Glochids are hair-like spines or short prickles, generally barbed, found on the areole

Areole

Areoles are an important diagnostic feature of cacti, and identify them as a family distinct from other succulent plants. The areoles on cacti are clearly visible; they generally appear as small light- to dark-colored bumps, out of which grow clusters of spines...

s of cacti

Cactus

A cactus is a member of the plant family Cactaceae. Their distinctive appearance is a result of adaptations to conserve water in dry and/or hot environments. In most species, the stem has evolved to become photosynthetic and succulent, while the leaves have evolved into spines...

 in the sub-family Opuntioideae. Cactus glochids easily detach from the plant and lodge in the skin, causing irritation

Irritation

Irritation or exacerbation, in biology and physiology, is a state of inflammation or painful reaction to allergy or cell-lining damage. A stimulus or agent which induces the state of irritation is an irritant...

 upon contact. The tufts of glochids in the areoles nearly cover the stem surfaces of some cactus species, each tuft containing hundreds of glochids; this may be in addition to, or instead of, the larger, more conspicuous cactus spines, which do not readily detach and are not generally barbed.

Mechanical irritant dermatitis

Reaction to the glochidia

Most cacti possess spines, some large enough to cause serious wounds. Glochids however, though smaller, commonly induce more troublesome, more persistent, dermatological manifestations in humans. Though minute, glochids commonly are barbed and once they have penetrated the skin barbed glochids are practically impossible to dislodge without leaving scraps of foreign material in the wound.

Implantation of glochidia in the skin does sometimes cause immediate irritation, but not always, as one may deduce from the presentation of patients with granulomatous

Granuloma

Granuloma is a medical term for a tiny collection of immune cells known as macrophages. Granulomas form when the immune system attempts to wall off substances that it perceives as foreign but is unable to eliminate. Such substances include infectious organisms such as bacteria and fungi as well as...

 lesion

Lesion

A lesion is any abnormality in the tissue of an organism , usually caused by disease or trauma. Lesion is derived from the Latin word laesio which means injury.- Types :...

s around glochidia, patients who have no recollection of the penetration that caused the acute

Acute (medicine)

In medicine, an acute disease is a disease with either or both of:# a rapid onset, as in acute infection# a short course ....

 injury, even when it is clear that the injury is far from fresh. Understandably, distraction or excitement might cause the victim to overlook brushing past a cactus and picking up a few hundred barely visible glochids. In such cases, the irritant reaction may have a delayed onset. Shanon reported that brushing his axillary skin with sabra fruit resulted in no symptoms for a half hour, followed by 1½ hours of "stabbing feelings". Winer reports immediate burning sensation, redness and swelling which remained for one to three days if the spines were removed. Depending on the exposure, widespread areas may be involved, even extending to hard palate, tongue, conjunctiva and cornea.

If the glochidia are not removed, a response may ensue that eventuates in granulomatous dermatitis. Within 24 to 72 hours there is the appearance of 2- to 5-mm, asymptomatic, domed, glistening papules, sometimes erythematous, with a central pin-point-sized black dot at the site of the injury. There may be groups of these papules. Vesicles and pustules and even focal ulceration may also occur. In some instances, diagnosis can be made easily by passing the fingers over the affected area and by feeling the embedded glochidia.

Left untreated, these lesions may last as long as 9 months. A biopsy of the later lesions reveals granuloma formation with plant material embedded in the dermis. The fragments of the barbed bristles gave strongly positive reactions with PAS. The presence of a cactus granuloma lesion is often followed by post-inflammatory hyperpigmentation.

Penetrating injuries can introduce pathogenic microorganisms into the wound. Examples include Clostridium tetani

Clostridium tetani

Clostridium tetani is a rod-shaped, anaerobic bacterium of the genus Clostridium. Like other Clostridium species, it is Gram-positive, and its appearance on a gram stain resembles tennis rackets or drumsticks. C. tetani is found as spores in soil or in the gastrointestinal tract of animals. C...

and Staphylococcus aureus

Staphylococcus aureus

Staphylococcus aureus is a facultative anaerobic Gram-positive coccal bacterium. It is frequently found as part of the normal skin flora on the skin and nasal passages. It is estimated that 20% of the human population are long-term carriers of S. aureus. S. aureus is the most common species of...

(from spines and thorns), Sporothrix schenckii

Sporothrix schenckii

Sporothrix schenckii is a thermally dimorphic fungus that can be found world-wide.The species is present in soil, and in vital and decomposing plant material such as peat moss. Colonies grow moderately rapidly at . They are moist, leathery to velvety, and have a finely wrinkled surface...

(from rose thorns, grasses, and sphagnum moss), Mycobacterium kansasii

Mycobacterium kansasii

Mycobacterium kansasii is a bacterium in the Mycobacterium family. The genus includes species known to cause serious diseases in mammals, including tuberculosis and leprosy, but this species is generally not dangerous to healthy people....

(from blackberries), Mycobacterium marinum

Mycobacterium marinum

Mycobacterium marinum is a free-living bacterium, which causes opportunistic infections in humans.- History :Although Aronson isolated this mycobacterium in 1926 from a fish, it was not until 1951 that it was found to be the cause of human disease by Linell and Norden...

(from cactus spines), and Mycobacterium ulcerans

Mycobacterium ulcerans

Mycobacterium ulcerans is a slow-growing mycobacterium that classically infects the skin and subcutaneous tissues, giving rise to indolent nonulcerated and ulcerated lesions. After tuberculosis and leprosy, Buruli ulcer is the third most common mycobacteriosis of humans. M...

(from spiky tropical vegetation).

Glochids from prickly pears (Opuntia

Opuntia

Opuntia, also known as nopales or paddle cactus , is a genus in the cactus family, Cactaceae.Currently, only prickly pears are included in this genus of about 200 species distributed throughout most of the Americas. Chollas are now separated into the genus Cylindropuntia, which some still consider...

species) can cause an extremely pruritic

Itch

Itch is a sensation that causes the desire or reflex to scratch. Itch has resisted many attempts to classify it as any one type of sensory experience. Modern science has shown that itch has many similarities to pain, and while both are unpleasant sensory experiences, their behavioral response...

, papular

Papule

A papule is a circumscribed, solid elevation of skin with no visible fluid, varying in size from a pinhead to 1 cm.With regard to the quote "...varying in size from a pinhead to 1cm," depending on which text is referenced, some authors state the cutoff between a papule and a plaque as 0.5cm,...

 eruption called sabra dermatitis, which can easily be confused with scabies

Scabies

Scabies , known colloquially as the seven-year itch, is a contagious skin infection that occurs among humans and other animals. It is caused by a tiny and usually not directly visible parasite, the mite Sarcoptes scabiei, which burrows under the host's skin, causing intense allergic itching...

 or fiberglass dermatitis

Contact dermatitis

Contact dermatitis is a term for a skin reaction resulting from exposure to allergens or irritants . Phototoxic dermatitis occurs when the allergen or irritant is activated by sunlight....

.

Sabra Dermatitis
The skin reaction of gatherers of the fruit was described in Israel and is known as "sabra dermatitis". This condition is characterized by a papular or vesicular

Cutaneous conditions

There are many conditions of or affecting the human integumentary system—the organ system that comprises the entire surface of the body and includes skin, hair, nails, and related muscle and glands.- Diseases :...

 reaction that is sometimes scabies-like. It has also been described as tinea

Tinea

Tinea is a general term used to describe skin mycoses. The term ringworm is even less precise, but is usually considered a synonym.It is sometimes equated with dermatophytosis, and it is true that most conditions identified as "tinea" are members of the imperfect fungi that make up the dermatophytes...

-like and dyshidrosis

Dyshidrosis

Dyshidrosis is a skin condition that is characterized by small blisters on the hands or feet...

-like. The hard palate and tongue are occasionally affected. Typical areas of involvement of this irritant dermatitis include fingers, wrists, genitals, thorax, and buttocks. Biopsy of these lesions will reveal that they contain glochidia. Glochidia may be transferred to the workers' clothing and thence to other individuals. It is recommended that the fruit should be picked only when wetted, and picking should be stopped when it is windy since the glochidia can become airborne.

Removal of Glochidia

If the glochidia are allowed to remain in the skin, a dermatitis may ensue that will persist for months. It may help to treat the affected area with a topical corticosteroid. However, since the presence of glochidia is the inciting factor, removal of these minute spines would seem to be a more rational approach.

Glochidia may be difficult to remove. Yanking out the bristles may result in leaving one or more 20-30 micrometre sized barbs in the skin, later to be manifest by granuloma formation. Attempts to suck out the glochidia are likely to result in their attachment to the tongue. Popular methods of removing glochidia have included spreading adhesive plaster over the area and ripping it off quickly or using melted wax (hot wax sometimes employed for removing hair). Martinez et al. studied various methods of removing glochidia from rabbit skin. They evaluated tweezers, glue, facial mask, adhesive tape, package-sealing tape, and tweezing followed by glue. The most effective single method was tweezing, which removed 76% of the spines. The method using a thin layer of household glue (Elmer's Glue-All, Borden Inc) covered with gauze, allowed to dry (about 30 minutes) and then peeled off resulted in removal of 63% of the spines. Facial mask and adhesive tapes removed about 40% and 30% of the spines, respectively, and produced more retention and inflammation three days after removal than no treatment. Repeated applications of adhesive tape did not improve the results. According to Martinez, the most effective method is to first use tweezers to remove clumps of spines followed by the application and removal of household glue, resulting in removal of 95% of the spines.

Unroofing the early vesicles or pustules may permit manual extraction of the spicules. Soaking unroofed papules may allow for extrusion of the glochidia. Faster resolution may be obtained by removing the papules. A method of treatment has been described for the granulomatous papules, and involves unroofing the granulomatous papules, removing the glochidia fragments under a dissecting microscope, and subsequently soaking the wound in an antibacterial solution.