Lymphocytic Choriomeningitis (LCM) is an infectious disease caused by a virus called lymphocytic choriomeningitis virus (LCMV). The disease is not very common, but it can strike women who are pregnant or are trying to become pregnant and there is some concern that it can result in the fetus becoming infected. LCMV is present in rodents, especially wild mice, including common house mice. Those who come into contact with urine, feces, saliva, or blood of wild mice are at risk of contracting LCM as are those who keep pet hamsters. Additionally, if you work in a laboratory involved in studying LCMV or the disease that it causes, you’re at risk as well. Symptoms of LCM usually come in two phases: First, there is a set of flu-like symptoms. This means chills, fever, body aches, headache, fatigue, stuffed or running nose, coughing, sneezing, sore throat, and nausea. Next, the person suffers symptoms of inflammation of the tissues that surround the brain and sometimes also of the brain itself. Such symptoms may include stiff neck, confusion, seizures, difficulty walking, very severe headache, and vomiting. Health authorities warn that symptoms can be particularly bad in pregnant women.
If there is a suspicion that you may be infected with LCMV, doctors will first order some basic blood tests that will provide information on your overall health status. These tests also will provide some clues as to the likelihood of LCM. The blood tests include a white blood cell (WBC) count, which can actually be low in LCMV. The tests include a platelet count, which also may be low, and they include levels of liver enzymes, which typically are slightly elevated in LCM. Doctors will also need to perform a lumbar puncture (LP) to draw fluid that circulates around the spinal cord. This fluid is called cerebrospinal fluid (CSF). Prior to performing an LP, doctors will order a computed tomography (CT) scan of the head to make sure that an LP would be safe. In an LP, a needle is inserted through the back of the lower spine to draw a sample of CSF. The CSF will then be tested to reveal signs of LCMV infection. These signs include a low concentration sugar in the CSF sample and also a high concentration of WBCs in the CSF, despite finding low concentrations of WBCs in blood samples. This situation of WBC counts indicates that an infection is present in the central nervous system and not in the blood. Actual diagnosis of LCM is achieved by finding certain antibodies in the CSF sample. Such antibodies are directed against the coat that surrounds the LCMV viruses and against the DNA of the virus.
LCM causes symptoms that usually come in two phases. The first phase, which happens 8-13 days after the person is exposed to the virus consists of mild flu-like symptoms, such as muscle aches, headache, fever, loss of appetite, fatigue, and nausea and vomiting. Not everybody experiences the first phase, however, or sometimes the symptoms are so mild that they are not noticed. In either case, there is then a period of a few days with no symptoms. If you had noticeable symptoms during the first phase, you will feel as though you were recovering, but then there is a second phase in with new symptoms, this time neurological symptoms. These include symptoms of meningitis: fever, stiff neck, and headache. The person also may experience confusion and drowsiness, trouble with vision, hearing, or with other senses, trouble with movement (including paralysis). All of these features suggest meningoencephalitis —inflammation of the brain and of the layers of connective tissue that surround and protect it. In some cases, the situation can progress to hydrocephalus, an excess of fluid around the brain and spinal cord.
Despite this very frightening course of symptoms, LCM usually is not fatal, but it can lead to infection of the embryo or fetus. If this happens during the first trimester (embryonic and early fetal period), the infection can lead to early pregnancy loss, meaning spontaneous abortion (miscarriage). If a fetal infection occurs later pregnancy, it can result in very severe birth defects, such as mental retardation, hydrocephaly (excess fluid in and around the brain) and, inflammation of the retina of the eye.
Treatment for LCM consists mostly of supportive measures, such as hospitalizing the patient, monitoring her, and providing fluids and treating fever. If needed, the patient may be given corticosteroids, which are relatively safe during pregnancy and it is possible to take them as a nursing mother too. It is known that corticosteroids build up in breast milk, but this is mostly during the first four hours after a dose is given. Consequently, some doctors who give this agent for suggest that the patient wait four hours after receiving each dose, then pump out her milk and discard it, then wait for new milk to accumulate and nurse the infant from that new milk. Such a regimen will add stress to the already stressful routine of a new mother. Consequently, you may find it more appealing to feed your newborn one of the many excellent infant formulas, but that’s if you can get hold of one. At the time of the writing of this article, in early June, 2022, the baby formula shortage continues to the point that women are now donating breast milk. A drug called ribavirin has shown promise against LCMV in laboratory animals, but there is concern that it could be harmful to the fetus. Future research is thus needed. Drugs to combat fever, such as acetaminophen in the United States and paracetamol in several other countries, are considered safe during pregnancy.