If you don’t live in Southeast Asia, South America, Africa, or the islands of the Pacific, chances are you will not come in contact with Filarial worms. The thread-like parasitic roundworm and their larvae have infected more than 170 million people in these areas. The filarial worm larvae transmit the disease through infected mosquitoes. The mosquito bites an infected individual and then it bites an uninfected individual. Once inside the body, the larvae make their way to a particular part of the body and they mature into adult worms. Although the disease can be debilitating, it is rarely fatal. According to The World Health Organization (WHO) filariasis one of only six “potentially eradicable” infectious diseases and has embarked upon a 20-year campaign to eradicate the disease.

The Centers for Disease Control (CDC), offers the following information about causes and symptoms:

Cases of lymphatic filariasis, the most common form of the disease, the disease is caused by the adult worms actually living in the lymphatic vessels near the lymph nodes where they distort the vessels and cause local inflammation. In advanced stages, the worms can actually obstruct the vessels, causing the surrounding tissue to become enlarged. In Bancroftian filariasis, the legs and genitals are most often involved, while the Malayan variety affects the legs below the knees. Repeated episodes of inflammation lead to blockages of the lymphatic system, especially in the genitals and legs. This causes the affected area to become grossly enlarged, with thickened, coarse skin, leading to a condition called elephantiasis.

In conjunctiva filariasis, the worms’ larvae migrate to the eye and can sometimes be seen moving beneath the skin or beneath the white part of the eye (conjunctiva). If untreated, this disease can cause a type of blindness known as onchocerciasis.

Symptoms vary, depending on what type of parasitic worm has caused the infection, but all infections usually begin with chills, headache, and fever between three months and one year after the insect bite. There may also be swelling, redness, and pain in the arms, legs, or scrotum. Areas of pus (abscesses) may appear as a result of dying worms or a secondary bacterial infection.

If you suspect that you have filarial worms, you should visit your physician as soon as possible. Your doctor will take a patient history and a blood test. The CDC mentions that the doctor will look for a pattern of inflammation and signs of lymphatic obstruction, together with the patient’s possible exposure to filariasis in an area where filariasis is common. The larvae (microfilariae) can also be found in the blood, but because mosquitoes are active at night, the larvae are usually only found in the blood between about 10 pm and 2 am. If filarial worm is caught early, it is easily treated through antibiotics.

Filarial Worm Prevention

Taking ivermectin can help prevent infection from mosquito bites. This may be especially useful for individuals that spend a significant amount of time outdoors and in highly infested areas. In addition you should:

• Limit outdoor activities at night, particularly in rural or jungle areas
• Wear long sleeves and pants and avoid dark-colored clothing that attracts mosquitoes
• Avoid perfumes and colognes
• Treat one or two sets of clothing ahead of time with permethrin (Duramon, Permanone).
• Wear DEET insect repellent or, especially for children, try citronella or lemon eucalyptus, to repel insects if sleeping in an open area or in a room with poor screens, use a bed net to avoid being bitten while asleep
• Use air conditioning, the cooler air makes insects less active

Please note that currently, there is no preventative vaccine for filarial worms

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