Exploring Spatial and Temporal Distribution of Cutaneous Leishmaniasis in the Americas, 2001-2011

Abstract

Methods: Cases reported in the period of 2001-2011 from 14/18 CL endemic countries were included in this study by using two spreadsheet to collect the data. Two indicators were analyzed: CL cases and incidence rate. The local regression method was used to analyze case trends and incidence rates for all the studied period, and for 2011 the spatial distribution of each indicator was analyzed by quartile and stratified into four groups.

Results: From 2001-2011, 636,683 CL cases were reported by 14 countries and with an increase of 30% of the reported cases. The average incidence rate in the Americas was 15.89/100,000 inhabitants. In 2011, 15 countries reported cases in 180 from a total of 292 units of first subnational level. The global incidence rate for all countries was 17.42 cases per 100,000 inhabitants; while in 180 administrative units at the first subnational level, the average incidence rate was 57.52/100,000 inhabitants. Nicaragua and Panama had the highest incidence but more cases occurred in Brazil and Colombia. Spatial distribution was heterogeneous for each indicator, and when analyzed in different administrative level. The results showed different distribution patterns, illustrating the limitation of the use of individual indicators and the need to classify higher-risk areas in order to prioritize the actions. This study shows the epidemiological patterns using secondary data and the importance of using multiple indicators to define and characterize smaller territorial units for surveillance and control of leishmaniasis.

Fig 1. Number of cutaneous leishmaniasis cases reported by 14 endemic countries (overall), and stratified by sub region, Americas region, 2001–2011.

The Plotted points correspond to actual counts of cases. The Lines consist in short term trends (fitted with LOESS). Source: PAHO/WHO. Data reported by the leishmaniasis control programs of the countries to PAHO/WHO through May 2012.

Fig 2. Annual incidence of cutaneous leishmaniasis per 100,000 inhabitants reported by 14 endemic countries (overall), and stratified by sub region, Americas region, 2001–2011.

The Plotted points correspond to actual CL incidences. The Lines consist in short term trends (fitted with LOESS). Source: PAHO/WHO. Data reported by the leishmaniasis control programs of the countries to PAHO/WHO through May 2012.

Fig 3

Spatial distribution of cutaneous leishmaniasis cases (A) and incidence rates per 100,000 inhabitants (B), stratified at national level by quartile, Americas region, 2011. (3A) Group 1- countries with ≥ 3 235 cases; Group 2—>1 376 to ≤ 3 234 cases; Group 3—>184 to ≤ 1 375 cases; and Group 4—≤183 cases. (3B) Group 1- Incidence rate ≥ 29.96/100 000 inhabitants; Group 2—incidence rate >11.07 to ≤ 29.95 cases/100 000 inhabitants; Group 3—incidence rate >1.90 ≤ 11.06 cases/100 000 inhabitants; and Group 4—≤ 1.989 cases/100 000 inhabitants. Source: PAHO/WHO. Data reported by the leishmaniasis control programs of the countries to PAHO/WHO through May 2012.

Fig 4

Spatial distribution of cutaneous leishmaniasis stratified by quartile for cases (A) and incidence rate of cases/100,000 inhabitants (B) at the first subnational administrative level, Americas region, 2011. (4A) Group 1—Units at the first subnational level with ≥299; Group 2—> 100 to ≤ 298 cases; Group 3—> 16 to ≤ 99 cases; and Group 4—≤ cases. (4B) Group 1- Units at the subnational administrative level with incidence rates ≥44.81 per 100 000 inhabitants; Group 2—incidence rates > 11.30 to ≤44.80 cases per 100 000 inhabitants; Group 3—incidence rates > 3.43 ≤ 11.29 cases per 100 000 inhabitants; and Group 4—incidence rates ≤ 3.43 cases per 100 000 inhabitants. Source: PAHO/WHO. Data reported by the leishmaniasis control programs of the countries to PAHO/WHO through May 2012.