In the context of the COVID-19 pandemic, the Pan American Health Organization / World Health Organization (PAHO / WHO) reiterates to Member States that vaccination and epidemiological surveillance of vaccine-preventable diseases should be considered as essential health services and should not be interrupted. In view of the declining diphtheria vaccine coverage, PAHO / WHO also reminds Member States of the importance of having a plan to immunize the most vulnerable populations and to maintain a permanent supply of diphtheria antitoxin for control potential epidemics.
Summary of the situation in the Americas
In 2021, between epidemiological week (SE) 1 and SE 42, four countries reported confirmed cases of diphtheria: Brazil with one case, Colombia with one fatal case, Haiti with 18 cases including 3 deaths, and the Republic Dominican with 18 cases including 12 deaths.
The Region of the Americas has reported a steady decline in immunization coverage since 2010. Immunization coverage for the third dose of diphtheria, tetanus and pertussis (DTP3) vaccine in the Region of the Americas has decreased from 94% to 84% between 2010 and 2020 Between January 2019 and January 2020, DTP3 coverage decreased by 33%. Declining coverage has been observed in most countries in the Region, increasing the population of individuals susceptible to vaccine-preventable diseases. In addition, the COVID-19 pandemic has also affected the epidemiological and laboratory surveillance systems for vaccine-preventable diseases.
Here is the epidemiological situation of diphtheria in Colombia, Haiti and the Dominican Republic, countries which have reported new confirmed cases since the epidemiological update on diphtheria published on June 25, 2021.
In Colombia, between EW 1 and EW 41 of 2021, 7 probable cases of diphtheria were reported, of which one was laboratory confirmed, 5 were rejected and one remainder under investigation.
During SEM 41 of 2021, a confirmed fatal case of diphtheria was reported in the department of Sucre in a 10-year-old Venezuelan woman who had resided in the municipality of Santiago de Tolú, department of Sucre, for 5 years. The case developed symptoms on September 27, 2021 and died on October 5; the case had no travel history and had an unknown vaccination history. The case was confirmed in the laboratory (positive for Corynebacterium diphtheriae by RT-PCR and with identification of the diphtheria toxin gene).
In the Dominican Republic, between SE 1 and SE 42 of 2021, a total of 56 probable cases of diphtheria were notified, including 18 confirmed (14 by laboratory and 4 by epidemiological link) including 12 confirmed deaths (11 by laboratory and one by epidemiological link ). Of the total cases reported in 2021, 31 were dismissed, one was classified as probable and 6 are still under investigation. (Figure 1) Information regarding the first 13 confirmed cases reported in 2021 was previously published in the Diphtheria Epidemiological Update published on April 23 and June 25, 2021.
Of the 18 confirmed cases between EW 1 and EW 42 of 2021, all were Dominican nationals, 11 were male, aged 1 to 14 years (median 8 years), all had an incomplete vaccination history, and none had reported a recent trip. the story. Confirmed cases have been reported in the provinces of Monte Plata (7 cases including 5 deaths), Santo Domingo (3 cases including 2 deaths), Elías Piña (3 cases including 2 deaths), San Cristobal (2 cases including 1 death) , Peravia (1 fatal case), Bahoruco (1 fatal case) and Hato Mayor (1 case). The most recent confirmed case exhibited symptoms on August 9, 2021 and was reported in the province of Monte Plata.
Between EW 1 and EW 42 of 2021, a total of 11 laboratory-confirmed deaths were reported, of which 7 were males and aged 1 to 14 years (median 5 years). The most recent fatal case appeared on July 27, 2021 and was reported in the province of Elías Piña.
Among the 14 cases in which Corynebacterium diphtheriae was isolated by culture, the results were confirmed by the United States Centers for Disease Control and Prevention (US CDC) to be Corynebacterium diphtheriae biovar mitis, toxigenic (producer of diphtheria toxin by test Elek).
The diphtheria vaccination schedule in the Dominican Republic includes 3 doses for children under 1 year of age, and 2 boosters that are given at 18 months and 4 years old. Vaccination with the third diphtheria booster is not systematically performed.
The country has a national vaccination policy for health workers.
The country is not reaching the minimum target of 95% immunization coverage set in the regional immunization action plan for DTP3 for children under 1 year of age. DTP4 coverage is less than 90%.
In Haiti, between SE 32 of 2014 and SE 38 of 2021, a total of 1334 suspected cases of diphtheria were reported, including 147 deaths; among them, 406 cases were confirmed (391 by laboratory and 15 by epidemiological link) including 80 confirmed deaths (table 1, figure 2).
Between SE 1 and SE 38 of 2021, the number of suspected cases reported (164 cases) is similar to the number of cases reported during the same period in 2019 (165 cases) but higher than the number of suspected cases reported during from the same period in 2020 (110 cases). Of the 164 reported cases, 17 were laboratory confirmed and one case was epidemiologically confirmed; there have been 3 deaths among the confirmed cases. Due to the prolonged transmission of the disease, diphtheria is considered endemic in Haiti.
Between 2015 and 2021, the case fatality rates among confirmed cases were 23% in 2015, 39% in 2016, 8% in 2017, 13% in 2018, 22% in 2019, 23% in 2020 and 17% in 2021.
Between EW 1 and EW 38 of 2021, of the 18 confirmed cases, 55.5% occurred in the 6 to 14 age group and 27.7% in the 1 to 5 age group. Of the deaths, one occurred in the 6 to 14 age group and two in the 1 to 5 year age group.
Between SE 1 and SE 38 in 2021, the highest cumulative incidence rates of suspected cases were recorded in the municipalities of Thiotte (32 cases per 100,000 inhabitants) in the Sud-Est department; Terrier Rouge (20.1 cases per 100,000 inhabitants) and Carice (19.2 cases per 100,000 inhabitants) in the Nord-Est department; and Plaine du Nord (19.0 cases per 100,000 inhabitants) in the Nord department.