Vertically transmitted infection
|Vertically transmitted infection|
|Classification and external resources|
A vertically transmitted infection is an infection caused by bacteria, viruses, or in rare cases, parasites transmitted directly from the mother to an embryo, fetus, or baby during pregnancy or childbirth. It can occur when the mother gets an infection as an intercurrent disease in pregnancy. Nutritional deficiencies may exacerbate the risks of perinatal infection.
The transmission can also be called mother-to-child transmission. A vertically transmitted infection can be called a perinatal infection if it is transmitted in the perinatal period, which is the period starting at a gestational age of 22 weeks to 28 (with regional variations in the definition) and ending seven completed days after birth.
The term congenital infection can be used if the vertically transmitted infection persists after childbirth.
Several vertically transmitted infections are included in the TORCH complex, which stands for:
- T – Toxoplasmosis / Toxoplasma gondii
- O – Other infections (see below)
- R – Rubella
- C – Cytomegalovirus
- H – Herpes simplex virus-2 or neonatal herpes simplex
The "other agents" under O include:
- Chickenpox (caused by varicella zoster virus)
Further information: HIV and pregnancy
- Human T-lymphotropic virus
Hepatitis B may also be classified as a vertically transmitted infection, but the hepatitis B virus is a large virus and does not cross the placenta, hence it cannot infect the fetus unless breaks in the maternal-fetal barrier have occurred, such as can occur in bleeding during childbirth or amniocentesis.
The TORCH complex was originally considered to consist of the four conditions mentioned above, with the "TO" referring to Toxoplasma. The four-term form is still used in many modern references, and the capitalization "ToRCH" is sometimes used in these contexts. The acronym has also been listed as TORCHES, for TOxoplasmosis, Rubella, Cytomegalovirus, HErpes simplex, and Syphilis.
A further expansion of this acronym, CHEAPTORCHES, was proposed by Ford-Jones and Kellner in 1995:
- C – Chickenpox and shingles
- H – Hepatitis B, C, (D), E
- E – Enteroviruses
- A – AIDS (HIV infection)
- P – Parvovirus B19 (produces Hydrops faetalis, but it is NOT teratogenic)
- T – Toxoplasmosis
- O – Other (Group B Streptococcus, Listeria, Candida, Lyme disease)
- R – Rubella
- C – Cytomegalovirus
- H – Herpes simplex
- E – Everything else sexually transmitted (gonorrhea, Chlamydia infection, Ureaplasma urealyticum, human papillomavirus)
- S – Syphilis
Signs and symptoms
The signs and symptoms of a vertically transmitted infection depend on the individual pathogen. It may cause subtle signs such as a influenza-like illness and may not even be noticed by the mother during the pregnancy. In such cases, the effects may be seen first at birth.
Symptoms of a vertically transmitted infection may include fever and poor feeding. The newborn is often small for gestational age. A petechial rash on the skin may be present, with small reddish or purplish spots due to bleeding from capillaries under the skin. An enlarged liver and spleen (hepatosplenomegaly) is common, as is jaundice. However, jaundice is less common in hepatitis B because a newborn's immune system is not developed well enough to mount a response against liver cells, as would normally be the cause of jaundice in an older child or adult. Hearing impairment, eye problems, mental retardation, autism, and death can be caused by vertically transmitted infections. The mother often has a mild infection with few or no symptoms.
The embryo and fetus have little or no immune function. They depend on the immune function of their mother. Several pathogens can cross the placenta and cause (perinatal) infection. Often, microorganisms that produce minor illness in the mother are very dangerous for the developing embryo or fetus. This can result in spontaneous abortion or major developmental disorders. For many infections, the baby is more at risk at particular stages of pregnancy. Problems related to perinatal infection are not always directly noticeable.
Babies can also become infected by their mothers during birth. Some infectious agents may be transmitted to the embryo or fetus in the uterus, while passing through the birth canal, or even shortly after birth. The distinction is important because when transmission is primarily during or after birth, medical intervention can help prevent infections in the infant.
During birth, babies are exposed to maternal blood and body fluids without the placental barrier intervening and to the maternal genital tract. Because of this, blood-borne microorganisms (hepatitis B, HIV), organisms associated with sexually transmitted disease (e.g., Neisseria gonorrhoeae and Chlamydia trachomatis), and normal fauna of the genitourinary tract (e.g., Candida albicans) are among those commonly seen in infection of newborns.
Virulence versus symbiosis
In the spectrum of optimal virulence, vertical transmission tends to evolve benign symbiosis. It is, therefore, a critical concept for evolutionary medicine. Because a pathogen's ability to pass from parent to child depends significantly on the hosts' ability to reproduce, pathogens' transmissibility tends to be inversely related with their virulence. In other words, as pathogens become more harmful to, and thus decrease the reproduction rate of, their host organism, they are less likely to be passed on to the hosts' offspring, since they will have fewer offspring.
Although AIDS is sometimes transmitted through perinatal transmission, its virulence can be accounted for because its primary mode of transmission is not vertical. Moreover, medicine has further decreased the frequency of vertical transmission of AIDS. The incidence of perinatal AIDS cases in the United States has declined as a result of the implementation of recommendations on HIV counselling and voluntary testing practices and the use of zidovudine therapy by providers to reduce perinatal HIV transmission.
The price paid in the evolution of symbiosis is, however, great: for many generations, almost all cases of vertical transmission will continue to be pathological—in particular if any other routes of transmission exist. Many generations of random mutation and selection are needed to evolve symbiosis. During this time, the vast majority of vertical transmission cases exhibit the initial virulence.
When physical examination of the newborn shows signs of a vertically transmitted infection, the examiner may test blood, urine, and spinal fluid for evidence of the infections listed above. Diagnosis can be confirmed by culture of one of the specific pathogens or by increased levels of IgM against the pathogen.
Treatment and prevention
Some vertically transmitted infections, such as toxoplasmosis and syphilis, can be effectively treated with antibiotics if the mother is diagnosed early in her pregnancy. Many viral vertically transmitted infections have no effective treatment, but some, notably rubella and varicella-zoster, can be prevented by vaccinating the mother prior to pregnancy.
IgG2 antibody may play crucial role in prevention of intrauterine infections and extensive research is going on for developing IgG2-based therapies for treatment and vaccination.
Each type of vertically transmitted infection has a different prognosis. The stage of the pregnancy at the time of infection also can change the effect on the newborn.
- Goldenberg RL (May 2003). "The plausibility of micronutrient deficiency in relationship to perinatal infection". J. Nutr. 133 (5 Suppl 2): 1645S–1648S. PMID 12730479.
- Definitions and Indicators in Family Planning. Maternal & Child Health and Reproductive Health. By European Regional Office, World Health Organization. Revised March 1999 & January 2001. In turn citing: WHO Geneva, WHA20.19, WHA43.27, Article 23
- Singh, Meharban (2010). Care of the Newborn. p. 7. Edition 7. ISBN 9788170820536
- Yu J, Wu S, Li F, Hu L (January 2009). "Vertical transmission of Chlamydia trachomatis in Chongqing China". Curr Microbiol. 58 (4): 315–320. doi:10.1007/s00284-008-9331-5. PMID 19123031.
- K E Ugen, J J Goedert, J Boyer, Y Refaeli, I Frank, W V Williams, A Willoughby, S Landesman, H Mendez, A Rubinstein (June 1992). "Vertical transmission of human immunodeficiency virus (HIV) infection. Reactivity of maternal sera with glycoprotein 120 and 41 peptides from HIV type 1". J Clin Invest 89 (6): 1923–1930. doi:10.1172/JCI115798. PMC 295892. PMID 1601999.
- Fawzi WW, Msamanga G, Hunter D, Urassa E, Renjifo B, Mwakagile D, Hertzmark E, Coley J, Garland M, Kapiga S, Antelman G, Essex M, Spiegelman D (1999). "Randomized trial of vitamin supplements in relation to vertical transmission of HIV-1 in Tanzania". Journal of Acquired Immune Deficiency Syndromes 23 (3): 246–254. PMID 10839660.
- Hisada M, Maloney EM, Sawada T, Miley WJ, Palmer P, Hanchard B, Goedert JJ, Manns A. (2002). "Virus markers associated with vertical transmission of human T lymphotropic virus type 1 in Jamaica". Clin Infect Dis. 34 (12): 1551–1557. doi:10.1086/340537. PMID 12032888.
- Lee MJ, Hallmark RJ, Frenkel LM, Del Priore G (1998). "Maternal syphilis and vertical perinatal transmission of human immunodeficiency virus type-1 infection". International Journal of Gynaecology and Obstetrics: the Official Organ of the International Federation of Gynaecology and Obstetrics 63 (3): 246–254. doi:10.1016/S0020-7292(98)00165-9. PMID 9989893.
- Hepatitis B by World Health Organization (WHO), retrieved November, 2011
- Kinney JS, Kumar ML (December 1988). "Should we expand the TORCH complex? A description of clinical and diagnostic aspects of selected old and new agents". Clin Perinatol 15 (4): 727–44. PMID 2850128.
- Abdel-Fattah SA, Bhat A, Illanes S, Bartha JL, Carrington D (November 2005). "TORCH test for fetal medicine indications: only CMV is necessary in the United Kingdom". Prenat. Diagn. 25 (11): 1028–31. doi:10.1002/pd.1242. PMID 16231309.
- Li D, Yang H, Zhang WH, et al. (2006). "A simple parallel analytical method of prenatal screening". Gynecol. Obstet. Invest. 62 (4): 220–5. doi:10.1159/000094092. PMID 16791006.
- Ford-Jones, E. L.; Kellner, J. D. (1995). ""Cheap torches": An acronym for congenital and perinatal infections". The Pediatric infectious disease journal 14 (7): 638–640. doi:10.1097/00006454-199507000-00028. PMID 7567307.
- Knoblauch H, Tennstedt C, Brueck W, et al. (July 2003). "Two brothers with findings resembling congenital intrauterine infection-like syndrome (pseudo-TORCH syndrome)". Am. J. Med. Genet. A 120A (2): 261–5. doi:10.1002/ajmg.a.20138. PMID 12833411.
- Vivarelli R, Grosso S, Cioni M, et al. (March 2001). "Pseudo-TORCH syndrome or Baraitser-Reardon syndrome: diagnostic criteria". Brain Dev. 23 (1): 18–23. doi:10.1016/S0387-7604(00)00188-1. PMID 11226724.
- Stewart, AD; Logsdon, JM; Kelley, SE (April 2005). "An empirical study of the evolution of virulence under both horizontal and vertical transmission". Evolution 59 (4): 730–739. doi:10.1554/03-330. PMID 15926685.
- Joo E, Carmack A, Garcia-Buñuel E, Kelly CJ (February 2000). "Implementation of guidelines for HIV counselling and voluntary HIV testing of pregnant women". Am J Public Health 90 (2): 273–6. doi:10.2105/AJPH.90.2.273. PMC 1446152. PMID 10667191.
- Cavalli-Sforza, Luigi Luca; Feldman, Marcus W. (1981). Cultural Transmission and Evolution: A Quantitative Approach. (Mpb-16). Princeton University Press. ISBN 978-0-691-08283-7.
- Syal K and Karande AA. IgG2 Subclass Isotype Antibody and Intrauterine Infections. Current Science Vol. 102, No. 11, 10 June 2012.