What Is Tungiasis?

Introduction

Tungiasis is a tropical disease that majorly affects people living in economically deprived regions of the world. It is a parasitic infection caused by the adult female sand flea called Tunga penetrans. Tungiasis was first reported in Central and South America in 1492, but there is some paleontological proof that the disease had existed for many centuries before this.¹ Since then, it has spread to several Caribbean islands and countries in sub-Saharan Africa.

Tungiasis is thought to affect over half the population of countries where it is endemic, with its occurrence noted to be even higher in children under 14 and the elderly.^1,2 Indeed, in some countries, 8 in 10 children are afflicted with tungiasis.³

Causative agent and transmission

Tungiasis is caused by the adult female sand flea called the Tunga penetrans. However, this flea is known by several names, including chigoe flea, jigger, nigua, pico and bicho de pie.^4,5 This female insect burrows underneath the skin and feeds on the blood of the affected individuals whilst it enlarges and produces eggs. Once the eggs are mature, the sand flea releases eggs over a period of 2 weeks and then dies. These eggs fall to the ground and develop into their larva, pupa and adult stages. The adult males die after fertilising the adult females, who go on to infect other individuals, beginning the lifecycle again.⁵

Sand fleas grow and mature faster in loose, dry, and sandy soils, which are more commonly seen in poor communities and urban slums. People living in these regions tend to walk about barefooted, which aids the transmission of the disease as the flea can easily burrow through the skin of the feet.^3,5,6

Due to technological advances and the presence of better transportation, this bug can be transported from one community to another using an affected individual as its means of transportation. That individual may board a bus or plane to another community or country, leading to the deposition of mature Tunga penetrans eggs in a new community.⁶

In some cases, this bug can infect other domestic animals, such as goats and sheep. In these rural communities, reared animals sometimes sleep in the same room as their owners to prevent them from being stolen. In these cases, sand fleas can produce and release their eggs from these animals, with the new fleas burrowing into the floor and later developing into adults, which can infect humans.⁶

Clinical presentation

The symptoms seen in this disease are largely due to the flea burrowing into the skin and the complications that arise because of that infestation. Symptoms include itching, swelling, pain, and peeling at the site of infection, which often get worse as the flea increases in size. The development of one or more nodules with a blackened centre is characteristic of tungiasis. This nodule can become infected by bacteria, leading to more swelling, itching and pain, as well as other more severe conditions such as abscesses, cellulitis, thrombophlebitis, or lymphangitis. Sometimes, this disease could cause auto-amputation (self-amputation) of the toes of the affected individual or cause the feet to be disfigured. This makes walking painful.^2,4,5,6

The itching and pain caused by tungiasis can sometimes be so severe that patients try to remove the flea with any sharp object they find, including needles, blades, or knives. These objects are usually not sanitised, and so blood-borne diseases like Hepatitis B, Hepatitis C, or HIV can be spread unknowingly.⁶

Tungiasis may also cause mental distress for those who have the disease, especially children, as they may be bullied in school for their itchy or disfigured feet. This causes low self-esteem, anxiety, or depression.^6,7

Diagnosis

Your doctor will diagnose you with tungiasis by asking relevant questions about your symptoms and examining your skin for lesions. It is important that you tell your doctor if you have recently travelled overseas and, if so, where you stayed and whether you were barefoot at any time. 

Your doctor will want to look at any skin lesions you have and may even look at your feet with a special magnifying camera called a dermatoscope to see if any fleas are still present. Under a dermatoscope, a burrowing sand flea looks like a brown or black ring with pores located at the centre. The flea can then be removed and studied further under a microscope to confirm a diagnosis.⁵

Usually, asking relevant questions and looking at your skin lesions should be enough to diagnose someone with tungiasis. However, if you are already exhibiting complications of the disease such as abscesses, cellulitis or amputations of the toes, your doctor would assess the severity of the complications through further examinations and investigations.

Treatment and management

No medications have been shown to be effective against the flea Tunga penetrans.^5,6 As such, tungiasis is most commonly treated by physically removing the flea from the feet with a disinfected needle. In more complicated cases, fleas must be removed surgically. In both cases, removal is usually accompanied by pain medications and followed by the administration of tetanus toxoid vaccines and antibiotics if any bacterial infections are present.^2,4,5,6

Another common way of treating this disease is by using special oils called dimethicone oils. Some studies have shown that this treatment is very effective in killing sand fleas.^2,3 However, tungiasis can also resolve on its own when the burrowing flea dies.^4,5

In more complicated cases, the course of treatment you are given depends on the complications present. Abscesses might need drainage, while bacterial infections would need antibiotics. Your doctor will properly assess you and determine what treatment is adequate for you.

Preventative measures are very important in managing tungiasis, as they protect not just you but also those around you by stopping the transmission of this infection. The most effective way to prevent this disease is by wearing footwear. Footwear provides a physical barrier between your feet and the fleas, stopping them from burrowing into your skin.^5,6

Sealing the ground or spraying it frequently with insecticides also helps to stop the transmission of tungiasis by killing fleas growing in the soil. Good hygiene, regular sweeping and frequent washing of hands and feet also have a role to play in prevention. Further, some studies have shown that regular use of certain repellent oils can prevent fleas from penetrating the skin, reducing your risk of infection.^2,4,5,6

Prognosis and outlook

Uncomplicated cases have a good prognosis, and patients normally recover fully - especially when they are diagnosed and treated promptly. The prognosis worsens considerably when complications are present, as they often result in severe or even permanent mutilation of the feet. Bacterial infections and pus collections are common side effects of tungiasis, and recurrent infestations in an individual can cause damage to the blood vessels, nerves, and lymphatic drainage system.

Complicated cases of tungiasis also have a more significant impact on patient’s mental health and general well-being. Children may find it difficult to concentrate in school because of their painful, itchy feet, leading to poor grades. Both children and adults with tungiasis may unfortunately feel or experience some form of social isolation.^2,6,7

Public health initiatives

More information about this disease is becoming available as more studies on the prevalence, transmission and treatment of tungiasis are released. The World Health Organisation is actively taking measures to improve the health and general well-being of affected populations and to increase public education on the disease and how to prevent it.²

Research is still ongoing to find an effective but affordable means of treatment. Dimethicone oils, while effective, are expensive and are not readily available in the areas that require them. Mechanical removal of the flea is not as safe as surgical removal, which can be very expensive.²

Summary

Tungiasis is a tropical disease that predominantly affects individuals in poorer and more rural areas. It is a skin infestation caused by the sand flea Tunga penetrans and can cause severe damage to the feet. Whilst full recovery is possible if the disease is diagnosed and treated promptly, affordable treatment is not yet available to those who need it the most. However, ongoing studies looking for better and cheaper treatment alternatives should soon help curb the impact of the disease.