A Guide to Human Skin Parasites – 3 Useful Tests

There is not much knowledge among people about human skin parasites, skin infections, and diseases that are hazardous to human health. So, here you will find a guide to human skin parasites. Everything you need to know about parasites and things related to them.

So let us find out what are human skin parasites.

1. Human Skin Parasites

Before we talk about human skin parasites and related diseases let us first find out what parasites have in common.

1.1. What are Parasites?

Parasites are organisms that live in or on their host organism and depends on them for all the nutrient and benefits at the expense of their host life. For instance, the simplest example is head lice or mosquitoes the ones that derive nutrients from their host body and benefit themselves by deriving their energy.

1.2. What are Human Skin Parasites?

As the name suggests human skin parasites are the ones that are found on or in the human body. The parasites which host the human body for their nutrient benefits are known to be human skin parasites. These include various parasites like protozoa, helminths¹, lice, or hookworms.

They can be categorized as endoparasites and ectoparasites. The endoparasites are the one that infects the body internally while the ectoparasites ²are the one that infects the skin superficially.

The causative agent can be present in contaminated food or water, and insects and animals might also carry these parasites with them. It is very important to beware of them as they are very dangerous to health. You will get to know more about the effects in the next further sections of the article.

2. Parasitic Infections

When the human body gets affected by a parasitic attack through causative agents such as bed bugs, body lice, and more, it is known as a parasitic infection. These are proven to be hazardous for human health as they start developing and soon turn into infestation for particular human skin parasites.

For instance, mites burrow and lay eggs. These eggs develop into larvae and it takes only a few months to become adult worms that set up their infestation into the connective tissue. Then symptoms of infections start getting visible on your body surface and allergic reactions.

Let us see what are the symptoms that might appear in infected people…

2.1. Symptoms

Symptoms that are found in infected human beings are the following:

1. Persistent Itch – you might encounter itching all over your body or the infected area.
2. Redness – rashes or skin redness can be visible.
3. Diarrhea – An upset stomach can cause diarrhea.
4. Dehydration – your body might get dehydrated easily.
5. Fever – sickness can be seen as flu-like symptoms.
6. Nausea – body gets less efficient and weak.
7. Vomiting – food poisoning or improper digestion might cause vomiting.
8. Muscle aches – parasitic infestations can cause aches or pains at the attacked site.
9. Weight loss – absorption of your body’s nutrients causes weakness and makes you lose weight.
10. Stomach cramps – intake of contaminated food or drinking water may cause parasitic infections and further lead to aches.

Three main types of parasites cause parasitic infections in the human body. Let us discuss them in detail:

2.2. Protozoa

They are very small organisms that can live inside your body and then multiply. One of the most common protozoan infectious diseases is Giardiasis³ which can be caused by giardia-infected drinking water. Plasmodium ⁴species are also the one that develops in mosquitoes and transmits to the human body through a mosquito bite.

A few infectious diseases that are caused by protozoa are:

2.2.1. Chagas Disease

• Carlos Chagas discovered it in the year 1909.
• It is caused by the Trypanosoma cruzi parasite.
• It transmits through the insect vector.
• It can affect the blood, muscle, oesophagus, and colon.
• It can not be left untreated, otherwise, it will turn into a hazardous cardiovascular and digestive problem.

2.2.2. Trichomoniasis

• It is a sexually transmitted disease.
• It is caused by the Trichomonas vaginalis parasite.
• It usually infects women, although it can also exist in men.
• It has no symptoms in the male human body.
• A female body can experience vaginal discharge with a fishy smell, pain during urination, and genital itching.

2.2.3. Malaria

• It is caused by the Plasmodium parasite.
• It is transmitted via female-infected Anopheles mosquitoes through biting.
• Though it is a life-threatening disease it is curable.
• It can cause fever, chills, and headaches. Also, it may lead to jaundice or anaemia.
• According to World Health Organization (WHO), in 2021 approx. 247 million people were diagnosed with malaria.

2.2.4. Toxoplasmosis

• It is caused by the Toxoplasma gondii parasite.
• It is known as parasitic pneumonia.
• It is dangerous for infected pregnant women as they might transfer it to their babies.
• It can be transmitted from eating meat that is not properly cooked or via cat faeces.
• It does not show any symptoms but can affect your liver, eyes, brain, and heart.

2.2.5. Cutaneous Amebiasis

• It is caused by trophozoites of Entamoeba histolytica the only human skin parasite in the Entamoeba group.
• It damages human skin and underlying skin tissues.
• It shows symptoms like dyspnea and chest pain.
• It might get cured in 2 weeks of the period but it might return soon if not treated properly.
• Clinical manifestations of the cutaneous lesion are a painful and foul-smelling ulcer and in the genital area development of a large exophytic ulcer.

2.3. Helminths

They are the worm parasitic invertebrates that are categorized as long, flat, and rounded. Such as flukes, or tapeworms. They are multi-cellular organisms that are visible to the naked eye.

These worms are found in contaminated soil that might be contaminated through human or animal-infected feces which contains helminths worms in them. The eggs hatch to turn into adult worms that can easily get into the human body by simply trespassing through the contaminated soil.

Let us talk about a few infectious diseases caused by these parasitic worms:

2.3.1 Guinea Worm Disease

• It is caused by the Dracunculus medinensis parasite.
• These parasites are mainly found in tropical regions.
• It affects the poor communities that do not have access to clean drinking water.
• It does not have any drug or vaccine prevention.
• It causes redness, skin swelling, and joint infections.

2.3.2. Clonorchiasis

• It is a liver fluke parasite, also known as Chinese or oriental liver fluke.
• It is mostly found across Asian parts.
• It can be caused by eating uncooked fish or food near the Asian parts where these parasites are present in large numbers.
• It affects the liver, bile duct, or gallbladder.
• It may show symptoms like diarrhoea, constipation, indigestion, and more abdominal issues.

2.3.3. Toxocariasis

• It is caused by parasitic roundworms that are usually found in dogs and cats.
• It is transmitted from animals to humans, which is known as zoonosis.
• It affects the eyes, stomach, and brain, causing itchiness, coughing, fever, and more.
• Those who are dog or cat owners are more prone to it.
• According to the Centers for Disease Control and Prevention (CDC), approx. 5% of American citizens are found with Toxocara antibodies.

2.3.4. Lymphatic Filariasis

• It is also known as Elephantiasis.
• It is a neglected tropical disease (NTD).
• Mosquito bites cause it.
• It affects the lymph system which may lead to lymphedema and elephantiasis.
• It causes enlargement of lymph nodes.

2.3.5. Anisakiasis

• Anisakid nematode parasites cause it.
• It gets into the intestine of the human body.
• It gets transmitted through infected larvae of uncooked fishes or squid.
• It affects the abdominal system causing diarrhea, abdominal pain, vomiting, and more.
• They might get out of your body after a few weeks but if not, then you might need to have an endoscopy or surgery.

2.4. Ectoparasites

These human skin parasites are those insects that live outside the human body such as lice, fleas, or bedbugs. One can get infected through direct contact via tick bite. They tend to burrow on the skin and live there for a long time creating conditions like lice infestations.

Let us find out a few infectious diseases that are caused by these ectoparasites:

2.4.1. Lice

• They get transmitted from one individual to another through direct head-to-head contact or via sharing personal stuff like hair combs and all.
• Three species of lice infestations are head lice (Pediculus humanus capitis), pubic louse (Pthirius pubis), and body lice (pediculus humanus capitis).
• They suck hosts’ blood to live longer. Otherwise, they shed off the host body in a day or two.
• They cause intense itching, bite marks, and the presence of lice eggs, that is, nits near the ear or neck.
• Pubic lice may be transmitted through sexual contact, so better to use protection.

2.4.2. Demodex

• They are tiny parasitic mites that are among the smallest arthropods.
• They have two species that are found in humans, known as Demodex folliculorum and Demodex brevis.
• They are found living in or near the hair follicles and hence infect the eyelashes or eyebrows.
• Immediately consult a dermatologist if you feel itching, bumpiness, or any kind of redness on your face or eye area.
• They cause demodicosis⁵ if they multiply themselves in large numbers.

2.4.3. Bed Bugs

• They are small insects that live on human clothing or bed area.
• They may travel from one infested area to another through furniture, luggage, or any item.
• They are known to spread disease, and also they cause itchiness that leads to secondary infection.
• They affect your night schedule by losing sleep because of their bites.
• You should be aware while wearing shoes when having bed bugs at your house because they tend to hide in darker places.

Suggested Reading: What Does a Bed Bug Look Like And How You Can Deal With It

2.4.4. Fleas

• They are very small insect parasites that feed on human blood to live.
• They can cause flea-borne typhus, plague, or cat scratch disease.
• They are most likely to infest animal beds and can transfer from there to bite humans.
• They are commonly found infecting dogs and cats.
• They show symptoms like redness, itchiness, and irritation.

2.4.5. Screwworm

• Scientifically known as Cochliomyia hominivorax.
• Their larvae are known to feed and infest human bodies.
• The female fly gets attracted towards the wound openings and starts infestation.
• To prevent larvae infestation, one needs to kill these larvae consecutively for a few days using a chemical substance to ensure complete vanishing of larvae.
• It shows symptoms like lethargy, smelly wounds, fever, and more.

So you see how many infections can be encountered by humans because of human skin parasites and how infected people can become a means of transmission. Let us move on to the next section, which gives you a detailed look into what is the most common parasite.

3. Giardia – the Most Common Parasite

Giardiasis is known to be the most common parasitic infection caused by protozoa Giardia duodenalis in the world. It has a life cycle of two stages only that including the first stage, Trophozoite, in which Giardia swims around and derives all the nutrients from the small intestine.

Then comes the second stage, a static Cyst development that can be present in faeces and contaminate the water. Collection of contaminated water and food at a place and its use causes transmission of the cyst from one location to another. Hence, spreading Giardiasis easily.

It is an oral-fecal infection which is why it is more prone in people living in unhygienic conditions. Also, it spreads through oral sexual activities like oral-anal contact. It is mainly a water-borne infection as Giardia’s favourable condition is the cold water as it is not friendly to the chlorine that is present in normal tap water. The presence of bile or carbohydrates facilitates the growth of the parasite in the small intestine.

Whereas the clinical presentation of giardiasis shows gastrointestinal distressful symptoms that may cause:

1. Chronic diarrhoea
2. Abdominal cramps
3. Fatigue
4. Weakness
5. Weight loss
6. Excessive gas
7. Nausea
8. Appetite loss
9. Headaches
10. Vomiting

If left untreated, it will turn into chronic Giardiasis, showing signs such as steatorrhea, heavy weight loss, malaise, and malabsorption. Few patients are also diagnosed with arthritis or asymmetric synovitis.

To diagnose, you can opt for a stool test in which the tester will look for the presence of parasite Giardia in your stool. If found and need to be treated, then the doctor might need to have an enteroscopy to have a clear look into your intestine.

Sometimes it may get over on its own, while on the other hand, it might prolong, so one might need to take medications as prescribed by the consultants, such as antiparasitic drugs. Some of the commonly used medications are:

1. Metronidazole
   • It is an antibiotic.
   • Taken for the duration of 5 to 7 days.
   • May cause Nausea.
   • Leaves a metallic taste.
2. Tinidazole
   • Works quite similarly and effectively to metronidazole.
   • It treats giardiasis usually in just one dose.
3. Nitazoxanide
   • It is best suitable for children.
   • It is available in liquid form.
   • Its dosage is three days.
4. Paromomycin
   • Suitable for pregnant women as it has lower chances of causing any birth defects.
   • Taken for the duration of 7 to 10 days.

Measures that one can take to have prevention against giardiasis:

• Washing your hands properly before and after eating, after using the toilet, and after coming in direct contact with any germ-carrying thing.
• Eat well-cooked, clean, and healthy food.
• Drink clean and clear water from a clean source. Avoid infestation of contaminated water.
• Practice safe sex activities, especially oral-anal sex.

Now you know everything related to the world’s most common parasitic infection. Let us discuss Epidermal parasitic skin diseases now.

4. Epidermal Parasitic Skin Diseases (EPSDs)

We have discussed almost everything related to human skin parasites and parasitic infections. Now we will see what EPSDs are and what major EPSDs are:

4.1. What are EPSDs?

Epidermal parasitic skin diseases are a category of parasitic infections in which parasites attack heterogeneously on human skin; that is, the parasites interact only with the upper layer of the human skin. It causes a considerable burden, but still, the scientific community does not focus much on this category of parasitic disease.

The debilitating impact of continuous itching can be seen in EPSDs. They are most likely to occur in low-maintenance, underdeveloped, unhygienic, low-resource, and poor parts of the world. This is because these parasitic diseases are a result of poor health conditions.

Let us see what the major EPSDs that can be diagnosed commonly are…

4.2. Major EPSDs are:

4.4.1. Scabies

• The causative agents are tiny mites.
• They burrow into the skin and show their effect gradually.
• They can cause Sarcoptes scabiei that causes intense itching in the infected area.
• It is caused by mite infestation on human skin for a long time.
• Permethrin and Sulfur cream contain chemicals that have the ability to kill these human skin parasites.

4.4.2. Pediculosis

• The causative agents are head lice and body lice infestations.
• It is categorized into three species Pediculus humanus capitis, Pediculus humanus corporis, and Pthirus pubis.
• They are transmitted through head-to-head contact and sharing hair accessories.
• They show symptoms like skin discolouration, itchiness, inflammation, and scalp bite marks.
• They feed human blood for their survival.

4.4.3. Tungiasis

• It is caused by female sand fleas known as Tunga penetrans that burrow inside the human skin.
• It shows effects and causes secondary infections, gangrene, and disfigurement.
• These fleas do not live longer, which is why they start healing within two weeks as these fleas die and shed off.
• Since they are sand feet, found usually in the skin of feet.
• Its full life cycle lasts around one month.

4.4.4. Myiasis

• It is caused by the infection of a fly larva (maggot).
• They feed on human skin tissues for survival.
• D. hominins and screwworms also result in myiasis.
• Larvae affect the open wounds and nasal, oral, or vaginal openings as well as the eyes and ears.
• Internal ophthalmomyiasis may cause vision loss or blindness.

4.4.5. Cutaneous Larva Migrans

• It is caused by Zoonotic hookworm that results in skin infections.
• Due to its creeping eruption, it is termed a cutaneous larva migrans.
• Infected animals such as dog or cat faeces get into the soil or sand and get transmitted to the human upper skin layer of the feet.
• Ancylostoma braziliense is the most common animal larvae.
• For treatment, topical thiabendazole, oral albendazole, or ivermectin medications can be taken as per the prescription provided by your consultant.

5. Tests and Treatments

Although it is better to maintain hygiene to remain preventive against these human skin parasites and related diseases, sometimes people get infected. So there are a few tests and treatments that can be useful and helpful in curing these infections and infestations. Let us discuss these tests and treatments:

5.1. Stool Ova and Parasite Test (O&P)

• It helps find the presence of parasites in your stool.
• You need to submit your stool sample to let the tester perform the test.
• If parasites are found in the sample, then you are found to be infected with the parasitic infestation.
• If found positive, you may need to provide stool a few more times to test treatment progress.
• Medications that can help in providing relief even after stopping consuming them are bismuth, antacids, antibiotics, and barium.

5.2. Tape Test

• The doctor suggests this test for children experiencing rectum itchiness.
• This test needs you to stick tape on your anus while sleeping.
• This is done to collect any pinworm eggs that might present on your genitalia.
• Then this tape will be sent to the laboratory for test.
• If any worms are found under the microscopic view, then the person is found to be infected.

5.3. Colonoscopy

• If the above-mentioned tests are proven failures, then this test is conducted at last by the doctors.
• In this test, a camera stuck to a thin tube is inserted inside the rectum and large intestine.
• This is done to get a clear view of the intestine and examine the gastrointestinal tract.
• Usually, patients are put under anaesthesia so that they do not feel any pain.

Now we are done with a proper guide on human skin parasites.

6. Final Note

Human skin parasites can leave minimal effects as well. They may turn out to be life-threatening to you. So it is important to take care of yourselves and avoid all the activities that may cause these parasites to use you as a host.

Always maintain hygiene and perform activities with care to prevent parasitic infections. You are now clearly aware of the symptoms and problems that might occur due to parasitic infestations and how you can test and treat them.

If you experience any serious issues, always immediately consult your doctor and start treatment as per the prescription. It is vital to take care of your surroundings as well because clean drinking water, surroundings, and proper hygiene are the only best ways to prevent these infections and diseases. Stay Healthy! 

7. Frequently Asked Questions

Q1. What Are the Common Skin Parasites in Humans?

The six major EPSDs are scabies, pediculosis (capitis, corporis, and pubis), tungiasis, and hookworm-related cutaneous larva migrans.

Q2. How Do You Know If You Have a Skin Parasite?

The most common symptoms of scabies, itching, and a skin rash, are caused by sensitization (“allergic” reaction) to the proteins and feces of the parasite. Severe itching (pruritus), especially at night, is the earliest and most common symptom of scabies.

Q3. What Kills Skin Parasites in Humans?

Crotamiton is an anti-parasite medicine that kills certain parasites that live or lay eggs in your skin. Crotamiton topical (for the skin) is used to treat scabies and to reduce itching associated with certain skin conditions.

Q4. Do Skin Parasites Go Away on Their Own?

Some parasites go away on their own, especially if you have a healthy immune system and maintain a balanced diet. However, talk to a healthcare provider if you have signs of a parasitic infection. They can make an official diagnosis and help prevent the spread of the parasite to others

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Last Updated on July 29, 2024 by Sathi Chakraborty, MSc Biology