Comment

Are leprosy case numbers reliable?

Leprosy is an infectious disease caused by Mycobacterium leprae. This study aimed to understand the distribution and impact of Hansen's disease in different regions of Brazil and the outcome of cases in recent years.

An ecological study was conducted throughout the Brazilian territory for 11 years (2008–2018). The mortality rates, new cases of the disease, and proportion of physical disability and cure were assessed. Data were obtained using DATASUS. GraphPad Excel and “Prisma” programs were used for tabulation and data processing. To present an accurate perspective from all regions, the data were normalized according to the population.

Overall, the results demonstrated a significant reduction in the number of leprosy cases in Brazil over the last decade (p < 0.05). North and Midwest regions showed higher mortality rates standardized by age (p < 0.05). The largest number of cases were found in Tocantins and Mato Grosso, inner states of Brazil (p < 0.05). The cure rates in the Southeast and South regions were negatively correlated with the mortality rate in these regions (p < 0.05).

Actions to control the spread and unfavorable outcomes of leprosy have been effective in the last decade in most Brazilian states. On the other hand, the states of Tocantins and Mato Grosso, in the North and Midwest regions of Brazil, need to intensify the fight against the disease. Notwithstanding, measures against leprosy should continue and be intensified in regions with greater aggravations, aiming at an effective homogeneous control of the disease.

Molecular epidemiology investigations are notoriously challenging in the leprosy field mainly because the inherent characteristics of the disease as well as its yet uncultivated causative agents, Mycobacterium leprae and M. lepromatosis. Despite significant developments in understanding the biology of leprosy bacilli through genomic approaches, the exact mechanisms of transmission is still unclear and the factors underlying pathological variation of the disease in different patients remain as major gaps in our knowledge about leprosy. Despite these difficulties, the last two decades have seen the development of genotyping procedures based on PCR-sequencing of target loci as well as by the genome-wide analysis of an increasing number of geographically diverse isolates of leprosy bacilli. This has provided a foundation for molecular epidemiology studies that are bringing a better understanding of strain evolution associated with ancient human migrations, and phylogeographical insights about the spread of disease globally. This review discusses the advantages and drawbacks of the main tools available for molecular epidemiological investigations of leprosy and summarizes various methods ranging from PCR-based genotyping to genome-typing techniques. We also describe their main applications in analyzing the short-range and long-range transmission of the disease. Finally, we summarise the current gaps and challenges that remain in the field of molecular epidemiology of leprosy.

The objective of this study was to analyze the trend of epidemiological and operational indicators of leprosy in Brazil, from 2001 to 2017. This was a time series study involving nine indicators. The inflection point regression model was used. Decreasing trends were observed for the following: general detection (−4.8%), children under 15 (−3.7%), prevalence (−7.0%), and grade 2/million inhabitants (−3.5%). The proportion of individuals with grade 2 disability showed an upward trend (2.0%) from 2001 as well as contacts examined from 2003 (5.0%). The proportions of cure and of individuals with a degree of disability assessed at the time of the diagnosis and the cure showed a stationary behavior. Although advances are noted, there are still challenges to be overcome.

This study analyzed the trend of leprosy indicators in Sergipe, between 2001 and 2015. It was a time series study that analyzed the trend for general detection coefficient, children under 15 years of age, and new cases with grade 2 disability. The joinpoint model was used. Two (2.6%) municipalities had an increasing trend in general detection coefficient, five (6.6%) had an increasing trend in detection rate in children under 15, and 19 (25.3%) had an increasing trend in detection coefficient of new leprosy cases with grade 2 disability. The findings suggest maintenance of the chain of transmission.

This ecological study aims to analyze both the tendency and the characteristics of leprosy in the elderly population in the state of Bahia, 2001–2017. The tendency was analyzed through joinpoint regression. Epidemiological variables were also included in the study. The average detection rate was 38.73/100,000, with prevalence of men (45.19/100,000). A downward trend occurred in both genders, from 2004, with a greater magnitude in women (annual percent change [APC] = −3.4%). Men presented higher proportions of the multibacillary forms and physical disabilities. The epidemiological scenario indicates the need of implementation of actions that stimulate early diagnosis and treatment of the elderly population.

The objective of this study was to describe the trend of detection of the disease in Brazil from 1990 to 2016. The joinpoint regression model was used. There was a significant trend of decreased detection in the country (average annual percent change  −1.8%) and in the South (average annual percent change = −3.5%) and Southeast regions (average annual percent change = −4.5%). The Northeast (average annual percent change = 0.2%), the Central-West (average annual percent change = −1.5%), and the North (average annual percent change = −2.6%) showed a stationary trend (p > 0.05). Eleven states showed a decreasing trend. Alagoas (average annual percent change = 2.1%) and Rio Grande do Norte (average annual percent change = 1.4%) presented significant increase (p < 0.001). The heterogeneous pattern of trend between regions and states shows that efforts are needed to eliminate the disease.