Epidemiological Update - Diphtheria in the Americas - Summary of the situation - 10 May 2019

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, Haiti and Venezuela reported confirmed cases.

The following is a summary of the epidemiological situation in Haiti and Venezuela.

In Haiti, between epidemiological week (EW) 32 of 2014 and EW 16 of 2019, there were 838 probable cases 1 reported, including 108 deaths; of these, 276 were confirmed (267 by laboratory criteria and 9 by epidemiological link) (Table 1).

The number of probable and confirmed cases reported between EW 1 and EW 16 of 2019 (56 cases) is higher than reported for the same period in 2017 (44 cases) and lower than the same period in 2018 (136 cases).

Of the 56 probable cases reported in 2019, 6 cases and 1 death were confirmed by laboratory. The case-fatality rate among cases confirmed by laboratory or epidemiological link was 23% in 2015, 39% in 2016, 8% in 2017, 13% in 2018, and 17% in 2019.

Among confirmed cases in 2019, the highest incidence rate is reported in the age group of 6 to 14-year-olds, followed by 1 to 5-year-olds. The fatal case occurred in a 5-year-old child.

In 2019, the highest cumulative incidence rate of the probable cases were reported in the communities of Acul du Nord (3.58 cases per 100,000 population) in the Nord Department and in Tabarre (3.07 cases per 100,000 population) in the Ouest Department.

In Venezuela, the diphtheria outbreak that began in July 2016 remains ongoing (Figure 2).
Since the beginning of the outbreak until EW 13 of 2019, a total of 2,752 suspected cases were reported (324 cases in 2016, 1,040 in 2017, 1,198 in 2018, and 190 in 2019); of these, 1,688 were confirmed (554 by laboratory and 1,134 by clinical criteria or epidemiological link). A total of 284 deaths were reported (17 in 2016, 103 in 2017, 151 in 2018, and 13 in 2019). In 2019, the highest case-fatality rate occurred in the age group of 5 to 9 years-old (7%), followed by 10 to 15 years-old (4%).

In 2018, 22 federal entities and 99 municipalities have reported confirmed cases. As of EW 13 of 2019, 16 of the federal entities, 45 municipalities, and 65 parishes are reporting cases.
Therefore, vaccination and control activities continue to be implemented.

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.

Advice for Member States

The Pan American Health Organization / World Health Organization (PAHO/WHO) reiterates to Member States the recommendations to continue their efforts to ensure vaccination coverage over 95% with the primary series (3 doses) and booster doses (3 doses). This vaccination scheme will provide protection throughout adolescence and adulthood (up to 39 years and possibly beyond). Booster doses of diphtheria vaccine should be given in combination with tetanus toxoid, using the same schedule and age-appropriate vaccine formulations, namely diphtheria, tetanus, and pertussis (DPT) for children aged 1 to 7 years old, and diphtheria toxoid (Td) for children over 7 years old, adolescents, and adults.

PAHO/WHO stresses that the most at-risk populations are unvaccinated children under 5 years of age, schoolchildren, healthcare workers, military service personnel, inmate communities, and persons who, due to the nature of their occupation, are in contact with a large number of persons on a daily basis.

Although travelers do not have a special risk for diphtheria infection, it is recommended that national authorities remind travelers going to areas with diphtheria outbreaks to be properly vaccinated prior to travel in accordance with the national vaccination scheme established in each country. If more than five years have passed since their last dose, a booster dose is recommended.

PAHO/WHO recommends that Member States strengthen their surveillance systems and their capacity of laboratory diagnosis through culture, ELEK test, and PCR for diphtheria toxin (tox) gene.

PAHO/WHO recommends maintaining a supply of diphtheria antitoxin.

Vaccination is key to preventing cases and outbreaks, and adequate clinical management reduces complications and mortality.