Pathology of lymphatic filariasis
- Author:
Joon-Wah Mak
- Publication Type:Review
- Keywords:
lymphatic filariasis, pathology, immunopathology, Brugia, Wuchereria
- From:International e-Journal of Science, Medicine and Education
2012;6(supp1):S80-S86
- CountryMalaysia
- Language:English
-
Abstract:
Developing and adult worms of the human
lymphatic filarial parasites (Wuchereria bancrofti,
Brugia malayi, and Brugia timori) are located mainly in
the lymphatic system and occasionally in aberrant sites
like subcutaneous and conjunctival cysts. Lymphatic
pathology ranging from dilatation of lymphatic channels
and lymphangiectasia are detected on ultrasonography in
apparently healthy, amicrofilaraemic, but filarial antigen
positive individuals in endemic areas. Microfilariae are
distributed in various organs and may be associated
with immune mediated pathology at these sites; tropical
pulmonary eosinophilia is characterized by intense
immune mediated destruction of microfilariae in the
lung parenchyma. In the spleen and other sites, nodular
granulomatous lesions can occur where microfilariae
are trapped and destroyed. The finding of Wolbachia
endosymbionts in all stages of lymphatic filarial parasites
has provided new insight on the adverse reactions
associated with anti-filarial chemotherapy. Inflammatory
molecules mainly lipopolysaccharide (LPS)-like
molecules released from endosymbionts on death of the
parasites are largely responsible for the adverse reactions
encountered during anti-filarial chemotherapy. Prenatal
tolerance or sensitization to parasite derived molecules
can immune-modulate and contribute to both pathology
and susceptibility/resistance to infection. Pathological
responses thus depend not only on exposure to
filarial antigens/infection, but also on host-parasiteendosymbiont factors and to intervention with antifilarial treatment. Treatment induced or host mediated
death of parasites are associated with various grades of
inflammatory response, in which eosinophils and LPS
from endosymbionts play prominent roles, leading
to death of the parasite, granulomatous formation,
organization and fibrosis.
The non-human primate (Presbytis spp.) model of
Brugia malayi developed for the tertiary screening
of anti-filarial compounds has provided unique
opportunities for the longitudinal study of the pathology
associated with lymphatic filariasis. The pathology in this
non-human primate model closely follows that seen in human lymphatic filarial infections and correlates with
clinical evidence of lymphatic pathology as detected
with ultrasonography. These studies also show that
successful treatment as detected by loss of motility and
calcification of worms on ultrasonography is associated
with reversal of early dilatations of lymphatic channels.
- Full text:W020150928578331070845.pdf
