A comb is a daily grooming tool used to detangle and style hair. Because of its direct contact with the scalp, a comb can become a vehicle for transmission when shared. The teeth can collect loose hairs, skin cells, oils, and microscopic organisms, transferring them between people. This article will detail the specific parasitic, fungal, and bacterial agents that can spread this way.
Parasitic Transmission
The most recognized organism transmitted by combs is the head louse, Pediculus humanus capitis. These tiny, wingless parasitic insects live on human heads and feed on blood from the scalp. Adult lice, about the size of a sesame seed, have claws adapted for gripping hair shafts, allowing them to crawl onto a comb’s teeth and transfer to a new host.
Transmission is not limited to adult lice. Female lice lay eggs, known as nits, cementing them to the base of hair shafts. These oval, yellowish-white eggs can be mistaken for dandruff but are not easily brushed away. A comb passing through infested hair can snag hairs with nits attached, depositing them onto another person’s head and starting a new infestation when they hatch in 7 to 10 days.
The life cycle from egg to adult takes about three weeks. This cycle shows why both lice and nits are problematic, as a single nit can start an infestation. While direct head-to-head contact is the primary way lice spread, shared combs are a secondary route of transmission.
Fungal and Bacterial Infections
Beyond visible parasites, combs can harbor microscopic fungi and bacteria. A common fungal infection of the scalp is tinea capitis, or scalp ringworm. This condition is caused by dermatophyte fungi that thrive on keratin, a protein in hair and skin, leading to red, scaly, and itchy patches that can cause hair loss. Fungal spores can contaminate a comb and infect the next person who uses it.
Bacterial infections can also spread through shared combs, especially if there are breaks in the scalp’s skin. Bacteria like Staphylococcus aureus can cause folliculitis or impetigo. Folliculitis is an inflammation of hair follicles appearing as small, red bumps, while impetigo is a skin infection that causes sores with a honey-colored crust.
A comb used on an infected scalp can collect these bacteria. Combing can also create micro-abrasions on the scalp, providing an entry point for the bacteria on a subsequent user. Scalp irritation or excessive sweating can increase the risk of these bacterial infections taking hold after transfer.
Viral Transmission Risks
Viral transmission via a comb is less common than parasitic or fungal spread, as it requires specific circumstances. The risk exists when an active, open lesion on the scalp is shedding viral particles. A comb could then pick up the virus and transfer it to another person.
One example is molluscum contagiosum, a viral infection causing small, raised bumps on the skin. The virus spreads through direct contact or by touching contaminated objects like hairbrushes. If a comb scratches these bumps, the virus could be transferred to the tool and then to another person’s skin. A case study noted electric trimmers were a likely source of transmission, showing grooming tools can act as fomites.
Viruses like herpes simplex also need an active lesion on the scalp to pose a risk. For transmission to occur, the comb must contact fluid from a blister and then quickly touch broken skin on another person. The conditional nature of this route makes it a theoretical, rather than a probable, risk for the general population.
Prevention and Proper Comb Hygiene
Personal Hygiene
Preventing disease transmission begins with not sharing combs. To maintain a clean comb, regularly remove all trapped hair from its teeth. After removing the hair, wash the comb thoroughly with soap and warm water to eliminate oils and grime.
For more robust cleaning, disinfection is necessary. Most plastic or metal combs can be soaked in a 70% isopropyl alcohol solution or a diluted bleach solution for about 10 minutes. After disinfecting, rinse the comb with clean water and let it dry completely before use. This routine cleaning and disinfecting reduces the presence of potential pathogens.
Professional Hygiene
In professional settings like barbershops and hair salons, hygiene standards are regulated to protect clients. A main practice is the disinfection of all non-porous tools between customers. Patrons should look for evidence that their stylist is using clean tools, such as removing them from a sealed container or a disinfectant jar.
This disinfectant is often Barbicide, an EPA-registered solution effective against bacteria, viruses, and fungi. The procedure involves cleaning tools of physical debris and then fully immersing them in the disinfectant for at least 10 minutes to ensure all pathogens are destroyed.