Epidemiological Update - Diphtheria (22 January 2019)

Diphtheria in the Americas - Summary of the situation

In 2018, three countries in the Region of the Americas (Colombia, Haiti, and the Bolivarian Republic of Venezuela) reported confirmed cases of diphtheria. In 2019, the outbreaks are ongoing in Haiti and Venezuela; both have reported cases in 2019 that occurred between December 2018 and January 2019.

The following is a summary of the epidemiological situation.

In Colombia, between epidemiological week (EW) 1 and EW 52 of 2018 there were 56 suspected diphtheria cases reported, of which 8 were confirmed, including 3 deaths. Among the suspected cases, one case fulfils the clinical criteria, with symptom onset in EW 50 of 2018; this is a 26-yearold female Venezuelan national living in Colombia. The laboratory results are pending for final classification of this case.

In Haiti, between EW 51 of 2014 and EW 52 of 2018, there were 785 probable cases1 reported, including 106 deaths; of these, 264 were confirmed (257 by laboratory criteria and 7 by epidemiological link).

The number of probable and confirmed cases reported in 2018 is higher than the total number of cases reported in 2017 and 2016, an increase that is attributed to increased sensitivity of the national surveillance system. The case-fatality rate among cases confirmed by laboratory or epidemiological link was 23% in 2015, 39% in 2016, 8% in 2017, and 14% in 2018.

In 2018, there were 373 probable cases reported (between EW 1 and EW 52), including 99 confirmed cases (94 by laboratory and 5 by epidemiological link). During the same period, there were 27 deaths reported (14 confirmed by laboratory or epidemiological link, 11 with no viable laboratory samples and 2 were discarded).

Among confirmed cases in 2018, the highest incidence rate is observed in the age group of 6 to 14-year-olds, followed by 1 to 5-year-olds. Most of the deaths (63%) occurred among the age group of 6 to 14-year-olds, followed by 1 to 5-year-olds.

In 2018, the highest cumulative incidence rates were reported in the municipalities of Gros-Morne, Artibonite Department (25.7 cases per 1000,000 population), Vallière, Nord-Est Department (21.2 cases per 100,000 population), La Victoire, Nord Department (9.5 cases per 100,000 population), and Cerca-Carvajal (12.9 cases per 100,000 population), Thomonde (11.3 cases per 100,000 population), and Savanette (22.1 cases per 100,000 population) in Centre Department.

In Venezuela, the diphtheria outbreak that began in July 2016 remains ongoing (Figure 2). Since the beginning of the outbreak until EW 2 of 2019, a total of 2,512 suspected cases were reported (324 cases in 2016, 1,040 in 2017, 1,102 in 2018, and 46 in 2019); of these, 1,559 were confirmed (448 by clinical criteria, 607 by epidemiological link, and 504 by laboratory). A total of 270 deaths were reported (17 in 2016, 103 in 2017, and 150 in 20182); 398 cases were discarded in 2018. The case-fatality rate among confirmed cases was 18% in 2016, 13% in 2017, and 20% in 2018.

In 2018, 22 federal entities and 99 municipalities have reported confirmed cases. Cases have been reported among all age groups. The incidence rate among children under 15 years old is 4 cases per 100,000 population, in 15 to 40-year-olds it is 3 cases per 100,000 population, and in persons over 40-years-old it is 1 case per 100,000 population.

As of EW 2 of 2019, there were 8 federal entities and 20 municipalities with 21 parishes reporting cases. Accordingly, vaccination and control activities continue to be implemented.