Filariasis is a parasitic infection transmitted to humans through mosquitoes. You might have heard of a condition called elephantiasis, where people have grossly enlarged limbs and genitals. This is a rare complication of filarial infection. 

After leprosy, filariasis is the second most common cause of disability throughout the world.¹ Albendazole is an FDA-approved drug used in the treatment of filariasis and many other parasitic infections.² In this article, we will discuss the role of albendazole in the treatment of filariasis.

What is filariasis?

Filariasis is a parasitic infection caused by the roundworms Wuchereria bancrofti and Bruga malayi. Filariasis is transmitted to humans through the bite of mosquitoes. 

During the early stages of the disease, the patient experiences fever, headache, chills, and skin lesions. Antiparasitic agents are used for the treatment of filariasis. 

If filariasis is left untreated, it can cause fibrosis and lymphatic obstruction. The symptoms may progress to swelling of the extremities, especially the external genitals and legs.³

Causes of filariasis

Filariasis is caused by roundworm parasites called nematodes. There are mainly 3 types of filarial worms causing the disease:⁴ These are:

1. Wuchereria bancrofti (90% cases) 
2. Brugia malayi
3. Brugia timori

How is filariasis transmitted to humans?

Filariasis spreads to humans through the bite of an infected mosquito. When an infected mosquito bites a healthy individual, mature filarial larvae are deposited on the skin. They travel through the body to reach the lymphatic vessels, where the mature larvae develop into adult worms. 

These adult worms remain in the lymphatic vessels for 6 to 8 years and disrupt their functioning. They produce large amounts of microfilariae or immature larvae, which circulate through the blood.⁴ These are collected by mosquitoes from where the disease spreads to another person. 

Types of filariasis

There are mainly two types of filariasis, lymphatic filariasis and onchocerciasis. Lymphatic filariasis is caused by a roundworm called Wuchereria bancrofti. River blindness, also known as onchocerciasis, is caused by another parasite called Onchocerca volvulus. 

Lymphatic filariasis

About 120 million people throughout the world have lymphatic filariasis. It is transmitted to humans through the bite of mosquitoes. Lymphatic filariasis causes skin thickness, disfigurement, fever, and swellings. Treatment involves the administration of albendazole combined with diethylcarbamazine.⁶

River blindness

River blindness is transmitted to humans through bloodsucking blackflies. It produces symptoms like itching, disfigurement, impaired vision, and blindness.

It is treated by the antiparasitic drug ivermectin.¹¹

Clinical presentation of filariasis

Lymphatic filariasis is categorised into 3 types based on the clinical presentation and symptoms:

1. Chronic filariasis

Chronic cases show lymphedema, elephantiasis and hydrocele.  Body deformities and disfigurement cause social stigma and affect the mental health of the patient.

2. Acute filariasis

Acute form of the disease shows local inflammation of skin and lymph vessels. It is characterised by lymphedema, elephantiasis, and secondary bacterial infections. It can be debilitating and may last for weeks.⁴ 

3. Asymptomatic

These cases show no signs and symptoms but can still damage the kidneys and lymphatic system.

Signs and symptoms of filariasis

Most patients affected by filariasis do not show any symptoms initially. Symptoms are produced only several years after the infection.⁵

Filariasis can cause skin thickening and enlargement of extremities in severe cases when left untreated. 

Signs and symptoms include:

• Lymphedema -swelling of legs (elephantiasis), genitalia, breast, and face.
• Thickening of skin
• Shortness of breath, wheezing and coughing
• Hydrocele - Swelling of scrotal sac
• Edema - swelling of the body
• Inflammation 
• Bacterial infections of skin
• Fever, chills, headaches

Albendazole

Albendazole is an antihelminthic drug used in the management of parasitic infections. It is used in the treatment of various infections such as:

1. Filariasis
2. Cystic hydatid disease caused by dog tapeworm Echinococcus granulosus
3. Parenchymal neurocysticercosis caused by pork tapeworm, Taenia solium
4. Pinworm disease caused by Enterobius vermicularis
5. Trichuriasis
6. Ascariasis
7. Giardiasis

It also has anticancer properties that act against tumour and parasitic cells.

Mechanism of action of Albendazole

Albendazole contains an active metabolite called albendazole sulfoxide, which causes degeneration of cell components inside the parasite. It also impairs glucose utilisation in the parasite and leads to depletion of the glycogen stores. The decreased energy stores of the parasite cause immobilisation and death of the organism.

Role of albendazole in treatment of filariasis 

According to the WHO, a mass treatment of the entire population is recommended once or twice every year for many years to eliminate the disease. A combination of two drugs involving albendazole and an antifilarial drug diethylcarbamazine or ivermectin is used in the treatment of filariasis.² 

Diethylcarbamazine is the first choice of drug for the management of lymphatic filariasis. Changes to this arise when other filarial organisms coexist and during mass drug administration.

Various drug regimens for management of filariasis 

• The normally recommended drug regimen for the management of filariasis is 6 mg/kg diethylcarbamazine for 12 days
• Doxycycline may be added to the regimen for a 6-week course
• Doxycycline for 23 days duration, which is then followed by a combination of doxycycline and albendazole for 7 days
• For mass drug administration, multidrug regimens are used. Either diethylcarbamazine alone or a combination of albendazole and ivermectin is recommended annually or semiannually⁷

Mass drug administration 

Mass drug administration is aimed to reduce the disease prevalence in endemic regions. Children and young adults are more susceptible to microfilarial infection in these regions. They are also more vulnerable to infections caused by geohelminths like roundworms and hookworms.

Filarial infection causes intestinal discomfort and malabsorption, along with impaired physical and intellectual development. Albendazole has been shown to have substantial beneficial benefits in the treatment of geohelminth infections.⁸

Albendazole combined with diethylcarbamazine is used for the elimination of lymphatic filariasis. Studies have shown that there is a pronounced reduction in the prevalence and intensity of microfilariae after a mass drug administration for about 3 to 5 rounds. 

This reduction is higher with the two-drug regimen, a combination of albendazole and ivermectin, in comparison to the single-drug regimen, involving diethylcarbamazine. This is more significant and evident in children and young adults.⁹

Side effects of albendazole

Albendazole has some side effects, such as:¹⁰

• Stomach pain
• Nausea
• Dizziness
• Allergic reactions like rashes and swelling of skin
• Fever
• Chills
• Changes in vision
• Seizure
• Diarrhea 

FAQs

What is Albendazole  used for?

Albendazole is an FDA-approved antihelminthic drug used to manage many parasitic infections.

What is the mass treatment for filariasis?

Mass treatment for filariasis involves the use of a combination of two drugs albendazole and diethylcarbamazine in endemic regions to eliminate filariasis.

What are the adverse effects of albendazole?

Albendazole is associated with some side effects like nausea, diarrhea, rashes, stomach pain, and rarely, seizure.

Summary

Filariasis is a parasitic infection transmitted to humans through mosquito bites. If filariasis is left untreated, complications like skin thickening, lymphedema, and disfigurement can occur. Albendazole is an FDA approved drug used in the treatment of filariasis. Mass drug administration involves a combination of albendazole and diethylcarbamazine for elimination of filariasis in endemic areas. Consult your doctor or healthcare professional if you experience any symptoms of filariasis. Timely treatment can help to avoid any complications associated with the infection.