Outbreaks can happen in areas where people may be unvaccinated or under-vaccinated, including the United States. Right now, measles outbreaks are occurring in every region of the world. Measles can enter the United States through infected travelers entering or travelling through to the U. Although measles was declared eliminated in the United States in , almost 1, cases of measles were reported in 31 states in the U.
The U. Centers for Disease Control and Prevention CDC staff in Atlanta and around the world work with partners and ministries of health to prevent, detect, and stop global measles outbreaks. CDC provides technical support to countries and partners to:. CDC focuses on countries with large measles outbreaks and countries with weak health systems, low immunization rates or gaps in coverage that make it more likely for outbreaks to spread, cross borders and possibly enter the U.
Skip directly to site content Skip directly to page options Skip directly to A-Z link. Global Immunization. Comparisons were made with reference measles virus strains 4. Amino acid sequences were inferred. Sequences were aligned with ClustalX software, while phylogenetic analysis was performed by distance methods with Phylip software package v. Sequences derived from this study were submitted to GenBank. Mean age at SSPE onset was 54 months range 40—75 months , and the mean lag period was 48 months range 33—68 months.
Most patients six of eight resided in the greater Buenos Aires metropolitan area, one from the northeastern region and the other from the northwestern region. In particular, patient 4 at 6 months of age had a clinical diagnosis of measles in September during the outbreak. Six months later, the patient received Measles Mumps Rubella MMR vaccine according to the official immunization schedules.
For patient 5, clinical diagnosis of measles was made at 10 months of age in September during the outbreak. At that time, he also had varicella; 2 months later, the patient received the MMR vaccine. Patient 6 was born in November and had no previous history of measles infection.
She also received antimeasles vaccine at 6 months of age during the measles outbreak when the vaccination age was lowered. Figure 1. Replacement changes found in N and H genes from subacute sclerosing panencephalitis patients. Sample Buenos Aires. The nt from the carboxyl terminus of N gene and a bp segment from H gene from three SSPE cases were analyzed and amino acid sequences were inferred.
When compared to Edmonston strain, not only were a higher number of mutations found in N gene 36 vs. Fixed replacements were detected at position in H protein and at position in N protein. Variability was detected in both genes. Changes found in SSPE samples related to D6 genotype, and the consensus sequence from last Argentine outbreak are summarized in Figure 1.
Figure 2. Phylogenetic relationships of subacute sclerosing panencephalitis SSPE strains. The neighbor-joining unrooted tree was plotted with Treeview 1. Reference measles virus strains are described 2. Wild-type genotype C1 in Distance methods were applied, and the matrix rendered similar results for both analyzed genes.
The tree was built with measles virus genotype reference strains and Argentine strains previously characterized from and outbreaks.
SSPE samples were strongly associated with wild-type D6 samples from the outbreak, supported by a bootstrap value of out of pseudoreplicates done. The unrooted tree for the carboxyl terminus of N gene was plotted Figure 2.
The measles vaccine was included in the regular immunization schedule in Argentina in Despite vaccination, several disease outbreaks have occurred Although we had previously performed a thorough molecular description of acute measles outbreaks, genetic characterization of SSPE has not yet been reported in Argentina 9.
SSPE results in widespread destruction of brain tissue, including both gray and white matter. Infectious virus likely reaches the brain at the time of the original systemic spread of measles virus, where the virus becomes clonal, disseminating gradually throughout the nervous system from the point of entry High levels of antimeasles antibodies are found both in serum and CSF, and their relative titers in the two compartments indicate intrathecal synthesis of immunoglobulins.
Measles virus in SSPE is characterized by a low expression of viral envelope proteins as a result of mutational events. Among such proteins, H is an attachment protein that mediates binding to cells and contributes to cell-to-cell fusion. The VI mutation was one of the fixed changes that we had detected in the outbreak, but one of the SSPE cases SSPE5 had a nonconservative VS change at the same position from hydrophobic to polar without charge 9.
Although this fragment is a relatively small portion of the H gene, it contains a major antigenic surface determinant aa— , which may be relevant for neurovirulence, as well as three linear epitopes containing conserved cysteines , , and Molecular data from the Argentine outbreak showed that the virus belonged to the D6 genotype and that analyzed regions were highly homogeneous and almost identical to other D6 strains isolated in South America 9.
Accordingly, a single chain of transmission could be responsible for the spread of the genotype from European countries to Brazil and then to Argentina The last Argentine outbreak began in July in the northeastern region of the country, bordering on Brazil; had its peak in greater Buenos Aires metropolitan area in July ; and ended in the northwestern region bordering on Bolivia in May Children in whom SSPE developed were born during the last measles outbreak and reached 6 months of age when the outbreak was at its peak.
Time lag between acute and SSPE onset was approximately 4 years, according to the reported data, but the rate for developing SSPE was higher than previously described 8. Phylogenetic analysis of three SSPE cases from the last outbreak clustered with D6 genotype that circulated in Argentina in Although the original sequence of the wild-type virus that caused acute infection is unknown, we have a consensus sequence that summarizes the outbreak; therefore, we infer that changes may have occurred since then and contributed to the development of SSPE.
Although all three patients had been immunized according to the schedule, vaccinal strains were not detected in brain tissue.
Our data show that these three patients had been infected with wild-type circulating D6 virus before immunization. Origin of measles virus: divergence from rinderpest virus between the 11th and 12th centuries. Virology Journal. Molecular mechanisms of measles virus persistence. Virus research.
Contemporary infectious exanthems. Clinical infectious diseases : an official publication of the Infectious Diseases Society of America. Marmoset lymphoblastoid cells as a sensitive host for isolation of measles virus. Journal of virology. The Journal of general virology. Sequence divergence of measles virus haemagglutinin during natural evolution and adaptation to cell culture. Journal of medical virology. Journal of Virology. Measles in Europe: an epidemiological assessment.
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