How do pubic lice differ from ordinary lice? - briefly
Pubic lice (Pthirus pubis) are larger, have a crab‑like appearance, and infest coarse hair such as pubic, axillary, or facial hair, whereas head and body lice (Pediculus humanus) are smaller, elongated, and live on finer scalp hair or clothing. Pubic lice feed rapidly and cause intense, localized itching, while other lice feed more slowly and spread more easily through direct contact or contaminated items.
How do pubic lice differ from ordinary lice? - in detail
Pubic lice (Pthirus pubis) and the more familiar head or body lice (Pediculus humanus capitis and Pediculus humanus corporis) belong to different genera and exhibit distinct biological and epidemiological characteristics.
The insects differ in size and shape. Pubic lice are about 1 mm long, broader and crab‑like, with a shorter abdomen and large, clawed legs adapted for grasping coarse hair. Head and body lice are elongated, up to 3 mm, with a slender body and legs suited for finer hair shafts.
Habitat preferences separate the species. Pubic lice inhabit the coarse hair of the genital region, perianal area, and occasionally chest or abdominal hair. Head lice reside on scalp hair, while body lice occupy clothing seams and lay eggs on fabric, moving to the skin only to feed.
Transmission routes also vary. Pubic lice spread primarily through direct sexual contact; occasional transmission can occur via contaminated bedding or towels. Head lice are transmitted by head‑to‑head contact or sharing combs, hats, or pillows. Body lice spread through prolonged use of infested clothing and poor hygiene.
Feeding behavior shows minor differences. All three feed on human blood, but pubic lice bite less frequently, causing localized itching in the pubic region. Head lice bite the scalp, leading to scalp irritation; body lice bite the trunk, often producing widespread pruritic lesions.
Reproductive traits diverge. Pubic lice lay 1–2 eggs (nits) per day, attaching them firmly to hair shafts close to the skin. The eggs hatch in 6–10 days. Head lice produce up to 10 eggs per day, cemented to scalp hair at a similar distance from the skin. Body lice lay 5–10 eggs per day on clothing fibers; the eggs hatch in 7–10 days, and the nymphs migrate to the skin to feed.
Treatment options reflect these differences. Topical insecticides (permethrin 1 % lotion, pyrethrin‑based shampoos) are effective for pubic and head lice. Body lice require washing or ironing infested clothing at ≥ 60 °C, combined with the same topical agents for skin infestation. Resistance to pyrethroids has been reported more frequently in head lice populations.
In summary, pubic lice differ from common head and body lice in morphology, preferred body region, transmission mode, egg‑laying site, and specific control measures. Recognizing these distinctions guides accurate diagnosis and appropriate management.