Cutaneous Myiasis: Causes And Types Of This Disease

Cutaneous myiasis is an infection of the skin caused by the larvae of certain fly species, such as Dermatobia hominis and the Calliphoridae or Oestridae families . The habitat of these species is humans or animals with a weakened immune system.

Fly larvae, as young stages of these insects, have a different anatomy, physiology and way of life than adult individuals. They feed on living or dead tissue of other organisms. In doing so, they destroy these tissues by attacking large areas of the skin.

Signs and symptoms vary depending on the species of fly causing them. The plagues of these insects usually occur in tropical countries. People from other countries diagnosed with cutaneous myiasis have recently visited a tropical country frequently.

Cutaneous myiasis – symptoms

The most common symptoms you may experience are:

• Itchy skin.
• The sensation of movement under the skin in this area.
• Sharp and stinging local pain.

Initially, a small red blister appears that can be mistaken for a regular insect bite or the initial stage of an ulcer. It then transforms into a larger tubercle with a hole in the center.

Unlike common house fly larvae, most myiasis larvae attack both healthy and dead tissue.

Clinical forms

1. Furuncle myiasis

Many flies that cause furuncle myiasis are known as flies. The best known species that cause the disease come from South and Central America, and sub-Saharan and tropical Africa.

Flies sometimes lay their eggs on other insects, such as mosquitoes, or on objects such as hanging clothes, and thus can come into contact with human skin.

The eggs hatch into larvae that penetrate the skin and develop into mature larvae. Without treatment, the larvae eventually emerge from the skin and fall to the ground to continue their life cycle.

Sometimes you can see a small part of the end of the larva sticking out of the skin. The larvae need oxygen, so if the opening in the skin is blocked, they can come out or at least come closer to the surface.

2. Growing myiasis with crossbones

In this case, the larva forms a cross as it migrates under the skin.

3. Subcutaneous myiasis

There are deep and painful lumps that disappear after a few days. However, they then reappear in close proximity until the ulcer opens, releasing the larvae.

4. Cavernous myiasis

Cavernous myiasis is the most destructive form of myiasis. This is because it affects the entire head, especially the paranasal sinuses and the external ear canal.

It is called the cavernous variety because it creates large cavities and leaves deposits that destroy tissues, cartilage and bones. It can even kill the patient. After passing through the bones of the skull, it can reach the brain causing inflammation and even bleeding and hemorrhages.

Treatment, diagnosis and prevention

The diagnosis of myiasis is based on a clinical examination. Sometimes an ultrasound is recommended to facilitate diagnosis and treatment.

For ulcers, soap and water, topical antiseptics, and oral antibiotics are used. In the case of boil myiasis, petroleum jelly or nail polish is applied to block the opening of the skin. The larvae generally appear spontaneously within 24 hours.

If the larvae die before your doctor removes them, they are more difficult to remove and often cause a severe inflammatory response. the person cleansing the wound should therefore try to extract the entire larva.

On the other hand, the drug ivermectin, administered orally or topically, can kill the larva or cause it to exit. In addition, the use of repellants is useful to prevent the deposition of mosquitoes that carry larvae of the flies.

Here is a series of measures to avoid infection by fly larvae:

• Close windows and doors after dark.
• Place mosquito nets or nets on the windows.
• Also, avoid keeping food, garbage, or accumulated fluids in your home.
• In addition, use mosquito repellent, especially in the most affected areas.

In addition, in tropical regions, it is advisable to iron all garments before use, especially if they have been dried outdoors, as fly eggs can stick to the fabric.