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| {| class="wikitable" | | {| class="wikitable" |
| !Type of filariasis | | !Factor |
| !Causative nematode | | !Role in pathogenesis |
| !Vectors
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| !Life cycle
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| !Illustrative image
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| !Comments
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| |- | | |- |
| | rowspan="2" |Lymphatic filariasis | | |Immune response of the host |
| |[[Wuchereria bancrofti]]
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| | | | | |
| * Culex as C. pipiens | | * In several studies, it has been noticed that there is a strong correlation between the host immune response and lymphoedema development. The immune response is higher in the lymphedema patients more than the patients with microfilariae just cirulating in the blood. |
| * Aedes as A. aegypti
| | * Hence, it is believed the role of the immune response in development of the lymphedema as it leads to inflammation and obstruction of the lymphatic vessels. |
| * [[Anopheles]] as A. arabinensis
| | * Infection by filariasis induces cell mediated immunity in response to the filarial antigens. This will lead to production of cytokines and interleukns. |
| * Coquillettidia.as C. juxtamansonia
| | * High levels of immunoglobulins (IgG1,2,3) has been detected in patients with lymphedema which increases the evidence of the role of the immune response in pathogenesis of the disease. |
| | rowspan="2" |
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| * Infected mosquito bite introduces the third stage larva onto the skin and then enters to the blood through the wound.
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| * The larvae develop to adult which reside in the '''lymphatic vessels'''.
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| * Adult worm produce sheathed microfiliae that migrate to lymph and blood. They have '''nocturnal periodicity'''.
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| * Another mosquito ingests the microfiliae. | |
| * The microfilariae lose their sheaths and work their way through the wall of the proventriculus and cardiac portion of the [[midgut]] to reach the thoracic muscles
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| * Microfiliae grow up inside the mosquito till third stage larvae.
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| * In another bite to a host skin the mosquito introduces the larvae onto the skin.
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| | rowspan="2" |[[Image:W bancrofti LifeCycle.gif|350 px|center]]
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| | rowspan="2" |
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| * The difference between the nematodes causing lymphatic filariasis is in the shape and size of the worm.
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| * The Brugia worms are similar to the W. bancrofti but smaller.
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| |-
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| |[[Brugia timori]] and [[Brugia malayi]]
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| * Mansonia | |
| * Aedes
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| |-
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| | rowspan="4" |Subcutaneous filariasis
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| |[[Loa loa filaria]]
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| * Chrysops
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| * C. silacea
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| * C. dimidiata
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| | rowspan="4" |
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| * Infected fly bite introduces the third stage larva onto the skin and then enters to the blood through the wound.
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| * The larvae develop to adult which reside in the '''subcutaneous tissue'''.
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| * Loa Loa adult worm produce sheathed microfilariae that are found in the blood during day and in the lungs during the non circulating phase. They have '''diurnal periodicity'''.
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| * Another fly ingests the microfiliae. | |
| * After ingestion, the microfilariae lose their sheaths and migrate from the fly's [[midgut]] through the [[hemocoel]] to the thoracic muscles of the [[arthropod]].
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| * Microfiliae grow up inside the fly till third stage larvae.
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| * The third-stage infective larvae migrate to the fly's proboscis and in another bite the cycle restarts.
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| | rowspan="4" |[[Image:L loa LifeCycle.gif|350 px|center]]
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| | rowspan="4" |
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| * Unlike Loa Loa filaria, Mansonella streptocerca , Mansonella ozzardi and Onchocerca volvolus produce '''unsheathed non-periodic microfilariae'''.
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| * Mansonela streptocerca adults residue in the dermis.
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| * Onchocerca volvulus adults residue mainly in the subcutaneous nodules. Their microfilariae can be found in the peripheral [[blood]], [[urine]], and [[sputum]] but are typically found in the [[skin]] and in the [[Lymphatic|lymphatics]] of connective tissue.
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| |- | | |- |
| |[[Mansonella streptocerca]] | | |Secondary bacterial infections |
| | | | | |
| * Midge (genus Culicoides) | | * Adenolymphangitis is a result of the inflammation induced by the filarial infection and the immune response. It is believed that it worsens the disease and leads to morbidity. |
| | * It affects the lower limbs resulting in cord like lesion of the lymphatic vessels and worsening of the filariasis. |
| |- | | |- |
| |[[Mansonella ozzardi]] | | |Worm antigens accumulation |
| | | | | |
| * Midge (genus Culicoides)
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| |- | | |- |
| |[[Onchocerca volvulus]] | | |Wolbachia bacteria |
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| * Blackfly (genus Simulium)
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| |-
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| |Serous cavity filariasis
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| |[[Mansonella perstans]]
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| * Midge (genus Culicoides)
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| * Blackfly (genus Simulium)
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| * Infected midge bite introduces the third stage larva onto the skin and then enters to the blood through the wound.
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| * The larvae develop to adult which reside in the different body cavities like [[peritoneal cavity]], [[pleural cavity]], and less frequently in the [[pericardium]].
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| * Adult worm produce unsheathed subperiodic microfilariae that reaches the blood stream.
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| * Another midge ingests microfilariae during a [[blood]] meal.
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| * After [[ingestion]], the microfilariae migrate from the midge's [[midgut]] through the [[hemocoel]] to the thoracic muscles of the [[arthropod]].
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| * Microfiliae grow up inside the midge till third stage larvae.
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| * The third-stage infective larvae migrate to the midge's proboscis and in another bite the cycle restarts.
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| |[[Image:M perstans LifeCycle.gif|350 px|center]]
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| | | | | |
| |} | | |} |
| Life cycles of the roundworms causing filariasis:
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