Scabies is a highly contagious skin condition caused by the infestation of a parasite known as the Sarcoptes scabiei mite. The mite burrows into the skin and creates intense itching, especially at night. The condition is spread through close skin contact, putting family members and intimate relationships at risk.
In 2009, the World Health Organization declared scabies a neglected skin disease, which remains a significant health concern in many underdeveloped countries. Early detection and treatment are crucial, as misdiagnosis can lead to outbreaks, increased morbidity, and a higher economic burden on society. Diagnosing scabies can be difficult as not everyone shows typical symptoms of infestation.
Epidemiology
Scabies is a widespread skin infection caused by the mite Sarcoptes scabiei. The estimated global prevalence of scabies is 300 million infected individuals each year, with the highest rates in developing countries and among populations living in poverty, poor hygiene, overcrowding, and malnutrition.
Scabies is most common among children and young adults, and outbreaks can occur in institutional settings such as schools, nursing homes, hospitals, and prisons. The World Health Organization has declared scabies a neglected skin disease, highlighting the need for increased attention and resources towards its control and management.
Anatomy
Pathophysiology
Within the epidermis’ superficial layers, adult female mites dig burrow underpasses of 1-10 millimeters long and lay 2-3 eggs daily. The eggs hatch approximately two to three weeks later, and the mites die 30-60 days after that. It is important to note that not all treatments can reach the eggs beneath the skin.
Papules may appear between two and five weeks after an infestation. These papules range from a few millimeters to a centimeter and are comma or tunnel shaped. Infestations typically develop under thin skin in places like the interdigital folds, navel region, areolae, and in men, the shaft of the penis.
Etiology
Both the dermal and epidermal layers of humans and animals contain Sarcoptes scabiei. The female mite burrows into the host’s stratum corneum to lay eggs, which initiates the infestation. It later transforms into nymphs, larvae, and adults. A person with the classic pattern of scabies may have a population of 10-15 mites.
In cases of classic scabies, it usually takes 10 minutes of skin contact with an infected individual for mites to spread to another human host. The disease can also be spread by the fomite, which spreads through bedding or clothing. Hyperkeratotic plaques, which can be diffuse or localized to the soles, palms, and areas under fingernails, are a common symptom of this scabies presentation.
Norwegian scabies, the crusted form, can have millions of mites on an individual. Due to chemotherapy, Diabetes, HIV, or advanced age, immunocompromised patients experience crusted scabies. This high density becomes infected after briefly contacting infected individuals and contaminated objects. The number of infesting mites is typically determined by the host’s immunological state and the extent of the infestation.
Genetics
Prognostic Factors
Scabies is a highly contagious skin condition caused by a mite infestation. The prognosis for scabies is generally good, with prompt and appropriate treatment.
Most people can expect to recover fully within several weeks of starting treatment, although the skin may remain itchy after the mites have been eliminated. If left untreated, scabies can persist for an extended period of time and cause discomfort and skin damage.
Clinical History
Clinical History
A patient’s history can effectively indicate scabies infection. This is characterized by itchy rashes that intensify at night, and if multiple close contacts (including family members) have similar symptoms, this can be further evidence of scabies. Lesions from scabies appear differently in adults and children. In adults, scabies rashes are commonly found on the inside of the wrists, between the fingers, on the top of the feet, in the armpits, on the elbows, around the waist, on the buttocks, and on the genital area.
Scabies is a skin condition characterized by the presence of pruritic papules and vesicles on the scrotum and penis in men, the areolae in women, and in infants and young children, on the scalp, face, neck, palms, and soles. It is also common in immunocompromised and elderly patients who may experience widespread, eczematous eruptions, and in patients with pre-existing skin conditions, such as atopic dermatitis, which can exacerbate the symptoms of scabies.
Patients who have been misdiagnosed with scabies and treated with topical corticosteroids may experience further delays in diagnosis as the symptoms may take on the form of vesicles, nodules, or pustules and become more widespread. The signs and symptoms of scabies tend to increase in intensity over a period of 2-3 weeks before the patient seeks medical attention.
However, in debilitated or immunocompromised patients, the urge to scratch may be absent. Scabies is known to occur in clusters and is more likely to be present in an individual with a rash and itching if there has been an outbreak in the community. It is important to consider scabies in the differential diagnosis when evaluating patients with these symptoms.
Physical Examination
Physical Examination
Clinical manifestations of scabies include primary and secondary lesions. Primary lesions are the initial signs of the infestation and may appear as small bumps, blisters, and burrows. Secondary lesions occur as a result of scratching and rubbing and may be the only visible sign of the condition. In such cases, a diagnosis can be made based on the history of the patient, the distribution of the lesions, and accompanying symptoms. Burrows are a hallmark of scabies and represent the tunnels created by the female mite in the epidermis. These burrows appear as thin, gray, wavy lines in the skin, measuring between 2-10mm in length.
They are not easily visible and require active searching to locate. High-risk areas for burrows include the webbed spaces between fingers, the flexor surfaces of the wrists and elbows, the axillae, the belt line, feet, scrotum in men, and areolae in women. In classic scabies, the lesions are commonly found in the axillae, elbow flexures, wrists, hands, and genital area, which is known as the circle of Hebra. Elderly individuals with scabies tend to have the lesions on their back, appearing as excoriations.
In infants and young children, burrows are frequently seen on the palms and soles. Immune-compromised patients may present with bullous lesions. Adults with scabies typically have erythematous papules and vesicles measuring 1-3mm in size, distributed in typical areas. The vesicles are clear fluid-filled blisters but may appear cloudy if more than a few days old. Papules, which are more likely a hypersensitivity reaction, are commonly seen on the penis shaft in men and the areolae in women.
In contrast, children with scabies often have involvement of the face and neck, as well as widespread eczematous eruptions on the trunk. Infants may also have papules, vesicles, and pustules on their palms and soles. Crusted scabies is characterized by thick, crusted, and hyperkeratotic skin lesions. These lesions can cover large areas of the skin and are often accompanied by scaling. The hands and arms are the most commonly affected areas, but other parts of the body can also be affected.
This form of scabies is caused by a high number of mites, which can range from thousands to millions. In some cases, there may be minimal itching or none at all. Nail dystrophy, scalp lesions, and subungual hyperkeratosis may also occur. Nodular scabies, which is seen in 7-10% of scabies patients, especially in young children, presents as pinkish-brown nodules that range in size from 2-20mm in diameter. These nodules are often found on the skin where the child cannot scratch, and mites are rarely found inside.
Treatment for scabies is available in several forms, and evidence suggests that the standard treatments such as topical crotamiton, permethrin, and systemic ivermectin have similar efficacy when used as directed. The most commonly used treatment is the topical permethrin 5% cream, which is applied once a week for two weeks, resulting in two total treatments.
Although effective, there are occasional reports of poor patient compliance, resistance, and rare allergic reactions. Another option is oral ivermectin, which is not approved by the US FDA for scabies treatment but is recommended due to its convenience, ease of administration, favorable side effect profile, and safety.
It is administered to individuals ten years and older, with two doses given two weeks apart if symptoms persist. The oral form of ivermectin has a higher rate of compliance compared to topical permethrin and reduces the likelihood of misapplication. In outbreaks of scabies, systemic ivermectin is considered superior to topical permethrin. Ensuring adequate treatment is crucial in densely populated settings such as prisons, homeless shelters, and healthcare facilities.
The treatment options for scabies can be limited for some individuals due to factors such as drug resistance, cost, accessibility, or potential toxicity, particularly for pregnant women and children. The occurrence of treatment failure and re-infection is widespread, and identifying the root cause can aid in avoiding the further spread of the parasite and controlling outbreaks within communities.
Some common causes of treatment failure include the failure to treat close contacts simultaneously, not disinfecting beddings and clothing during the treatment process, and not adhering to the prescribed treatment plan. In crusted scabies, treatment failure may result from mites resistant to ivermectin. In such instances, moxidectin is recommended as an alternative therapy for those with known ivermectin-resistant scabies.
Topical-It instructs the patient to thoroughly wash and clean the affected area, remove any loose scales or debris, and then dry the skin. Then, the patient is instructed to apply a thin layer of the medication to the entire body, from the neck to the toes, massaging it into the skin. The patient is instructed to repeat this process 24 hours later and then take a bath 48 hours after the final application to cleanse the body. Additionally, if live mites are still present, the patient may repeat the treatment after 7-10 days
Apply a thin lotion coating and massage it into the skin all over your body, avoiding the face. After 8–12 hours, take a bath and remove the medication
Apply a thin lotion coating and massage it into the skin all over your body, avoiding the face. After 8–12 hours, take a bath and remove the medication
For three days, apply 6% ointment before bedtime each night.
Using soap and water, thoroughly wash and dry the whole body.
Apply from the neck down to the whole body and rub it in gently, allow it to stay for 24 hours.
Wash the body thoroughly using water and soap within 24 hours after your previous treatment
Indicated for Scabies
Cream: From head to the toe area, apply the 5% cream, leave it for 8-14 hours, and wash it; if live mites are reappeared, reapply in 7 days
One-time application is generally sufficient for a curative effect
Head Lice and Nits (Eggs)
Cream/ liquid or lotion: Apply to rinsed hair, and leave it for nearly 10 minutes; wash and comb it to remove nits and eggs; if live mites are reappeared, reapply in 7 days
One-time application is generally sufficient for a curative effect
Topical-It instructs the patient to thoroughly wash and clean the affected area, remove any loose scales or debris, and then dry the skin. Then, the patient is instructed to apply a thin layer of the medication to the entire body, from the neck to the toes, massaging it into the skin. The patient is instructed to repeat this process 24 hours later and then take a bath 48 hours after the final application to cleanse the body. Additionally, if live mites are still present, the patient may repeat the treatment after 7-10 days
Apply a thin lotion coating and massage it into the skin all over your body, avoiding the face. After 8–12 hours, take a bath and remove the medication
For three days, apply 6% ointment before bedtime each night.
Using soap and water, thoroughly wash and dry the whole body.
Apply from the neck down to the whole body and rub it in gently, allow it to stay for 24 hours.
Wash the body thoroughly using water and soap within 24 hours after your previous treatment.
Indicated for Scabies
Age >2 months
Cream: From head to the toe area, apply the 5% cream, leave it for 8-14 hours, and wash it; if live mites are reappeared, reapply in 7 days
One-time application is generally sufficient for a curative effect
Age <2 months
Safety and efficacy not established
Head Lice and Nits (Eggs)
Age >2 months
Cream/ liquid or lotion: Apply to rinsed hair, and leave it for nearly 10 minutes; wash and comb it to remove nits and eggs; if live mites are reappeared, reapply in 7 days
One-time application is generally sufficient for a curative effect
Age <2 months
Safety and efficacy not established
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References
https://www.ncbi.nlm.nih.gov/books/NBK544306/
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Scabies is a highly contagious skin condition caused by the infestation of a parasite known as the Sarcoptes scabiei mite. The mite burrows into the skin and creates intense itching, especially at night. The condition is spread through close skin contact, putting family members and intimate relationships at risk.
In 2009, the World Health Organization declared scabies a neglected skin disease, which remains a significant health concern in many underdeveloped countries. Early detection and treatment are crucial, as misdiagnosis can lead to outbreaks, increased morbidity, and a higher economic burden on society. Diagnosing scabies can be difficult as not everyone shows typical symptoms of infestation.
Scabies is a widespread skin infection caused by the mite Sarcoptes scabiei. The estimated global prevalence of scabies is 300 million infected individuals each year, with the highest rates in developing countries and among populations living in poverty, poor hygiene, overcrowding, and malnutrition.
Scabies is most common among children and young adults, and outbreaks can occur in institutional settings such as schools, nursing homes, hospitals, and prisons. The World Health Organization has declared scabies a neglected skin disease, highlighting the need for increased attention and resources towards its control and management.
Within the epidermis’ superficial layers, adult female mites dig burrow underpasses of 1-10 millimeters long and lay 2-3 eggs daily. The eggs hatch approximately two to three weeks later, and the mites die 30-60 days after that. It is important to note that not all treatments can reach the eggs beneath the skin.
Papules may appear between two and five weeks after an infestation. These papules range from a few millimeters to a centimeter and are comma or tunnel shaped. Infestations typically develop under thin skin in places like the interdigital folds, navel region, areolae, and in men, the shaft of the penis.
Both the dermal and epidermal layers of humans and animals contain Sarcoptes scabiei. The female mite burrows into the host’s stratum corneum to lay eggs, which initiates the infestation. It later transforms into nymphs, larvae, and adults. A person with the classic pattern of scabies may have a population of 10-15 mites.
In cases of classic scabies, it usually takes 10 minutes of skin contact with an infected individual for mites to spread to another human host. The disease can also be spread by the fomite, which spreads through bedding or clothing. Hyperkeratotic plaques, which can be diffuse or localized to the soles, palms, and areas under fingernails, are a common symptom of this scabies presentation.
Norwegian scabies, the crusted form, can have millions of mites on an individual. Due to chemotherapy, Diabetes, HIV, or advanced age, immunocompromised patients experience crusted scabies. This high density becomes infected after briefly contacting infected individuals and contaminated objects. The number of infesting mites is typically determined by the host’s immunological state and the extent of the infestation.
Scabies is a highly contagious skin condition caused by a mite infestation. The prognosis for scabies is generally good, with prompt and appropriate treatment.
Most people can expect to recover fully within several weeks of starting treatment, although the skin may remain itchy after the mites have been eliminated. If left untreated, scabies can persist for an extended period of time and cause discomfort and skin damage.
Clinical History
A patient’s history can effectively indicate scabies infection. This is characterized by itchy rashes that intensify at night, and if multiple close contacts (including family members) have similar symptoms, this can be further evidence of scabies. Lesions from scabies appear differently in adults and children. In adults, scabies rashes are commonly found on the inside of the wrists, between the fingers, on the top of the feet, in the armpits, on the elbows, around the waist, on the buttocks, and on the genital area.
Scabies is a skin condition characterized by the presence of pruritic papules and vesicles on the scrotum and penis in men, the areolae in women, and in infants and young children, on the scalp, face, neck, palms, and soles. It is also common in immunocompromised and elderly patients who may experience widespread, eczematous eruptions, and in patients with pre-existing skin conditions, such as atopic dermatitis, which can exacerbate the symptoms of scabies.
Patients who have been misdiagnosed with scabies and treated with topical corticosteroids may experience further delays in diagnosis as the symptoms may take on the form of vesicles, nodules, or pustules and become more widespread. The signs and symptoms of scabies tend to increase in intensity over a period of 2-3 weeks before the patient seeks medical attention.
However, in debilitated or immunocompromised patients, the urge to scratch may be absent. Scabies is known to occur in clusters and is more likely to be present in an individual with a rash and itching if there has been an outbreak in the community. It is important to consider scabies in the differential diagnosis when evaluating patients with these symptoms.
Physical Examination
Clinical manifestations of scabies include primary and secondary lesions. Primary lesions are the initial signs of the infestation and may appear as small bumps, blisters, and burrows. Secondary lesions occur as a result of scratching and rubbing and may be the only visible sign of the condition. In such cases, a diagnosis can be made based on the history of the patient, the distribution of the lesions, and accompanying symptoms. Burrows are a hallmark of scabies and represent the tunnels created by the female mite in the epidermis. These burrows appear as thin, gray, wavy lines in the skin, measuring between 2-10mm in length.
They are not easily visible and require active searching to locate. High-risk areas for burrows include the webbed spaces between fingers, the flexor surfaces of the wrists and elbows, the axillae, the belt line, feet, scrotum in men, and areolae in women. In classic scabies, the lesions are commonly found in the axillae, elbow flexures, wrists, hands, and genital area, which is known as the circle of Hebra. Elderly individuals with scabies tend to have the lesions on their back, appearing as excoriations.
In infants and young children, burrows are frequently seen on the palms and soles. Immune-compromised patients may present with bullous lesions. Adults with scabies typically have erythematous papules and vesicles measuring 1-3mm in size, distributed in typical areas. The vesicles are clear fluid-filled blisters but may appear cloudy if more than a few days old. Papules, which are more likely a hypersensitivity reaction, are commonly seen on the penis shaft in men and the areolae in women.
In contrast, children with scabies often have involvement of the face and neck, as well as widespread eczematous eruptions on the trunk. Infants may also have papules, vesicles, and pustules on their palms and soles. Crusted scabies is characterized by thick, crusted, and hyperkeratotic skin lesions. These lesions can cover large areas of the skin and are often accompanied by scaling. The hands and arms are the most commonly affected areas, but other parts of the body can also be affected.
This form of scabies is caused by a high number of mites, which can range from thousands to millions. In some cases, there may be minimal itching or none at all. Nail dystrophy, scalp lesions, and subungual hyperkeratosis may also occur. Nodular scabies, which is seen in 7-10% of scabies patients, especially in young children, presents as pinkish-brown nodules that range in size from 2-20mm in diameter. These nodules are often found on the skin where the child cannot scratch, and mites are rarely found inside.
Treatment for scabies is available in several forms, and evidence suggests that the standard treatments such as topical crotamiton, permethrin, and systemic ivermectin have similar efficacy when used as directed. The most commonly used treatment is the topical permethrin 5% cream, which is applied once a week for two weeks, resulting in two total treatments.
Although effective, there are occasional reports of poor patient compliance, resistance, and rare allergic reactions. Another option is oral ivermectin, which is not approved by the US FDA for scabies treatment but is recommended due to its convenience, ease of administration, favorable side effect profile, and safety.
It is administered to individuals ten years and older, with two doses given two weeks apart if symptoms persist. The oral form of ivermectin has a higher rate of compliance compared to topical permethrin and reduces the likelihood of misapplication. In outbreaks of scabies, systemic ivermectin is considered superior to topical permethrin. Ensuring adequate treatment is crucial in densely populated settings such as prisons, homeless shelters, and healthcare facilities.
The treatment options for scabies can be limited for some individuals due to factors such as drug resistance, cost, accessibility, or potential toxicity, particularly for pregnant women and children. The occurrence of treatment failure and re-infection is widespread, and identifying the root cause can aid in avoiding the further spread of the parasite and controlling outbreaks within communities.
Some common causes of treatment failure include the failure to treat close contacts simultaneously, not disinfecting beddings and clothing during the treatment process, and not adhering to the prescribed treatment plan. In crusted scabies, treatment failure may result from mites resistant to ivermectin. In such instances, moxidectin is recommended as an alternative therapy for those with known ivermectin-resistant scabies.
Topical-It instructs the patient to thoroughly wash and clean the affected area, remove any loose scales or debris, and then dry the skin. Then, the patient is instructed to apply a thin layer of the medication to the entire body, from the neck to the toes, massaging it into the skin. The patient is instructed to repeat this process 24 hours later and then take a bath 48 hours after the final application to cleanse the body. Additionally, if live mites are still present, the patient may repeat the treatment after 7-10 days
Apply a thin lotion coating and massage it into the skin all over your body, avoiding the face. After 8–12 hours, take a bath and remove the medication
Apply a thin lotion coating and massage it into the skin all over your body, avoiding the face. After 8–12 hours, take a bath and remove the medication
For three days, apply 6% ointment before bedtime each night.
Using soap and water, thoroughly wash and dry the whole body.
Apply from the neck down to the whole body and rub it in gently, allow it to stay for 24 hours.
Wash the body thoroughly using water and soap within 24 hours after your previous treatment
Indicated for Scabies
Cream: From head to the toe area, apply the 5% cream, leave it for 8-14 hours, and wash it; if live mites are reappeared, reapply in 7 days
One-time application is generally sufficient for a curative effect
Head Lice and Nits (Eggs)
Cream/ liquid or lotion: Apply to rinsed hair, and leave it for nearly 10 minutes; wash and comb it to remove nits and eggs; if live mites are reappeared, reapply in 7 days
One-time application is generally sufficient for a curative effect
Topical-It instructs the patient to thoroughly wash and clean the affected area, remove any loose scales or debris, and then dry the skin. Then, the patient is instructed to apply a thin layer of the medication to the entire body, from the neck to the toes, massaging it into the skin. The patient is instructed to repeat this process 24 hours later and then take a bath 48 hours after the final application to cleanse the body. Additionally, if live mites are still present, the patient may repeat the treatment after 7-10 days
Apply a thin lotion coating and massage it into the skin all over your body, avoiding the face. After 8–12 hours, take a bath and remove the medication
For three days, apply 6% ointment before bedtime each night.
Using soap and water, thoroughly wash and dry the whole body.
Apply from the neck down to the whole body and rub it in gently, allow it to stay for 24 hours.
Wash the body thoroughly using water and soap within 24 hours after your previous treatment.
Indicated for Scabies
Age >2 months
Cream: From head to the toe area, apply the 5% cream, leave it for 8-14 hours, and wash it; if live mites are reappeared, reapply in 7 days
One-time application is generally sufficient for a curative effect
Age <2 months
Safety and efficacy not established
Head Lice and Nits (Eggs)
Age >2 months
Cream/ liquid or lotion: Apply to rinsed hair, and leave it for nearly 10 minutes; wash and comb it to remove nits and eggs; if live mites are reappeared, reapply in 7 days
One-time application is generally sufficient for a curative effect
Age <2 months
Safety and efficacy not established
https://www.ncbi.nlm.nih.gov/books/NBK544306/
medtigo
Scabies
Updated :
August 30, 2023
Scabies is a highly contagious skin condition caused by the infestation of a parasite known as the Sarcoptes scabiei mite. The mite burrows into the skin and creates intense itching, especially at night. The condition is spread through close skin contact, putting family members and intimate relationships at risk.
In 2009, the World Health Organization declared scabies a neglected skin disease, which remains a significant health concern in many underdeveloped countries. Early detection and treatment are crucial, as misdiagnosis can lead to outbreaks, increased morbidity, and a higher economic burden on society. Diagnosing scabies can be difficult as not everyone shows typical symptoms of infestation.
Scabies is a widespread skin infection caused by the mite Sarcoptes scabiei. The estimated global prevalence of scabies is 300 million infected individuals each year, with the highest rates in developing countries and among populations living in poverty, poor hygiene, overcrowding, and malnutrition.
Scabies is most common among children and young adults, and outbreaks can occur in institutional settings such as schools, nursing homes, hospitals, and prisons. The World Health Organization has declared scabies a neglected skin disease, highlighting the need for increased attention and resources towards its control and management.
Within the epidermis’ superficial layers, adult female mites dig burrow underpasses of 1-10 millimeters long and lay 2-3 eggs daily. The eggs hatch approximately two to three weeks later, and the mites die 30-60 days after that. It is important to note that not all treatments can reach the eggs beneath the skin.
Papules may appear between two and five weeks after an infestation. These papules range from a few millimeters to a centimeter and are comma or tunnel shaped. Infestations typically develop under thin skin in places like the interdigital folds, navel region, areolae, and in men, the shaft of the penis.
Both the dermal and epidermal layers of humans and animals contain Sarcoptes scabiei. The female mite burrows into the host’s stratum corneum to lay eggs, which initiates the infestation. It later transforms into nymphs, larvae, and adults. A person with the classic pattern of scabies may have a population of 10-15 mites.
In cases of classic scabies, it usually takes 10 minutes of skin contact with an infected individual for mites to spread to another human host. The disease can also be spread by the fomite, which spreads through bedding or clothing. Hyperkeratotic plaques, which can be diffuse or localized to the soles, palms, and areas under fingernails, are a common symptom of this scabies presentation.
Norwegian scabies, the crusted form, can have millions of mites on an individual. Due to chemotherapy, Diabetes, HIV, or advanced age, immunocompromised patients experience crusted scabies. This high density becomes infected after briefly contacting infected individuals and contaminated objects. The number of infesting mites is typically determined by the host’s immunological state and the extent of the infestation.
Scabies is a highly contagious skin condition caused by a mite infestation. The prognosis for scabies is generally good, with prompt and appropriate treatment.
Most people can expect to recover fully within several weeks of starting treatment, although the skin may remain itchy after the mites have been eliminated. If left untreated, scabies can persist for an extended period of time and cause discomfort and skin damage.
Clinical History
A patient’s history can effectively indicate scabies infection. This is characterized by itchy rashes that intensify at night, and if multiple close contacts (including family members) have similar symptoms, this can be further evidence of scabies. Lesions from scabies appear differently in adults and children. In adults, scabies rashes are commonly found on the inside of the wrists, between the fingers, on the top of the feet, in the armpits, on the elbows, around the waist, on the buttocks, and on the genital area.
Scabies is a skin condition characterized by the presence of pruritic papules and vesicles on the scrotum and penis in men, the areolae in women, and in infants and young children, on the scalp, face, neck, palms, and soles. It is also common in immunocompromised and elderly patients who may experience widespread, eczematous eruptions, and in patients with pre-existing skin conditions, such as atopic dermatitis, which can exacerbate the symptoms of scabies.
Patients who have been misdiagnosed with scabies and treated with topical corticosteroids may experience further delays in diagnosis as the symptoms may take on the form of vesicles, nodules, or pustules and become more widespread. The signs and symptoms of scabies tend to increase in intensity over a period of 2-3 weeks before the patient seeks medical attention.
However, in debilitated or immunocompromised patients, the urge to scratch may be absent. Scabies is known to occur in clusters and is more likely to be present in an individual with a rash and itching if there has been an outbreak in the community. It is important to consider scabies in the differential diagnosis when evaluating patients with these symptoms.
Physical Examination
Clinical manifestations of scabies include primary and secondary lesions. Primary lesions are the initial signs of the infestation and may appear as small bumps, blisters, and burrows. Secondary lesions occur as a result of scratching and rubbing and may be the only visible sign of the condition. In such cases, a diagnosis can be made based on the history of the patient, the distribution of the lesions, and accompanying symptoms. Burrows are a hallmark of scabies and represent the tunnels created by the female mite in the epidermis. These burrows appear as thin, gray, wavy lines in the skin, measuring between 2-10mm in length.
They are not easily visible and require active searching to locate. High-risk areas for burrows include the webbed spaces between fingers, the flexor surfaces of the wrists and elbows, the axillae, the belt line, feet, scrotum in men, and areolae in women. In classic scabies, the lesions are commonly found in the axillae, elbow flexures, wrists, hands, and genital area, which is known as the circle of Hebra. Elderly individuals with scabies tend to have the lesions on their back, appearing as excoriations.
In infants and young children, burrows are frequently seen on the palms and soles. Immune-compromised patients may present with bullous lesions. Adults with scabies typically have erythematous papules and vesicles measuring 1-3mm in size, distributed in typical areas. The vesicles are clear fluid-filled blisters but may appear cloudy if more than a few days old. Papules, which are more likely a hypersensitivity reaction, are commonly seen on the penis shaft in men and the areolae in women.
In contrast, children with scabies often have involvement of the face and neck, as well as widespread eczematous eruptions on the trunk. Infants may also have papules, vesicles, and pustules on their palms and soles. Crusted scabies is characterized by thick, crusted, and hyperkeratotic skin lesions. These lesions can cover large areas of the skin and are often accompanied by scaling. The hands and arms are the most commonly affected areas, but other parts of the body can also be affected.
This form of scabies is caused by a high number of mites, which can range from thousands to millions. In some cases, there may be minimal itching or none at all. Nail dystrophy, scalp lesions, and subungual hyperkeratosis may also occur. Nodular scabies, which is seen in 7-10% of scabies patients, especially in young children, presents as pinkish-brown nodules that range in size from 2-20mm in diameter. These nodules are often found on the skin where the child cannot scratch, and mites are rarely found inside.
Treatment for scabies is available in several forms, and evidence suggests that the standard treatments such as topical crotamiton, permethrin, and systemic ivermectin have similar efficacy when used as directed. The most commonly used treatment is the topical permethrin 5% cream, which is applied once a week for two weeks, resulting in two total treatments.
Although effective, there are occasional reports of poor patient compliance, resistance, and rare allergic reactions. Another option is oral ivermectin, which is not approved by the US FDA for scabies treatment but is recommended due to its convenience, ease of administration, favorable side effect profile, and safety.
It is administered to individuals ten years and older, with two doses given two weeks apart if symptoms persist. The oral form of ivermectin has a higher rate of compliance compared to topical permethrin and reduces the likelihood of misapplication. In outbreaks of scabies, systemic ivermectin is considered superior to topical permethrin. Ensuring adequate treatment is crucial in densely populated settings such as prisons, homeless shelters, and healthcare facilities.
The treatment options for scabies can be limited for some individuals due to factors such as drug resistance, cost, accessibility, or potential toxicity, particularly for pregnant women and children. The occurrence of treatment failure and re-infection is widespread, and identifying the root cause can aid in avoiding the further spread of the parasite and controlling outbreaks within communities.
Some common causes of treatment failure include the failure to treat close contacts simultaneously, not disinfecting beddings and clothing during the treatment process, and not adhering to the prescribed treatment plan. In crusted scabies, treatment failure may result from mites resistant to ivermectin. In such instances, moxidectin is recommended as an alternative therapy for those with known ivermectin-resistant scabies.
https://www.ncbi.nlm.nih.gov/books/NBK544306/
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