Introduction

Tungiasis is a parasitic skin disease caused by the female sand flea Tunga penetrans. Originally from South America, it was introduced into sub-Saharan Africa in the 19th century.¹ Tungiasis is considered a neglected tropical disease, particularly in resource-limited communities.² It is commonly seen among travellers, residents of urban slums, and riverside communities.³

In 2020, the prevalence of diagnosed individuals with tungiasis in sub-Saharan African regions was reported at 33.4%. Accurate diagnosis is essential to enable timely treatment, prevent complications such as secondary infections, chronic inflammation, or tissue damage, and avoid misdiagnosis with other dermatological conditions, which could lead to inappropriate treatments and delayed care.⁴ Differentiating tungiasis from similar skin conditions is therefore critical to effective management.

Pathophysiology and clinical presentation of tungiasis 

Life cycle of tunga penetrans

Infestation begins when the female sand flea penetrates the host's skin, typically through poorly sanitised areas such as beaches or stables. The flea usually targets the toes, soles, periungual areas, lateral foot edges, and heels, burrowing head-first into the epidermis while leaving the posterior abdomen exposed.⁵

Once embedded, the flea feeds on the host's blood and undergoes hypertrophy, causing its abdomen to swell to a size of about 1 cm (up to 2,000 times its original size) as it matures and produces eggs. Over approximately two weeks, the flea releases eggs through the exposed part of its abdomen, which fall to the ground and continue the life cycle.⁶ Following egg release, the flea dies, and the host’s immune system begins to eliminate the parasite, forming lesions in the process.

Key clinical features

The primary symptom of tungiasis is pruritus (itching). Localised pain, tenderness, and irritation in the area also occur. If the parasite remains embedded, a brown-coloured papular lesion forms, initially 0.5–2 mm in size, surrounded by erythema. As hypertrophy progresses, lesions enlarge to 3–10 mm in diameter with a small central black dot. Inflammation may result in ulceration, heat, pain, erythema, and flaking of the surrounding epidermis³.

Differential diagnosis: similarities and distinguishing features 

Scabies

Scabies is a parasitic infestation caused by tiny mites called Sarcoptes scabiei. The condition is similar to tungiasis due to the tiny mites causing the infestation by laying eggs and causing an itchy rash on the skin. 

Similarities:

• Pruritus (itching)
• Caused by arthropods 
• Cluster lesions 

Distinguishing features: 

• Scabies lesions are found in intertriginous areas (e.g., wrists, elbows, groin)
• Presence of mite burrows rather than embedded fleas

Cutaneous myiasis

Cutaneous myiasis is a common clinical type of myiasis. It is a parasitic skin infestation caused by larvae (maggots).⁷ 

Similarities:

•  Lesions with a central opening

Distinguishing features:

• Larger lesion size in myiasis, often exuding serous fluid
• Larvae, rather than adult fleas, are present

Bacterial skin infections

Bacterial skin infections are caused by bacteria, leading to symptoms such as inflammation, pain, redness and more.⁸ Bacterial skin infections have similarities to secondary infections in tungiasis.

Similarities: 

• Swelling
• Erythema

Distinguishing features:

• No central black dot in bacterial infections
• Purely bacterial aetiology rather than parasitic

Fungal infections

Fungal infection (mycosis) is a skin disease caused by a fungus, which can be found on plants, dirt and household surfaces

Similarities: 

• Skin thickening
• Pruritus
• Scaling

Distinguishing features:

• Lack of localised nodules or embedded fleas in fungal infections
• Fungal infections typically have an annular lesion with scaling at the edge

Plantar warts

Plantar warts, also known as verrucae plantari, are caused by the human papillomavirus (HPV).⁹

Similarities: 

• Hyperkeratotic lesions on the soles of the feet

Distinguishing features:

• The presence of thrombosed capillaries (black dots) in warts differs from flea-associated nodules

Diagnostic tools and techniques 

Clinical examination

Diagnosis begins with clinical assessment. Key features include visible eggs attached to the posterior end of the flea and brownish excretory threads, which are pathognomonic. Lesions are usually localised to the feet, especially periungual areas, soles, and interdigital spaces. Multiple clustered lesions may appear in endemic areas or after repeated exposure. Swelling, erythema, and potential secondary infection may accompany the lesions.^10,11

Dermatoscopy

Dermatoscopy is a non-invasive skin imaging technique that can be utilised for the diagnosis of skin lesions.¹² For tungiasis, it can reveal the embedded flea’s abdomen and the surrounding inflammatory response. Eggs or excretory products may also be observed.¹³

Histopathology

Histopathology examination can confirm the presence of embedded fleas and provide insight into tissue reactions. Features include epidermal thinning, eggs within the flea’s abdomen, inflammation triggered by immune cells (neutrophils, eosinophils, macrophages), and microvascular damage leading to haemorrhage and oedema.^14-16

Imaging (atypical or severe cases)

• Ultrasound: Useful for detecting embedded fleas in clustered lesions or when the lesion is obscured^2,17
• X-ray: Detects deep tissue involvement or complications such as osteomyelitis in chronic cases^2,18

Combined use of these diagnostic methods supports differentiation from other conditions and informs targeted treatment strategies.

Management implications of accurate diagnosis 

Appropriate treatment for tungiasis

Tungiasis does not have a standard treatment; however, surgical extraction of the flea is commonly performed.¹⁹ Secondary bacterial infections can be prevented by using antiseptic applications.

Avoidance of mismanagement

Accurate diagnosis prevents complications such as secondary bacterial infections and chronic inflammation, and allows selection of appropriate therapeutic interventions, including antifungal creams if indicated.²⁰

Public health perspective

As a neglected tropical disease, education of healthcare workers and communities in endemic regions is vital. Awareness campaigns, environmental sanitation, and integration into national health programmes can reduce disease burden.¹

Conclusion 

Tungiasis is a parasitic skin condition characterised by a central black dot and local inflammation. Early recognition and accurate diagnosis are essential for effective treatment and to prevent misdiagnosis. This can be difficult due to various differentials such as scabies, myiasis, bacterial infections, and fungal diseases. Therefore, education on the topic is essential for individuals in these endemic regions to reduce the disease burden. Future efforts should focus on developing affordable diagnostic tools, increasing awareness through healthcare worker training, and implementing sustainable public health strategies, including environmental sanitation and integration into national health programs. 

FAQs

What is tungiasis?

A parasitic skin condition caused by a sand flea, specifically a female sand flea. It breaks through the epidermis of the skin on the foot when someone steps on it. It is more common in subtropical areas with poor sanitation and sandy environments. 

Symptoms to look out for:

• Small black dot at the centre of a swollen, red lesion
• Itching, pain, and inflammation around the affected area
• Possible ulceration or secondary infection if left untreated

How is tungiasis different from other insect bites?

Unlike general insect bites:

• Tungiasis lesions grow larger over time as the flea matures
• The black dot represents the embedded flea’s body
• Persistent itching and pain are more severe compared to typical insect bites