A recent publication in the Clinical Infectious Disease Journal highlights an investigation identifying a cluster of Guinean patients with drug resistant leprosy infections . Some of the patients were identified to have dapsone-resistant Mycobacterium leprae, as well as a single case demonstrating rifampicin resistance . This finding is significant because while the prevalence of leprosy has declined greatly, there are still approximately 200,000 new cases of leprosy reported globally each year . The emerging threat of drug-resistant leprosy infection could pose a serious public health risk if left unaddressed.
Leprosy is a curable infectious disease that primarily affects the peripheral nerves, skin, upper respiratory tract, eyes, and nasal mucosa. This disease is caused by a slow-growing bacterium known as Myobacterium leprae, which has an incubation period of approximately five years [2, 5]. Leprosy causes discoloration and lumps on the skin, and, if not treated early, can cause disfigurement and deformities . Leprosy is typically found in tropical areas of Africa and Asia.
First-line antibiotics used to treat leprosy include: dapsone, rifampicin, and clofazimine; second-line drugs include: ofloxacin, minocycline and clarithromycin. Resistance to the first-line drugs could have a large impact on leprosy control programs because reliance on second-line antibiotics is not as effective for treatment, particularly if rates of leprosy infection begin to increase.
There has been a massive decline in the prevalence of leprosy following the global implementation of multidrug therapy (MDT) in the 1980s by the World Health Organization (WHO), however there are still over 200,000 new leprosy cases recorded every year. In 2014, 313 cases of leprosy were identified in Guinea, but data on resistant infections were not collected.
The recently published study collected 24 skin biopsy samples from leprosy patients during 2012 to 2015, and analyzed genes associated with resistance for any evidence of mutations. The researchers also examined a subset of these cases and performed whole-genome sequencing and epidemiologic investigation to determine the existence of drug-resistant leprosy. The results found three patients living in the Kankan region of Guinea with evidence of dapsone-resistant leprosy and one patient living in the Boke region of Guinea with evidence of rifampicin-resistant leprosy .
The WHO states that drug resistant leprosy is not presently a serious concern. However, it recognizes the potential for an increase of rifampicin-resistant strains of leprosy if patients are not compliant with their drug regimens . It is important to monitor the rates of resistance closely, so that effective measures to combat the problem can be developed and deployed.
The WHO announced a two-pronged strategy to combat the potential threat of drug resistant leprosy with the Global Leprosy Programme, which includes the following :
- Closely monitor trends in occurrence of relapses after treatment with MDT due to drug resistance
- Promote research on developing new drugs for non-rifampicin containing regimens to limit and treat patients who relapse after completing one or more courses of MDT due to resistant strains of M. leprae (secondary resistance) and those new patients who are not responding to standard MDT regimen (primary resistance)
The emergence of drug-resistant leprosy in Guinea is cause for serious concern. The findings of this study are important in highlighting the need for increased monitoring, prevention and control methods to combat the further emergence of drug resistant leprosy.