Clinical and molecular epidemiology of the current Venezuelan diphtheria epidemic. A hospital-based experience

Abstract

Purpose: Since July 2016, Venezuela has experienced a large diphtheria outbreak with over 1,710 accumulated cases (1,086 of them confirmed), and 160 deaths, as of May 2018. Available clinical and epidemiological information is very limited. Response to this emergency has been hampered by a profound ongoing healthcare crisis Methods & Materials: In cooperation with the Bernhard-Nocht Institute for Tropical Medicine in Hamburg and the Instituto Carlos III in Spain, a multicenter network of medical professionals from various regions of the country with disease activity was recently assembled, in order to accomplish a prospective, observational investigation, aimed to describe the clinical and molecular epidemiologic patterns of hospitalized cases and their direct family contacts Results: Until now, 37 suspected or confirmed diphtheria patients and 10 close contacts have been followed (37% males, 63% females). Mean age of onset was 17 years, median 11 years (age range: 1 to 66 years). The most frequent location of lesions was pharyngeal-tonsillar combinated (35,1%); however, other location such as tonsillar (29,7%), pharyngeal (21,6%) laryngotracheal (10,8%) and nasal (2,7%) were also observed. All patients received antibiotics, but only 67% of them diphtheric antitoxin. Delay in antitoxin administration was the rule (average: 2.4 days). Only 23% of the patients had a complete basic diphtheria immunization schedule and 36% of them developed clinical complications. Overall the case fatality rate (CFR) was 16,21%. Three bacterial isolates were characterized as toxigenic C. diphtheria biotype mitis, multilocus sequence type ST 174 Conclusion: The diphtheria outbreak in Venezuela remains active, reflecting the inadequacy of the strategies of outbreak contention implemented. The high CFR observed in this series may be related to the delay in antitoxin administration and the use of suboptimal doses. The marked predominance of adolescents and adults suggests the need of vaccine boosters doses among the non-pediatric population. Available data indicates that the ST 174 sequence identified has not been circulating in the region in recent years.