Filariasis

What is Filariasis?

Filariasis is a disease triggered by a long-lasting infection by parasites that are spread through mosquito bites. This persistent infection can cause swelling in your arms and legs, build up of fluid in the scrotum known as hydroceles, and lumps in the testes. It’s the second most common cause of lasting deformities and disabilities globally, only behind leprosy. This issue, known as Lymphatic Filariasis (LF), is classified as a neglected tropical disease currently.

The Global Programme to Eliminate Lymphatic Filariasis is making efforts to stop this disease from spreading by providing large scale medicine distributions to people living in areas where the disease commonly occurs. There are several programs in place to motivate people to take part in these medication distributions.

What Causes Filariasis?

Filariasis is a disease caused by three types of tiny worm-like parasites: Wuchereria bancrofti, Brugia malayi, and Brugia timori. These parasites are passed to humans by five types of mosquitoes, including Aedes, Anopheles, Culex, Mansonia, and Ochlerotatus.

Risk Factors and Frequency for Filariasis

This condition affects 120 million people across 72 countries worldwide, particularly in tropical and subtropical climates. Countries most impacted include those in Asia, Africa, the Western Pacific, South America, and the Caribbean. Among them, Haiti, Dominican Republic, Guyana, and Brazil have endemic levels of the disease. It’s also notable that one-third of children in these affected regions carry this infection, but don’t show symptoms. Half of the infected individuals are in their 30s or 40s, and the disease tends to impact men ten times more than women.

Signs and Symptoms of Filariasis

Filariasis, a disease linked to parasitic worms, often presents itself in various ways. The most frequently seen symptom is hydrocele, a swelling in the scrotum in males. This usually doesn’t affect children, becoming noticeable only after puberty and into one’s 20s or 30s.

Other possible symptoms of filariasis include:

• Filariatic fever – This presents with symptoms including inflammation of the lymph glands, headache, fever, chills, and a general feeling of unwell.
• Filarial abscess – This can cause localized swelling and pain. If the abscess ruptures, it may discharge dead worms. This can also lead to lump formation under the skin.
• Acute dermatolymphangioadenitis (ADL) – This is characterized by repeated inflammation bouts leading to a build-up of fluid, a condition known as lymphedema.

Lymphedema can be categorized into different stages based on its severity:

• Grade I – Temporary swelling of an extremity
• Grade II – Permanent swelling of an extremity which could be either soft or hard
• Grade III – Permanent, hard swelling of an extremity with skin thickening
• Grade IV – Permanent, hard swelling of an extremity with a thick, lumpy appearance reminiscent of elephant skin

Another condition that can result from filariasis is tropical pulmonary eosinophilia, an extreme immune response to the infection. Symptoms can include a type of lung disease that affects how much the lungs can inflate, along with wheezing, difficulty in breathing, and an increase in specific type of white blood cells (eosinophils).

Testing for Filariasis

If you are suspected to have a specific infection, your healthcare provider might need to run several tests to make an accurate diagnosis. The Centers for Disease Control and Prevention (CDC) advises taking two samples of blood to visualize under a microscope. This is done by pricking your finger or through a method called venipuncture where blood is taken directly from a vein, typically in your arm. The blood tests are typically done after 8 pm because the tiny worms causing the infection are most active at night. These samples are then treated with chemicals like Giemsa or H&E stain to make it easier to see the infection under the microscope.

Another method to identify this infection is a type of genetic test called PCR, which detects the presence of infection antigens. In simple terms, antigens are substances that trigger your body’s immune system. This method is the best way to identify the infection as it can even detect the infection in its hidden or ‘latent’ stages. However, this specific test for detecting the W. bancrofti infection, which is caused by a parasite, is not currently approved by the FDA.

In men who might be carrying the infection without showing any symptoms, a scrotal ultrasound might be recommended. The ultrasound can reveal the movement of adult worms in their bodies, a pattern often referred to as the “filarial dance sign”. It suggests the presence of worms moving in the lymphatic vessels, which is a part of your body’s immune system.

Treatment Options for Filariasis

Diethylcarbamazine (DEC) has been commonly used as a treatment method for patients with certain ailments. However, if a patient also has Loa loa, a type of worm infection, or onychomycosis, a fungal infection of the nails, it’s best to avoid using DEC, as it can potentially worsen eye disease and cause brain disease.

The World Health Organization (WHO) generally recommends using a combination of three drugs, ivermectin, albendazole, and DEC for treating certain patients. This combination effectively treated up to 96% of patients in one study for up to three years. However, it’s important to note that this triple therapy should not be used in areas where Loa Loa is common.

In areas where Loa Loa is common, it’s better to use doxycycline. This drug not only helps in slowing the inflammation and thickening of the skin that leads worsening swelling, but also targets Wolbachia, a type of bacteria found in parasitic worms.

Currently, there is no vaccine to prevent filariasis, a group of diseases caused by a type of parasitic worm, but research towards developing one is ongoing.

For patients with severe symptoms, surgical treatments can be considered. These treatments aid in reducing build-up of skin and improve fluid drainage from the affected areas. Topical coumarin and flavonoids, a group of naturally occurring substances that help with blood thinning, have also been shown to reduce body swelling. A very specific type of laser treatment has shown promising results in managing skin lesions and abnormal connections between lymph vessels and skin surface.

Managing conditions like lymphedema, a type of swelling due to damaged lymph vessels, in the long term can be challenging. Repeated attacks can occur even in the absence of the parasitic worm causing filariasis. Strategies for managing this condition include maintaining skin hygiene, wearing comfortable shoes, using compression bandages, regular washing with soap and water, regular use of pneumatic compression devices, limb elevation, applying cold or heat as needed, and using antibiotic and antifungal creams to prevent worsening of inflammation. This helps in avoiding sudden worsening of the condition.

What else can Filariasis be?

When making a diagnosis, doctors might consider several conditions that can produce similar symptoms. These conditions include:

• Various kinds of filariasis (a type of parasitic disease) such as Onchocerca, Dirofilaria, Brugia, Dipetalonema, Loaina, Meningonema
• Lymphoma (a type of cancer)
• Testicular tumors
• Birth defects affecting the lymphatic system
• Pelvic cancer
• Damage to the lymphatic system caused by surgery or radiation treatment

What to expect with Filariasis

The chance of getting better from filariasis, a disease caused by infection with parasites spread by mosquitoes, is high if it’s detected early and treated promptly, preventing more severe health problems. Typically, the disease can be treated with 5 annual doses of medications called DEC, sometimes combined with ivermectin or albendazole. However, symptoms usually don’t show up until later in life when the amount of worms in the body has increased.

The most severe form of filariasis is known as Elephantiasis, which results from years of ongoing infections. The disease can also cause a condition known as lymphedema, or swelling in body tissues. There are ways to treat lymphedema, but managing it becomes harder once the disease progresses to its advanced stages.

Possible Complications When Diagnosed with Filariasis

Occult filariasis refers to an infection in body tissues without any trace of it in the blood. Possible outcomes of this infection can include:

• Tropical pulmonary eosinophilia – a condition characterized by lung inflammation and an elevated number of eosinophils, a type of white blood cell, in the blood
• Filarial arthritis – inflammation of joints due to this parasite infection
• Filarial-associated immune complex glomerulonephritis – a kidney condition related to the immune response to this infection
• Filarial breast abscesses – pus-filled pockets in the breast resulting from the infection

Loiasis is another infection that can occur alongside occult filariasis. It’s important to treat with caution as severe reactions, including brain disorders, can occur if it’s treated with the drug ivermectin.

Receiving targeted medical treatments may also have some side effects. These are likely due to the body wide inflammation caused by the activity of the filarial parasites. Reported complications include fever, chills, and small but distinct changes in measures of heart and blood vessel function, such as systolic blood pressure, although these changes do not lead to extremely low blood pressure (hypotension).

Preventing Filariasis

The World Health Organization supports several strategies to control the spread of diseases caused by insects. These include using nets treated with insecticides, spraying insecticides indoors, personal protection measures like wearing long sleeves and using bug spray, and giving preventative medicines to people who are at high risk.

For travelers, the risk of developing lymphatic filariasis, a disease caused by certain types of microscopic worms, is very low. That’s because it takes many years and multiple bites from infected mosquitoes before a person can get infected. Plus, these worms can’t reproduce in mosquitoes, making it harder for the disease to spread.