Scabies is a common skin condition caused by microscopic mites called Sarcoptes scabiei. The female mite burrows into the skin and lays eggs, causing an intensely itchy rash. Scabies is contagious and spreads quickly through close physical contact. While scabies causes a bothersome rash, it does not affect deeper body systems or show up on routine blood tests.
What is scabies?
Scabies is an infestation of the skin by the human itch mite Sarcoptes scabiei. The microscopic female mite burrows into the epidermis, the outer layer of skin, and lays eggs. The burrowing and eggs irritate the skin, causing an extremely itchy rash to develop. Scabies is very contagious and can spread quickly through close physical contact, shared bedding or clothing, and sexual contact. People most at risk include:
- People who are in close contact with someone who has scabies
- Young children
- Elderly in nursing homes
- People with weakened immune systems
- Sexually active people
While scabies causes bothersome symptoms on the skin, it is a superficial skin condition and does not affect deeper tissues or organs.
What does the scabies rash look like?
When scabies mites burrow into the skin, they cause intense itching, which can begin before the rash is visible. After several weeks of infestation, a pimple-like itchy rash develops which commonly affects:
- Between the fingers
- Sides and webs of the fingers
- Around the wrists and elbows
- Underarms
- Around the breasts
- Around the waist and belly button
- Thighs
- Genitals
- Buttocks
- Shoulder blades
The rash is made up of small red bumps or blisters and zigzagging burrows in the skin. Scratching can cause the rash to become infected.
Do scabies mites spread to organs?
Scabies mites only survive on the skin and do not burrow deeper to infect organs or the bloodstream. They spread by direct, prolonged physical contact with an infected person and do not travel inside the body. Even in cases of severe, long-standing scabies infestation called crusted scabies, the mites remain superficial and do not penetrate into deeper tissues.
What tests diagnose scabies?
Scabies is primarily diagnosed based on the appearance and distribution of the characteristic rash. A doctor will often scrape off a small piece of skin where mites may be present and examine it under a microscope to look for mites, eggs, or mite fecal matter. Blood tests are not used in diagnosing scabies.
Do scabies affect blood cell counts?
There is no evidence that scabies impacts the number or appearance of cells in the blood. A complete blood count (CBC) includes:
- White blood cell (WBC) count – Scabies does not affect WBCs, which fight infection.
- Red blood cell (RBC) count – Scabies does not affect RBC number or lead to anemia.
- Hemoglobin – Scabies does not impact the oxygen-carrying protein in RBCs.
- Hematocrit – The percentage of blood composed of RBCs is not altered.
- Platelets – Scabies does not affect clot-forming platelets.
Even in severe crusted scabies, blood cell counts remain normal and are not impacted by the skin infestation.
Do scabies show up on blood chemistry tests?
Common blood chemistry tests include:
- Basic metabolic panel: Measures sodium, potassium, chloride, bicarbonate, blood urea nitrogen, creatinine, and glucose. Scabies does not affect the results.
- Liver function tests: Evaluate levels of proteins, liver enzymes, and bilirubin. Scabies does not cause abnormal liver tests.
- Lipid panel: Checks cholesterol and triglyceride levels. Scabies does not alter lipid metabolism.
- Blood proteins: Tests for plasma proteins like albumin. Scabies does not affect protein levels.
In summary, scabies is confined to the skin and does not directly impact blood cell counts or blood chemistry. All lab test results would be expected to be within the normal range.
Could scabies indirectly affect blood test results?
While scabies itself does not directly change blood test results, severe itching and scratching can potentially cause secondary changes like:
- Low red blood cell count: If severe scratching causes bleeding and iron deficiency anemia.
- High white blood cell count: If open sores become infected, leading to increased WBCs.
- Low albumin: If poor nutrition from decreased appetite due to discomfort.
- High blood glucose: If significant stress and loss of sleep affects glucose metabolism.
However, these are all theoretical secondary effects and not direct results of the scabies infestation itself. Most people with scabies have entirely normal CBC and blood chemistry test results.
Does scabies increase inflammation markers?
Inflammation markers like erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are sometimes tested to look for inflammatory or infectious conditions. There is limited evidence that severe crusted scabies may slightly increase CRP levels in some people due to skin inflammation. However, the CRP increase would be minimal and ESR is not affected. Milder scabies does not typically impact these inflammatory markers at all.
What about other blood tests?
Scabies is not known to directly impact any other blood test results, including:
- Thyroid tests like TSH, T3, and T4
- Antibody tests like ANA, RF, anti-CCP
- Vitamin levels like Vitamin D, B12, and folate
- PSA levels
- Troponin and CK-MB enzymes tests of heart injury
- Blood cultures checking for bacteria
Any abnormalities in these blood test results in a patient with scabies would be unrelated to the scabies infestation.
Conclusion
In summary, scabies mites remain on the skin surface and do not directly affect blood cell counts, blood chemistry, inflammatory markers, or any other blood test results. Severe itching could potentially cause secondary changes like anemia or elevated white blood cells in some people. But in general, scabies does not show up on routine laboratory testing, and any abnormalities found would not be caused by the scabies itself and instead indicative of an unrelated medical condition warranting further evaluation.