Distinguishing between dermatitis caused by ants and shingles

Contact dermatitis caused by insects (especially ants) is often misdiagnosed as shingles. However, shingles usually has systemic symptoms first, painful wounds, while dermatitis caused by insects appears suddenly, with a burning sensation.

An article by Dr. Duong Huu Thanh, Deputy Head of Dermatology Department of Hue Central Hospital, posted on VnExpress.net clearly shows how to distinguish between these two types.

Contact dermatitis caused by insects but misdiagnosed as shingles is very common and has been mentioned in many documents. This confusion has been reported from referrals to the Dermatology Department - Hue Central Hospital in the past 3 years. According to our research, the confusion rate is up to 80.4%.

1. Contact dermatitis caused by insects:

There are many types of insects that cause dermatitis, here we only mention cases of dermatitis with clinical symptoms similar to shingles. The disease used to appear in the months of changing seasons, when there were storms, and there were epidemics in some places. Until now, it has not been determined exactly which type of insect causes the disease. Some authors believe that the cause may be the three-compartment ant (depending on the locality, it has names such as: needle ant, lac ant, curved-butt ant, locked ant, chin-pair ant...), scientific name is Paedérus, is a type of beetle found all over the world but is often found in hot and humid tropical regions such as Asia and Africa. The body is long and thin, about 7-10 mm, has 3 pairs of legs, the body has 2 red rings, 3 black rings, can fly and run very fast, likes light, especially fluorescent lights.

The three-compartment ants often hide on the banks of fields, under piles of excess materials, around stubble, lawns, bushes, vegetable fields, unfinished construction sites, and garbage dumps. After the rains, when the water is flooded and there is no place to live, they fly into the house following the light and land on towels, clothes, bedding, blankets, etc. When human skin comes into contact with their secretions through those objects or accidentally hits the insects to death on the skin, the disease will appear right in that area.

Symptom:

- The disease often appears suddenly after waking up in the morning, in exposed areas such as: neck, face, hands, feet..., It can also be in other skin areas but less common, usually a lesion on one or both sides, red inflammation like scratches, tending to form long streaks. The patient feels burning, mild swelling, little itching, accompanied by many small, pale yellow pimples like pustules, in the folds the lesion can be on both sides of the face. If treated properly, after about 5 to 7 days the lesion will dry, the general condition usually does not change much, can be infected or spread and become an epidemic.

- Diagnosis is mainly based on clinical.

Some pictures of contact dermatitis caused by insects.

Treatment:

- Locally: Wash the wound with solutions such as saline or clean water to neutralize the chemicals causing burns caused by insects, use soothing topical medications such as: lake water, zinc cream, corticoid cream... If infected, we can use additional topical antibiotic cream. Antihistamines usually only reduce irritation and itching.

- Whole body: Almost no intervention is needed unless there are signs of secondary infection.

Evolution:

If treated properly and promptly, it will heal in about a week, leaving no scars.

Disease prevention:

- If the windows do not have screens, they should be closed when it rains in the evening and care should be taken when working under lights.

- Check towels, clothes, beds, mats... before use.

- Clean up piles of materials and trash around the house.

- Do not dry clothes and towels outside when it rains in the late afternoon.

- If you find insects, avoid direct contact and find a way to remove them without letting them come into contact with your skin.

- You should see a dermatologist, do not buy medicine to treat yourself.

2. Shingles (herpes zoster, zoster, shingles).

Herpes zoster lesions.

Symptoms: Often seen in people who have had chickenpox before, the virus then moves to live latently in the sensory ganglia in the lumbar nerve. When the body is weak, tired, or after stressful working days, suffering from other diseases that weaken the immune system such as tuberculosis, AIDS... the virus will reactivate through the nerves and cause disease.

- Initially there is usually a mild fever of about 38oC, headache, fatigue, back pain, pain along the nerves in the skin area where the lesion is about to appear and only appears on one side of the body (except in AIDS patients).

- Next, blisters appear, often linked together (clustered), close observation can see a depression in the middle on the surface of the blisters.

- Pain but not itching, the older you get the more pain you get.

- Common location is intercostal.

- Often associated with lymphadenitis.

Treatment: Oral and topical Acyclovir, anti-inflammatory, analgesic and sedative.

Progression: The disease will heal in 2 to 3 weeks, after healing it may leave signs of skin discoloration, in elderly patients post-herpetic neuralgia is very common.

3. Notes and differential diagnosis:

Factors that lead to confusion between these two diseases are:

- The painful burning lesions of insect contact dermatitis are easily confused with the pain of shingles.

- The skin in the affected area is red and inflamed.

- It is even easier to mistake contact dermatitis caused by insects for one side (because shingles usually only affects one side).

Differential diagnosis of two diseases:

Conclude:

- These two diseases have a very high rate of confusion, so it is necessary to distinguish before treatment.

- Do not treat if the diagnosis is unclear.

- Treatment of contact dermatitis caused by insects is very simple as presented and can be applied at all primary health care facilities.

- There should be community propaganda for prevention.

According to VnExpress