dracunculiasis

Dracunculiasis (also known as guinea worm disease) is a potentially disabling infection caused by the parasite Dracunculus medinensis.

Epidemiology

As recently as the mid-1980s, dracunculiasis was endemic to the Nile Valley, central and western Africa, India, Pakistan, Iran, and other parts of the Arabian peninsula, with approximately 3.5 million cases per annum .

From the 1980s there has been a concerted WHO campaign to eradicate dracunculiasis worldwide. The total number of cases globally in 2007 dropped below 10,000 for the first time ever in 2007, plummeting to 542 cases in 2012. Since then cases have remained in double-digit territory, for example 28 in 2018, although there was a small increase in 2019, when 54 cases were seen .

Clinical presentation

The radiologic finding of a calcified guinea worm is common in areas that previously had endemic dracunculiasis.

In the vast majority of cases (one report cites 89%), patients who were found to have calcified guinea worms were asymptomatic.

Pathology

Etiology

Infection occurs with the ingestion of water containing the vector water fleas infected with larvae of Dracunculus medinensis (meaning "little worm from Medina"). The fleas are killed by gastric acid in the stomach freeing the larvae which eventually migrate to the subcutaneous tissues. There, the female larvae subcutaneously burrow to their point of exit which is normally in the patient's lower limbs. The larvae mature into worms, mate, and form a blister on the skin through which their larvae are expelled .

The skin eruption is usually very painful and the patient eases the pain by bathing. The larvae escape into the water to be eaten by water fleas completing their life cycle .

If a female worm dies before reaching the skin surface, it may calcify within the subcutaneous tissues. Calcification is the usual fate of the male worm.

Radiographic features

Plain radiograph

Typically the diagnosis is made on plain films, with linear irregular calcifications located in the soft tissue being the hallmark.

Differential diagnosis

General considerations include:

• dermatomyositis
• chronic vascular insufficiency
• burns

Siehe auch:

• Dermatomyositis

und weiter:

• gluteal injection site granuloma
• dystrophic soft-tissue calcification