Lymphatic Filariasis Morphology and Life Cycle Quiz

Filarial Worms Overview

• Filarial worms belong to the superfamily Filarioidea.
• Main mode of transmission for filarial worms is through vector-borne routes, primarily by mosquitoes.

Specific Filarial Species and Conditions

• Loa loa causes calabar swellings and allergic reactions in humans.
• Characteristics of 'unsheathed' microfilariae include an absence of a sheath around the body.
• Mesocestoides corti is classified under serous cavity filariasis.
• 'Calabar swellings' and allergic reactions are linked to the antigen from the filarial worm Loa loa.

Historical Observations in Filarial Research

• Clarke described elephantiasis in 1709 in Cochin, referring to it as "elephantiasis."
• William C. B. W. M. Smith first observed microfilaria in hydrocele fluid of a patient from Havana, Cuba in 1863.
• Dr. Robert M. C. C. Clos first reported the presence of microfilariae in chylous urine in 1868.
• Sir Ronald Ross first demonstrated nocturnal periodicity of microfilariae in peripheral blood.

Filarial Worm Habitat and Life Cycle

• Adult worms of Wuchereria bancrofti are typically found in the lymphatic system of the human body.
• The definitive host for the microfilaria of Wuchereria bancrofti is the female mosquito.
• Female adult worms of Wuchereria bancrofti range in size from 8-10 cm.

Microfilariae Characteristics and Vector Behavior

• The part of the microfilaria that represents the rudimentary excretory system is the excretory canal.
• 'Nocturnal' microfilaremia in peripheral blood correlates with the nocturnal feeding habits of the mosquito vector.
• 'Diurnal subperiodic' microfilaremia in certain areas is linked to environmental factors affecting mosquito behavior.

Microfilariae Lifespan and Infectivity

• Microfilariae have a lifespan of approximately 1-2 years in the human body if not taken up by a female vector mosquito.
• A minimum of 5 microfilariae per drop of blood is necessary for infecting a mosquito.

Clinical Manifestations and Diagnosis

• A typical manifestation caused by adult worms in lymphatic filariasis is the development of lymphedema.
• A unique feature of elephantiasis in human filariasis is the thickening of the skin and underlying tissues.
• A characteristic feature of lymphoedema in filariasis includes swelling in limbs due to impaired lymphatic drainage.

Immune Response and Laboratory Diagnosis

• Occult filariasis is caused by immune reactions to filarial antigens, leading to invisible but present infections.
• An eosinophil count of greater than 1000 cells/μL in Tropical Pulmonary Eosinophilia may indicate a possible filarial infection.
• The blood smear examination is a common laboratory test used to detect the presence of microfilariae in peripheral blood.

Treatment of Lymphatic Filariasis

• Diethylcarbamazine (DEC) is the recommended drug for the treatment of lymphatic filariasis.