Loiasis (Loa Loa Infection) (Eye Worm)

Loiasis is an infection caused by the worm Loa loa, manifested by swelling and pain as the larvae migrate under the skin and soft tissues. It can pass beneath the white’s of the eye and is thus also known as the ‘eye worm.’

Where does it occur?

It occurs primarily in the African rain forest, especially the Congo River basin in central Africa.

How is it transmitted?

It is transmitted by the bite of the deer fly.

Is it contagious from person to person?

It is not contagious from person to person.

What is the risk for travelers?

The risk is low to moderate for those traveling to the African rainforest but higher if engaged in extensive outdoor activities or long term stays.

How soon after exposure will one develop symptoms?

Symptoms are usually seen years after exposure, but can develop as early as a few months after.

What are the signs and symptoms?

Symptoms are usually itching of the skin followed by pain and swelling of the involved area – commonly wrists, ankles, chest and face but can occur anywhere. The swellings are generally a few inches in diameter and do not dimple upon pressure. These can last from a few hours to a few days and recur for years. Adult worms may be seen as they migrate underneath the skin or the conjunctiva but may disappear in 10- 15 minutes.

Are there any lab tests to diagnose the illness?

Diagnosis is made by detecting the larvae in blood smears which are usually positive if drawn during the daytime. There is a specific loa loa DNA PCR test available and individual have increased eosinophil counts on their blood smear.

Is there any treatment?

Medications like diethylcarbamazine, ivermectin and albendazole are used for treatment but severe allergic reactions may occur and needs to be given in a supervised setting.

What preventive measures can be taken?

Take protective measures of wearing long sleeve clothing, staying in screened accommodations and apply insect repellant containing DEET.

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