What Is Filariasis? – Causes, Symptoms & Diagnosis

Filariasis is a parasitic disease caused by some species of nematodes belonging to Filarioidea. This disease is vector-borne and is spread by mosquitoes and black flies. Wuchereria bancrofti is the most famous causal organism of the disease. Filariasis is prevalent in tropical and subtropical regions of Asia, Africa, the Western Pacific, and Central and South America. The disease is a significant public health concern, and efforts to control and eliminate the disease involve a combination of vector control, drug administration, and health education.

What is Filariasis?

Filariasis is an infectious disease that is transmitted by vectors like mosquitoes and black flies. It is caused by nematodes belonging to the superfamily of worms, Filarioidea. The disease is prevalent in regions having tropical climates. Based on the part of the body infected, the disease can be classified into three types: Lymphatic filariasis, subcutaneous filariasis, and serous cavity filariasis.

• In lymphatic filariasis, the lymphatic system is infected resulting in blocked lymph vessels and swelled lymph nodes. This is the most common type of filariasis.
• Subcutaneous filariasis is characterized by the infection subcutaneous layer of the skin and corneal portion of the eyes.
• Serous cavity filariasis is characterized by the infected serous cavity of the abdomen.

The Causal Organisms of Filariasis

The causative agents of filariasis are thin thread-like nematodes that appear white or transparent under a microscope. To date, around a hundred species of filarial worms have been identified. However, three of them are comparatively popular. These worms are Wuchereria bancrofti, Brugia malayi, and Brugia timori.

Transmission of Filariasis

The transmission of filarial worms involves a complex life cycle that includes both human hosts and mosquito vectors. The process of transmission is as follows:

1. The filarial worms reside and reproduce inside the humans.
2. When a mosquito bites the infected human the larvae called microfilariae is also sucked in by the mosquitoes along with the blood.
3. This larvae grow in the stomach of the mosquito for 10-14 days.
4. Once the larvae has covered up this growth period and become infective, they migrate to the salivary glands of the mosquito.
5. This mosquito bites a healthy person and transmits the larvae to his blood stream.
6. These microfilariae now migrate to the lymphatic system, or other regions of the body where they could infect.
7. Once established into the human body the larvae grow up into adult and reproduce. In the same way the cycle goes on.

Symptoms of Filariasis

Patients having filariasis may or may not exhibit any symptoms. However some common symptoms of filariasis are:

1. Fever, chills, and headache.
2. Skin lesions in the early stages (between 3 to 9 months from insect bite).
3. Lymphedema due to the blockage of lymph vessels during late stages.
4. Swelling and redness of limbs.
5. Sometimes pus retention may result.

In advance stages of disease secondary infection may result. This can result in rashes, abdominal pain and discomfort, loss of vision due to damage of cornea, choroid, retina, and even the optic nerve. Abnormal pigmentation of skin is also observed in certain cases. If neglected, these symptoms can lead to elephantiasis, i.e. gross enlargement of limbs and genital area.

Diagnosis of Filariasis

Diagnosis of filariasis involves detection of filarial worms in blood. These worms are nocturnally active and hence the blood samples of the patient is collected at night and checked under microscope. Apart from this antibody testing is also done to check for further infections.

Treatment of Filariasis

Filariasis does not have a cure till date but researches are going on to find one. However, medications and control can be administered to manage the symptoms and progress of the disease. Some common methods of treatment include:

• Administration of antiparasitic drugs like Diethylcarbamazine, ivermectin, and albendazole.
• Administration of broad spectrum antibiotics in combination to prevent and control secondary infection.
• Use of compression bandages, limb elevation, and skin hygiene are crucial in cases where lymphedema has occurred.
• In some advance cases, surgery may be performed to remove the worms from blocked regions in order to alleviate symptoms and improve functions.

Prevention of Filariasis

There is a popular saying, ” Prevention is better than cure”. In case of filariasis this saying is true. Since, the disease does not have a cure till date, it is important to implement strategies to control the spread or outbreak of this disease. Some steps to prevent and control filariasis is as follows:

• Mass drug administration programs should be implemented in endemic areas to treat entire populations with antiparasitic medications. This will help to reduce the overall burden of the disease and interrupts the transmission cycle.
• Use of mosquito repellents and wearing full sleeved shirts and full length trouser.
• Use of mosquito nets sprayed with pesticides.
• Maintaining proper sanitation practices and cleaning areas to reduce breeding places of mosquitoes.
• Introducing programs to educate people regarding the measures to prevent transmission of filariasis and its risk factors.

Conclusion

To summarize, filariasis, is a group of parasitic diseases caused by filarial worms that belong to the family Filarioidea. The most common filarial parasites affecting humans include Wuchereria bancrofti, Brugia malayi, and Brugia timori. These parasites are transmitted through the bites of infected mosquitoes. Control measures focus on preventing mosquito bites and administering antifilarial medications.

FAQs on Filariasis

1. What is the Main Cause of Filariasis??

The main cause of filariasis is the infection by parasitic worms belonging to super family Filarioidea. These are thin thread like worms that primarily infect the lymphatic system of humans however some of these parasites do infect the skin, and the genitals.

2. How is Filaria Spread?

Filaria is spread through mosquito bites. The filarial worms get into the gut of mosquito when the mosquito bite an infected individual. The worms mature to reach their infective stage within the mosquito and then migrate to its salivary gland.

3. What are the Symptoms of Filariasis?

Fever, chills, swollen lymph nodes, skin lesions, elephantiasis, abdominal discomfort, damaged cornea, etc. are some of the major symptoms of filariasis.

4. How do you Treat Filaria?

The primary treatment for filariasis involves the use of antifilarial medications such as diethylcarbamazine (DEC) or ivermectin. Sometimes supportive measures are taken to manage symptoms and prevent secondary infections.

5. What is the Test for Filaria?

The diagnostic test for filariasis typical microscopic examination of blood samples to detect the presence of microfilariae i.e. the larval form of the parasitic worms. In some cases, molecular techniques like polymerase chain reaction (PCR) are also used for accurate detection and identification of filarial parasites.

6. Can Filariasis cause Death?

Filariasis itself is not fatal but if left untreated it can lead to severe complications like lymphedema, secondary infections, or metabolic constraints that might lead to death or disability in the long run.