Vertical transmission

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Vertical transmission (also called mother-to-child transmission, or MTCT) means that an infection is spread from a mother to her fetus during pregnancy or childbirth. Vertically transmitted infections are usually caused by bacteria or viruses.

If the baby still has the infection after he or she is born, the infection may be called a congenital infection.

Examples[change | change source]

Here are some examples of infections that can be vertically transmitted.

Sexually transmitted infections[change | change source]

Many (but not all) sexually transmitted infections (STIs) can be vertically transmitted. STIs that can be spread from mother to fetus include:

Hepatitis[change | change source]

Almost every type of hepatitis can be vertically transmitted. Hepatitis C, D, and E can be spread during pregnancy or childbirth.[6]

Hepatitis B cannot be spread during pregnancy. However, it can be spread during childbirth if the infant touches its mother's blood or other body fluids.[7]

Group B streptococcal infection[change | change source]

In developed countries, Group B streptococcal infection is the most common cause of bacterial infections in newborns. It can cause infections that are very dangerous to newborns, like meningitis, septicaemia, and pneumonia. These infections can kill a newborn or cause serious long-term health problems.[8][9]

Other examples[change | change source]

An infant with skin problems caused by congenital rubella
A baby with microcephaly (left) compared to a baby with a typical head size. Zika fever seems to cause microcephaly in fetuses

How these infections spread[change | change source]

There are two main ways that infections can be spread during pregnancy or childbirth.

Through the placenta[change | change source]

Diagram of the placenta

The placenta surrounds and protects the fetus during pregnancy. It keeps the mother's blood from mixing with the fetus's. However, some infections can cross the placenta and infect the fetus.[3] This is called perinatal infection.

These infections are especially dangerous because they affect the fetus while it is still developing. This is why many vertically transmitted infections are most dangerous to the fetus early on in a pregnancy. All of the fetus's important organs start to grow by the time the fetus is nine weeks old, and they grow the most early on in the pregnancy.[17] If the fetus gets an infection while important parts of its body are developing, the infection can cause problems in the way those parts of the body grow.

These infections are also dangerous because a fetus does not have an immune system of its own. It depends on its mother's immune system. If the mother has an infection that has not been treated, and her immune system cannot fight off the infection, the fetus will not be able to fight off the infection either.[18]

During childbirth[change | change source]

During pregnancy, the placenta protects the fetus from its mother's blood. However, during childbirth, the placenta stays in the womb while the baby travels through the birth canal. While it is being born, the mother's blood and other body fluids get on the baby, and the baby also touches its mother's genitals. Because of this, infections that are carried in the blood, in body fluids, or in sores on the mother's genitals can infect the baby.[3]

Infections are usually more dangerous for newborns and infants than for adults. This is because it takes about six months for an infant's immune system to develop completely.[18] Until the infant's immune system is fully grown, it will not be able to fight off infections as well as an adult could.

Sometimes, medical treatment, like antibiotics, can prevent a baby from getting infections that spread during childbirth.[19]

Prevention[change | change source]

Some vertically transmitted infections can be prevented if the mother gets vaccines before getting pregnant. These infections include HPV, chickenpox, measles, and rubella.[13] However, while these vaccines are common in developed countries, many people in developing countries do not have good medical care and cannot get vaccines.

Other vertically transmitted infections, like syphilis, can be cured with antibiotics before the mother gets pregnant.[2]

Sexually transmitted infections can often be prevented by having safer sex.

Vaccination can prevent many vertically transmitted infections. This woman is getting vaccinated for rubella (Brazil, 2008)

The United States Centers for Disease Control and Prevention (CDC) suggests these ways of preventing vertically transmitted infections:[20][21]

  • Before getting pregnant, a woman should get tested for chlamydia, gonorrhea, HIV, and other sexually transmitted infections
  • A woman's doctor should teach her how to eat safely to prevent getting listeriosis or toxoplasmosis
  • To avoid getting toxoplasmosis, pregnant women should not clean cat litter boxes and should wear gloves when gardening (the parasite that causes toxoplasmosis can be spread through cat feces)

The World Health Organization says that mothers with HIV can lower their baby's risk of getting vertically transmitted HIV to 2% if:[1]

  • The mother takes HIV medications during pregnancy
  • The infant gets HIV medications for 4-6 weeks after being born
  • The mother does not breastfeed her baby (HIV can spread through breast milk)

Related pages[change | change source]

References[change | change source]

  1. 1.0 1.1 Shaffer, Nathan (2010) WHO 2010 Revised Recommendations: Use of Antiretroviral Drugs for Treating Pregnant Women and Preventing HIV Infection in Infants (PMTCT ARV Guidelines) . World Health Organization, 4-9. Report. Retrieved on February 10, 2016.
  2. 2.0 2.1 Berman SM 2004. "Maternal and Congenital Syphilis: Pathophysiology and treatment of maternal syphilis". Bulletin of the World Health Organization (World Health Organization) 82 (6): 433-438. http://www.who.int/bulletin/volumes/82/6/433.pdf. Retrieved February 10, 2016. 
  3. 3.0 3.1 3.2 3.3 3.4 "STDs during Pregnancy – CDC Fact Sheet". CDC.gov. United States Centers for Disease Control and Prevention. February 3, 2016. Retrieved February 9, 2016. 
  4. Kimberlin DW 2007. "Herpes simplex virus infections of the newborn". Seminars in Perinatology 31 (1): 19–25. doi:10.1053/j.semperi.2007.01.003. PMID 17317423. 
  5. Sinal SH; Woods CR 2005. "Human papillomavirus infections of the genital and respiratory tracts in young children". Seminars in Pediatric Infectious Diseases 16 (4): 306–16. doi:10.1053/j.spid.2005.06.010. PMID 16210110. 
  6. Tosone G; Maraolo AE; et al. 2014. "Vertical hepatitis C virus transmission: Main questions and answers". World Journal of Hepatology 6 (8): 538–548. doi:10.4254/wjh.v6.i8.538. PMC 4163737. PMID 25232447. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4163737/#__ffn_sectitle. 
  7. "Hepatitis B". WHO.int. World Health Organization. Retrieved February 10, 2016. 
  8. Libster R; Edwards KM; et al. 2012. "Long-term outcomes of group B streptococcal meningitis". Pediatrics 130: e8-15. http://pediatrics.aappublications.org/content/pediatrics/130/1/e8.full.pdf. 
  9. M.S. Edwards; V. Nizet (2011). Infectious Diseases of the Fetus and Newborn Infant chapter=Group B Streptococcal Infections (7th ed.). Elsevier. pp. 419–469. ISBN 978-0-443-06839-3. 
  10. Torgerson PR; Mastroiacovo P 2013. "The global burden of congenital toxoplasmosis: a systematic review". Bulletin of the World Health Organization 91 (7): 501–508. doi:10.2471/BLT.12.111732. ISSN 0042-9686. PMID 23825877. 
  11. Boussault P; Boralevi F; et al. 2007. "Chronic varicella-zoster skin infection complicating the congenital varicella syndrome". Pediatr Dermatol 24 (4): 429–32. doi:10.1111/j.1525-1470.2007.00471.x. PMID 17845179. http://www3.interscience.wiley.com/resolve/openurl?genre=article&sid=nlm:pubmed&issn=0736-8046&date=2007&volume=24&issue=4&spage=429. 
  12. Ohji G; Satoh H; et al. 2009. "Congenital measles caused by transplacental infection". Pediatric Infectious Diseases Journal (28) 2 (166-7). doi:10.1097/INF.0b013e31818a5d83. 
  13. 13.0 13.1 McLean, Huong; Redd, Susan; et al. (April 1, 2014). "Chapter 15: Congenital Rubella Syndrome. In "Manual for Surveillance of Vaccine-Preventable Diseases"". CDC.gov. United States Centers for Disease Control and Prevention. Retrieved February 10, 2016. 
  14. Janakiraman V 2008. "Listeriosis in Pregnancy: Diagnosis, Treatment, and Prevention". Reviews in Obstetrics and Gynecology 1 (4): 179-185. PMID PMC2621056. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2621056/. Retrieved February 10, 2016. 
  15. Wiwanitkit V 2010 (January). "Unusual mode of transmission of dengue". Journal of Infection in Developing Countries 4 (1): 51–4. PMID 20130380. http://www.jidc.org/index.php/journal/article/view/20130380. 
  16. Peterson, Emily E.; Staples, Erin S.; et al. (January 22, 2016). "Interim Guidelines for Pregnant Women During a Zika Virus Outbreak — United States, 2016". www.cdc.gov/mmwr. MMWR Early Release on the MMWR website. pp. 30–33. 
  17. Storck, Susan (September 30, 2013). "Fetal Development". MedlinePlus. United States National Library of Medicine. Retrieved February 10, 2016. 
  18. 18.0 18.1 M’Rabet L; Vos AP; et al. 2008. "Breast-Feeding and its Role in Early Development of the Immune System in Infants: Consequences for Health Later in Life". The Journal of Nutrition (American Society for Nutrition) 138 (9): 17825-17905. http://jn.nutrition.org/content/138/9/1782S.short. Retrieved February 2, 2016. 
  19. "Transmission and Risk Factors". CDC.gov. United States Centers for Disease Control. June 1, 2014. Retrieved February 10, 2016. 
  20. "Preconception Health and Health Care: Infectious Disease". CDC.gov. United States Centers for Disease Control and Prevention. September 3, 2014. Retrieved February 10, 2016. 
  21. "Parasites – Toxoplasmosis (Toxoplasma infection)". CDC.gov. United States Centers for Disease Control and Prevention. January 10, 2013. Retrieved February 10, 2016.