Implementation Challenges of Community Directed Treatment with Ivermectin Program for Control of Onchocerciasis in Ulanga, Tanzania

Onchocerca volvulus microfilariae in the anterior chambers of the eye and ocular adverse events after a single dose of 8 mg moxidectin or 150 µg/kg ivermectin: results of a randomized double-blind Phase 3 trial in the Democratic Republic of the Congo, Ghana and Liberia

BACKGROUND

After ivermectin became available, diethylcarbamazine (DEC) use was discontinued because of severe adverse reactions, including ocular reactions, in individuals with high Onchocerca volvulus microfilaridermia (microfilariae/mg skin, SmfD). Assuming long-term ivermectin use led to < 5 SmfD with little or no eye involvement, DEC + ivermectin + albendazole treatment a few months after ivermectin was proposed. In 2018, the US FDA approved moxidectin for treatment of O. volvulus infection. The Phase 3 study evaluated SmfD, microfilariae in the anterior chamber (mfAC) and adverse events (AEs) in ivermectin-naïve individuals with ≥ 10 SmfD after 8 mg moxidectin (n = 978) or 150 µg/kg ivermectin (n = 494) treatment.

METHODS

We analyzed the data from 1463 participants with both eyes evaluated using six (0, 1-5, 6-10, 11-20, 21-40, > 40) mfAC and three pre-treatment (< 20, 20 to < 50, ≥ 50) and post-treatment (0, > 0-5, > 5) SmfD categories. A linear mixed model evaluated factors and covariates impacting mfAC levels. Ocular AEs were summarized by type and start post-treatment. Logistic models evaluated factors and covariates impacting the risk for ocular AEs.

RESULTS

Moxidectin and ivermectin had the same effect on mfAC levels. These increased from pre-treatment to Day 4 and Month 1 in 20% and 16% of participants, respectively. Six and 12 months post-treatment, mfAC were detected in ≈5% and ≈3% of participants, respectively. Ocular Mazzotti reactions occurred in 12.4% of moxidectin- and 10.2% of ivermectin-treated participants without difference in type or severity. The risk for ≥ 1 ocular Mazzotti reaction increased for women (OR 1.537, 95% CI 1.096-2.157) and with mfAC levels pre- and 4 days post-treatment (OR 0: > 10 mfAC 2.704, 95% CI 1.27-5.749 and 1.619, 95% CI 0.80-3.280, respectively).

CONCLUSIONS

The impact of SmfD and mfAC levels before and early after treatment on ocular AEs needs to be better understood before making decisions on the risk-benefit of strategies including DEC. Such decisions should take into account interindividual variability in SmfD, mfAC levels and treatment response and risks to even a small percentage of individuals.

Integration of onchocerciasis morbidity management and disability prevention services in the healthcare system in Tanzania: a call for action and recommendations

Onchocerciasis is among the Neglected Tropical Diseases (NTDs) responsible for dermatological, ophthalmological, and neurological manifestations. With the ongoing burden of onchocerciasis clinical manifestations, morbidity management, and disability prevention services are required to alleviate the suffering of the affected populations. Unfortunately, despite the ongoing transmission of onchocerciasis, morbidity management, and disability prevention services are limited in Tanzania. Therefore, this article highlights the concept of onchocerciasis morbidity management and disability prevention, along with the significance of its adoption in the healthcare system in Tanzania. We further provide recommendations on where and how to start.

Impact of a bi-annual community-directed treatment with ivermectin programme on the incidence of epilepsy in an onchocerciasis-endemic area of Mahenge, Tanzania: A population-based prospective study

BACKGROUND

Community-directed treatment with ivermectin (CDTi) is used to eliminate onchocerciasis. However, despite 25 years of annual CDTi in Mahenge, Tanzania, the prevalence of onchocerciasis and onchocerciasis-associated epilepsy remained high in certain rural villages. Therefore, in 2019, bi-annual CDTi was introduced in the area. This study assessed the impact of the programme on the incidence of epilepsy in four villages.

METHODOLOGY

Door-to-door epilepsy surveys were conducted prior to (2017/18) and after (2021) implementing a bi-annual CDTi program. All household members were screened for epilepsy symptoms using a validated questionnaire, and suspected cases were examined by a medical doctor to confirm/reject the diagnosis of epilepsy. The prevalence and annual incidence of epilepsy, including nodding syndrome, were calculated with 95% Wilson confidence intervals with continuity correction. The latter was also done for CDTi coverage in 2016 and 2021.

RESULTS

Precisely 5,444 and 6,598 persons were screened for epilepsy before and after implementing the intervention. The CDTi coverage of the overall population was 82.3% (95%CI: 81.3-83.2%) in 2021 and sustained in both distribution rounds (81.5% and 76.8%). The coverage was particularly high in children and teenagers aged 6 to 18 years (93.2%, 95%CI: 92.1-94.2%). The epilepsy prevalence remained similar: 3.3% (95%CI: 2.9-3.9%) in 2017/18 versus 3.1% (95%CI: 2.7-3.5%) in 2021. However, the incidence of epilepsy declined from 177.6 (95%CI: 121.2-258.5) in 2015-2017 and 2016-2018 to 45.5 (95%CI: 22.2-89.7) in 2019-2021 per 100,000 persons-years. The incidence of probable nodding syndrome varied from 18.4 (95%CI: 4.7-58.5) to 5.1 (95%CI: 0.3-32.8). None of the nine incidence cases of epilepsy for which information on ivermectin intake was available took ivermectin in the year they developed their first seizures.

CONCLUSION

A bi-annual CDTi programme should be implemented in areas with high prevalence of onchocerciasis and epilepsy. High CDTi coverage among children is particularly important to prevent onchocerciasis-associated epilepsy.

Factors associated with low-uptake of ivermectin in Mahenge, an area with high prevalence of onchocerciasis and epilepsy in Tanzania: A qualitative perspective

Introduction

Despite over 20 years of community-directed treatment with ivermectin (CDTI) in Mahenge area in Tanzania, the prevalence of onchocerciasis has remained high (over 40% in children 6-10 years using antibody testing and 49% using skinsnips in adults). The area has one of the highest prevalence of epilepsy, exceeding 3.5% in some of rural villages.

Methods

Between June and July 2019, in four rural villages using qualitative methods, we assessed factors potentially associated with the persistence of high Onchocerca volvulus transmission.

Results

Eleven focus group discussions were organized with persons with epilepsy and their caretakers, community resource persons, and community drug distributors (CDDs), and two in-depth interviews with district programme coordinators of neglected tropical diseases (NTD). Factors considered being responsible for the persistence of onchocerciasis transmission included not taking ivermectin during CDTI for fear of adverse reactions such as itching, swelling and misconception that the drug causes infertility. Challenges for high CDTI coverage included, long walking distance by CDDs to deliver drugs to households, persons being away for farming, low awareness of the disease including the association between onchocerciasis and epilepsy and limited supervision by the NTD coordinators.

Conclusion

Ivermectin uptake in Mahenge should be optimised by continuous advocacy about the importance of taking ivermectin to prevent onchocerciasisassociated morbidity and by improving supervision during CDTI.

Burden and factors associated with onchocerciasis transmission among school-aged children after more than 20 years of Community Directed Treatment with Ivermectin in Ulanga district, Tanzania: A school-based cross-sectional study

Onchocerciasis transmission in the Ulanga District of Morogoro-Tanzania is still ongoing despite more than 20 years of Community Directed Treatment with Ivermectin (CDTI) in the area. Even though surveys conducted over the years in the area have revealed a decrease in the prevalence of onchocerciasis, the prevalence of comorbidities suggested to be associated with this filarial infection, as epilepsy, is rising in endemic regions. This fact suggests continued transmission of Onchocerca volvulus and emphasizes the need for the evaluation of factors associated with it among school aged children. Therefore, this study determined the current burden of onchocerciasis in children aged 6 to 12 years and factors associated with continued transmission despite more than 20 years of CDTI in Ulanga District, Morogoro Region-Tanzania. A school-based cross-sectional study was conducted among 270 children aged 6 to 12 years in Ulanga District. Participants were tested using the OV-16 IgG4 Rapid Test. An interview-administered questionnaire was used to assess disease-associated symptoms, knowledge of onchocerciasis, and factors associated with continued transmission of the disease among participants. Descriptive statistics, chi-square test, and logistic regression were performed during data analysis. The prevalence of onchocerciasis was 19.6% (53/270), with boys being more infected; prevalence increased with increasing age groups and was higher in rural areas. Sex (AOR = 2.2, 95% CI: 1.13-4.28), age group of 11-12 years (AOR = 31.45, 95% CI: 2.73-362.27), and not taking ivermectin (AOR = 3.17, 95% CI: 1.53-6.58) were the only significant factors identified to be associated with the transmission of onchocerciasis in this study. The high prevalence of onchocerciasis among school age children in Ulanga district suggests continued transmission in the area. Therefore, a need to integrate CDTI with health education on the importance of ivermectin uptake.