Abstract:
One key factor influencing the manifestation of malaria is naturally acquired
immunity (NAI) against the parasite, which is developed after repeated
exposure by people living in endemic areas. Efforts to further decrease the
incidence of malaria have resulted in the implementation of a wide variety of
malaria control and elimination measures, each with the potential to alter the
development of NAI. We monitored total IgG against PfEBA-175 antigen
quarterly over a 13-month period in individuals living in a high malaria
transmission setting (Obom) where a mass test, treat and track (MTTT)
exercise was rolled out. 1200 individuals without any symptoms of malaria
aged between 7 months and 90 years were enrolled on the study and donated
finger-pricked blood that was used to prepare dried blood spots (DBS). Out of
this number, 314 individuals who were present for all four sampling time
points were selected for the study. Genomic DNA was extracted from the DBS
from these individuals for PCR estimate of P. falciparum. Antibodies were
also eluted from the DBS and used for PfEBA-175-specific ELISA. The
results were stratified by age into 0-4 years, 5-9 years, 10-15 years and 16+
years groups. Across visits, there was a gradual rise in antibody levels at each
time point, however, this was not statistically significant. Individuals aged 16
and above had higher antibody titres than individuals aged 15 and below. The
study revealed that all the age categories had higher antibody titres with mean
significant differences at the end of the period except those in the age group
10-15 years whose differences in antibody titres at the end of the study were
not statistically significant. Generally, higher antibody levels were associated
with those infected compared to the uninfected. This study established that
MTTT intervention does not significantly reduce antibody titres against the
PfEBA-175 antigen after a year of its rollout in an endemic community.
