex mosquitoes and onchocerciasis transmitted by Simulium blackflies. 

Diphenylamine has shown activity against the body louse, chiggers, housefly, and, as the chloro derivative, against the red spider mite. Diarylamines have also been reported to have antiradiation activity (48). 

The two species that belong to this group include Pediculus humanus capitis (head louse) and P. humanus corporis (body louse). The eggs (or nits) remain firmly attached to the hair, and in about 10 days the lice hatch to form nymphs, which mature in 2 weeks. The lice become attached to the base of the hair follicle and feed on the blood of the host.10 Pubic or crab lice are found on the hairs around the genitals, but may occur... 

Body louse Anoplura down in 1 hour 0.1% gave 88% (26)... 

For example, the German encyclopedia Der grofie Brockhaus, vol. VI of the 1930 Leipzig edition, contains a comprehensive article on epidemic typhus. This acute infectious disease is spread only by the body louse 100... 

Successful control and prevention of epidemic typhus consists of enforcing all measures available to destroy the body louse. ... 

By 1952 DDT-resistance had been developed in populations of important pests of apple, cabbage, potatoes, tomatoes and grapes, besides the body louse, the bedbug, two species of fleas, and several species of mosquitoes (Table II). 

Cotton Spodoptera Egypt Body Louse Japan... 

Phthiriasis palpebrarum is an imcommon eyelid infestation by Phthiruspubis (crab louse) and, less commonly, by the Pediculus bumanus species, P. humanus var. capitis (head louse) and P humanus var. corporis (body louse). The term pediculosis refers to infestation by the two P humanus species and should not generally be used when referring to eyelid manifestations. 

Three species of lice occur as parasites on humans. These lice are blood suckers, and they can be disconcertingly abundant under unsanitary conditions. The human louse, Pediculus humanus, occurs as two races, which feed on different parts of the body. The head louse, capitis race, occurs in the hairs of the head, to which it attaches its whitish eggs, also known as nits. The body louse corporis race, also known as the cootie, feeds on the human body, and hides and lays its... 

A recent study in Australia demonstrated that PBO effectively synergizes the toxicity of the pyrethroids cypermethrin. del tame l hr in. cyhalothrin and alpha-cypennclhrin against the sheep body louse. Bovioolu avis (Levot, 1994). Cypermethrin synergized with PBO is now an established means of controlling resistant sheep body liee in Australia. 

Genetic analysis and biochemical studies have shown that kdr resistance is linked to one of the building blocks of the sodium channels in the axon (the gene for the so-called a-subunit). The gene has been sequenced in R-and S-flies. The substitution of a leucine residue with a phenylalanine residue makes the difference. Equivalent mutations have been found in pyre-throid-resistant strains of several other insect species. Two point mutations in the a-subunit of the sodium channels are associated with super-kdr resistance. Such mutations have been detected in the housefly, horn fly, diamond moth, and body louse. It may cause several hundred-fold resistance. It is interesting to note that if knockdown, and not death, is used as the endpoint, the resistance level is much higher. 

Infestations with ectoparasites such as body lice and scabies are conunon throughout the world. These conditions have a significant impact on public health in the form of disabling pruritus, secondary infection, and in the case of the body louse, transmission of life-threatening illnesses such as typhus. Topical and oral medications are available to treat these infestations. 

Several distinct Rickettsiae species cause typhus fevers in humans. Each agent produces disease with a distinct epidemiology, but all cause illness, usually with fever, headache, or rash, or a combiitation of these. Treatment of all forms of typhus is similar and include.s administration of appropriate antibiotics (tor example, the tetracycline class) and supportive care relapses are infrequent. Epidemic typhus is passed from perst)n to person by the body louse. Endemic, or murine, typhus occurs worldwide and is transmitted by rat fleas. Different tickbome typhus fevers occur in Europe, Africa, the Americas, Australia, and Asia. Scrub typhus, transmitted by rodent mites, occurs in a large area from the Indian subcontinent to Australia and in much of Asia, including Japan, China, Korea, and parts of Russia. 

It is not certain when people first started wearing elothes. Scientists estimate that this happened more than 100,000 years ago, beeause the body louse (pediculus humanus humanus) apparently diverged from the head louse (pedi-culus humanus capitis) at that time. The first elothes were made from natural materials animal skin and furs, grasses and leaves and the first needles are recorded about 30,000 years ago. 

Typhus is caused by the rickettsial Rickettsia prowazekii and most often spread by another arthropod, the body louse. The Latin name was given in honor of Ricketts and another pioneering researcher, Stanislas von Prowazek. Both scientists eventually died from typhus as a result of their research. 

In order to establish a simplified bioassay method with head lice, knockdown ratios in response to phenothrin concentrations was analyzed, in changing treatment hours by the method of continuous contact of lice with insecticide-impregnated filter paper (28), We used the long-established insecticide-susceptible strain of body louse, NIID, as a reference. Figure 3A shows that phenothrin effectively knocked down adult body lice after 3 hours treatment. Similar result was obtained fi om 1st instar nymphs, though knock down speed was relatively low (Figure 3B). 

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