Persistent leg swelling in a young adult
The next patient to enter your clinic is a male in his early twenties. He complains of persistent right lower extremity swelling that has been going on for two years. The patient states that in addition to his right leg swelling he also has several wounds that do not seem to be healing. He denies any antecedent trauma or prolonged immobility. He has no other complaints and denies fever, chest pain, shortness of breath, and abdominal pain.
Vital Signs: Temp 37.1C, HR 82 bpm, BP 122/84 mmHg, RR 16/min
General: Young adult male, non-toxic appearing, in no acute distress
HEENT: NCAT, PERRL, no conjunctival pallor, moist mucus membranes
Cardiac: RRR with normal S1, S2
Pulmonary: Lungs CTAB, with normal work of breathing
Abdomen: Soft, non-tender, non-distended
Extremities: There is marked edema of the right lower extremity involving the foot through the lower leg as well as several chronic-appearing wounds at various stages of healing without any surrounding erythema or purulence
+ What is the Most Likely Diagnosis?
Although no definitive testing is available in this clinic, the patient’s presentation is most consistent with lymphatic filariasis. Lymphatic filariasis is transmitted by the mosquito (in Africa, the Anopholes mosquito) and is caused by the parasitic roundworm Wucheria bancrofti. When the mosquito takes a blood meal, it transmits W. bancrofti in the larval stage to the human. When the larvae mature into adults, they mate in the lymphatic system, releasing millions of microfilariae. The microfilariae cause damage to the lymphatics, resulting in chronic lymphedema and in some patients hydroceles can form. With impaired lymphatic drainage, patients develop recurrent bacterial skin and soft tissue infections, resulting in hardened, thickened skin commonly referred to as “elephantiasis”.
Definitive diagnosis of the disease is made with a blood smear, with greatest sensitivity achieved when blood samples are taken at night (when microfilariae are most active). Testing for antifilarial IgG is also available. Lymphatic filariasis is treated with diethylcarbamazine (DEC). Of note, DEC is contraindicated in those with onchocerciasis coinfection, as its use worsen the ocular disease. Similarly, DEC must be used with caution in patients with loiasis co-infection, as its use in patients with this disease may lead to encephalopathy and death. Unfortunately, while treatment may prevent worsening lymphatic damage, it does not reverse existing lymphatic injury. Dosing of 6 mg/kg for one day reduces the occurrence of both acute and chronic cases for one year. For optimal clearance of infection a regimen of 6 mg/kg for twelve days is recommended but should be given under the supervision of a physician.
For travelers who spend only a limited time in endemic areas are at low risk for infection. This is because symptoms only develop after many repeated infection over the course of months to years. Nevertheless, appropriate precautions against mosquito bites are advised.
AUTHORED BY Jeremy Liebman, MD
POSTED BY GRACE LAGASSE, MD
- Centers for Disease Control and Prevention. Lymphatic filariasis. (2013).
- Klion, AD. Lymphatic filariasis: Epidemiology, clinical manifestations, and diagnosis. UpToDate. Accessed 2/23/2018.
- Taylor, M.J., Hoerauf, A., Bockarie, M. (2010). Lymphatic filariasis and onchocerciasis. Lancet, 376(9747), 1175-85.