Peace Habomugisha

Transmission of Onchocerciasis in Wadelai Focus of Northwestern Uganda Has Been Interrupted and the Disease Eliminated

Wadelai, an isolated focus for onchocerciasis in northwest Uganda, was selected for piloting an onchocerciasis elimination strategy that was ultimately the precursor for countrywide onchocerciasis elimination policy. The Wadelai focus strategy was to increase ivermectin treatments from annual to semiannual frequency and expand geographic area in order to include communities with nodule rate of less than 20%. These communities had not been covered by the previous policy that sought to control onchocerciasis only as a public health problem. From 2006 to 2010, Wadelai program successfully attained ultimate treatment goal (UTG), treatment coverage of ≥90%, despite expanding from 19 to 34 communities and from 5,600 annual treatments to over 29,000 semiannual treatments. Evaluations in 2009 showed no microfilaria in skin snips of over 500 persons examined, and only 1 of 3011 children was IgG4 antibody positive to the OV16 recombinant antigen. No Simulium vectors were found, and their disappearance could have sped up interruption of transmission. Although twice-per-year treatment had an unclear role in interruption of transmission, the experience demonstrated that twice-per-year treatment is feasible in the Ugandan setting. The monitoring data support the conclusion that onchocerciasis has been eliminated from the Wadelai focus of Uganda.

Serosurveillance to Monitor Onchocerciasis Elimination: The Ugandan Experience

Uganda is the only African country whose onchocerciasis elimination program uses a two-pronged approach of vector control and mass drug distribution. The Ugandan program relies heavily upon the use of serosurveys of children to monitor progress toward elimination. The program has tested over 39,000 individuals from 11 foci for Onchocerca volvulus exposure, using the Ov16 ELISA test. The data show that the Ov16 ELISA is a useful operational tool to monitor onchocerciasis transmission interruption in Africa at the World Health Organization (WHO) recommended threshold of < 0.1% in children. The Ugandan experience has also resulted in a re-examination of the statistical methods used to estimate the boundary of the upper 95% confidence interval for the WHO prevalence threshold when all samples tested are negative. This has resulted in the development of Bayesian and hypergeometric statistical methods that reduce the number of individuals who must be tested to meet the WHO criterion.

Community-directed interventions strategy enhances efficient and effective integration of health care delivery and development activities in rural disadvantaged communities of Uganda

The community‐directed interventions (CDI) strategy achieved a desired coverage of the ultimate treatment goal (UTG) of at least 90% with ivermectin distribution for onchocerciasis control, and filled the gap between the health care services and the communities. However, it was not clear how its primary actors – the community‐directed health workers (CDHW) and community‐directed health supervisors (CDHS) – would perform if they were given more responsibilities for other health and development activities within their communities. A total of 429 of 636 (67.5%) of the CDHWs who were involved in other health and development activities performed better than those who were involved only in ivermectin distribution, with a drop‐out rate of 2.3%. A total of 467 of 864 (54.1%) of CDHSs who were involved in other health and development activities also maintained the desired level of performance. They facilitated updating of household registers (P < 0.05), trained and supervised CDHWs, and educated community members about onchocerciasis control (P < 0.001). Their drop‐out rate was 2.6%. The study showed that the majority of those who dropped out had not been selected by their community members. Therefore, CDI strategy promoted integration of health and development activities with a high potential for sustainability.

The disappearance of onchocerciasis from the Itwara focus, western Uganda after elimination of the vector Simulium neavei and 19 years of annual ivermectin treatments

The Itwara onchocerciasis focus is located around the Itwara forest reserve in western Uganda. In 1991, annual treatments with ivermectin started in the focus. They were supplemented in 1995 by the control of the vector Simulium neavei, which was subsequently eliminated from the focus. The impact of the two interventions on the disease was assessed in 2010 by nodule palpations, examinations of skin snips by microscopy and PCR, and Ov16 recombinant ELISA. There was no evidence of any microfilaria in 688 skin snips and only 2 (0.06%) of 3316 children examined for IgG4 were slightly above the arbitrary cut off of 40. A follow up of the same children 21 months later in 2012 confirmed that both were negative for diagnostic antigen Ov-16, skin snip microscopy and PCR. Based on the World Health Organization (WHO) elimination criteria of 2001 and the Uganda onchocerciasis certification guidelines, it was concluded that the disease has disappeared from the Itwara focus after 19 years of ivermectin treatments and the elimination of the vector around 2001. Ivermectin treatments were recommended to be halted.

Transmission of Onchocerca volvulus by Simulium neavei in Mount Elgon Focus of Eastern Uganda Has Been Interrupted

The study determined that Simulium neavei-transmitted onchocerciasis in Mount Elgon onchocerciasis focus had been interrupted. Annual mass treatment with ivermectin changed to two times per year along with vector elimination in 2007. Then, baseline microfilaria (mf) prevalence data of 1994 in five sentinel communities were compared with follow-up data in 2005 and 2011. Blood spots from 3,051 children obtained in 2009 were analyzed for Onchocerca volvulus immunoglobulin G4 antibodies. Fresh water crab host captures and blackflies collected indicated their infestation with larval stages of S. neavei and presence or absence of the vector, respectively. Mf rates dropped from 62.2% to 0.5%, and 1 (0.03%) of 3,051 children was positive for O. volvulus antibodies. Crab infestation dropped from 41.9% in 2007 to 0%, and S. neavei biting reduced to zero. Both remained zero for the next 3 years, confirming interruption of onchocerciasis transmission, and interventions were halted.

Traditional kinship system enhanced classic community-directed treatment with ivermectin (CDTI) for onchocerciasis control in Uganda.

The challenges of community-directed treatment with ivermectin (CDTI) for onchocerciasis control in Africa have been: maintaining a desired treatment coverage, demand for monetary incentives, high attrition of community distributors and low involvement of women. This study assessed how challenges could be minimised and performance improved using existing traditional kinship structures. In classic CDTI areas, community members decide upon selection criteria for community distributors, centers for health education and training, and methods of distributing ivermectin. In kinship enhanced CDTI, similar procedures were followed at the kinship level. We compared 14 randomly selected kinship enhanced CDTI communities with 25 classic CDTI communities through interviews of 447 and 750 household members and 127 and 64 community distributors respectively. Household respondents from kinship enhanced CDTI reported better performance (P<0.001) than classic CDTI on the following measures of program effectiveness: (a) treatment coverage (b) decision on treatment location and (c) mobilization for CDTI activities. There were more female distributors in kinship enhanced CDTI than in classic CDTI. Attrition was not a problem. Kinship enhanced CDTI had a higher number of community distributors per population working among relatives, and were more likely to be involved in additional health care activities. The results suggest that kinship enhanced CDTI was more effective than classic CDTI.

Monitoring ivermectin distributors involved in integrated health care services through community-directed interventions: a comparison of Cameroon and Uganda experiences over a period of three years (2004-2006)

Objectives  To assess and compare the effectiveness of ivermectin distributors in attaining 90% treatment coverage of the eligible population with each additional health activity they take up.

Transmission of Onchocerca volvulus Continues in Nyagak-Bondo Focus of Northwestern Uganda after 18 Years of a Single Dose of Annual Treatment with Ivermectin

The objective of the study was to determine whether annual ivermectin treatment in the Nyagak-Bondo onchocerciasis focus could safely be withdrawn. Baseline skin snip microfilariae (mf) and nodule prevalence data from six communities were compared with data collected in the 2011 follow-up in seven communities. Follow-up mf data in 607 adults and 145 children were compared with baseline (300 adults and 58 children). Flies collected in 2011 were dissected, and poolscreen analysis was applied to ascertain transmission. Nodule prevalence in adults dropped from 81.7% to 11.0% (P < 0.0001), and mf prevalence dropped from 97.0% to 23.2% (P < 0.0001). In children, mf prevalence decreased from 79.3% to 14.1% (P < 0.0001). Parous and infection rates of 401 flies that were dissected were 52.9% and 1.5%, respectively, whereas the infective rate on flies examination by polymerase chain reaction (PCR) was 1.92% and annual transmission potential was 26.9. Stopping ivermectin treatment may result in onchocerciasis recrudescence.

Involvement of women in community-directed treatment with ivermectin for the control of onchocerciasis in Rukungiri district, Uganda: a knowledge, attitude and practice study

A study of knowledge, attitudes and practice was carried out in the Rukungiri district of Uganda, in order to investigate the involvement of women in community-directed treatment with ivermectin (CDTI), for the control of onchocerciasis. The data analysed came from interviews with 260 adult women (one from each of 260 randomly-selected households in 20 onchocerciasis-endemic communities), community informants, and participatory evaluation meetings (PEM) in eight communities. The women who had been treated with ivermectin in 1999 generally had more knowledge of the benefits of taking ivermectin, were more likely to have attended the relevant health-education sessions and were more involved in community decisions on the method of ivermectin distribution than the women who had not received ivermectin in that year. There were fewer female community-directed health workers (CDHW) than male CDHW in the communities investigated. The reasons for not attending health-education sessions, not participating in community meetings concerning the CDTI, and the reluctance of some women to serve as CDHW were investigated. The most common reasons given were domestic chores, a reluctance to express their views in meetings outside their own kinship group, suspicions that other women might take advantage of them, and a lack of interest. Most of the women interviewed (as well as other community members) felt that there were relatively few women CDHW. The women attributed this to a lack of interaction and trust amongst themselves, which resulted in more men than women being selected as CDHW. The rest of the community members were not against women working as CDHW. It is recommended that communities be encouraged to select women to serve as CDHW in the CDTI, and that the performances of male and female CDHW be compared.

After a decade of annual dose mass ivermectin treatment in Cameroon and Uganda, onchocerciasis transmission continues

Objective  To evaluate the effectiveness of 10 years’ annual single dose ivermectin treatment on onchocerciasis transmission in hyperendemic areas of Cameroon and Uganda.