Congenital Infections: Toxoplasmosis and Rubella (The “T” and “R” of TORCH)

Congenital infections are infections from organisms (pathogens) that spread from the mother to the baby, either during fetal life, or during delivery. If the infection spreads to the fetus during pregnancy, this is called transplacental transmission, because it happens as a result of the pathogenic organism penetrating from the mother’s blood through the placenta. If the child receives the infection during delivery, this is called peripartum transmission. In many cases, congenital disease as a result of infections that in otherwise adults and children would be subclinical, meaning that they do not produce symptoms that are severe, or that show up as mild disease. In other cases, the pathogenic organism does cause serious disease in adults and children, but the effects of infection are even worse in fetuses and neonates (newborn infants). Today, we’ll look at two congenital infections: toxoplasmosis and rubella. To group congenital infections together, doctors use the acronym TORCH.

TORCH stands for several pathogenic organisms, and categories pathogens that cause congenenital disease, namely: Toxoplasmosis, Others (such as syphilis, listeriosis, varicella-zoster, parvovirus B19), Rubella, Cytomegalovirus (CMV), and Herpes simplex virus (HSV). Lets look more closely at some of these infections.

T for Toxoplasmosis: Toxoplasmosis is caused by an organism called Toxoplasma gondii. This is a protozoan, meaning that it consists of a single, complex cell that has some animal-like qualities. In healthy people, including pregnant women, infection with T. gondii typically is very mild. Typically, you would develop a flu-like illness with fever, body pains, and swollen lymph nodes, similar to mononucleosis, but with differences that can be seen in laboratory testing. Alternatively, the condition may not even noticeable, because the immune system keeps the infection in check. In contrast, in people who are immunocompromised, meaning that their immune systems are weak, toxoplasmosis can develop as a very severe disease.

During pregnancy, T. gondii is a potential danger, because you may have toxoplasmosis and not realize it. The main sources of infection come from cat litter and undercooked meat. In our culture, generally, cat litter is the number one risk for pregnant women, since people tend to be aware that eating undercooked meat puts you at risk for various other diseases, so they make sure to eat meat that is cooked adequately. However, if you fancy steak tartare, or especially pork tartare, this is something to avoid while pregnant. If you have a cat, you should avoid being around cat feces or litter. Leave it to others to change the litter.

As a congenital infection, toxoplasmosis produces what doctors call the “classic triad”: This means chorioretinitis (a type of eye infection), hydrocephalus (fluid in the head, causing an enlarged skull, and intracranial calcifications (calcium deposits in the brain and in layers surrounding it). Since T. gondii can cross the placenta, it can begin harming the baby early, so it can be one of the worse congenital infections. Neonates with this infection may suffer convulsions, due to the changes in the brain.

On the other hand, if T. gondii crosses the placenta later in pregnancy, the baby may not look sick at first, but may develop cataracts leading to blindness during childhood, or as late as teenage life.

Congenital rubella:  Caused by rubella virus, rubella is entirely preventable as there is a vaccine that women should have received prior to becoming pregnant. Indeed, the vaccine is given during childhood. In the past, rubella has been called “German measles” and also “3-day measles”. It causes fever, rash, join swelling, an lymph node swelling. One interesting fact about rubella is that it played a role in Apollo 13, a 1970 NASA mission, in which an explosion aboard the spacecraft’s service module prevented the astronauts from landing on the Moon and turned the mission into a struggle just to get the three men home alive. A few days before the mission launched in April, 1970, astronaut Charlie Duke –who later would fly to the Moon on Apollo 16– developed rubella, because there had been no vaccine during his childhood. Because Duke had been in contact with the Apollo 13 crew, and because Apollo 13 command module pilot (CMP), Ken Mattingly, had never had rubella, the backup CMP Jack Swigert, was swapped in to replace Mattingly just a couple of days before the launch. This was necessary, because, had he developed rubella, Mattingly would have been become ill in space, just when his two crewmates were exploring the surface of the Moon, ill enough to pose a danger to himself and crewmates, because he would not have been able to concentrate on his work.

For a newoborn with congenital rubella syndrome (CRS), however, infection with rubella virus is even wose that what might has struck astronaut Mattingly (who, by the way, turned out not to have caught rubella from Duke). Such infants typically show what is called “blueberry muffin” skin, the result of skin cells taking over the production of blood cells. Blueberry muffin skin also can affect newborns with various other TORCH infections. In CRS, newborns also develop deafness, a cardiovascular defect called patent ductus arteriosus (PDA), cataracts in the yes, and an enharged liver.

In case of rubella and toxoplasmosis, as with all TORCH infections, prevention is not only the best treatment, but is vital. Vaccination, prior to pregnancy, is the one and only preventive measure for rubella, while the best way to prevent toxoplasmosis is to avoid handling cat litter. We’ll look at some other TORCH conditions in another post.

David Warmflash
Dr. David Warmflash is a science communicator and physician with a research background in astrobiology and space medicine. He has completed research fellowships at NASA Johnson Space Center, the University of Pennsylvania, and Brandeis University. Since 2002, he has been collaborating with The Planetary Society on experiments helping us to understand the effects of deep space radiation on life forms, and since 2011 has worked nearly full time in medical writing and science journalism. His focus area includes the emergence of new biotechnologies and their impact on biomedicine, public health, and society.

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