Sustainable Control of Onchocerciasis: Ocular Pathology in Onchocerciasis Patients Treated Annually with Ivermectin for 23 Years: A Cohort Study

Abstract

The evolution and persistence of ocular pathology was assessed in a cohort of Onchocerca volvulus infected patients treated annually with ivermectin for 23 years. Patients were resident in rural Central and Kara Region of Togo and ocular examinations included testing of visual acuity, slit lamp examination of the anterior eye segment and the eye fundus by ophthalmoscopy. Before ivermectin treatment, vivid O.volvulus microfilariae (MF) were observed in the right and left anterior eye chamber in 52% and 42% of patients (n = 82), and dead MF were seen in the right and left cornea in 24% and 15% of cases, respectively. At 23 years post initial treatment (PIT), none of the patients (n = 82) presented with MF in the anterior chamber and cornea. A complete resolution of punctate keratitis (PK) lesions without observable corneal scars was present at 23 years PIT (p<0.0001), and sclerosing keratitits (SK) lessened by half, but mainly in patients with lesions at early stage of evolution. Early-stage iridocyclitis diminished from 42%(rE) and 40%(lE) to 13% (rE+lE)(p<0.0001), but advanced iridocyclitis augmented (p<0.001) at 23 years PIT compared to before ivermectin. Advanced-stage papillitis and chorioretinitis did not regress, while early-stage papillitis present in 28%(rE) and 27%(lE) of patients at before ivermectin regressed to 17%(rE) and 18%(lE), and early-stage chorioretinitis present in 51%(rE+lE) of cases at before ivermectin was observed in 12%(rE) and 13%(lE) at 23 years PIT (p<0.0001). Thus, regular annual ivermectin treatment eliminated and prevented the migration of O. volvulus microfilariae into the anterior eye chamber and cornea; keratitis punctata lesions resolved completely and early-stage sclerosing keratitits and iridocyclitis regressed, whilst advanced lesions of the anterior and posterior eye segment remained progressive. In conclusion, annual ivermectin treatments may prevent the emergence of ocular pathology in those populations still exposed to O.volvulus infection. Trial Registration: www.pactr.org PACTR201303000464219)

Onchocerca volvulus infection and serological prevalence, ocular onchocerciasis and parasite transmission in northern and central Togo after decades of Simulium damnosum s.l. vector control and mass drug administration of ivermectin

“… The ocular pathologies, their grades of evolution and extent were classified as described previously [ 12 ]. …”

“…The present results support previous observations that annual ivermectin treatments eliminate and prevent the migration of O . volvulus Mf into the anterior eye chamber and cornea, with punctate keratitis resolving completely and early-stage sclerosing keratitits and iridocyclitis regressing, whereas advanced lesions of the anterior and posterior eye segment remain progressive [ 12 , 13 , 35 ]. Annual ivermectin treatments may prevent the emergence of ocular pathology in those populations still exposed to O .…”

“…All participants gave their informed consent for having an ocular evaluation and were examined by experienced ophthalmologists for ocular onchocerciasis lesions and additionally present ocular pathology. The ophthalmology examinations were performed by MB and TS and ocular pathologies, their grades of evolution and extent were classified as described previously [ 12 ]. All participants acknowledged having received ivermectin annually for several years through community directed treatment with ivermectin (CDTI).…”

Analysis of age-dependent trends in Ov16 IgG4 seroprevalence to onchocerciasis

“…In West Africa many countries, including Togo, under the Onchocerciasis Control Program (OCP) launched in 1974, successfully controlled onchocerciasis, initially through intensive vector control and subsequently through MDA with ivermectin [ 31 – 34 ]. In some countries, such as Mali and Senegal, elimination appears feasible [ 35 , 36 ].…”

Mansonella perstans , Onchocerca volvulus and Strongyloides stercoralis infections in rural populations in central and southern Togo

“…In Togo epidemiological evaluations on M. perstans are rare, surveys on O. volvulus are important especially under the aspect of mass drug administration (MDA) of ivermectin which is performed since decades ( Banla et al, 2014 ), and data on the prevalence of S. stercoralis infection are not available. We have accomplished immune-epidemiological and molecular surveys on the prevalence of M. perstans , O. volvulus and S. stercoralis in rural areas in central and southern Togo.…”