University of Arizona Study Published in Clinical Infectious Diseases
Warns Pregnant Women about the Risk of Rodents
Aug. 9, 2001
Contact: Kate Jensen, (520) 626-7217 Pregnant women should be cautious about contact with pet hamsters, wild or laboratory mice according to a study by Leslie Barton, M.D., professor of Pediatrics and pediatric infectious disease specialist at the University of Arizona, published in the August 1 edition of Clinical Infectious Diseases.

Dr. Barton, along with colleagues around the world, have reported that when pregnant women come in contact with rodents carrying a disease called Lymphocytic Choriomeningitis Virus (LCMV), it can damage the developing fetus.

"When a healthy adult or pregnant woman contracts LCMV, it may be completely asymptomatic or it may manifest as a mild flu," Dr. Barton says. "The real risk with this infection is in the transmission to the unborn baby."

To date, more than 49 infants worldwide have been diagnosed with LCMV. Dr. Barton has diagnosed three cases of congenital LCMV in Arizona. In one instance, twin girls from Cochise County were born to a mother who unknowingly contracted LCMV during pregnancy. One girl has vision problems; the other is severely developmentally delayed and has seizures. "These are isolated cases," Dr. Barton says. "And certainly not every mouse or hamster carries this virus. But pregnant women deserve to have this information to avoid unnecessary risks during pregnancy."

More than 90 percent of the babies who have been identified as contracting the LCMV virus in utero had adverse outcomes, with vision problems being the most common. Within one group of 38 infants Dr. Barton studied, 84 percent had neurological problems such as cerebral palsy, mental retardation, seizures, as well as decreased visual acuity.

Mice and hamsters are the primary sources of LCMV infections. Humans acquire this virus by direct contact with infected rodents or by inhaling the virus once it has been aerosolized.

LCMV is not a new disease. It was first identified in 1933 in a woman who was thought to have a form of encephalitis. In 1955, it was first recognized in the U.K. as a virus that could cause congenital disease. A mother with LCMV virus delivered a baby who developed the disease a week later and died shortly thereafter. During the ensuing years, individual cases of congenital LCMV infection have been identified in Germany, France, Lithuania and across the United States.

"We really don't know with certainty how many infants have been affected by LCMV while in utero," reports Dr. Barton, "because we don't routinely look at LCMV as a possible cause of congenital blindness or retardation."

Dr. Barton believes that the public and the medical profession should be made aware of the hazard that wild, pet and laboratory rodents pose to pregnant women. The message to pregnant women is similar to the warning they receive about toxoplasmosis -- the parasite that can be present in cat litter.

"We don't advise pregnant women to get rid of their pet cat to prevent congenital toxoplasmosis," Dr. Barton says. "They should just find someone else to change the cat litter during their pregnancy."

Some simple precautions can probably protect pregnant women from contracting LCMV.

If you have a pet hamster, have someone else take care of it while you are pregnant.

If you are cleaning up after wild mice, wear gloves and spray the area with water to avoid the possibility of aerosolizing the LCMV virus.

If you work with mice in a laboratory setting - the mice should be tested for LCMV.

Dr. Barton collaborates with Marilyn Mets, M.D., Department of Ophthalmology, Children's Memorial Hospital at Northwestern University in Chicago.

If pregnant women have concerns about possible exposure to LCMV, they can call the Pregnancy Risk Line, 1-888-285-3410 or 626-3410.

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Will Pregnant Women Get Sick From Hamsters?
By Doran Jones
The primary concern with any rodent and pregnancy is LCMV (Lymphocytic Choriomengingitis Virus) or Viral Meningitis. Mice, Rats, Hamsters, and other rodents can pass this to humans and other animals.

LCMV is usually not fatal to adult humans. In fact, most cases are so mild they go vastly unreported. The mortality rate is about 1%. It's thought that about 2 to 10 percent of the human population have already contracted and recovered from LCMV based on serological (blood work) studies conducted in urban areas of the US. The symptoms are very much like a cold or flu.

The first stage of the virus typically begins with fever, malaise, anorexia, muscle aches, headache, nausea, and vomiting. Other symptoms that appear less frequently include sore throat, cough, joint pain, chest pain, testicular pain, and parotid (salivary gland) pain. Most cases do not proceed to a second stage but a few days after the first stage passes, the victim may develop a fever, headache, and a stiff neck. There are other more acute and sometimes fatal symptoms that can develop at the same time; these are not common.

The above are the symptoms and concerns for non-pregnant humans. However when a woman is pregnant a whole new set of problems arise should she become infected. LCMV is one of the few viruses that can pass the placental barrier. A fetus that get LCMV is commonly born with severe birth defects or may even die.

Before you all panic, realize that with one or two hamsters the risk is low. I worked at a laboratory where I handled up to 1000 animals. We lab workers were required to wear protection whenever we were in the animals' rooms. Both the workers and animals were tested regularly.

How do you get LCMV? Well, there are a number of ways to get it. The more common way is through handling an animal that passes the infection through urine to the hand of the human who then either touches his eyes or mouth. Another way is though airborne dust that contains dried urine or feces.

To avoid problems keep your rodent area clean; bleach and disinfectants kill the virus readily. Change bedding on a regular basis. Wash your hands before and after handling the animals. Don't allow wild animals access to your hamstery. If you are pregnant consult with your vet and doctor about this. It's probably wise to avoid contact with your animals for the duration of your pregnancy.

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