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Scabies

Category: Illness or disabilities

Type

Involuntary

Introduction and description

 

Scabies is a contagious skin infestation by the mite Sarcoptes scabiei

Crusted scabies is a more severe form of the disease.  It typically only occurs in those with a poor immune system or those on immunosuppressants.

The mite is very small and usually not directly visible. Diagnosis is based on the signs and symptoms.  The word scabies is from Latin: scabere, "to scratch".

Scabies is one of the three most common skin disorders in children, along with ringworm and bacterial skin infections. As of 2010 it affected approximately 100 million people (1.5% of the world population) and is equally common in both sexes. The young and the old are more commonly affected. It also occurs more commonly in the developing world and tropical climates.   Scabies appears to be on the increase.  Several sources suggest an escalation of scabies in France, for example.

Symptoms

 

The most common symptoms are severe itchiness and a pimple-like rash. Occasionally tiny burrows may be seen in the skin. When first infected, usually two to six weeks are required before symptoms occur. If a person develops a second infection later in life, symptoms may begin within a day. These symptoms can present across most of the body or just certain areas such as the wrists, between fingers, or along the waistline. The head may be affected, however this is typically only in young children, and not in older children or adults. The itch is often worse at night. Scratching may cause skin breakdown and an additional bacterial infection of the skin.

crusted scabies

 Cause

Scabies is caused by infection with the female mite Sarcoptes scabiei. The mites burrow into the skin to live and deposit eggs.

Often only between ten and fifteen mites are involved in an infection.

In crusted scabies, however, people may have millions of mites, making them much more contagious. In these cases spread of infection may occur during brief contact or via contaminated objects.

Scabies is most often spread during a relatively long period of direct skin contact with an infected person.  Spreads of disease may occur even if the person has not developed symptoms yet. Crowded living conditions such as those found in child care facilities, group homes, and prisons increase the risk of spread.

Areas with a lack of access to water also have higher rates of disease.

Pharmaceutical Treatments

There are two main medications used by doctors to treat scabies, Ivermectin and Pyrethrin. 

Ivermectin

Ivermectin is a medication that is used against many types of parasites. It is used to treat head lice, scabies, river blindness, strongyloidiasis, and lymphatic filariasis, among others.  According to Wikipedia, its use against mites such as scabies is usually limited to cases that prove to be resistant to topical treatments or that present in an advanced state (such as Norwegian scabies), but from the evidence from PubMed, this may not be the case, it may be being used far more generally.

One reason why is that over and over again, in trials Ivermectin appears to be superior to the older remedies such as sulphur ointment, for example:

This study aimed at comparing the efficacy and safety of oral ivermectin vs. sulfur 10% ointment for the treatment of scabies. In total, 420 patients with scabies were enrolled, and randomized into two groups: the first group received a single dose of oral ivermectin 200 μg/kg body weight, and the second group received sulfur 10% ointment and were told to apply this for three successive days. Treatment was evaluated at intervals of 2 and 4 weeks, and if there was treatment failure at the 2-week follow-up, treatment was repeated. A single dose of ivermectin provided  a cure rate of

  • 61.9% at the 2-week follow-up, which increased to
  • 78.5% at the 4-week follow-up after repeating the treatment.

Treatment with single applications of sulfur 10% ointment was effective in

  • 45.2% of patients at the 2-week follow-up, which increased to
  • 59.5% at the 4-week follow-up after this treatment was repeated.

…. The delay in clinical response with ivermectin suggests that it may not be effective against all the stages in the life cycle of the parasite. PMID:  26342502


 But not one of these trials considered the long term safety or ecological impact of this drug.

 

One of the trade names of Ivermectin is Stromectol and you will see from the observation below that it is not without its side effects – one of which is death.  In cases of filariasis or river blindness, the risk may be worthwhile, but in the case of scabies, it may be considered a risk too far.  The main concern is neurotoxicity, manifesting as central nervous system depression, and ataxia.  Collie-like herding dogs can be severely poisoned by ivermectin and environmentally, it is something of a disaster.  Field studies have demonstrated the dung of animals treated with ivermectin supports a significantly reduced diversity of invertebrates, and the dung persists longer.

Since drugs that inhibit CYP3A4 enzymes often also inhibit P-glycoprotein transport, the risk of increased absorption past the blood-brain barrier exists when ivermectin is administered along with other CYP3A4 inhibitors. These drugs include statins, HIV protease inhibitors, many calcium channel blockers, and glucocorticoids such as dexamethasone, lidocaine, and the benzodiazepines.  If we look at the eHealthme website which summarises the Adverse Drug Reports submitted by doctors to the FDA and SEDA we find that:

Most common Stromectol side effects are:

  • Weakness in Stromectol (860 reports)
  • Fever in Stromectol (793 reports)
  • Headache in Stromectol (608 reports)
  • Conjunctival Haemorrhage in Stromectol (413 reports)
  • Encephalopathy in Stromectol (404 reports)
  • Consciousness - Decreased in Stromectol (368 reports)
  • Dizziness in Stromectol (326 reports)
  • Depressed Level Of Consciousness in Stromectol (287 reports)
  • Fatigue in Stromectol (287 reports)
  • Joint Pain in Stromectol (286 reports)

The vast majority of these rather indicate that is exactly what this drug has done.

Pyrethrin

Permethrin is a medication and chemical widely used as an insecticide, acaricide, and insect repellent. It is a first-line treatment medically for scabies and used as a cream.  It belongs to the family of synthetic chemicals called pyrethroids and according to Wikipedia:

... functions as a neurotoxin, affecting neuron membranes by prolonging sodium channel activation. It is not known to rapidly harm most mammals or birds, but is toxic to fish and cats. In cats it may induce hyperexcitability, tremors, seizures, and death. In general, it has a low mammalian toxicity and is poorly absorbed by skin.

And this implies, it is absorbed by the skin, albeit poorly.  It also means that if any is ingested by accident you will be ill.  If we now use the eHealthme web site and the Adverse Drug Reports submitted by doctors to the FDA and SEDA, we find the following:

Most common Permethrin side effects:

  • Breathing Difficulty in Permethrin (37 reports)
  • Chest Pain in Permethrin (32 reports)
  • Campbell De Morgan Spots in Permethrin (32 reports)
  • Drug Exposure During Pregnancy in Permethrin (27 reports)
  • Rash Maculo-papular in Permethrin (26 reports)
  • Drug Ineffective in Permethrin (23 reports)
  • Paraesthesia in Permethrin (22 reports)
  • Nausea in Permethrin (22 reports)
  • Cholecystitis Chronic in Permethrin (15 reports)
  • Blister in Permethrin (15 reports)

 Most common side effects by gender  :

Female

Male

Drug Exposure During Pregnancy

Death

Campbell De Morgan Spots

Chest Pain

Rash Maculo-papular

Oedema Peripheral

Nausea

Campbell De Morgan Spots

Dyspnoea

Dyspnoea

Cholecystitis Chronic

Angina Unstable

Abdominal Pain

Myocardial Infarction

Cholelithiasis

Drug Ineffective

Pregnancy With Injectable Contraceptive

Hypersensitivity

Talipes

Leukocytoclastic Vasculitis

 

 Other pharmaceuticals

Crotamiton -  is a drug that is used as a scabicidal. It is a prescription lotion based medicine that is applied to the whole body and is applied 2 to 3 times, with a 24-hour delay in between applications, after which the patient is asked to take a shower no sooner than after 48 hours. “Use near the eyes, or breaks in the skin, must be avoided”. The mechanism of action of crotamiton is unknown, however it is toxic to the scabies mite.

Lindane - Lindane, also known as gamma-hexachlorocyclohexane, (γ-HCH), gammaxene, and Gammallin organochlorine that has been used both as an agricultural insecticide and as a pharmaceutical treatment for lice and scabies.  Lindane is a neurotoxin.  In humans, lindane affects the nervous system, liver and kidneys, and may well be a carcinogen. “It is unclear whether lindane is an endocrine disruptor.”

Wikipedia
The World Health Organization classifies lindane as "Moderately Hazardous," and its international trade is restricted and regulated under the Rotterdam Convention on Prior Informed Consent.  In 2009, the production and agricultural use of lindane was banned under the Stockholm Convention on persistent organic pollutants. A specific exemption to that ban allows it to continue to be used as a second-line pharmaceutical treatment for lice and scabies.

 Alternative natural chemical and plant based treatments

 

A number of safe alternative treatments are also available.  According to the PubMed papers that have tested these options, the essential thing is to keep going with the treatment for as long as possible.  Just because it looks like they are beginning to disappear doesn’t mean they have and you have to persist, sometimes long after they appear to have gone.  Other recommendations are

  • Decontamination of bedding and clothing – both can harbour the mite and it will simply reappear.  Very hot washing or placing items in a freezer will help to kill the mites
  • Treatment of close contacts – other members of the family may be the source, but their systems might be better at keeping the mite at bay.  Close contacts of patients, including animal,s need to be treated too.

Let us look first at the natural chemicals that have scabicide activity according to Dr Duke’s phytochemical database

Scabicides

Chemical

Dosage

References

BENZYL-BENZOATE

--

Merck 11th Edition

ROTENONE

--

Dr James Duke’s own analysis

SULFUR

--

Martindale's 29th

 

Sulphur ointment

As we can see from the papers, sulphur ointment applied externally is in many cases very effective.  It has also proved safe.  If we use an analogy, if you have woodworm in your fence, then a flame thrower will be more effective and quicker acting than a simple ‘woodworm wash’, but there won’t be much left of your fence afterwards using the flame thrower, sulphur leaves you with the fence.

Benzyl benzoate

Benzyl benzoate is a naturally occurring chemical.  It can be found in a number of plants, some of which are edible some not.  We have provided an observation from Dr Duke listing those plants.

Benzyl benzoate (BB) is one of the oldest drugs used for the treatment of scabies and is recommended as the "first-line intervention" for the cost-effective treatment of the disease. Though a promising candidate, its application is reported to be associated with irritation of the skin and eye [sic], resulting in poor patient compliance. PMID: 26669889

Yambean

 Another alternative as a food is the Yambean.  According to Dr Duke’s analysis of chemicals with Antiscabies activity, this is the only natural one that is safe to ingest:

Chemical

Dosage

References

12-ALPHA-HYDROXYROTENONE

--

*

*Unless otherwise noted all references are to Duke, James A. 1992. Handbook of phytochemical constituents of GRAS herbs and other economic plants. Boca Raton, FL. CRC Press.

And the only plant with this chemical is Pachyrhizus erosus – the Yambean.  The chemical shown is in the whole plant including the root, and it is the root that is eaten.

Rotenone

According to Dr Duke’s analysis, Rotenone is:

Activity

*Reference

Acaricide

Merck 11th Edition

Antifeedant

*

Antitumor (ED50=0.01-0.3ug/ml

*

Bruchicide

*

Convulsant

*

Ectoparasiticide

Merck 11th Edition

Insecticide

Jacobson, M., Glossary of Plant-Derived Insect Deterrents, CRC Press, Inc., Boca Raton, FL, 213 p, 1990.

Larvicide

Martindale's 29th

Pediculicide

Martindale's 29th

Pesticide

*

Piscicide

*

Pulicide

Martindale's 29th

Scabicide

*

 The presence of the term ‘convulsant’ should ring alarm bells, not a chemical one would wish to place anywhere near one’s mouth or open wounds.

The seed of the yambean plant, mentioned above, has rotenone in it but it is not the seed you consume.  This said, it does make the Yambean a most interesting plant.

Any other plants found to be of interest are in the observations.

 

References and further reading

  • Ann Parasitol. 2015;61(2):79-84.  The efficacy of oral ivermectin vs. sulfur 10% ointment for the treatment of scabies.  Alipour H1, Goldust M2.  1Tabriz University of Medical Sciences, Aras Branch, Tabriz, Iran. 2Young Researchers and Elite Club, Qaemshahr Branch, Islamic Azad University, Qaemshahr, Iran.
  • Ann Dermatol Venereol. 2016 Jan;143(1):9-15. doi: 10.1016/j.annder.2015.10.588. Epub 2015 Dec 3. [Therapeutic failure in scabies : An observational study].  [Article in French]  De Sainte Marie B1, Mallet S2, Gaudy-Marqueste C1, Baumstarck K3, Bentaleb N1, Loundou A3, Hesse S1, Monestier S1, Grob JJ1, Richard MA1

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