@article{fdi:010061996,
  title = {{R}eproductive status of {O}nchocerca volvulus after {I}vermectin treatment in an {I}vermectin-naive and a frequently treated population from {C}ameroon},
  author = {{N}ana-{D}jeunga, {H}. {C}. and {B}ourguinat, {C}. and {P}ion, {S}{\'e}bastien and {B}opda, {J}. and {K}engne-{O}uafo, {J}. {A}. and {N}jiokou, {F}. and {P}richard, {R}. {K}. and {W}anji, {S}. and {K}amgno, {J}. and {B}oussinesq, {M}ichel},
  editor = {},
  language = {{ENG}},
  abstract = {{A}uthor {S}ummary {O}nchocerciasis, also known as river blindness, is a parasitic disease due to the filarial nematode {O}nchocerca volvulus. {I}t affects more than 37 million people worldwide, most of them (99%) living in {A}frica. {T}he control of river blindness is, up to now, based on annual or six-monthly mass treatment with ivermectin. {T}his drug kills {O}. volvulus microfilariae (mf) present in the skin and the eyes and prevents for 3-4 months the release of new mf by female worms (embryostatic effect). {I}n {G}hana, after 10-19 years of repeated treatments, the emergence of adult parasite populations not responding as expected to ivermectin was postulated. {I}n this study, the reproductive status of female worms was compared, just before and 80 days after ivermectin treatment, between frequently treated and ivermectin-naive cohorts from {C}ameroon. {I}n both groups, embryogenesis of {O}. volvulus was not affected by ivermectin. {H}owever, the accumulation of microfilariae (mf) in the females uteri expected after ivermectin was less marked in the frequently treated population, suggesting that the temporary sequestration of mf following treatment may have been weakened in this group. {A}fter 13 years of repeated annual treatments, the embryostatic effect of ivermectin on {O}. volvulus still occurs but the present findings, associated with observations of higher rates of skin repopulation by mf in the same individuals, suggest that this effect has been decreased. {B}ackground {F}or two decades, onchocerciasis control has been based on mass treatment with ivermectin ({IVM}), repeated annually or six-monthly. {T}his drug kills {O}nchocerca volvulus microfilariae (mf) present in the skin and the eyes (microfilaricidal effect) and prevents for 3-4 months the release of new mf by adult female worms (embryostatic effect). {I}n some {G}hanaian communities, the long-term use of {IVM} was associated with a more rapid than expected skin repopulation by mf after treatment. {H}ere, we assessed whether the embryostatic effect of {IVM} on {O}. volvulus has been altered following frequent treatment in {C}ameroonian patients. {M}ethodology {O}nchocercal nodules were surgically removed just before ({D}0) and 80 days ({D}80) after a standard dose of {IVM} in two cohorts with different treatment histories: a group who had received repeated doses of {IVM} over 13 years, and a control group with no history of large-scale treatments. {E}xcised nodules were digested with collagenase to isolate adult worms. {E}mbryograms were prepared with females for the evaluation of their reproductive capacities. {P}rincipal {F}indings {O}ocyte production was not affected by {IVM}. {T}he mean number of intermediate embryos (morulae and coiled mf) decreased similarly in the two groups between {D}0 and {D}80. {I}n contrast, an accumulation of stretched mf, either viable or degenerating, was observed at {D}80. {H}owever, it was observed that the increase in number of degenerating mf between {D}0 and {D}80 was much lower in the frequently treated group than in the control one ({I}ncidence {R}ate {R}atio: 0.25; 95% {CI}: 0.10-0.63; p = 0.003), which may indicate a reduced sequestration of mf in the worms from the frequently treated group. {C}onclusion/{S}ignificance {IVM} still had an embryostatic effect on {O}. volvulus, but the effect was reduced in the frequently treated cohort compared with the control population.},
  keywords = {{CAMEROUN}},
  booktitle = {},
  journal = {{P}los {N}eglected {T}ropical {D}iseases},
  volume = {8},
  numero = {4},
  pages = {e2824},
  ISSN = {1935-2735},
  year = {2014},
  DOI = {10.1371/journal.pntd.0002824},
  URL = {https://www.documentation.ird.fr/hor/fdi:010061996},
}