If you have pets at home, be alert to tinea capitis!

Author: Li Ruoyu, Chief Physician, Peking University First Hospital

Reviewer: Yang Rongya, Chief Physician, Seventh Medical Center, PLA General Hospital

Tinea capitis is an infectious disease of the hair and scalp caused by dermatophytes. It mainly occurs in children, especially preschoolers, and is often caused by contact with animals infected with dermatophytes.

Because children's immune function is often not particularly sound, especially preschool children, the sebaceous glands of the scalp are not fully developed, and the sebaceous glands can secrete some long-chain fatty acids, which have a certain protective effect on the scalp and can resist dermatophyte infection. Healthy adults have the secretion of long-chain fatty acids and are generally immune to these fungal infections.

Therefore, for families with pets, especially those with children, they must pay attention to check whether the pets have local hair loss or scabs. If skin damage is found, go to the pet hospital for diagnosis and treatment in time. The objects that the pet has come into contact with must also be disinfected to avoid transmission to children.

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When children who have contact with pets develop hair loss patches or lesions such as erythema, desquamation, and pustules on their scalp, they should suspect that they have been infected with tinea capitis and need to go to the hospital's dermatology department for examination and diagnosis in time.

First, the doctor will conduct a comprehensive examination of the child, and may focus on observing the characteristics of hair loss, hair breakage, redness, swelling, and pustule formation, etc. In addition, the doctor will check how many ringworms there are on the scalp, whether there are any other ringworms on the body, etc.

In addition, some tools are also used to assist in diagnosis. For example, the Wood's lamp is a UV lamp, and many tinea capitis lesions will produce fluorescence under the irradiation of UV lamps. When irradiating the lesion area of ​​tinea capitis, if it is white ringworm from an animal source, it will generally produce very bright, green fluorescence, so this inspection method can help us detect lesions that are invisible to the naked eye, thereby discovering latent infection areas, and can also help us monitor the effectiveness of treatment. However, not all tinea capitis produce fluorescence.

Fungal microscopic examination is an important means to help us diagnose tinea capitis. The infected hair is pulled out and placed under a microscope for observation after magnification. This examination method is more professional and can determine whether the hair is affected externally or internally. This can help distinguish which type of tinea capitis it is. Generally speaking, white ringworm only forms a hair sheath around the hair, while black spot ringworm invades the hair, causing the hair to break easily. The microscope is helpful for identification.

We can also culture the infected hair for fungi to find out which pathogens are causing the infection, which can help us choose treatment methods. If possible, we can also perform fungal microscopy or culture on the hair of sick cats and dogs at home to see if they are the same bacteria that the child is infected with, which can help determine the source of infection.

In addition to these classic methods, there are also some newer inspection methods, such as dermatoscope, which is a polarized light detection method. Under the dermatoscope, it is possible to more clearly observe whether the diseased hair has hair sheaths or broken hairs, such as some structures like commas and some structures like telegram codes, which are more clearly observed under the dermatoscope.

Generally speaking, by combining clinical manifestations, hair loss conditions, hair breakage characteristics, and then adding mycological examinations, Wood's lamp examinations, dermoscopy, etc., it is possible to confirm whether a child has tinea capitis and what type of tinea capitis it is.

Of course, adults may also suffer from tinea capitis, such as people with diabetes, or people with low immune function due to long-term use of glucocorticoids, immunosuppressants and other drugs. Under such conditions, they may also be infected with tinea capitis.

When a family member has tinea capitis, they may become a source of infection, causing the pathogen to spread from person to person, so multiple family members may suffer from tinea capitis at the same time. In addition, in some collective gathering environments, such as childcare centers and schools, people will have close contact with each other, and collective illness may also occur.

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When a person has tinea capitis, the prevention and treatment should follow the five-word principle of "apply, apply, shave, wash, and disinfect". In terms of prevention, the patient should be isolated at home, and all the items used, such as bedding, cleaning supplies, towels, pillowcases, etc., should be disinfected and processed in time. They can be boiled, steamed, or soaked in disinfectant. While actively treating, the spread of pathogens can be blocked to protect the people around them.