出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/08/31 02:04:22」(JST)
| Crab louse | |
|---|---|
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Phthiraptera |
| Suborder: | Anoplura |
| Family: | Pthiridae |
| Genus: | Pthirus |
| Species: | P. pubis |
| Binomial name | |
| Pthirus pubis (Linnaeus, 1758) |
|
| Synonyms | |
|
Pediculus pubis Linnaeus, 1758 |
|
The crab louse (Pthirus pubis, also pubic louse) is an insect that is an obligate ectoparasite of humans, feeding exclusively on blood.[1] The crab louse usually is found in the person's pubic hair. Although the louse cannot jump, it can also live in other areas of the body that are covered with coarse hair, such as the eyelashes. Humans are the only known hosts of the crab louse, although a closely related species, Pthirus gorillae, infects gorilla populations. The human parasite diverged from Pthirus gorillae approximately 3.3 million years ago.[2]
An adult crab louse is about 1.3–2 mm long (slightly smaller than the body louse and head louse), and can be distinguished from those other species by its almost round body. Another distinguishing feature is that the rearmost two pairs of legs of a crab louse are much thicker than the front legs and have large claws.[3]
The eggs of the crab louse are laid usually on the coarse hairs of the genital and perianal regions of the human body. Crab lice may also be found on other areas of the body that have coarse and relatively sparse coverings of hair, such as the beard, moustache, eyelashes, underneath the arms. They do not generally occur on the finer hair of the scalp.[3][4]
The female lays about three eggs a day. The eggs take 6–8 days to hatch, and there are three nymphal stages which together take 10–17 days before the adult develops, making a total life cycle from egg to adult of 16–25 days. Adults live for up to 30 days.[3] Crab lice feed exclusively on blood, and take a blood meal 4–5 times daily.
Infestations of crab lice are known as pediculosis pubis or phthiriasis pubis (which, unlike the generic name of the louse, is spelled with a phth). Infestation of the eyelashes is referred to as pediculosis ciliaris or phthiriasis palpebrarum.[5]
The main symptom of infestation with crab lice is itching, usually in the pubic-hair area, resulting from hypersensitivity to louse saliva, which can become stronger over two or more weeks following initial infestation. In some infestations, a characteristic grey-blue or slate coloration appears (maculae caeruleae) at the feeding site, which may last for days.
Current worldwide prevalence has been estimated at 2% of the human population, but accurate numbers are difficult to gauge because crab lice infestations are not considered a reportable condition by many governments, and many cases are self-treated or treated discreetly by primary physicians.[6]
Crab lice usually infect a new host only by close contact between individuals, usually through sexual intercourse. Adults are more frequently infested than children. Non-sexual transmissions may occur among family and roommates through the use of shared towels, clothing, beds or closets. They can only survive a short time away from the warmth and humidity of the human body.
It has recently[when?] been suggested that an increasing percentage of humans removing their pubic hair has led to reduced crab louse populations in some parts of the world.[7][8] Because the World Health Organization and other authorities do not record statistics for pubic louse infestation, there is virtually no hard data to support this supposition.
| Wikimedia Commons has media related to Pubic lice. |
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| リンク元 | 「性感染症」 |
| 関連記事 | 「Phthirus」 |
♂：淋菌性尿道炎 ＞ クラミジア性尿道炎 ＞ 性器ヘルペス ＞ 尖圭コンジローマ ♀：クラミジア性尿道炎 ＞ 性器ヘルペス ＞ 尖圭コンジローマ ＞ 淋菌性尿道炎
| 病原体 | 感染症 | 原因ウイルス |
| ウイルス | 性器ヘルペス | 単純ヘルペスウイルス |
| 尖圭コンジローマ、子宮頚癌 | ヒト乳頭腫ウイルス | |
| B型肝炎 | B型肝炎ウイルス | |
| C型肝炎 | C型肝炎ウイルス | |
| エイズ | ヒト免疫不全ウイルス | |
| 成人T細胞白血病 | ヒトTリンパ球向性ウイルス | |
| サイトメガロウイルス感染症 | サイトメガロウイルス | |
| 伝染性軟属腫 | 伝染性軟属腫ウイルス | |
| 伝染性単核症 | EBウイルス | |
| 細菌 | 梅毒 | 梅毒トレポネーマ |
| 性器クラミジア感染症 | クラミジア・トラコマチス | |
| 淋病 | 淋菌 | |
| 軟性下疳 | ヘモフィルス・デュクレイ | |
| 鼠径部肉芽腫 | 肉芽腫カリマトバクテリウム | |
| 赤痢 | 赤痢菌 | |
| 非淋菌性尿道炎 | クラミジア・トラコマチス、マイコプラズマ、ウレアプラズマ | |
| 真菌 | 口腔カンジダ症 | カンジダ |
| 非淋菌性尿道炎 | カンジダ | |
| 寄生虫、 原虫 |
いろいろ | トリコモナス |
| 非淋菌性尿道炎 | 腟トリコモナス | |
| アメーバ赤痢 | 赤痢アメーバ | |
| 毛ジラミ症 | Phthirus pubis | |
| 疥癬 | 疥癬虫 | |
| 白癬 | Trichophyton rubrum, Trichophyton mentagrophytes | |
| ランブル鞭毛虫下痢症 | ランブル鞭毛虫 |
ケジラミ、ジラミ属