Abnormal Development - Rubella Virus

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Introduction

Rubella Virus, transmission electron micrograph (Image: CDC USA)

Rubella virus (Latin, rubella = little red), also known as "German Measles" (due to early citation in German medical literature), infection during pregnancy can cause congenital rubella syndrome (CRS) with serious malformations of the developing fetus. The type and degree of abnormality relates to the time of maternal infection.

Rubella peaked in 1964 and 1965, when 12.5 million cases were reported (USA). As a result, 20,000 babies were born with birth defects, 6,200 babies were stillborn, and an estimated 5,000 births were aborted, both naturally and assisted. At that time no treatment by vaccination existed and this only became available in 1969. The disease was dangerous because in children it was almost unnoticable and pregnant women often did not know that they had been exposed.

Children infected with rubella before birth (a condition known as congenital rubella) are at risk for the following: growth retardation; malformations of the heart, eyes, or brain; deafness; and liver, spleen, and bone marrow problems.

The complete genomic sequence (Dominguez etal., 1990) of Rubella is now known. Rubella is a 9755 bp single stranded RNA positive-strand virus with no DNA stage (Togaviridae; Rubivirus) encoding nonstructural protein, capsid protein, glycoproteins E1 and E2. (More? Genome)

Some Recent Findings

Controlling rubella and preventing congenital rubella syndrome – global progress, 2009 "In 2009, a total of 121,344 rubella cases were reported to WHO from 167 countries, a 82% decrease from 2000" An update on cardiovascular malformations in congenital rubella syndrome (CRS) "We searched the English literature from 1941 through 2008 to identify studies that used cardiac catheterization or echocardiography to evaluate the cardiovascular malformations in CRS. Although published studies of CVMs in CRS have in general reported patent ductus arteriosus (PDA) as the CVM phenotype most commonly associated with CRS, among CRS cases evaluated by catheterization, branch pulmonary artery stenosis was actually more common than PDA. Moreover, although the combination of branch pulmonary artery stenosis and PDA was more common than either branch pulmonary artery stenosis or PDA alone, isolated branch pulmonary artery stenosis was twice as common as isolated PDA. ...Among children with suspected CRS, clinical evaluations for the presence of cardiovascular malformations should include examinations for both branch pulmonary artery stenosis and PDA."

WHO Rubella Information

• Causative agent - Virus
• Reservoir - Humans
• Spread - Close respiratory contact and aerosolized droplets
• Transmission period - A few days before to seven days after rash; up to one year of age in congenitally infected
• Subclinical infection - Common
• Duration of natural immunity - Lifelong
• Risk factors for infection (for unvaccinated individuals) - Highly transmissible; crowding; low socioeconomic status
• Case-fatality rate - Less than 0.1 percent (dependent on care)
• Vaccine (number of doses); route - Rubella (one or two); subcutaneous
• Vaccine efficacy - 95 percent (at 12 months and up)
• Duration of immunity after primary series - Lifelong in most; presumed rare cases of waning immunity after one dose, not two
• Schedule - First dose at 12 to 15 months; when given, a second dose with measles vaccine
• Status as of the end of 2001 - 110 countries in 2003
• Comments - Lower efficacy when maternal antibody present

The World Health Organization recommends that the combination measles-rubella or measles-mumps-rubella vaccines be introduced only after careful evaluation of public health priorities within each country and following the establishment of an adequate program for measles control as demonstrated by high coverage rates as part of a well-functioning childhood immunization program.

Sources: WHO 2002, 2004.

Congenital Rubella Syndrome Abnormalities

The following are some examples of abnormalities associated with Congenital Rubella Syndrome (CRS).

Vision

• cataracts
• micropthalmia
• glaucoma
• retinitis

Hearing

• sensorineural deafness

Neural

• mental retardation
• meningoencephalitis
• (rare) progressive rubella panencephalitis
• microcephaly

Cardiovascular

• patent ductus arteriosis
• atrial septal defect
• ventricular septal defect
• peripheral pulmonic stenosis

Endocrine

• insulin dependent diabetes mellitus
• thyroiditis

Other Systems

• general growth retardation
• radiolucent bone disease
• heptosplenomegaly
• heamatologic abnormalities (thrombocytopenia, purpura)
• pneumonitis

References

Textbooks

• Medical Microbiology. 4th edition. Baron S, editor. Galveston (TX): University of Texas Medical Branch at Galveston; 1996. Chapter 55 Togaviruses: Rubella Virus | Chapter 54Alphaviruses (Togaviridae) and Flaviviruses (Flaviviridae) | Table 55-1 Abnormalities Associated with Congenital Rubella Syndrome | Figure 55-3 Incidence rates of rubella USA 1966-1993
• Molecular Biology of the Cell. 4th edition. Alberts B, Johnson A, Lewis J, et al. New York: Garland Science; 2002. Viruses Exploit Host Cell Machinery for All Aspects of Their Multiplication
• Disease Control Priorities in Developing Countries. 2nd edition. Jamison DT, Breman JG, Measham AR, et al., editors. Washington (DC): World Bank; 2006. Chapter 20Vaccine-preventable Diseases
• Antenatal Care: Routine care for the healthy pregnant woman. NICE Clinical Guidelines, No. 62. National Collaborating Centre for Women's and Children's Health (UK). London: RCOG Press; 2008 Mar. 10.8. Rubella

Reviews

<pubmed>16580940</pubmed> <pubmed>12944671</pubmed>

Articles

21108356 21116802 20861325 <pubmed>20655079</pubmed>

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Cite this page: Hill, M.A. (2024, May 3) Embryology Abnormal Development - Rubella Virus. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Abnormal_Development_-_Rubella_Virus

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© Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G