Leprosy in French Guiana 2007–2014: a re‐emerging public health problem

dear editor, In 1991, the World Health Organization (WHO) set the aim of eliminating leprosy as a public health problem by decreasing world prevalence to < 1 case per 10 000 inhabitants.1 This objective had been reached in French Guiana by the time an epidemiological study was performed in 2006.2 French Guiana is a French overseas department in South America, and it enjoys a universal healthcare system and greater development than neighbouring countries (Brazil and Suriname). It has a population of 296 000, of mixed ancestries, including African American, Europeans and Amerindians. Many immigrants from Brazil have recently settled in French Guiana. They often work as illegal gold miners and experience very harsh working conditions in the isolated forest areas of the hinterland. The main objective of this study was to estimate the incidence and prevalence of leprosy in French Guiana.

Between 1 January 2007 and 31 December 2014, in all health centres of French Guiana, all new cases of histologically confirmed active leprosy and all patients on leprosy treatment were enrolled in the study. We defined autochthonous cases as adults born or living in French Guiana for more than 10 years, or children born and living in French Guiana. Incidence and prevalence rates were calculated on the basis of the 2012 census data.

During the study period, 125 new cases were recorded. The average annual incidence rate was 0·67 per 10 000 inhabitants (Fig. 1a). Children aged below 16 years represented 8·8% of cases. Most patients (88%) were from other countries (56% from Brazil). Of the 125 cases, 27 (21·6%) were autochthonous. Leprosy was multibacillary for 55% of patients. Clinical symptoms were present for more than 1 year for 34% of patients. Disability level (DL)1 and DL2 were present, respectively, in 37 (29·6%) and 18 (14·4%) patients. Of the patients with DL2, 60% were Brazilians, and these were mostly gold miners. Incomplete treatment was recorded for 47% of patients, while 6% received no treatment and 32% were lost to follow‐up.

Figure 1.

(a) Annual incidence and (b) annual prevalence of leprosy in French Guiana, 2007–2014.

During the study period, 190 prevalent cases were followed in French Guiana. The average annual prevalence was 1·01/10 000 inhabitants. The annual prevalence ranged from 0·51 to 1·23/10 000 inhabitants in 2007–2014 (Fig. 1b). Between 2009 and 2014, this rate was always 1 or higher. Comparing the data from this study with the data of the previous period 1997–2006,2 we observed a significant increase in the annual number of new cases (P = 0·025). There was also a significant increase in the proportion among Brazilian patients (30% vs. 56%; P = 0·001). A box and whisker plot comparing the incidence of leprosy during the two periods 1997–2006 and 2007–2014 can be obtained by direct application to the corresponding author.

In French Guiana, the annual incidence rate of leprosy has considerably decreased since the early 1980s, with < 1 case per 10 000 inhabitants between 1996 and 2005.2 However, since 2006, there has been a significant increase of incidence, with two peaks of > 1 case per 10 000 inhabitants. Since 2009, the incidence of leprosy in French Guiana has exceeded the WHO threshold, and becoming a public health problem. In 2006, Domergue et al., using similar methodology, concluded that leprosy was no longer a public health problem in French Guiana,2 but our results suggest a re‐emergence. The presence of locally acquired cases in our study suggests an autochthonous transmission. This finding is also supported by the proportion of children with leprosy, which is higher than in Brazilian3 or previous Guianan2 studies.

During the second half of the 20th century, leprosy in French Guiana used to affect mostly Bushinengue (Marroon) people living on the Maroni river.2 Our study shows a shift in epidemiological profile towards Brazilians (56% of new cases), probably reflecting the gradual increase in illegal gold mining in French Guiana.4, 5 The proportion of patients with DL2 at the time of diagnosis was double that of the global or Brazilian reported rates (6·5%).1, 3 The advanced presentations in this neglected population are probably linked to a lack of healthcare access.5 High proportions of multibacillary leprosy in our study suggest bacilli circulation and a greater risk of evolution towards DL2.6

A little more than half of all patients had received complete treatment according to WHO criteria. Untreated patients were generally patients lost to follow‐up. This can be explained by the great mobility of isolated communities in French Guiana.

In conclusion, our study shows that over the past 8 years leprosy has re‐emerged as a significant public health problem in French Guiana. Continuous epidemiological monitoring is necessary to update the situation of leprosy control in French Guiana and to help improving public health strategies. Special efforts should be dedicated to delivering appropriate care to Brazilian gold miners. These results should make the international community aware of specific needs in these parts of the world.