Գլխավոր Հիվանդություններ Vertically transmitted infection

A vertically transmitted infection (or mother-to-child transmission) 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. Classification 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. Examples Bacteria, viruses, and other organisms are able to be passed from mother to child. 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: Coxsackievirus Chickenpox (caused by varicella zoster virus) Chlamydia HIV Further information: HIV and pregnancy Human T-lymphotropic virus Syphilis Zika fever, caused by Zika virus, can cause microcephaly and other brain defects in the child. 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,[10] 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, C (D), E E – Enteroviruses A – AIDS (HIV infection) P – Parvovirus B19 (produces Hydrops faetalis secondary to aplastic anemia) 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 genetic conditions of Aicardi-Goutieres syndrome are possibly present in a similar manner.

Routes The main routes of transmission of vertically transmitted infections are across the placenta (transplacental) and across the female reproductive tract during childbirth. Transplacental 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. During childbirth 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, body fluids, and to the maternal genital tract without the placental barrier intervening. 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. Pathophysiology 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. In dual inheritance theory, vertical transmission refers to the passing of cultural traits from parents to children. Diagnosis 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.

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