Symptoms of Listeriosis
Listeriosis can be a tricky diagnosis in pregnancy. At times the bacteria cause no symptoms at all or cause an illness that may be confused with a urinary tract infection or a flu that is managed with fluids and acetaminophen. Low-grade fever, headache, and muscle pain are common. Less commonly there can be diarrhea and cramps.
While the mother may suffer minimally from listeriosis, the baby's situation is life-threatening. Delivery usually unloads the largest amount of the infection from the mother's body, causing immediate improvement. Treatment of the mother with antibiotics may or may not help the undelivered baby.
The onset of premature labor in a baby already compromised will have an obstetrician weighing the risk vs. benefit of delivery. Certainly delivery is indicated in the late third trimester so that the newborn can be treated, but in cases of severe prematurity, there is no best answer for a difficult question.
In the real world, obstetricians don't obtain blood cultures and other tests for listeriosis on every woman with a low-grade fever, headache, or muscle aches. They can't.