There are several ways of penetrating the infection to the fetus. The most frequent is the diaplacental pathway. In a typical form, he studied Reiss and Mestwerdt, who were referring to infection of the fetus with listeriosis.
Schultz lists the causative agents of infectious diseases that have the ability to penetrate the placental barrier. It lists the viruses of rubella, poliomyelitis, mumps, smallpox, measles, chicken pox, herpes, flu, rabies and infectious jaundice. Bacteria penetrate through the placenta cocci( streptococci, staphylococci, pneumococci, gonococci), gram-negative rods of typhoid, paratyphoid, Maltese fever, sapa, tularemia, gram-positive rods of tuberculosis, listeriosis, leprosy, diphtheria( toxin), spore-forming bacteria of anthrax, tetanus), spirochetes of syphilis, recurrent typhus, Vasiliev-Weil disease. Among the simplest microorganisms mention flagellate parasites that cause disease leishmaniasis and trypanosomiasis( Chagas disease), and a variety of protozoa that are the ca
use of toxoplasmosis and malaria. Finally, among the parasites of animals that can penetrate the placenta include fluke, echinococcosis, hookworm and ascarids.
In addition to such a direct route, infection to the fetus can penetrate due to primary infection of amniotic fluid. Infection can occur in a variety of ways:
1. Ascending: a) from the birth canal in case of damage to the amniotic membranes. It was established that the amniotic fluid, even after a slight violation of the integrity of the fetal bladder, is infected in 50% of the women after 6 hours and in the rest after 24 hours;b) by entering the infection through the birth canal when attempting to abort the pregnancy, as well as through an instrumental route;by introducing an infection during sexual intercourse.
2. A downward path: a) direct infection of the amniotic fluid from the mother through the syncytium and villi of the chorion. As Dellepianae notes, the penetration of microbes to the fetus through the infected placenta and the membrane can occur when there was a certain concentration in the uterus beforehand. It is also possible to form foci of infection both in the placenta itself, in its villi;b) from the abdominal cavity through the fallopian tubes.
Of the amniotic fluid to the fetus, the infection can in turn come in several ways: a) through the gastrointestinal tract due to swallowing the fetal amniotic fluid;b) through the respiratory tract of the fetus, causing changes in the bronchi and bronchioles. Clinical and roentgenological studies have shown the ability of the intrauterine fetus from early pregnancy to aspirate the amniotic fluid( as well as swallow it).In the human fetus, this was shown by Davis and Potter;c) through the skin of the fetus;d) by penetrating into the bloodstream of the fetus through the injured amniotic membranes and vessel walls located on the surface of the placenta and umbilical cord. Grasso, citing the Morison scheme, which explains the pathways of infection to the fetus, notes that initially it can accumulate in the umbilical cord, and then through the umbilical vessels spread to the intrauterine
In addition to the above options, infection of the fetus can occur during the birth of the act during the passage of the child through the birth canal.
The possibility of contracting the fetus germinatively, that is, due to infection of the egg cell or sperm cells, is being rejected.
Thus, it is not difficult to see that the pathways of infection to the fetus are very different. They can also be combined with each other. A number of factors that can influence the penetration of infection from the mother to the fetus and the nature of the damage inflicted to it( type of infection and severity, duration of pregnancy and some others) are established.
It should be noted that damage to the fetus can occur not only as a result of the influence of the pathogen itself or its toxins, but also as a result of the adverse effect on it of fever and disrupted in the mother due to this or that infectious disease of metabolism.
In rickettsial and viral infections, unlike bacterial infections, pathogenicity is only marginally determined by toxins, soluble antigens or released enzymes, and is mainly associated with disorders caused by the presence and multiplication of rickettsias and viruses in the host cell.
Read more Nature of fetal damage in prenatal infections