This post is the 10th in a series highlighting the WHO’s list of 17 Neglected Tropical Diseases (now technically 18 as mycetoma was added to the list at the 69th World Health Assembly in May 2016). To read the previous posts in this series click here.
Mycobacterium leprae causes leprosy, which can result in a chronic infection that causes permanent damage to the skin, eyes, nerves and limbs if left untreated. It is spread through droplets in the air, although it is not spread very efficiently, and symptoms can take 20 years to show, which is why we don’t see huge outbreaks of leprosy around the world. Leprosy, also known as Hansen’s disease, has been known to affect humans throughout history. Leprosy symptoms were described in ancient texts from China, Egypt and India. So many people had leprosy in the past that leprosariums (like sanitariums for TB patients) were built and people with leprosy were sent there, which further added to the stigma that people with leprosy faced from their community. However, the high burden of disease that was seen in the past is not seen anymore. In 2015, more than 200 000 cases of leprosy were diagnosed, compared to more than 5.2 million in 1985.
Since the 1940s there have been drugs to cure leprosy and since 1995 WHO has made leprosy drugs available for free to all persons. Drug treatment has been a major factor in the large decrease in cases worldwide. More than 16 million people have been treated for leprosy over the past 20 years. Because of the success of curing leprosy, the world “eliminated” leprosy in 2000. Yes, you read that right. There are still over 200 000 cases per year of leprosy but it is technically “eliminated”. Let me explain. WHO considers a disease eliminated if the prevalence falls below 1 case per 10 000 people. This goal for elimination was set in 1991 and achieved on time in the year 2000. So even though there are pockets of leprosy occurring in small communities, all nations (minus a few really small ones) have eliminated leprosy. So what about those people who live in those really small nations or those small communities which still have leprosy.
Leprosy control is still an important part of the WHO’s strategies. In 2016 WHO launched the Global Leprosy Strategy 2016-2020: Accelerating towards a leprosy-free world. This global strategy aims to refocus and reinvigorate efforts to control leprosy and prevent disabilities, especially in children and endemic areas. Part of this strategy involves seeking out cases of leprosy, instead of waiting for people to come seek healthcare. Due to the social stigma that still surrounds leprosy, many people do not seek treatment until it is too late to prevent lifelong disability. India mounted a huge campaign to go door-to-door seeking out leprosy cases. The 300 000 health workers reached more than 320 million people and found thousands of “hidden” cases.
For all my readers in the US, please don’t think leprosy doesn’t occur in the US anymore, or that it is just a disease “they” get (they being any person who lives in non-Western countries, the Global South, low or middle income countries, etc.). In 2014, the New York Times wrote this article about Mr. Ramirez from Houston, who was diagnosed with leprosy in 1968. In the southern part of the US, 9-banded armadillos have been shown to be carriers of leprosy, which has resulted in cases of leprosy transmission in the US. You won’t get leprosy just by touching an armadillo, the bacteria isn’t spread that easily. But this goes to show you that leprosy isn’t some disease of the past, it still exists in the US and around the world.