Radiologic identification of dracunculiasis in a nonendemic region: A case report

Abstract

Dracunculiasis (Guinea worm disease) is a parasitic infection caused by Dracunculus medinensis, now nearing global eradication. We report a rare case from a nonendemic region involving a 75-year-old woman with a 10-day history of dull, radiating left hip pain and intermittent discomfort for 2 months. Examination revealed localized tenderness, mild muscle weakness, and restricted hip mobility. Laboratory results were normal. Pelvic radiography and computed tomography demonstrated dense, serpentine intramuscular calcifications along the left adductor muscles, highly suggestive of a calcified D. medinensis. Given the patient’s clinical history, imaging findings, and regional rarity of the disease, a presumptive diagnosis was made without histological confirmation. The patient improved with physiotherapy and declined surgery. This case highlights the need to consider parasitic infections in the differential diagnosis of intramuscular calcifications, even in countries where the disease is considered eradicated, to avoid misdiagnosis and unnecessary interventions.

Introduction

Parasitic infections involving the musculoskeletal system are uncommon but can present with a wide range of imaging features that mimic neoplastic, vascular, or inflammatory conditions. These infections are more frequently seen in endemic regions, but globalization and population mobility mean they may also occur in nonendemic areas, often creating diagnostic challenges for clinicians and radiologists unfamiliar with their presentation [1,2].

Dracunculiasis (Guinea worm disease) is a waterborne parasitic infection caused by Dracunculus medinensis. Transmission occurs through ingestion of water containing infected copepods (water fleas). Once ingested, larvae are released in the stomach, penetrate the intestinal wall, and migrate to subcutaneous tissues, where the gravid female worm emerges after approximately 1 year, often causing a painful blister—typically in the lower limbs [3,4].

Once widespread, dracunculiasis has seen a dramatic decline due to global eradication campaigns, decreasing from an estimated 3.2 million cases in Africa in 1986 to just 14 cases in 2023 and 13 in 2024 [3,5]. The disease is now considered eradicated in most regions, with sporadic cases persisting mainly in parts of Chad, Ethiopia, and South Sudan [3,5]. In Saudi Arabia, the last recent case has been reported since 2007 [6], underscoring its rarity in this region.

This report describes a rare case of dracunculiasis in a patient from a nonendemic region presenting with intramuscular calcifications. The presentation closely resembled other calcifying soft tissue conditions, highlighting the importance of maintaining parasitic infections in the differential diagnosis of other similar appearing conditions, even in countries where the disease is considered eradicated.

Case presentation

A 75-year-old woman with a medical history of hypertension, osteopenia, and prediabetes with no family history of parasitic or musculoskeletal conditions, presented to the orthopedic outpatient clinic with a 10-day history of dull, aching left hip pain radiating down the left lower limb. She reported intermittent episodes of similar discomfort over the preceding 2 months. The pain was worsened by ambulation and prolonged standing and was partially relieved with rest and oral analgesics. There was no history of trauma, systemic symptoms, or visible skin changes.

Physical examination revealed localized tenderness at the left greater trochanteric region, with asymmetrical muscle weakness in the left quadriceps and hamstring muscles. Passive and active range of motions in the left hip were restricted, with mild disuse-related functional decline. No limb swelling or neurologic deficits were observed.

Laboratory investigations, including complete blood count, erythrocyte sedimentation rate, C-reactive protein, renal function tests, liver enzymes, and urinalysis, were all within normal limits.

Pelvic radiography revealed serpiginous, ring-like calcifications in the soft tissue medial to the proximal femoral diaphysis, without adjacent bony cortical erosion (Fig. 1). Further evaluation with computed tomography (CT) of the left thigh demonstrated a dense, linear, serpentine intramuscular calcification along the course of the adductor muscle group, measuring approximately 6.7 mm in craniocaudal length (Fig. 2). MRI could have further characterized surrounding muscle edema, fibrosis, and the relationship of calcifications to neurovascular structures, potentially narrowing the differential diagnosis but was not feasible due to the patient's financial and logistical constraints.

Fig. 1.

Frontal pelvic radiograph demonstrates 2 dense, serpentine, and partially ring-like calcifications within the soft tissues of the proximal medial left thigh (arrow). The calcifications are separate with longitudinal and transverse course relative to the thigh axis. The adjacent femoral cortex is intact, with no evidence of cortical erosion, periosteal reaction, or other destructive osseous changes.

Fig. 2.

Axial (A, D), coronal (B, E), and sagittal (C, F) reformatted noncontrast CT images of the left thigh in soft-tissue and bone windows, along with 3-dimensional (3D) volume-rendered reconstruction (G), demonstrate 2 dense, linear, serpentine intramuscular calcifications confined to the proximal adductor muscle group (arrow). The largest measures 6.7 mm in craniocaudal length. There is no extension to the tendon, bone, or joint capsule. No associated soft-tissue mass, surrounding edema, or fluid collection is identified. The adjacent musculature shows preserved architecture without significant fatty atrophy, aside from mild reduction in hamstring bulk. The left femur demonstrates intact cortical and trabecular architecture with no cortical erosion, periosteal reaction, or other aggressive osseous changes. The 3D reconstruction provides additional clarity on the calcific morphology and spatial relationship to surrounding structures (G).

Intramuscular calcifications encompass a broad differential diagnosis that can be refined by integrating clinical context. In this case, myositis ossificans, dystrophic calcification and chronic muscular injury were excluded due to the absence of surgical or traumatic history. Genetic causes were considered unlikely, as they typically present with earlier onset and systemic manifestations. Notably, the calcifications demonstrated a distinctive linear, serpentine morphology, a pattern highly suggestive of parasitic infection.

The patient was referred to physiotherapy for symptomatic management and strengthening exercises. She demonstrated clinical improvement, with better mobility and increased muscle strength over subsequent sessions. Surgical excision was discussed and offered, but the patient declined intervention and did not attend scheduled follow-up in the orthopedic clinic.

Discussion

Although dracunculiasis has become exceedingly rare, especially in nonendemic regions, occasional cases continue to be reported in the literature. The majority occur in developing nations across Africa and Asia, particularly in areas with limited access to safe drinking water [7,8]. In 1986, an estimated 3.2 million people in Africa were infected; by 2016, this had declined to only 25 cases in Chad, Ethiopia, and South Sudan [5]. More recently, 14 cases were reported worldwide in 2023 and 13 in 2024 [3]. In Saudi Arabia, the last known case was described in 2007 [6], and before that in 1975 [9], underscoring the rarity of the current report.

The typical clinical manifestation of dracunculiasis is the emergence of a painful skin vesicle from which the worm extrudes, most often in the lower limbs [10]. This distribution is partly explained by the female worm’s geotropism, with approximately 93% of calcifications occurring in the lower extremities [11]. Other reported sites include the breast, scrotum, bladder, uterus, heart and peritoneum [12,13]. Calcification usually results from the death of the worm within tissues and may remain asymptomatic [14], although symptoms can occur when lesions are located near joints or neurovascular bundles.

Radiologically, calcified D. medinensis typically appears as a long, beaded, or serpentine structure; when coiled or fragmented, it may appear whorled or amorphous [10]. In this case, CT revealed a dense, serpentine calcification tracking along the adductor muscle group, measuring approximately 6.7 cm in craniocaudal length. While such morphology is highly suggestive of dracunculiasis, it is not pathognomonic. The decision to proceed with CT rather than MRI was based on CT’s superior spatial resolution for calcified lesions, wider availability, and immediate accessibility at the treating facility. MRI was recommended to assess associated soft tissue changes, but it was not performed due to financial and logistical constraints. The diagnosis was made radiologically by integrating imaging appearance, anatomical location, clinical history, and epidemiologic rarity in the region.

Several conditions may mimic the imaging appearance of calcified D. medinensis. Calcified filarial worms, such as Loa loa or Onchocerca volvulus, are usually smaller and localize to the hands and feet [10]. In cysticercosis, “rice-grain” calcifications align with muscle fibers and are typically multiple [15]. Myositis ossificans, often post-traumatic, demonstrates zonal ossification with peripheral bone formation and central lucency—features absent in this case [16]. Dystrophic calcification due to chronic muscle injury appears irregular or amorphous [10], while calcinosis in scleroderma involves skin and subcutaneous tissue [17]. Vascular malformations can also calcify but are distinguishable with Doppler ultrasound. Other less common considerations include inflammatory myopathies such as dermatomyositis and chronic venous insufficiency, although these conditions typically present with different clinical and imaging profiles.

In the acute phase, management of dracunculiasis traditionally involves gradual extraction of the worm, often by winding it around a stick over several days [12,18]. For calcified remnants, treatment is usually conservative unless the lesion causes pain, functional impairment, or compressive symptoms, in which case surgical excision may be considered [10]. Our patient improved with physiotherapy and declined surgery.

The absence of MRI and histopathologic confirmation are limitations. However, the integration of clinical and radiologic findings provided a strong presumptive diagnosis. Radiologists should maintain awareness of parasitic etiologies when encountering intramuscular linear calcifications, even in regions where the disease is considered eradicated.

Conclusion

Although dracunculiasis is considered eradicated in most countries, isolated cases may still occur and present with imaging findings that mimic more common musculoskeletal conditions. In this patient, the combination of clinical history, epidemiologic context, and CT features—while not pathognomonic—were highly suggestive of a calcified Dracunculus medinensis. Awareness of such parasitic etiologies is essential when evaluating serpentine intramuscular calcifications, particularly in the lower limbs, to avoid unnecessary invasive procedures. This case underscores the enduring diagnostic value of radiologic assessment in rare parasitic infections and the importance of maintaining a broad differential diagnosis, even in nonendemic settings.

Leaning points

• •Maintain parasitic infections in the differential – Even in nonendemic countries, rare parasitic infections like dracunculiasis can present with imaging findings that mimic more common musculoskeletal disorders.
• •Radiologic pattern recognition is crucial – Long, serpentine intramuscular calcifications on radiographs or CT should raise suspicion for dracunculus medinensis, particularly in the lower limbs.
• •Epidemiologic awareness helps narrow diagnosis – Knowledge of the disease’s near-eradication and rare occurrence in certain regions supports targeted interpretation of unusual imaging findings.
• •MRI may offer additional diagnostic value – Although CT clearly depicts calcifications, MRI can assess associated muscle and soft tissue changes, further refining the differential.
• •Management is usually conservative for calcified remnants – Surgical excision should be reserved for symptomatic cases, while physiotherapy can improve functional outcomes.
• •Histologic confirmation is not always necessary – In the right clinical and imaging context, a presumptive diagnosis can be confidently made without invasive procedures.

Patient consent

Written consent for the case to be published (including images, case history, and data) was obtained from the patient for publication of this case report.