Epidemiological Update - Diphtheria - 16 April 2018

Diphtheria in the Americas - Summary of the situation

In 2017, four countries in the Region of the Americas—Brazil, the Dominican Republic, Haiti, and the Bolivarian Republic of Venezuela—reported confirmed diphtheria cases. In 2018 as of epidemiological week (EW) 14 of 2018, four countries in the Region—Brazil, Colombia, Haiti, and Venezuela—have reported suspected and confirmed diphtheria cases.

The following is a summary of the situation in each country with reported suspected and confirmed cases in 2018.

In Brazil in 2017, there were 42 suspected cases reported in 14 states. Of the reported cases, 5 were confirmed in four states: Acre (1), Minas Gerais (2), Roraima (1 fatal case, imported from Venezuela), and São Paulo (1). The remaining 37 cases were ruled out. Three of the 5 confirmed cases (2 in Minas Gerais and 1 in São Paulo) had received the full vaccination scheme. The confirmed cases range from 4 to 66 years of age (median 19 years), and four are male and one is female. Additionally, in EW 14 of 2018, 6 suspected cases were reported in 6 states; one reported in the state of Roraima (imported from Venezuela) is currently under investigation. As of EW 14, none were confirmed.

In Colombia in EW 7 of 2018, a fatal confirmed case of diphtheria imported from Venezuela was reported in La Guajira Department. The case is a 3-year-old Venezuela national with an unknown vaccination history. Onset of symptoms was on 2 January 2018 and the case died on 8 January. The case was laboratory-confirmed based on clinical, epidemiological, and laboratory criteria (Gram-positive bacilli and RT-PCR positive for Corynebacterium diphtheriae with no identification of biotype or positive toxin).

In Haiti, since the beginning of the outbreak at the end of 2014 up to EW 6 of 2018, there have been 410 probable cases of diphtheria reported, including 75 deaths.1 Reported case-fatality rates were 22.3% in 2015, 27% in 2016 and 10.7% in 2017 and 2018. During the first four epidemiological weeks of 2018, 2 to 5 probable cases per EW were reported similar to that observed during the last four weeks of 2017.

Females accounted for 57% of the total probable cases in 2015, 50% in 2016, 60% in 2017, and 47% in 2018 (up to EW 6). With respect to vaccination coverage, between 2015 and 2018 the unvaccinated cases accounted for 17% (2018) to 38% (2015) of the total cases. Children less than 10 years of age accounted for 64% of the probable cases reported between 2017 to EW 4 of 2018.

Since the beginning of the outbreak the departments reporting the highest number of probable cases are Artibonite, Centre, and Ouest.

In Venezuela, the diphtheria outbreak that began in July 2016 remains active (Figure 1). Since the start of the outbreak until EW 10 of 2018, a total of 1,602 suspected diphtheria cases were reported (324 cases in 2016, 1,040 in 2017, and 238 in 2018), of which 976 were confirmed by laboratory (314) or epidemiological-link (662), and 142 died (17 in 2016, 103 in 2017, and 22 in 2018). The cumulative case fatality rate is 14.5%.