Infectious vs. Communicable Diseases

Infectious diseases are caused by pathogenic microorganisms such as bacteria, viruses, fungi, or parasites that multiply within the host. Not all infectious diseases are communicable. For example, tetanus is infectious but is acquired through wounds rather than person-to-person transmission. Communicable diseases are a subset of infectious diseases that can spread directly, such as through contact or respiratory droplets, or indirectly, via contaminated food, water, or vectors like mosquitoes. Therefore, while all communicable diseases are infectious, not all infectious diseases are communicable.

Filaria (Filariasis)

Filaria is a parasitic disease caused by thread-like nematode worms, mainly affecting the lymphatic system and leading to lymphatic filariasis.

Causative Agents:

• Wuchereria bancrofti (~90% of cases)
   
• Brugia malayi
   
• Brugia timori
   

Transmission:
Filarial worms are transmitted through infected mosquitoes:

• Culex: urban/semi-urban areas
   
• Anopheles: rural areas
   
• Aedes: some Pacific islands
   
• Mansonia: Brugia species

Mosquito bites deposit larvae on the skin, which enter the lymphatic system, mature into adult worms, and produce microfilariae in the blood, mainly at night.

Symptoms:

• Lymphoedema and elephantiasis of limbs, genitals, and breasts
   
• Acute attacks with fever, redness, and swelling
   
• Hydrocele in men
   
• Chyluria (milky urine)
   

Diagnosis:

• Blood smear examination (10 PM–2 AM) for microfilariae
   
• Antigen detection tests (ICT, ELISA)
   
• Ultrasound to visualize adult worms
   

Treatment:

• Diethylcarbamazine (DEC) for microfilariae and adult worms
   
• Ivermectin for microfilariae
   
• Albendazole in combination therapy
   
• Management of chronic symptoms through hygiene, limb elevation, exercises, and surgery for hydrocele
   

Prevention:

• Mass drug administration in endemic areas
   
• Vector control: bed nets, indoor spraying, larvicides, eliminating breeding sites
   
• Personal protection: repellents, protective clothing
   
• Health education to raise awareness
   

Effective filaria control focuses on interrupting transmission, reducing morbidity, and preventing long-term disability, ensuring healthier communities.