A case report published in Eurosurveillance on an adult with an imported case of leprosy in Ireland shows that there are notable challenges in tackling the disease in settings where it is rare. The affected individual was one of five individuals with leprosy reported in Ireland in the past decade. The authors report challenges faced in the public health response due to a delayed recognition of the symptoms by healthcare providers, a lack of specific Irish and European guidelines, and contact tracing in a congregate setting.
Ahead of World Leprosy Day, this case study highlights the need for public health guidelines tailored to countries where the disease is very rare as well as strategies to reduce stigma related to the disease. Leprosy is one of 24 neglected tropical diseases targeted for elimination by the World Health Organization (WHO) in its 2021-2030 roadmap. Though it is uncommon in Europe, it still represents a high burden of disease worldwide, with 182,815 cases reported across the globe.
Case overview
The case involved a person in their 30s who was born and raised in the Caribbean, where leprosy is common. They had moved to Ireland 2 years prior to diagnosis from southern Brazil, where incidence of leprosy is also high. The individual initially reported to a healthcare provider in late 2023 with neurological symptoms and lightened skin lesions. The patient was diagnosed after a 7-month investigation through a skin biopsy. After being treated with a multi-drug therapy, they recovered from the infection.
The contact tracing strategy and risk assessment were based on WHO guidelines and policy documents, as there were no specific guidelines available in Ireland. Most of the international guidance on contact tracing comes from low- and middle-income countries, as few high-income countries have developed their own guidelines. There are considerable inconsistencies in guidelines across different countries on contact tracing, post-exposure prophylaxis eligibility, and follow-up approaches for affected individuals and contacts.
Public health response
Researchers identified a close contact as any person who had been in contact with the untreated initial case for at least 20 hours per week, for at least 3 months in the preceding year, based on the WHO definition.
One of the individual's eight housemates, their partner and a work-related contact were identified as close contacts under the WHO criteria. Ten other adults were also considered potential close contacts. Given the stigma of the disease, the public health experts ruled out extensive contact tracing of all household members, as it could have threatened the individual's livelihood and access to housing, both of which were reported to be precarious.
Based on WHO, Western Australian and British guidelines, clinicians offered chemoprophylaxis with single-dose rifampicin to the three true close contacts for the affected individual. This treatment has been shown to offer a protective effect in leprosy contacts where the disease is common. However, there is some uncertainty on whether these outcomes also apply to settings where leprosy is rare, with international guidelines being less consistent.
The incubation period for leprosy is highly variable and ranges from 2 to 5 years, but can be shorter or extend up to 20 years or more. Most international guidelines recommend an annual follow-up for close contacts given this unusually long incubation period, with some variation on the duration of follow-up. Arrangements where therefore made with local primary physicians to conduct yearly follow-ups with the three contacts for the case for a minimum of 5 years, as recommended by the World Health Organization.
Recommendations
The report shows the significant challenges in responding to leprosy in high-income countries where it is rare. Countries should consider developing tailored strategies for these settings, which should prioritise ongoing education of healthcare professionals on the disease, as well as robust measures to counter stigma and improve access to mental health for affected individuals. The authors also recommend a more harmonised approach to responding to sporadic cases, with greater standardisation across public health guidelines.
