Imported Genotype 2B Rubella Virus Caused the 2012 Outbreak in Anqing City, China

<div><p>A rubella outbreak occurred in Anqing city of Anhui province, China, from February to July of 2012, and a total of 241 clinically diagnosed or lab-confirmed patients were reported. The highest number of rubella cases during this outbreak was recorded in teenagers between 10 and 19 years of age who had not previously received the rubella vaccine. Genotyping results indicated that the genotype 2B rubella virus (RV) was responsible for the outbreak. However, a phylogenetic analysis showed that the genotype 2B RVs isolated in Anqing City were not related to 2B RVs found in other cities of Anhui province and in other provinces of China, thus providing evidence for importation. After importation, the transmission of Anqing RVs was interrupted owing to an effective immunization campaign against rubella, suggesting the timeliness and effectiveness of contingency vaccination. Strengthening rubella surveillance, including the integration of epidemiologic information and laboratory data, is a vital strategy for rubella control and elimination. In addition, except for routine immunization, targeted supplementary immunization activities aimed at susceptible groups according to sero-epidemiological surveillance data also play a key role in stopping the continuous transmission of rubella viruses and in preventing further congenital rubella syndrome cases.</p></div

The geographic distribution of rubella cases in Anqing City, Anhui province, China.

<p>The geographic distribution of rubella cases in Anqing City, Anhui province, China.</p

Phylogenetic analysis of the sequences of 27 RVs from the outbreak in Anqing city (shown in red), 14 domestic genotype 2B RVs (2000–2014) (shown in blue), and 50 international genotype 2B RVs (1968–2014) downloaded from the GenBank database based on the WHO standard 739-nt window.

<p>Phylogenetic analysis of the sequences of 27 RVs from the outbreak in Anqing city (shown in red), 14 domestic genotype 2B RVs (2000–2014) (shown in blue), and 50 international genotype 2B RVs (1968–2014) downloaded from the GenBank database based on the WHO standard 739-nt window.</p

Phylogenetic analysis of 27 rubella virus (RV) sequences from the outbreak in Anqing city and 13 RVs from other cities in Anhui province in 2012, as well as the World Health Organization (WHO) reference sequences based on the WHO standard 739-nt window.

<p>The 32 WHO reference strains are indicated by blue triangles. The viruses from other cities are indicated by bold italic font. The viruses from 6 counties, 3 districts, and 1 county-level city of Anqing outbreak are indicated by different colors; and the first case of the outbreak is indicated by a red circle.</p

Phylogenetic analysis of the sequences of 27 Anqing RVs (shown in red), 10 RVs collected in 5 cities of Anhui province between 2012 and 2014 (shown in blue), and 11 2B RVs from other provinces of China during 2011–2014 based on the WHO standard 739-nt window.

<p>Genotype 1E and 2B WHO reference strains are indicated by blue triangles.</p

Number of reported rubella cases by age group.

<p>Number of reported rubella cases by age group.</p