The elimination of human African trypanosomiasis: Monitoring progress towards the 2021-2030 WHO road map targets

BACKGROUND

Human African trypanosomiasis (HAT) is a neglected tropical disease that usually occurs in rural areas in sub-Saharan Africa. It caused devastating epidemics during the 20th century. Sustained, coordinated efforts by different stakeholders working with national sleeping sickness control programmes (NSSCPs) succeeded in controlling the disease and reducing the number of cases to historically low levels. In 2012, WHO targeted the elimination of the disease as a public health problem by 2020. This goal has been reached and a new ambitious target was stated in the WHO road map for NTDs 2021-2030 and endorsed by the 73rd World Health Assembly: the elimination of gambiense HAT transmission (i.e. reducing the number of reported cases to zero). The interruption of transmission was not considered as an achievable goal for rhodesiense HAT, as it would require vast veterinary interventions rather than actions at the public health level.

METHODOLOGY/PRINCIPAL FINDINGS

Data reported to WHO by NSSCPs were harmonized, verified, georeferenced and included in the atlas of HAT. A total of 802 cases were reported in 2021 and 837 in 2022. This is below the target for elimination as a public health problem at the global level (< 2000 HAT cases/year); 94% of the cases were caused by infection with T. b. gambiense. The areas reporting ≥ 1 HAT case/10 000 inhabitants/year in 2018-2022 cover a surface of 73 134 km2, with only 3013 km2 at very high or high risk. This represents a reduction of 90% from the baseline figure for 2000-2004, the target set for the elimination of HAT as a public health problem. For the surveillance of the disease, 4.5 million people were screened for gambiense HAT with serological tests in 2021-2022, 3.6 million through active screening and 0.9 million by passive screening. In 2021 and 2022 the elimination of HAT as a public health problem was validated in Benin, Uganda, Equatorial Guinea and Ghana for gambiense HAT and in Rwanda for rhodesiense HAT. To reach the next goal of elimination of transmission of gambiense HAT, countries have to report zero cases of human infection with T. b. gambiense for a period of at least 5 consecutive years. The criteria and procedures to verify elimination of transmission have been recently published by WHO.

CONCLUSIONS/SIGNIFICANCE

HAT elimination as a public health problem has been reached at global level, with seven countries already validated as having reached this goal. This achievement was made possible by the work of NSSCPs, supported by different public and private partners, and coordinated by WHO. The new challenging goal now is to reach zero cases by 2030. To reach this goal is crucial to maintain the engagement and support of donors and stakeholders and to keep the involvement and coordination of all partners. Along with the focus on elimination of transmission of gambiense HAT, it is important not to neglect rhodesiense HAT, which is targeted for elimination as a public health problem in the WHO road map for NTDs 2021-2030.

A framework for scabies control

Scabies is a neglected tropical disease (NTD) that causes a significant health burden, particularly in disadvantaged communities and where there is overcrowding. There is emerging evidence that ivermectin-based mass drug administration (MDA) can reduce the prevalence of scabies in some settings, but evidence remains limited, and there are no formal guidelines to inform control efforts. An informal World Health Organization (WHO) consultation was organized to find agreement on strategies for global control. The consultation resulted in a framework for scabies control and recommendations for mapping of disease burden, delivery of interventions, and establishing monitoring and evaluation. Key operational research priorities were identified. This framework will allow countries to set control targets for scabies as part of national NTD strategic plans and develop control strategies using MDA for high-prevalence regions and outbreak situations. As further evidence and experience are collected and strategies are refined over time, formal guidelines can be developed. The control of scabies and the reduction of the health burden of scabies and associated conditions will be vital to achieving the targets set in WHO Roadmap for NTDs for 2021 to 2030 and the Sustainable Development Goals.

Trachoma prevalence in Niger: results of 31 district-level surveys

BACKGROUND

The leading cause of preventable blindness worldwide is trachoma, a condition caused by an infection of the inner eyelid. In Niger, a landlocked republic in Western Africa, surveys in 1988-89 identified trachoma as endemic in all but one region and, as a result, there is a National Prevention of Blindness Program plan to eliminate trachoma by 2015.

METHODS

Thirty-one districts in eastern and western Niger were surveyed for trachoma prevalence from May 2009 to March 2012 as part of routine program impact evaluations. Prevalence surveys were implemented independently in each district using a two-stage cluster random design. Probability proportional to size was used to randomly select villages and 25 households were selected in each cluster. The prevalence of trachoma of clinical grade trachomatous follicular (TF) was estimated in children aged 1-9 years, and the prevalence of blinding trachoma, trachomatous trichiasis (TT), was measured in adults aged ≥15 years.

RESULTS

A total of 14 211 households was surveyed; 58 617 individuals were evaluated for clinical signs of trachoma, of whom 27 087 were children aged 1-9 years. District-wide implementation of the full SAFE strategy is warranted in 16 districts where TF prevalence exceeds 10% and targeted implementation of the SAFE strategy (surgery for trichiasis; antibiotic therapy to control transmission; facial cleanliness for hygiene promotion; environmental change for improvements in access to water and sanitation) is recommended in the remaining 15 districts. The prevalence of TT among adults exceeded 1% in nine districts, suggesting that surgical services to treat TT should be implemented district-wide.

CONCLUSIONS

These results establish the need for continued SAFE strategy implementation throughout Niger.

The prevalence of blinding trachoma in northern states of Sudan

Background

Despite historical evidence of blinding trachoma, there have been no widespread contemporary surveys of trachoma prevalence in the northern states of Sudan. We aimed to conduct district-level surveys in this vast region in order to map the extent of the problem and estimate the need for trachoma control interventions to eliminate blinding trachoma.

Methods and Findings

Separate, population based cross-sectional surveys were conducted in 88 localities (districts) in 12 northern states of Sudan between 2006 and 2010. Two-stage cluster random sampling with probability proportional to size was used to select the sample. Trachoma grading was done using the WHO simplified grading system. Key prevalence indicators were trachomatous inflammation-follicular (TF) in children aged 1–9 years and trachomatous trichiasis (TT) in adults aged 15 years and above. The sample comprised 1,260 clusters from which 25,624 households were surveyed. A total of 106,697 participants (81.6% response rate) were examined for trachoma signs. TF prevalence was above 10% in three districts and between 5% and 9% in 11 districts. TT prevalence among adults was above 1% in 20 districts (which included the three districts with TF prevalence >10%). The overall number of people with TT in the population was estimated to be 31,072 (lower and upper bounds = 26,125–36,955).

Conclusion

Trachoma mapping is complete in the northern states of Sudan except for the Darfur States. The survey findings will facilitate programme planning and inform deployment of resources for elimination of trachoma from the northern states of Sudan by 2015, in accordance with the Sudan Federal Ministry of Health (FMOH) objectives.

Trachoma is an infectious disease which is caused by a bacterium, Chlamydia trachomatis and is the leading cause of preventable blindness, estimated to be responsible for 2.9% of blindness globally. The World Health Organization (WHO) recommends an integrated strategy for control and elimination of blinding trachoma known as SAFE, which stands for: surgery; antibiotics; facial cleanliness; and environmental improvement. In order to identify districts where trachoma is a public health problem, we undertook 88 district-level surveys in 12 northern states of Sudan. Our findings revealed that interventions to prevent blinding trachoma are recommended in 14 out of 88 districts where the prevalence of trachomatous inflammation-follicular (TF) in children aged 1–9 years exceeded the WHO thresholds for intervention. Services to provide surgery to those with trachomatous trichiasis (TT) should be prioritized in 20 districts where prevalence of TT in adults exceeded 1%. These findings are important since they will help the Sudan Federal Ministry of Health (FMOH) to prioritize resources for elimination of trachoma.

Integrated implementation of programs targeting neglected tropical diseases through preventive chemotherapy: proving the feasibility at national scale

In 2006, the United States Agency for International Development established the Neglected Tropical Disease (NTD) Control Program to facilitate integration of national programs targeting elimination or control of lymphatic filariasis, onchocerciasis, schistosomiasis, soil-transmitted helminthiasis and blinding trachoma. By the end of year 3, 12 countries were supported by this program that focused first on disease mapping where needed, and then on initiating or expanding disease-specific programs in a coordinated/integrated fashion. The number of persons reached each year increased progressively, with a cumulative total during the first three years of 98 million persons receiving 222 million treatments with donated drugs valued at more than $1.4 billion. Geographic coverage increased substantially for all these infections, and the program has supported training of more than 220,000 persons to implement the programs. This current experience of the NTD Control Program demonstrates clearly that an integrated approach to control or eliminate these five neglected diseases can be effective at full national scale.

Evaluation of the prevalence of trachoma 12 years after baseline surveys in Kidal Region, Mali

OBJECTIVE

After prevalence surveys in all eight regions, Mali started a national programme to control trachoma in 1998. In the sparsely populated desert region of Kidal, where active trachoma prevalence was 46.2% in children under 10, no interventions beyond routine eye-care services were implemented. We estimated the prevalence of trachoma in Kidal, 12 years after baseline mapping surveys, to determine whether interventions to control trachoma were warranted.

METHODS

A total of 2165 individuals from 477 households were examined for clinical trachoma signs in a cluster survey using the WHO simplified grading system. Individual and household risk factors for trachoma were assessed.

RESULTS

The prevalence of follicular trachomatous inflammation (TF) in children 1-9 years of age was 15.6% (95% CI 11.8-19.5%). Trachomatous trichiasis (TT) was observed in 4 persons for an overall prevalence in all ages of 0.16% (95% CI 0.0-0.35%). Estimated household latrine coverage in the region was 33.1% (95% CI 14.0-52.2%). Residents of 52.8% of surveyed households reported access to a water source outside geographical boundaries of their communities.

CONCLUSIONS

In the absence of control interventions, the prevalence of clinical signs of trachoma among children was substantially lower than estimates 12 years earlier. The current prevalence of active trachoma remains above the threshold adopted by WHO, yet there is little evidence of chronic blinding trachoma.

[Evaluation of cocoa oil for individual protection against Simulium damnosum s.i]

Thanks to larviciding and distribution of ivermectine, transmission of onchocerciasis was virtually halted in all countries covered by the WHO Onchocerciasis Control Program (OCP). However as a result of this success vector control has been stopped in most areas covered by the program and a recrudescence of files is an increasing problem. In some rural communities fly biting hinders normal agricultural activity. Since local farmers cannot afford ground larviciding, many rely on topical repellents. For this reason, development of an inexpensive method of individual protection is a major priority. The purpose of this study carried out in the savannah area of the Côte d'Ivoire was to assess the repellent properties of cocoa oil, which is frequently used in some rural areas of the Côte d'Ivoire to prevent fly biting. Results showed that cocoa oil provides excellent protection against Simulium damnosum s.l.