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Pubic lice are small, six-legged creatures that infect the pubic hair area and lay eggs. These lice can also be found in armpit hair and eyebrows.

蝨蝨有三種,陰蝨、頭蝨和體蝨

Causes

Pubic lice are known as Phthirus pubis. Lice infestation is found mostly in teenagers and usually spreads during sexual activity.

Sometimes, pubic lice can spread through contact with objects such as toilet seats, sheets, blankets, or bathing suits at a store. However, this type of spreading is rare.

Animals cannot spread lice to humans.

Other types of lice include:

Risk factors include:

  • Having multiple sexual partners
  • Having sexual contact with an infected person
  • Sharing bedding or clothing with an infected person

雖然最常見於陰部,但陰蝨在絕大部份人類毛髮上均可生存。它的身體較頭蝨寬闊,腳部較寬廣,使它可於疏落的毛髮間攀爬。除了陰毛外,陰虱也可在頭髮、睫毛、鬍鬚和腋毛處寄生。

和其他蝨子一樣,陰蝨以人類的血液為食物,因此陰蝨棲息的患處會不時感到痕癢。另外,陰蝨亦可能帶有其他病菌,使患者產生感染。

陰蝨的傳播途徑主要是性交,因此陰蝨感染被認為是性傳播疾病的一種。衣物和床鋪也是陰蝨的重要傳播途徑。廁所則不會傳染陰蝨,因為廁所的平面光滑,缺乏可讓蝨子停留的條件。如廁前不久如患有陰蝨患者剛使用過,亦有被傳染之可能。

生命週期

陰虱為不完全變態發育,其生活史分為:卵、若蟲和成蟲三個階段。

  1. :陰蝨的蟲卵一般都緊附在陰毛的毛幹根部上,呈淡紅色或鐵鏽色的橢圓形,類似於點狀血痂。孵化期約為一星期。
  2. 若蟲:若蟲是陰虱自卵孵化後,成長為成蟲之前的形態。若蟲的樣子與成蟲相似,但是要小很多。若蟲的成長期亦為一星期左右。
  3. 成蟲:陰虱的成蟲呈灰白色或褐色,雌蟲一般比雄蟲為大。

一般陰蝨的壽命是30天,但所有脫離人體的陰蝨均會在2天內死亡。

雄蝨.....公蝨

公    

雌性:

母  

Symptoms

Almost anyone with pubic lice will have itching in the area covered by pubic hair (it often gets worse at night). This itching may start soon after getting infected with lice, or it may not start for up to 2 - 4 weeks after contact.

Other symptoms:

  • Skin reaction that is bluish-gray in color
  • Sores (lesions) in the genital area due to bites and scratching

被陰虱寄生後,通常會出現如下徵症:

  1. 陰部搔癢,特別是夜間搔癢更甚;
  2. 陰部出現紅疹、丘疹、血痂或青斑;
  3. 內褲上有鐵鏽色粉末狀或顆粒狀虱糞;
  4. 陰毛根部可發現鐵鏽色或紅褐色橢圓形蟲卵;
  5. 陰毛處發現陰虱活動。
皮  

Exams and Tests

An examination of the outer genital area shows small gray-white oval eggs (nits) attached to the hair shaft. It may also reveal adult lice. The health care provider might also see scratch marks or signs of an infection, such as impetigo.

Because pubic lice may cause an eye infection (blepharitis) in young children, their eyelashes should be examined for evidence of lice with a high-powered magnifying glass.

Adult lice may be easily identified under the microscope. Their crab-like appearance is the reason that pubic lice are referred to as "the crabs."

Teenagers with pubic lice may need to be tested for other sexually transmitted infections (STIs).

Treatment

Pubic lice are best treated with a prescription wash containing permethrin, such as Elimite or Kwell:

  • Thoroughly work the shampoo into the pubic hair and surrounding area for at least 5 minutes.
  • Rinse well.
  • Comb the pubic hair with a fine-toothed comb to remove eggs (nits). Applying vinegar to pubic hair before combing may help loosen nits, but the hair should be dry when applying the shampoo.
  1. 剃淨陰毛及肛周毛髮並將其焚燒;
  2. 將被污染的衣物、床單、被罩蒸煮或開水澆燙消毒,殺滅蟲卵及成蟲;
  3. 使用熱水及肥皂(硫磺皂)清洗陰部或是買Malathione洗劑
  4. 由於感染方式為接觸感染,必須請所有有接觸的人都一起治療

A single treatment is all that is usually needed. If another treatment is recommended, it should be done 4 days to 1 week later.

Over-the-counter medications for the treatment of lice include Rid and Nix. Malathione lotion is another treatment option.

While you are treating pubic lice, wash all clothing and linens in hot water. Items that cannot be washed may be sprayed with a medicated spray or sealed (suffocated) in plastic bags and not used for 10 - 14 days. It is important for all intimate contacts to be treated at the same time.

People with pubic lice should be evaluated for other sexually-transmitted infections at the time of diagnosis.

Malathion Lotion 

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Outlook (Prognosis)

The proper treatment, including thorough cleaning, should get rid of the lice.

Possible Complications

The constant scratching and digging can cause the skin to become raw, and secondary infections may develop.

When to Contact a Medical Professional

Call for an appointment with your health care provider if:

  • You or your sexual partner has symptoms of pubic lice
  • You try over-the-counter lice treatments and they are not effective
  • Your symptoms continue after treatment

Prevention

Avoid sexual or intimate contact with infected people. If you are sexually active, use safe sex practices to avoid getting lice.

Good personal hygiene is always recommended. If possible, avoid trying on bathing suits while you are shopping. However, if you must try them on, be sure to wear your underwear. This may prevent transmission.

Alternative Names

Pediculosis - pubic lice; Lice - pubic; Crabs

References

Habif TP, ed. Clinical Dermatology. 5th ed. Philadelphia, Pa:Mosby Elsevier;2009: pp 590-594.

Diaz JH. Lice (pediculosis). In: Mandell GL, Bennett JE, Dolin R. Mendell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 7th ed. Philadelphia, Pa:Churchill Livingstone Elsevier;2009:chap 293.


之前介紹過的頭蝨:

[WebMD] Head Lice Grow Resistant to Treatments 頭蝨的治療阻抗性日增

 

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