Scabies are a penetratingly itchy parasitic skin infection. Scabies occur worldwide but it is mainly problematic in overcrowding, poor sanitation and social disturbance areas. In recent years, Ivermectin and Permethrin have evolved as the most pertinent treatment options for scabies.
What is Ivermectin?
Ivermectin belongs to the anthelmintic class of drugs and is used to treat various parasitic infections. It is used across the world to treat many infections and infections including sarcoptic mange. Ivermectin is effective at curing scabies and preventing new lesions caused by mites. When used to treat scabies, generally Ivermectin is well tolerated with mild and temporary adverse effects.
What are Scabies?
Scabies is an invasion of the skin by a mite called Sarcoptes scabiei. This infection transmits indirectly through fomites or direct skin-to-skin contact. Typically the symptoms of scabies are visible 3 to 6 weeks after an infestation. In patients with past exposure to mites, symptoms may be visible as early as 24 hours after the exposure.
Lesions appear in scabies containing pruritic erythematous papules with abrasions. Usually, the lesions are symmetrical and include the interdigital networks, the flexural feature of the wrist, the peri-umbilical region, the axillae, elbows, feet, buttocks, the peri-areolar region in women and the genital area in men.
Scabies mites usually transfer from person to person through direct skin contact, sexual contact, used clothes etc. Scabies mites usually survive for 30 to 60 days. Scabies mites survive outside the host for up to three days.
Crusted Scabies
The severe form of scabies is called crusted scabies and occurs in immunosuppressed patients such as AIDS patients, patients manifesting with widespread hyperkeratosis, largely over the scalp and extremities. Crusted scabies are also known as Norwegian scabies.
Non-Crusted Scabies
Unlike crusted scabies, patients with non-crusted scabies have fewer mites on their skin scrapings. Non-crusted scabies may occur in any healthy person due to skin-to-skin contact with any infected person however crusted scabies develop in people with weak immune system because of a medical condition such as HIV infection or in elderly people.
Ivermectin and Scabies Mites
Ivermectin is a designated treatment for scabies, a parasitic infestation of the skin caused by scabies mites that leads to itch, uneasiness and inflammation and in some populations linked with the development of thoughtful secondary infection.
Ivermectin is effective for treating typical scabies not responding to topical treatments, crusted scabies, in aged-care home settings and scabies in community epidemics. Although typical topical treatments for scabies effectively treat most patients with scabies when used appropriately, Ivermectin has a significant role in managing endemic scabies particularly when obedience with the head-to-toe application of topical agents is tough.
In Australia Aboriginal and Torres Strait Islander groups and people in residential aged-care facilities are the people at greater risk of developing scabies infestation. Ivermectin has been proven to be effective in both settings over topical treatments.
Ivermectin is an advantageous treatment option for patients with typical scabies infection when:
The treatment with successive topical Permethrin and Benzyl benzoate has been completed at least 4 weeks earlier and has failed.
The topical treatment is contraindicated when the patient is allergic to Pyrethrins or Pyrethroids and can not use Permethrin. If the patient has acutely inflamed, weeping or raw skin and can not use Benzyl benzoate. Ivermectin treatment is also used for treating crusted scabies in conjunction with keratolytics and scabicides.
Oral Ivermectin for Scabies
Oral Ivermectin medication has been proven to be more effective than a placebo and has been successfully used in the community management of endemic scabies. Oral ivermectin has been used for the treatment of crusted scabies also called hyperkeratotic or atypical scabies that does not respond to topical treatment alone.
This medication has also been used for the treatment of other types of scabies that are difficult to treat. For example, if a topical treatment has not worked or can not be used to treat scabies oral Ivermectin has shown considerable outcomes in that case.
Ivermectin is Not an Ovicidal
Ivermectin is an indicated solution for scabies that is caused by scabies mites. However, when it comes to the treatment of scabies mites, oral Ivermectin may not work effectively against the ova, which is why a repeat dose of Ivermectin is required usually for complete eradication of the infection.
Within two weeks of the initial dose of Ivermectin, the second dose should be administered when the parasitological examination is positive or new particular lesions develop. For crusted scabies, the second dose should be given within eight to fifteen days of the initial dose of Ivermectin and concomitant topical treatment may be necessary for such patients.
First-line Treatments for Treating Scabies
The first-line treatments for scabies are oral Ivermectin and topical Permethrin 5% cream. Single doses of oral Ivermectin 200 mg have shown strong effects in many studies, however, it is not more effective than appropriately applied Permethrin.
Therefore oral Ivermectin should be kept for when the proper application of a topical anti-scabies solution is not practicable or not possible such as for severe schematization or as a part of a treatment regimen in crusted scabies and resistant cases.
The pharmacological management of scabies is dedicated to eliminating scabies mites, easing symptoms and diminishing the occurrence of secondary infection. According to Australian guidelines, the initial therapy for typical scabies is topical Permethrin 5 cream.
It is recommended scabies treatment of choice for children above 6 months of age and adults due to high efficacy and low toxicity and usually, it is well tolerated by patients. When topical treatment does not work, your healthcare provider may suggest using Ivermectin.
Advantages Of Ivermectin Over Topical Solutions In Aboriginal Communities
In Australia, scabies and allied complications including acute post-streptococcal glomerulonephritis strangely affect remote communities. The occurrence of scabies in remote central and northern Aboriginal communities has been evaluated at around 50% in children and 25% in adults.
In regions with endemic scabies, low levels of uptake of topical treatment have been noticed. Certain environmental factors such as crowded living spaces lead to the inability to apply topical treatments. The hot and humid climate also impedes the optimal use of topical solutions. Therefore, it leads to a low drive to repeat the treatment solutions.
Being an oral treatment, Ivermectin allows us to overcome the matter of inconvenience. Oral Ivermectin has been successfully used in community management of endemic scabies in other areas. Although there are no particular clinical trials in these locations to determine the best practice, Ivermectin will likely be advantageous for community-based treatment solutions in remote Aboriginal communities.
A 3-year program was conducted in the Solomon Islands in which mass single-dose Ivermectin was given to approximately 1600 people combined with treatment of any close contacts and decreased scabies occurrence significantly from 25% to less than 1% after 4 months. The occurrence of impetigo also reduced remarkably from 40% to 21%.
Reasons To Begin With Oral Ivermectin For Typical Scabies Treatment
Always begin with a proper complete course of topical treatments before opting for Ivermectin treatment. If the primary outcome is not satisfactory or your symptoms do not improve continue 3 weeks post using topical treatment with Permethrin or Benzyl benzoate make sure to address and consider the possible reasons for failure of topical treatment.
If the reasons for the failure of topical treatment include the patient not applying topical solution correctly, incorrect or no diagnosis, an unknown source of re-infestation, insufficient contact tracing or post-treatment itch mistaken for failure of treatment then Ivermectin may not be indicated. Whereas if none of these reasons is the cause of failure of treatment, your doctor is likely to prescribe oral Ivermectin.
Reserve use of Ivermectin as Second-line treatment for scabies
Just a few effective treatments are available for scabies and the advancement of new treatments is improbable in future. Clinical resistance to the Ivermectin drug has been recognised with in-vitro confirmation in patients with crusted scabies. This resistance developed post-administration of repeated schedules of multiple Ivermectin doses.
Ivermectin is not ovicidal (the agent that kills eggs), therefore the second dose is necessary for the complete eradication of infection. Taking two doses of Ivermectin has been demonstrated to enhance the effectiveness of treatment and may lessen the development of resistance to Ivermectin.
Why Does Ivermectin Resistance Occur?
Ivermectin resistance can occur as a result of exposure-induced changes to chloride ion channels influencing the binding period of Ivermectin. Biochemical studies in mites associated detoxification genes linked with metabolic resistance as a potential reason for Ivermectin resistance.
Use of Ivermectin for Typical Scabies
Ivermectin is an anthelmintic agent that is considered a safe and active treatment for river blindness when given as a single dose of oral Ivermectin 150 to 200 mg/kg of body weight. Subjective reports of improvement in patients with mite Sarcoptes scabiei show that this ectoparasitic disease known as scabies might be cured using Ivermectin.
Topical Permethrin Acts Faster Than Ivermectin
A Cochrane systematic review comprised two randomized control trials to compare Permethrin cream with oral Ivermectin. Both trials found 200 mg/kg body weight of oral Ivermectin mediocre to Permethrin at one or two weeks.
In one trial Ivermectin was administered as single or two doses separated by one week, depending on the patient’s response to the first dose. After a 2-week follow-up Ivermectin group had shown a 100% cure rate however when Permethrin and Ivermectin were compared at one week, the Permethrin group had a considerably higher cure rate than Ivermectin.
In the other trial, Permethrin performed better than Ivermectin in the review. A single application of Permethrin was effective in 97.8% of patients while a single dose of ivermectin was effective in 70% of patients and 95% of patients after the second dose given at two weeks.
After the Cochrane review four more randomised control trials have shown that in one trial, Ivermectin was inferior to Permethrin at one week and not statistically considerably different in the other three trials. Variations in the length of follow-up may clarify some of the heterogeneity in the outcomes of these trials.
The Effectiveness Of Ivermectin Over Benzyl Benzoate Is Not Clear
Benzyl benzoate (25%) with or without containing tea tree oil can be advised to be used as an alternative to Permethrin topical agent. In certain cases, this agent may cause skin irritation immediately after you use it. Lower concentrations such as 10% may be used in children.
The noteworthy heterogeneity across the trials comparing Benzyl benzoate and systemic Ivermectin makes it tough to reach a conclusion about which is more effective. In all these trials just one dose of Ivermectin was administered so the effectiveness of treatment may have been underrated.
The Cochrane systematic review comprised five randomized control trials comparing topical Benzyl benzoate and oral Ivermectin. In one trial Ivermecin was superior to Benzyl benzoate at 4 weeks. In three trials, Ivermectin was not statistically different at one, three and four weeks. In one trial Ivermectin was inferior with a higher rate of treatment failure with a single dose of Ivermectin than with topical Benzyl benzoate. Differences in treatment regimens and follow-up length may clarify some heterogeneity in outcomes.
Use Of Ivermectin For Crusted Scabies
Custer scabies may develop several mites which are extremely infectious. Ther dermatological distribution of scabies mites in patients with this type of scabies is usually atypical which may include the head. Along with the complications, secondary bacterial infections of the skin may occur in such patients.
Ivermectin treatment is the only indicated solution in guidelines as first-line treatment in combination with topical treatment to treat crusted scabies. No randomized controlled trials are there to compare Ivermectin with other treatments for crusted scabies.
Oral Ivermectin Paired With Topical Treatments
Observational studies have demonstrated that Ivermectin is an effective treatment option post-failure of topical treatment in the case of crusted scabies. There are records from small case series and uncontrolled trials using multiple doses of oral Ivermectin in combination with topical treatment.
An open-label study was performed in Australia where 20 patients with crusted scabies refractory to topical treatment were involved. Eight patients showed great response after the last dose of oral Ivermectin combined with Permethrin and Keratolytics.
Keratolytic therapy was used when Permethrin was not used and patients were treated with one to three doses of Ivermectin 200 mg/kg at 14 days intervals. 9 patients had partial response and three patients have shown minimal improvement.
Multiple Doses of Oral Ivermectin Can Work Remarkably
A case study was performed by Commonwealth University, Richmond to evaluate the best treatment option for crusted scabies. It was the case of a bone marrow transplant patient who developed crusted scabies mite. The patient did not respond to usual topical solutions for scabies mite including topical Permethrin and topical Ivermectin.
The concerned people contacted The Centers for Disease Control and Prevention for the right suggestion. The CDC recommended a seven-dose Ivermectin regimen. After the third dose, the patient began to improve remarkably and after seven doses, the skin eruptions were completely resolved. This case study supports the use of multiple doses of Oral Ivermectin to treat crusted scabies.
Is Ivermectin Effective for Scabies?
An open-label study was conducted in which oral Ivermectin was given as a single dose of 200 mg/kg to 11 patients with scabies who were otherwise healthy and 11 patients with scabies who were also infected with HIV (Human Immunodeficiency Virus) and 7 of those patients had AIDS (Acquired Immunodeficiency Syndrome).
All patients involved in the study got a complete dermatological and physical examination, scraping from the skin of all patients found positive for scabies. All the patients were examined again after two and four weeks of treatment when the scrapings were repeated for scabies. During or before the four-week study period, patients did not use any other scabicides.
After a single dose of Ivermectin, 11 otherwise healthy patients had no evidence of scabies after four weeks. Out of 11 patients with scabies and HIV 2 patients had less or equal 10 scabies lesions before treatment, 2 patients had 11 to 49 lesions, 4 patients had greater or equal 50 lesions and 2 patients had heavily crusted skin lesions.
In eight patients the scabies was cured after a single oral dose of Ivermectin. Two patients got a second dose after two weeks of the first treatment. Out of 11 patients with HIV, 10 had no evidence of scabies after four weeks.
Ivermectin administered as a single dose, is effective for scabies treatment in otherwise healthy patients (uncomplicated scabies) as well as in many patients infected with HIV.
Ivermectin Seems To Be Successful For Treating Patients With Crusted Scabies
A Cochrane systematic review included seven randomized controlled trials of oral Ivermectin compared with topical treatments or placebo available in the UK along with four more randomized controlled trials of oral Ivermectin that were published after Cochrane systematic review. All these trials evaluated the safety and effectiveness of oral Ivermectin to treat crusted scabies or complicated scabies.
In one randomized controlled trial, the clinical response in the oral Ivermectin group was superior in comparison to the placebo group. In one randomised controlled trial Ivermectin was superior to Benzyl benzoate, not statistically meaningfully different in three trials and inferior in one trial.
In three trials, Ivermectin was mediocre compared to Permethrin treated patients and not statistically significantly different. The rates of Ivermectin treatment failures varied extensively in these trials ranging from 7% to 70%. Variations in the treatment routines and the length of follow-up may clarify some of the heterogeneity in the outcomes of various studies.
So, overall the evidence shows that Ivermectin efficiently work in patients with crusted scabies, particularly after the failure of topical therapy. In many patients with crusted scabies refracted to topical therapy or topical Permethrin, multiple doses of Ivermectin in combination with topical therapy demonstrated a complete response after the last dose of Ivermectin.
Potential Adverse Reactions Associated with Use of Ivermectin for Scabies Mite
Adverse effects of ivermectin white treating scabies are mild and temporary. In the randomized controlled trials for uncomplicated or classical scabies, the adverse events noticed in patients treated with oral Ivermectin included worsening symptoms including pruritus, headache, irritation, pustular rash, nausea, cellulitis, mild diarrhoea and abdominal pain.
The trials were not big enough to evaluate potential serious adverse effects that are usually rare. In certain cases, transient exacerbation of pruritus may occur in the initial period of treatment.
Warnings for The Use of ivermectin
Ivermectin is an antiparasitic agent highly recommended for treating worm infestations. Most evidence shows that oral Ivermectin treatment is a safe and effective solution for scabies mites. The safety of Ivermectin in pregnant women, lactating mothers and children weighing below 5 kg has not been established.
It is recommended to take ivermectin with food. For patients with crusted scabies, Ivermectin treatment should be paired with a topical agent for superior outcomes. Depending on the severity of the scabies infestation, Ivermectin should be taken in three or five doses as recommended by your healthcare provider.
Do not take Ivermectin if you ever had an allergic reaction to Ivermectin or any ingredient of this drug. Tell your doctor about your medical history and any other medications, health supplements or herbal products you are using to avoid any possible side effects.
