Epidemiological Update – Diphtheria – 15 December 2017

Diphtheria in the Americas – Summary of the situation

Between epidemiological week (EW) 1 and EW 49 of 2017, Brazil, the Dominican Republic, Haiti, and the Bolivarian Republic of Venezuela reported confirmed diphtheria cases. The following is a summary for each country.

In Brazil, up to EW 49 of 2017, 14 states reported a total of 42 suspected diphtheria cases, including 41 which were confirmed in Acre, Minas Gerais, Roraima, and São Paulo states; 1 by laboratory testing and 3 by clinical criteria. Out of the four cases, 2 were not vaccinated (including the laboratory confirmed case) and 2 had an uncompleted vaccination schedule.

The confirmed cases range between 4 and 51 years of age, and include 3 males and 1 female. There was 1 fatal confirmed case; this is the previously reported laboratory confirmed case imported from Venezuela. There were no secondary cases related to this case nor have there been additional imported cases reported in Brazil.

In the Dominican Republic, there were 3 confirmed diphtheria cases reported in the last diphtheria epidemiological update of 15 November 2017; however, the Ministry of Public Health and Social Assistance has since reported that only one was confirmed for diphtheria as the other two cases were discarded by clinical criteria (1) and by laboratory (1). No fatal case was reported.

In Haiti, the outbreak began at the end of 2014 and has continued to occur with a total of 348 probable diphtheria cases reported up to EW 48 of 2017, including 46 deaths. An increase in cases is observed in the last trimester of 2017 compared to the preceding trimester (Figure 1).

Between EW 1 and EW 48 of 2017, 152 probable cases were reported, with a case fatality rate of 10%. Of these cases, 59% are female and 76% are infants under the age of ten. The vaccination history of the probable cases is the following: 11% were vaccinated and 89% did not know or did not have information on their vaccination status. Most of the probable cases (71%) were reported in the departments of Artibonite and Ouest (38% and 33%, respectively); this is similar to what was observed in 2016 with 70% of the cases reported in the same two departments.

Of the 152 probable cases reported in 2017, samples were taken from 141 cases, of which 64 (45%) were laboratory confirmed, 52 were discarded, and 25 remain under investigation. Of the confirmed cases, 81% (52) are from the departments of Artibonite and Ouest.

Epidemiological surveillance is being intensified to detect the population at risk and to implement public health measures, including a vaccination campaign expected to take place in 2018.

In Venezuela, between EW 28 of 2016 and EW 48 of 2017, a diphtheria outbreak was reported, starting from Sifontes municipality, Bolívar state and spreading to 21 other states in the country. A total of 933 probable diphtheria cases were reported, 324 of which occurred in 2016. From EW 1 to EW 48 of 2017, 609 probable cases of diphtheria were reported (21% case fatality rate), of which 227 were laboratory confirmed (by isolation or polymerase chain reaction).

Among the confirmed cases (198 cases), 14% have a history of vaccination and 56% are female. The most affected individuals are those aged 11 or older, which accounted for 72% of the confirmed cases.

The Venezuela Ministry of People’s Power for Health is intensifying vaccination activities in municipalities with cases and a vaccination campaign is planned to begin in early 2018. All federal entities have been alerted and epidemiological surveillance, active case search, follow-up of contacts, diagnostic capacity are being strengthened.


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