engleski

15 years of molecular epidemiology of measles virus in Croatia

Measles is a highly contagious systemic viral disease transmitted by respiratory secretions. It is characterized by fever, coryza, cough and conjunctivitis, followed by a generalized maculopapular rash and transient immune deficiency. Complications of measles infection related to respiratory tract and central nervous system occur relatively frequently. One of the most serious consequences of measles infection is the onset of invariably fatal subacute sclerosing panencephalitis (SSPE), which develops years after recovery from primary illness. Among the vaccine- preventable diseases, measles is one of the most common causes of death in children under the age of 5. In Croatia, measles vaccination was introduced in the national childhood vaccination schedule in 1968 and was replaced by the combined measles, mumps and rubella (MMR) vaccine in 1976. Vaccine coverage rates for the first MMR dose are more than 94% since 2004. In the last two decades, usually less than 10 measles cases have been reported annually, with the exception of three import-related outbreaks (2003-2004, 2008 and 2014-2015). Genetic characterization of wild type and SSPE strains detected in Croatia is being performed since 2003. In-house RT-PCR methods for amplification and sequencing of complete measles genomes have been established ; genotyping based on N450 (450 nucleotides encoding for the last 150 amino acids of the N protein) is performed. In the period 2003-2017, 6 wild type and 3 SSPE strains have been detected, isolated and sequenced. Similar to contemporaneous epidemiological data from other European countries, strains detected in Croatia belong to genotypes D4, B3 and D8. Genetic characterization of the genuine Edmonston-Zagreb vaccine was also done. Sequencing of longer genomic regions lead to identification of different deviations from canonical measles virus genomic organisation, observed in few Croatian strains. Various indels, with or without the change of total genome length were detected, demonstrating evolutionary changes in viral genome properties.

measles virus ; molecular epidemiology ; genetic characterization

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