Parasitic Worms Hiding in Man's Scrotum Caught on Video

A man suffering from pain and swelling in his genital area was found to have parasitic worms swimming around in his scrotum, and doctors managed to capture them on video.

Images of the parasites have been featured in a case study of the man's infection published in The New England Journal of Medicine (NEJM) and authored by medics Amit Sahu and Bharat Aggarwal at the Max Super Specialty Hospital in New Delhi.

The 26-year-old man sought medical attention at the hospital after experiencing the pain and swelling, as well as low-grade fevers, for one month, the authors wrote. When doctors examined him, they observed tenderness and swelling on the right side of his scrotum, the bag of skin that holds the testicles.

They then conducted an ultrasound examination, which revealed the possible presence of microscopic, thread-like worms in the scrotum. Further tests, including an analysis of the man's blood, confirmed the presence of the parasitic nematode species Wuchereria bancrofti.

Infection with this species of nematode, or roundworm, as well as two other species in the Filariodidea family, can result in a disease known as lymphatic filariasis.

The disease is characterized by damage to the lymphatic system, which maintains the body's fluid balance and fights infections. While most lymphatic filariasis infections are asymptomatic, the disease can lead to abnormal enlargement of certain body parts—including swelling of the scrotum in men—and cause pain and permanent disability. Patients are often stigmatized because of their visible symptoms and may experience a loss of income, which can contribute to poverty.

The disease, which is spread among people by mosquitoes, affects more than 120 million people across the tropical and subtropical regions of Asia, Africa, the western Pacific and parts of the Caribbean and South America, figures from the U.S. Centers for Disease Control and Prevention show. Infections have not occurred in the United States to date.

Mosquitoes become infected with the immature larvae, or microfilariae, of these parasitic roundworms after biting an infected host and ingesting their blood. These larvae mature inside mosquitoes and can then be transmitted to other individuals via another bite.

After the mature larvae enter the human body, they move into the vessels of the lymphatic system, where they develop into adult worms. These worms live in these vessels, where they can survive for six to eight years, producing millions of immature larvae in this time, which circulate in the blood. The microfilariae can then be transmitted to another person via a mosquito intermediary, completing the cycle.

People are usually infected in childhood, but if symptoms do appear, they tend not to develop until years later. Despite this, even asymptomatic individuals without obvious clinical signs can still contribute to spreading the disease, and they may also experience hidden damage to their lymphatic system that goes unnoticed.

People living for long periods in regions where the disease is found are most at risk. Individuals who visit these areas are at very low risk because repeated mosquito bites over several months or years are usually required to contract the disease.

In the NEJM case study, the doctors wrote that the ultrasound revealed "linear structures" moving within one of the lymphatic vessels in the man's scrotum. In the disease, this observation is known as a "filarial dance sign." This sign represents the undulations of live worms that have moved into the lymphatic vessels, causing dysfunction.

People who are infected with the adult worms can be treated with the anti-parasitic drug diethylcarbamazine. In the case of the patient in India, doctors put him on a three-week course of the medication, and his symptoms resolved.

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