STATUS OF HUMAN ONCHOCERCIASIS AND ONCHOCERCA VOLVULUS ANTIGEN-SPECIFIC IgA, igM AND igG CLASS AND SUBCLASS ANTIBODIES AND CIRCULATING EOSINOPHILS IN CLINICAL ONCHOCERCIASIS PATIENTS FROM KACHIA LGA OF KADUNA STATE, NIGERIA. BY MARCH,
STATUS OF HUMAN ONCHOCERCIASIS AND ONCHOCERCA VOLVULUS ANTIGEN-SPECIFIC IgA, igM AND igG CLASS AND SUBCLASS ANTIBODIES AND CIRCULATING EOSINOPHILS IN CLINICAL ONCHOCERCIASIS PATIENTS FROM KACHIA LGA OF KADUNA STATE, NIGERIA. BY MARCH,
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Date
1996-03
Authors
HUDU, OKANKHAMAME OSUE
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Abstract
From an estimated population of 1400 people in 6 villages made
up of mostly non-migrant farmers, 531 of the 900 persons aged
>15 years were skin snipped and examined for onchocerciasis
related dermal and ocular lesions. 201 (37.9%) and 77 (14.5%) had
microfilariae (mf) in one or both iliac crest skin snips and
palpable nodule (N) respectively. The geometric mean mf load or
community mf load (CMFL) per skin snip for those aged 20 years
and above was 1.54 while the mean mf density (MFD) was 6.7±17.6
with a range of 0-345. The mf and N prevalence rates were 41.8%
and 13.9% in the male cohort (n-237) and 34.8% and 15% in the
female cohort (n-294). Infection intensity based on MFD were
7.4±16 and 6.2±18.8 respectively. Those with one or more dermal
and ocular pathology were 10.2% and 5.8%, while papular
onchodermatitis (6.9%) and optic nerve disease (OND) or pale disc
(4.5%) were apparently the most predominant clinical disorders.
Parasitologic and clinical manifestations increased with
increasing age. The absence of obstructive lymphatic disease and
low blindness rate, 7 (1.3%) in one eye and 2 cases involving both
eyes could be an indication that the disease state is in a nascent
endemic phase. Antibody responses to female adult worms of
Onchocerca volvulus SDS-extracted crude antigens, recombinant
DNA antigen coded Ov.1.9, and antigenic epitopes defined by
monoclonal antibodies designated Cam8, Cam22 and Cam28 were
tested in both indirect and competitive enzyme-linked
immunosorbent assay (FLISA). Cases (n-95) with proven
parasitologic or clinical evidences had the highest mean optical
density (OD) value of 0.58±0.15, 0.38±0.12, 0.34±0.10 and
0.43±0.12 for IgG, lgG1, lgG3 and lgG4 antibodies against the
x iv
SDS extract compared to control group (n-7) with corresponding
values of 0.12±0.03, 0.06±0.04, 0.06±0.05 and 0.04±0.05.
Reactivity of sera varied with infection status. About 35%, 71%
and 86% of infection sera inhibited binding of Cam8, Cam22 and
Cam28 mAbs to SDS extract. Patients with chronic skin diseases
(n-20) had more antibody levels in contrast to those manifesting
OND (n-12): 0.65±0.14 vs 0.50±0.13 and 0.33±0.08 vs 0.28±0.10
for IgG and lgG3 response to SDS extract and 0.64±0.22 vs
0.48±0.25 for IgG against Ov1.9. A similar pattern was recorded
for percentage Cam22 and Cam28 inhibitions. But for blood
eosinophil levels the reverse was the case with 3.7±7.2 and
524.5*501.0 vs 11.3%±7 and 766.9±557.6 of differential and
absolute counts. A combination of high eosinophil and low
antibody levels that characterise OND group may not be an
epiphenomenal occurrence. A follow-up of 32 patients 2 months
post-initial ivermectin treatment showed a slightly remarkable
change in IgG antibody against SDS-extract from 0.53±0.15 to
0.68*0.13 equivalent to mean percentage change of 20.5%±29.6 in
patients with skin changes (n-18). Post-treatment antibody
changes were more in N+ or low MFD (<19.5 mf/ skin snip) than N
and high MFD (>20mf/skin snip). A percentage change >10% was
recorded in 16 (50%) and 7 (21.9%) for IgG against SDS-extract
and Ovl.9 while increase in inhibition was more in Cam22
followed by Cam8 and least in Cam28. Serodiagnostic sensitivity
of IgG was by far higher than those of IgA and IgM, but only slight
differences between the isotypes (lgG1, lgG3 and lgG4) with 98%,
37% and 36% respectively. Further evaluation of the specificity of
the assays is recommended.
Description
A THESIS SUBMITTED TO THE POSTGRADUATE SCHOOL, AHMADU BELLO UNIVERSITY,ZARIA,IN PARTIAL FULFILMENT OF THE REQUIREMENT FOR THE AWARD OF THE DEGREE OF MASTER IN SCIENCE
Keywords
STATUS, HUMAN, ONCHOCERCIASIS, ONCHOCERCA, VOLVULUS ANTIGEN-SPECIFIC IgA,, igM AND igG CLASS, SUBCLASS ANTIBODIES, CIRCULATING EOSINOPHILS, CLINICAL, ONCHOCERCIASIS, PATIENTS, KACHIA LGA, KADUNA STATE, NIGERIA