Scabies is a common skin condition caused by the human itch mite, Sarcoptes scabiei var. hominis. These microscopic mites burrow into the outer layer of the skin, causing intense itching and a characteristic rash. The ink test offers a simple, visual aid to help locate these subtle signs.
Identifying Scabies Burrows
Scabies burrows are distinct, visible tracks created by the female mite as it tunnels just beneath the skin’s surface to lay eggs. They appear as thin, irregular, slightly raised lines, often grayish-white or skin-colored. Burrows can range in length from a few millimeters to a centimeter or more.
While burrows can be found anywhere on the body, they are commonly observed in certain areas. These include the webbing between the fingers, wrists, elbows, armpits, and around the waist. In very young children, burrows may also be present on the palms, soles of the feet, face, and scalp. Finding these characteristic burrows indicates a scabies infestation.
Applying the Ink Test
The ink test, also known as the burrow ink test, is a straightforward method to make scabies burrows more visible. To perform this test, you will need washable ink, such as from a fountain pen or a non-toxic marker, and an alcohol wipe or alcohol-soaked cotton ball. A magnifying glass and a good light source can also aid visualization.
Begin by cleaning the skin area where a burrow is suspected. Apply a small amount of washable ink directly over the suspected burrow. Gently rub the ink into the area using a finger or cotton swab, ensuring the ink covers the skin surface. After a few seconds, use an alcohol wipe or alcohol-soaked cotton ball to carefully wipe away any excess ink from the skin.
Understanding Test Outcomes
After wiping away the excess ink, carefully examine the treated skin area. If a scabies burrow is present, the ink will become trapped within the tunnel, making it appear as a distinct, dark, often zig-zag or wavy line. In some instances, a tiny dark dot, representing the mite itself, might be visible at one end of the burrow.
Conversely, if no burrow is present, the ink will wash away completely, leaving no distinct lines or patterns. Burrows can sometimes be subtle, obscured by scratching, or very faint, potentially leading to a false negative result. The ink test is a helpful tool for visualizing burrows, especially when difficult to see with the naked eye.
What to Do Next
Regardless of the ink test outcome, this test is a preliminary identification tool, not a definitive diagnosis. A positive ink test suggests scabies, but a negative result does not completely rule it out, as burrows can be hard to find or few in number.
If you suspect a scabies infestation based on the ink test or other symptoms, consulting a healthcare professional is the next appropriate step. They can provide a confirmed diagnosis through further examination, which may include skin scrapings analyzed under a microscope. Self-diagnosis and self-treatment are not recommended, as specific prescription medications are required to effectively eliminate scabies mites.