What is Bancroftian Filariasis?

Bancroftian filariasis, which accounts for 90% of lymphatic filariasis cases, is a major cause of acquired swelling in the lymphatic system, only coming second to leprosy as the leading infectious disease causing disability globally. This disease mainly affects the lymphatic system and can show a wide variety of symptoms. These can range from acute symptoms, such as severe inflammation of the lymph nodes and vessels, filarial fever, and an increased count of a certain type of white blood cell in the lungs, to chronic symptoms. These chronic symptoms may progress to conditions like hydrocele (swelling in the scrotum), lymphedema (swelling caused by lymph fluid buildup), and, in extreme cases, elephantiasis (hardening and thickening of the skin).

In filariasis, long-term inflammation of the lymphatic system occurs, leading to scarring. This eventually results in lymphedema, a condition characterized by swelling due to fluid buildup. Most of the time, this affects the legs, but the swelling can also occur in the genitals, arms, and breasts.

What Causes Bancroftian Filariasis?

The disease is caused by a roundworm named Wuchereria bancrofti. This roundworm grows and multiplies inside the lymphatic system of humans, producing immature worm-like creatures known as microfilariae. These microfilariae enter the bloodstream, and when mosquitoes bite an infected person, they take in these immature worms. These mosquitoes can then spread the disease to other people when they bite them.

Risk Factors and Frequency for Bancroftian Filariasis

Bancroftian filariasis, a long-lasting tropical disease that is often overlooked, is widespread in over 72 countries. These include areas in South East Asia, Sub Saharan Africa, islands of the Pacific, and certain parts of Latin America. Around 70 million people globally are affected by this disease, which is caused primarily by the parasite Wuchereria bancrofti in 90% of cases.

An estimated 36 million people around the world get severely sick from this disease.
About 25 million are suffering from hydrocele – a fluid buildup in a body cavity.
Another 15 million people suffer from lymphedema – a condition of localized fluid retention and tissue swelling.

The World Health Organization (WHO) recognizes the importance of this disease and aims to eradicate it by 2020. This goal is not just about preventing unnecessary suffering; it’s also about reducing poverty since the costs associated with managing the disease’s effects are significant.

Signs and Symptoms of Bancroftian Filariasis

There are different categories people can fall into when it comes to the disease:

Endemic normals (EN) – These are people living in areas where the disease is common, but they are not infected and show no signs of the disease.
Chronic (CH) – These are people who’ve had complications such as elephantiasis, or hydrocele, or both for more than four years.
Asymptomatic carriers (AS) – These are people who carry the disease, but don’t show any symptoms.

The symptoms of the disease can be divided into two categories: acute and chronic.

Acute symptoms include:

Acute adenolymphangitis – This happens as a result of the body’s immune response to the antigens released by dying worms. It’s characterized by sudden fever and painful lymph node swelling. In males, the genitals are often involved, resulting in painful epididymitis.
Filarial fever – This is characterized by episodes of fever that resolve on their own, without any associated lymph node swelling.
Tropical pulmonary eosinophilia – This is characterized by repeated bouts of dry cough and wheezing at night.

Chronic symptoms include:

Lymphedema – This is the most common symptom that happens over a long time due to chronic damage to the lymphatic vessels. It usually presents with swelling of the limbs, either upper or lower, depending on whether the inguinal or axillary lymphatic vessels are involved. Swelling typically starts as pitting edema, which later turns into hard, non-pitting type. Elephantiasis is the most severe type of lymphedema, characterized by extreme swelling of the limbs, genitalia, and breasts. The skin becomes thick and hard due to hyperpigmentation and hyperkeratosis.
Hydrocele – This is one of the debilitating effects linked with chronic disease. Hydrocele can be one-sided or both-sided, resulting in enlargement of the scrotum. It can be very large, reaching up to 40 cm (about 15.5 inches).

Other symptoms include chyluria, hematuria, swelling of the lymph nodes in the groin and armpits, testicular or groin pain, and peeling skin.

Testing for Bancroftian Filariasis

Understanding a patient’s travel history and the local prevalence and persistency of the health condition is invaluable in diagnosing the disease. A blood test often reveals a higher-than-normal count of a specific type of white blood cell called eosinophils. In spite of recent medical advancements, the primary method for diagnosis is examining a blood sample taken at night under a microscope. In this test, a staining method called Giemsa is used to highlight microfilariae – a type of parasite – in the bloodstream.

A newer test called the circulating filarial antigen test is increasingly being used. It’s about 97% effective in catching the disease and almost 100% accurate in confirming it. This test is becoming more popular because it is simple to use and can also spot the illness in patients who don’t show microfilariae in their blood tests.

Other strategies for diagnosis include the membrane filtration method, ultrasonography (which in this context shows a ‘filarial dance sign’ indicating infestation), lymphoscintigraphy (a medical imaging technique), immunochromatographic tests (a type of rapid diagnostic test) and advanced molecular techniques like in situ hybridization (ISH), fluorescence in situ hybridization (FISH), and polymerase chain reaction (a method used to amplify DNA segments).

Treatment Options for Bancroftian Filariasis

Diethylcarbamazine (DEC) is a common global treatment for filarial infection. The Centers for Disease Control and Prevention (CDC) advises taking DEC at a dosage of 6 mg/kg/day either as a one day or 12-day treatment. However, if patients live in areas where onchocerciasis (river blindness) or loiasis (eye worm) are prevalent, they shouldn’t take DEC as it can potentially cause a dangerous reaction.

When DEC is taken, it may create an immune response similar to what’s seen in river blindness. Patients can experience symptoms like headaches, joint pain, dizziness, loss of appetite, general discomfort, and skin rashes. In such cases, a combination of doxycycline and either ivermectin or albendazole is recommended.

Patients with significant swelling in the limbs (elephantiasis) or fluid-filled sacs in the scrotum (hydrocele) won’t see improvements with medicine alone. Surgical treatment might be necessary, particularly for those with hydrocele. Patients with swollen limbs should be managed by a therapist specialized in lymphedema, who will highlight the importance of cleanliness, raising the limbs, exercises, caring for the skin and any wounds, and wearing suitable footwear.

While not commonly used, steroids can help reduce swelling in these patients. There’s limited evidence showing that doxycycline, taken daily for 4 to 6 weeks, can help kill adult worms and prevent the progression of lymphedema. Suramin, a medicine commonly used for river blindness, might have a role in treating lymphatic filariasis, but more research is needed to confirm its effectiveness.

Bancroftian filariasis is a disease affecting the lymphatic system, but it’s not the only one. There are other conditions that might look like it and affect the same system in the body. For a correct diagnosis, factors such as the patient’s age, their travel history, family medical history, whether they live in an area where the disease is common, and their living conditions should be considered.

Conditions that might be mistaken for Bancroftian filariasis include:

Brugia malayi (another type of parasitic infection)
Brugia timori (another type of filariasis)
Sporotrichosis (a rare fungal infection)
Lymphosarcoma (a type of cancer of the lymphatic system)
Cancer of the testis or scrotum
Congenital hydrocele (fluid in the scrotum present at birth)
Epididymal cysts (fluid-filled lumps in the coiled tube above the testicles)
Milroy syndrome (genetic condition causing swelling of the limbs)
Bacterial lymphadenitis (infection of the lymph nodes)

What to expect with Bancroftian Filariasis

Diethylcarbamazine works remarkably well for acute cases of this disease. Unfortunately, those with severe chronic damage in their lymph system, showing up as lymphedema or elephantiasis, don’t respond as well. These chronic forms have a bleak outlook. Patients with a condition called hydrocele might benefit from surgery, but it often comes back. The disease has an enormous impact, leaving the person unable to carry out everyday tasks.

Possible Complications When Diagnosed with Bancroftian Filariasis

The worst outcome of the disease is a condition called elephantiasis, which can occur in people who have been dealing with a filarial infection for a long time. This disease can also cause complications like hydrocele (a buildup of fluid in the scrotum). Additionally, medicine used to treat the disease can cause potentially dangerous side effects.

Common complications and reactions:

Elephantiasis
Hydrocele
Encephalopathy (a brain condition) as a side effect of treatment
Potential death, especially when the medication is used in areas with a high prevalence of a similar disease, loiasis

Preventing Bancroftian Filariasis

To prevent getting the disease, it’s critically important to avoid mosquito bites and take measures to control mosquitoes. If you’re a tourist, it’s best to avoid areas where the disease is common. For those who travel to such areas, it’s recommended to sleep under a mosquito net, wear long shirts and pants, and use mosquito repellent on skin that’s not covered by clothing. Currently, there’s no vaccine against this disease.

If you have swelling in the arms or legs (a condition known as lymphedema), practice good personal hygiene and clean the swollen areas with an antiseptic solution every day. Wearing compression stockings, sticking to a regular exercise routine, and placing a pillow under the swollen limb while sleeping can help minimize swelling.

For patients who have chyluria (a condition where fat and proteins are present in the urine), it’s crucial to limit fatty foods consumption. On the other hand, a diet high in protein and medium-chain triglycerides (a type of fat) is beneficial. This dietary advice can help manage the condition effectively.