Filariasis

Filariasis is a parasitic infection caused by thread-like nematode worms from the Filarioidea family. It spreads to humans through the bites of infected mosquitoes and other blood-feeding insects. The disease mainly targets the lymphatic system, leading to lymphatic filariasis, and can also affect the skin and subcutaneous tissues, resulting in conditions such as onchocerciasis (river blindness).

1.0Introduction of Filariasis

• Lymphatic filariasis (elephantiasis) is a disease caused by parasites or worms (microfilariae) that weaken and disfigure a person. 
• Disfigurement can be in the form of enlargement of the entire leg or arm, breasts and genitals. 
• This happens when parasites attack the lymph nodes and vessels that maintain the delicate balance between the tissues and blood- an important component of the body's immune system. 
• The thread-like worms, which can be 4-12 cm long, live and mature as adults in the body's lymph nodes and vessels for 4-6 years. 
• The adult worms breed other thread-like worms (microfilariae), which can again be transferred to another person through mosquito bites.

2.0Filariasis Infectious Agent

• Filariasis is caused by the nematode worm, either Wuchereria bancrofti or Brugia malayi  round, coiled and thread-like parasitic worms belonging to the family filaridea.  

3.0Stages of Development of Filariasis

• The filariasis worm has three distinct stages of development during a lifetime, namely: (1) egg, (2) larva, and (3) worm. 
• Egg: The microfilariae from an infected person are transferred to a mosquito, which releases eggs, which grow into larvae in 7-21 days. 
• Larva: The larvae migrate to the mosquitoes' mouth parts (proboscis). When the mosquito carrying the larvae in its proboscis bites another person, these larvae are released into that person's bloodstream. 
• Worm: These microfilariae stay and multiply in the bloodstream and attack the lymph nodes and lymph vessels, resulting in malaise or fever (the signs and symptoms of an infected person) and eventually disfigurement or enlargement of body parts. 

4.0Signs and Symptoms of Filariasis

• Among the people in endemic areas, the development of the disease may take a long time. 
• Overt signs and symptoms are usually observed during adulthood, even though the infection may have been acquired in childhood. 
• Physical symptoms include pain, swollen limbs, and bad-smelling lesions in the skin; enlargement of the arms, legs, breasts, or vulva; difficulty in walking and mobility; and damage to the lymphatic system and kidneys. 
• Psychosocial symptoms: personal shame, lost/diminished economic productivity, becoming a burden to the family and community and social loss (lost or broken marriages, lost parenthood opportunities).
• Keep away from the breeding sites of mosquitoes carrying filariae. 
• Keep away from the breeding sites of mosquitoes carrying filariae, usually the leaves of pandanus, banana, pakil, taro (gabi), abaca, and any exiled plants. 
• Persons who live in or travel to areas where filariasis occurs should avoid being bitten by mosquitoes by protecting themselves with mosquito repellants, wearing protective clothing and/or sleeping under mosquito nets.
• Detect and treat the disease early. If a person is suspected of infection, send a blood sample for examination. If the sample is found positive for filariasis, ensure the person is treated appropriately. 
• Schools and communities where filariasis is known to occur should participate in mass treatment programmes for the population to prevent cross-infection. 
• Help lessen the suffering of persons with filariasis. Carefully wash the infected areas using soap and water. 

5.0Human Filarial Infections

6.0Filariasis Host

• Man is a natural host.  
• Age: all ages are susceptible.  
• Gender: Male > Female  
• Migration facilitates the spread to non-endemic areas.  
• Immunity develops after many years of exposure.  
• Social factors: urbanization, industrialization, migration, illiteracy, poverty, poor sanitation, and sanitation.

Environmental Factors

• Climate favoring vector  
• Temperature :22-38 deg  
• 70% relative humidity  Poor Drainage, sewage disposal, lack of town planning.
• Common breeding places: cesspools, soakage pits, ill-maintained drains, septic tanks, open ditches, etc.

Methods of Control

• Chemotherapy 
• Vector control