Black piedra is a dermatological hair disease of a fungal nature, mainly characteristic of tropical countries with warm and humid climates. This condition is manifested by the appearance on the hair of the head (less often – a beard or mustache) of inconspicuous black nodules measuring 1-2 millimeters of rocky density, in the future – hair fragility and alopecia. Diagnosis is made by examining the hair, microscopy of nodules, sowing scrapings on special media to identify the pathogen. For treatment, both physical techniques are used (shaving the hair) and the treatment of the hair with special substances that are harmful to the fungus.
B36.3 Black Piedra
Black piedra is an anthroponotic mycosis affecting the cuticle of the hair of the head, beard and mustache, common in regions with a warm climate. For the first time this condition was described in 1878, later it turned out that the disease is spread almost throughout the tropical belt – in the countries of South America, Africa and Southeast Asia. Among the patients with black piedra, women aged 25 to 40 years predominate, in men and children this pathology is extremely rare.
Basically, the disease is transmitted from person to person, but the presence of the pathogen in the soil and water of standing reservoirs gives reason to assume other ways of infection. Indirectly, the possibility of other transmission routes is also proved by the fact of more frequent development of black piedra in swimmers and fishermen – some types of algae in freshwater lakes contain a large amount of the pathogen fungus. An important role in the spread of the disease is played by the level of hygiene of the population and the cultural characteristics of some peoples. Thus, the customs of tightly braiding hair, rubbing vegetable oils into them or wearing tight hats contribute to a heavier flow of black piedra.
The causative agent of the black piedra is the microscopic mold Piedraia hortae, which has the ability to develop both on the surface and in the thickness of the hair shaft. There is a correlation between the probability of infection, the severity of symptoms of pathology and the level of human immunity – with a significant weakening of the body’s defenses, infection can be transferred to the skin and even internal organs. However, most often the pathogen of the black piedra affects only the hair.
Infection with black piedra can occur when using common combs, hats, sometimes through bed linen. Cases of infection have been reported when washing hair in water from stagnant reservoirs, contact with the fur of some animals (while the latter act only as carriers of the fungus).
Non-compliance with the rules of personal hygiene (rare washing of the head) facilitates infection and contributes to the more pronounced development of the pathogen of the black piedra. In addition, this condition develops more often in weakened individuals, patients with diabetes mellitus, various variants of immunodeficiency, oncological diseases. Because of this, in the presence of a black piedra, a dermatologist often recommends a general examination to identify possible hidden pathologies.
After infection, the fungus begins to develop in the cuticle of the hair shaft, showing a tendency to grow along the course of the hair. After some time, Piedraia hortae forms spores – their densely packed groups are visually defined as nodules on the surface of the rod. Skin lesions with black piedra are extremely rare and are usually observed in people with immunodeficiency, this fungus never affects nails.
It has been noticed that most often the fungus affects straight hair, whereas in persons with wavy or curly hair, pathology is much less common. For the first time after infection, the black piedra does not manifest itself in any way – there are no subjective symptoms (itching, irritation) of this disease, and individual nodules on the hairs often go unnoticed. As the fungal lesion progresses, there are more and more such nodules.
Visually, they are usually poorly visible (especially with black hair color), but can be determined by touch when passing hairs between the fingers. In some cases, individual “packages” of spores can merge with each other, forming a kind of coupling. Nodules with a black piedra are very dense, which is reflected in the name of the disease (“piedra” – stone), with a large number of them, in the case of combing the hair, crunching, sometimes of a metallic nature, can be heard.
In the normal course of the disease, mycelium and fungal spores do not penetrate deep into the hair shaft, so there are no violations of its structure and growth. In advanced cases of black piedra, signs of increased hair fragility gradually increase. If the rules of personal hygiene are not followed and (especially) the hair is tied in a tight bundle, it is possible that nodules from different hairs stick together. This leads to the development of a characteristic symptom of the black piedra – the “Columbian tangle”. This is the name of a bundle of hair stuck together due to mycosis, outwardly similar to a sheaf of wheat or barley. In far-advanced cases of black piedra, alopecia occurs. The disease is chronic and can last for many months or even years.
Usually, the definition of a black piedra in clinical dermatology is not particularly difficult due to the specific symptoms of the disease. However, in temperate latitudes, difficulties often arise due to the poor awareness of doctors about this pathology due to its rarity in this climate. An important diagnostic criterion of the black piedra in this case will be the presence in the patient’s history of a recent trip to tropical countries. Less often, infection occurs without leaving, from another person who recently arrived from a trip.
- Objective data. When examining the hair, very dense black nodules of 1-2 millimeters in size are revealed. When bending the affected hair, a crunch may be heard due to the destruction of the structure of the fungus.
- Laboratory tests. In controversial cases, microscopic and mycological studies are resorted to to confirm the diagnosis of the black piedra. When examining the affected hairs or scrapings from them under a microscope, a fungus with a wide mycelium is detected, from which dense, usually rectangular arthrospores are formed. For the diagnosis of black piedra, sowing on Saburo medium is also used – if there is Piedraia hortae on the hair, black or gray colonies of rounded shape are formed on the nutrient medium.
Differential diagnosis is performed with pediculosis and false piedra – a contagious trichological disease of bacterial origin.
The simplest and most effective approach to the treatment of black piedra is the complete removal (shaving) of the hair cover. Since Piedraia hortae in the vast majority of cases affects exclusively the hair rods, after such a procedure, the pathogen is eliminated, and the grown hair turns out to be healthy. However, not all patients approve of this method of treating black piedra, especially when you consider that the disease mainly affects young women who do not want to shave their heads.
When refusing to remove hair, various antifungal agents are used – amicazole and its analogues. It is also effective to wash the head in a solution of 0.1% mercury dichloride solution, combing the hair with a thick comb followed by washing with shampoo or antifungal solutions. The duration of treatment of black piedra varies depending on the degree of damage to the hair, but usually is at least a month.
Prognosis and prevention
With proper treatment or shaving of the affected hairline, the prognosis of the black piedra is favorable – patients recover completely and restore the normal appearance of their hair. In the absence of treatment, as well as in the presence of concomitant diseases (diabetes mellitus, immunodeficiency, malignant tumors), alopecia and fungal lesions of internal organs may develop.
For the prevention of black piedra, it is necessary to observe the rules of personal hygiene (especially when traveling to tropical countries), avoid bathing in reservoirs with standing water, do not use other people’s combs, hats, hair ornaments. There are also frequent cases of infection with Piedraia hortae when using local “folk” hair care products, therefore, they should not be purchased and used.