Head lice / louse
The head louse (Pediculus humanus capitis) is an obligate ectoparasite of humans that causes head lice infestation (pediculosis capitis).[1]
Head lice are wingless insects spending their entire lives on the human scalp and feeding exclusively on human blood.[1] Humans are the only known hosts of this specific parasite, while chimpanzees host a closely related species, Pediculus schaeffi. Other species of lice infest most orders of mammals and all orders of birds,[1] as well as other parts of the human body.
Lice differ from other hematophagic ectoparasites such as fleas in spending their entire lifecycle on a host.[2] Head lice cannot fly, and their short, stumpy legs render them incapable of jumping, or even walking efficiently on flat surfaces.[2]
The non-disease-carrying head louse differs from the related disease-carrying body louse (Pediculus humanus humanus) in preferring to attach eggs to scalp hair rather than to clothing. The two subspecies are morphologically almost identical, but do not normally interbreed, although they will do so in laboratory conditions. From genetic studies, they are thought to have diverged as subspecies about 30,000–110,000 years ago, when many humans began to wear a significant amount of clothing.[3][4] A much more distantly related species of hair-clinging louse, the pubic or crab louse (Pthirus pubis), also infests humans. It is visually different from the other two species and is much closer in appearance to the lice which infest other primates.[5] Lice infestation of any part of the body is known as pediculosis.[6]
Head lice (especially in children) have been, and still are, subject to various eradication campaigns. Unlike body lice, head lice are not the vectors of any known diseases. Except for rare secondary infections that result from scratching at bites, head lice are harmless, and they have been regarded by some as essentially a cosmetic rather than a medical problem. Head lice infestations might be beneficial in helping to foster a natural immune response against lice which helps humans in defense against the far more dangerous body louse, which is capable of transmission of dangerous diseases.[7]
Kennett
Kennett is a city in and the county seat of Dunklin County, Missouri, United States.[6] The city is located in the southeast corner (or “Bootheel“) of Missouri, 4 miles (6.4 km) east of Arkansas and 20 miles (32 km) from the Mississippi River. It has a population of 10,932 according to the 2010 Census.[7] It is the largest city in the Bootheel, a mostly agricultural area.
White settlers built log cabins in the area in the first half of the 19th century, naming their settlement Chilletecaux in honor of a Delaware Indian chief who lived there. The town was renamed Butler in the late 1840s. Due to mail delivery problems because of other jurisdictions named the same, the settlement was renamed as Kennett, in honor of the mayor of the city of St. Louis, Luther M. Kennett.[8]
In the 1890s, a railroad reached the area, stimulating growth in the town. In that same period, the state began construction of a massive drainage program in the St. Francis River basin, which was floodplain and wetlands. In the 20th century, after timber clearing, the area was developed for cultivation of cotton and other commodity crops.[9]