Signs and Symptoms of Filariasis

Filariasis, predominantly a disease of tropical countries, is caused by types of parasitic worms called nematodes. Also known as roundworms, there are more than 28,000 types of nematodes. The filarial parasites, slender and threadlike, are tissue-dwelling worms. Microfilaria are the larva of the parent worm and are transmitted by mosquitoes and other biting insects. Flies and mosquitoes act as vectors, or carriers, spreading the disease from victim-to-victim. At a minimum, all filarial infections cause some type of skin problems but the signs and symptoms vary depending on the type of infectious worm.

Onchocerciasis, also known as River Blindness, is caused by the microfilaria and not the adult worms. Very severe itching (pruritus) is caused by the microfilaria just underneath the skin (subcutaneous tissue). Eczema and secondary infections are not uncommon due to the intractable itching. Conjunctivitis and photophobia occur when the eyes are involved. In many stricken individuals, this eventually leads to blindness. Lymph system involvement is another manifestation of the filarial diseases. One of the many responsibilities of the lymph system is to return body fluids back into the bloodstream. When the lymph system is obstructed, fluid builds up in the tissues of the body. In onchocerciasis, obstruction of the lymphatic system generally occurs in the groin area leading to scrotal enlargement up to the size of a basketball.

Loiasis is an infection where the worms live in the subcutaneous tissues and cause intermittent itching and swelling. Called Calabar swellings, they are most frequently found on the wrists and knees. Worms that are moving in the body are sometimes are visible in the sclera of the eyes of infected people. Worms have also been seen in the penis and nipples of men and women.

Bancroftian filariasis and Malayan filariasis are two diseases that share many of the same signs and symptoms. The adult worms live in the lymph system and nodes while the microfilaria live in the bloodstream. Signs of infections usually do not present until after six months of being infected. The symptoms most commonly begin with inflammation in the genital area or extremities. Acute-onset, recurrent bouts of fever, chills, headache and malaise are some of the signs and symptoms. Lymphedema may begin to accumulate in the extremities and genital area. Mild attacks may resolve in a few days with lymphedema diffusing out of the tissues in several weeks. The worst symptoms involve chronic lymphedema which leads to elephantiasis. Affecting the genitals and entire limbs, the size and weight of the affected body parts leads to physical disability.

Fortunately, global plans to stop the spread of filariasis, with its heavy toll on its victims, not the least of which is shame and social stigmatization, are underway and on track to potentially be successful by 2020.