Global leprosy (Hansen disease) update 2024: Beyond zero cases – what elimination of leprosy really means
ILEP Technical Commission commentary
The Global Leprosy Update for 2024 has been published by the WHO Global Leprosy Programme in the Weekly Epidemiological Review (WER) and updated in the Global Health Observatory. This much-awaited report has a mix of encouraging trends and a few issues of concern. The report applies the Leprosy Elimination Framework (LEF) published in 2023, to track progress.
It is encouraging to see 188 countries reporting in 2024 (an increasing trend), from all 6 WHO regions including all 23 of what WHO classifies as global priority countries for leprosy. However, a notable exception has been the United States of America which did not submit data despite consistently submitting data in previous years. This is an issue of concern since state-level reports indicate detection of new locally acquired cases in 2024. Globally, 172,717 new cases of leprosy were reported in 2024 including 9,397 children, 69,394 (40.2%) women and 9,157 (5.3%) with Grade 2 disability. Though new cases overall have decreased by 5.5% compared to 2023 (182,815), there are mixed trends in new case detection data among the global priority countries. Thirteen of the 23, including India, have shown a decrease while the remaining 10 have shown an increase of around 25% (e,g. the Philippines, Comoros and Sudan). It is a matter of concern that the 10-year trends for new case detection in some of the 23 global priority countries seem to be stagnant. The decreased number reported by India (approximately 7,000 cases) may be due to lack of activities (case detection campaigns). On the other hand, this decrease could be a true reflection of the leprosy situation in the country, as it is in line with decreasing numbers (new patients as well as the child rate) in the previous years. Perhaps this may be a positive development.
Unfortunately, the decrease in new case detection in South Sudan (by 60.2%), Somalia (by 34.2%) and Ethiopia (19.3%) is most likely due to worsening security affecting leprosy programmes.
Using a DHIS2-based software allows for more detailed and disaggregated data on leprosy cases to be reported to the WHO. New child cases reported were 9,157 which is a slight decrease from 2023 (10,322). An interesting metric is the disaggregated age-related data for 2,298 of these new child cases reported by 56 countries. 78.8% were aged 10-14 years, 22.6% aged 6-9 years and 4.6% aged <6 years. This implies that almost 25% of new child cases are under the age of 10 and need an adapted MDT regimen from the standard child pack which is supplied by the WHO for children aged 10-14. A matter of concern is the number of children with Grade 2 disability at the time of diagnosis – 289 (3.1%). This implies not only delayed diagnosis but also a new generation having to grow up with the burden of leprosy-related disability.
Encouragingly, 75 countries submitted data on leprosy reactions (14,689 cases with Type 1 reactions and 5,652 with ENL). This data most likely reflects the presence of reaction at the time of initial diagnosis, and the number is most likely much higher as a large percentage of persons diagnosed with leprosy develop reactions after starting MDT. Hopefully, this data will start to appear in future reports, especially for reactions that may have happened during the period on MDT. For the first time, nerve function assessments done at the completion of treatment were reported for almost 16% of new cases.
A major area of concern is that the active case finding data is very limited, with only 90 countries (including 20 global priority countries) providing data on contact screening (9,914 new cases detected through contact tracing). Of these, only 37 countries (including 9 global priority countries) provided data on PEP provision. The reasons for this are unclear, but may include some academic objections and, probably more importantly, significant inertia and logistic difficulties, as well as availability of rifampicin.
MDT, with its ability to quickly reduce infectiousness and limit disability, has to be taken regularly and completely to maximize and safeguard its impact. Out of the record 188 countries reporting this year, data on treatment completion rates for MB and PB were available for only 96 (representing ≈51%) and 81 (representing ≈43%) countries, respectively. Additionally, antimicrobial resistance (AMR) reports were received from only 23 countries. An issue of concern here is that India has not submitted AMR data for the past 3 years. Urgent deliberate actions are required to improve treatment and AMR surveillance and reporting as critical quality measures of leprosy control services.
Whilst surveillance is below standard recommendations, for countries with available data, treatment completion rates were highly variable and sub-optimal (<85%) in 9 countries for MB and 7 countries for PB, while a worrying total number of 4,365 individuals (3,850 diagnosed as MB and 515 diagnosed as PB) were lost to follow-up during the reporting year. Additionally, out of 2,109 cases tested for resistance, 27 cases were resistant to rifampicin (26 of these were re-treatment cases), 23 to dapsone (20 of these were re-treatment cases) and 4 re-treatment cases were resistant to both rifampicin and dapsone. Tailored interventions to support adherence to MDT are urgently needed.
The number of countries that reported adverse drug reactions in relation to MDT increased, with 32 countries reporting a total of 263 adverse drug reactions of which 235 were related to dapsone. Continuing to gather data on this issue will support the research for newer anti-leprosy drugs.
The report also highlights 81 discriminatory laws reported by countries. However, ILEP’s database shows 140 discriminatory laws. This difference in numbers is mainly because WHO’s report includes information directly reported by countries through DHIS2. Perhaps ILEP should coordinate with WHO to reflect the correct number of discriminatory laws in existence.
In summary, it is encouraging to see an increasing number of countries reporting leprosy data and a decreasing trend in the number of new cases detected, including a continuous gradual reduction in the child rate over the last 15 years. However, critical challenges also remain and need to be addressed. These include ongoing transmission, stagnant or increasing burden of new cases in some of the 23 priority countries, low participation from countries in AMR surveillance and increasing number of cases in island countries despite ongoing, active work. If the good progress achieved thus far is to be consolidated, more countries need to be encouraged to do active case finding through contact screening and PEP.
Of note, Jordan became the first country to be verified and acknowledged by WHO for the elimination of leprosy disease in 2024. The year 2025 marks 50 years of WHO’s partnership with the Nippon Foundation and 25 years of partnership with Novartis – this is the foundation for the global provision of MDT, so a definite cause for celebration.
The WHO report ends with an important message: “a person-centred approach must remain integral to all efforts!”