Also known as herpes-zoster for the virus that causes it, shingles is a delayed stage of an infection with a virus called varicella-zoster (VZ), the virus that causes chickenpox. The main differences between chickenpox and shingles are the symptoms and the timing of the infection.
Shingles occurs in approximately 4 cases per 1,000 people in the US. The number increases to 10 per 1,000 in people above age 60.5, but women of childbearing age can develop shingles due to their having chickenpox in the past. Shingles also can develop from a type of VZ given to you as the chickenpox vaccine, but the chances are higher that you can develop shingles if you have had chickenpox and thus have the virus in your cells. Overall, the incidence of shingles during pregnancy is thought to be fairly low.
Chickenpox is what is called the acute stage of VZ infection, the stage that develops within a few days of getting infected and that subsides within a couple of weeks. The classic symptoms of chickenpox are a very itchy rash all over the body, cough, fever, headache, and loss of appetite. Traditionally, chickenpox was a disease of childhood, because it tends to be extremely contagious. Thus, when one child had it, the virus would spread rapidly. The introduction of a chickenpox vaccine in the 1990s led to a dramatic reduction in the chickenpox incidence. However, many women who are pregnant today had chickenpox as children or teens.
Instead of eliminating the VZ virus from your system, the immune system simply fights it off and then keeps the virus suppressed. However, the virus hides in the nervous system, specifically in the sensory nerves of the body and face. It does not cause symptoms, as long as your immune system keeps it in check. This is called the latency stage of infection, and in most people it lasts for the rest of life. But when the immune system is compromised, or when the immune system weakens with age, the VZ that’s hiding in the nervous system can cause another symptomatic stage of the disease with symptoms different from those of chickenpox. Known as shingles, this condition also features a rash, but rather than being all over the body the lesions of the rash erupt along sensory dermatomes, which are regions of the skin that follow sensory nerves on their way to the spinal cord. Although there can be some itching, the main symptom in the shingles rash is extreme pain.
As for diagnosis of shingles, generally, the rash of shingles is so distinctive along dermatomes that your doctor can make a diagnosis just be seeing it. However, sometimes there is just pain without a rash, and sometimes the rash looks similar to the rashes of other viruses, such as herpes simplex, and, or to the rashes of a bacterial infection such as impetigo. Shingles also can look similar to contact dermatitis, insect bites, scabies, folliculitis, a skin yeast infection, and several other conditions, including drug reactions. When there is doubt but also suspicion that you could have shingles, samples can be taken of the fluid from the skin sores or scabs, or saliva. The sample then can be tested with polymerase chain reaction (PCR), a test that amplifies DNA sequences, including the sequences of any viruses that are present. Those sequences then can be compared with known sequences, including the sequence of VZ virus. Along with identifying VZ, these tests can distinguish between VZ caught during childhood (called wild-type VZ) and VZ of a chickenpox vaccine.
In addition to a burning shooting pain on affected dermatomes, shingles also produces tingling sensations called paresthesia, plus it can give you fever, chills, headache, urination problems, and diarrhea. If shingles is not treated immediately, it’s possible that you can develop serious complications, such continued pain in the affected dermatomes after the blisters have healed, and skin infections. Also possible as a complication is ophthalmic shingles, which is a VZ infection of the eyes causing pain and infections that can lead to blindness. The fever of shingles can be harmful to the fetus or embryo, if you do not treat the fever immediately with fever-lowering medication (such as acetaminophen or paracetamol).
Although surrounded by controversy, there is some concern that the VZ virus may harm the child directly. It’s known that women who get chickenpox during the first 20 weeks of pregnancy, and especially from gestational week 8 to gestational week 20, carry a small but real risk (0.4 – 2 percent) of having a baby with congenital varicella syndrome (CVS). CVS is a collection of very severe congenital defects that include underdeveloped legs and arms, a brain that is small and underdeveloped, and eye and skin problems. On the other hand, if you happen to develop chickenpox during the last few days before delivery, your baby could be born with neonatal varicella, which can be fatal. In both cases, however, we are talking about chickenpox, meaning an acute infection of VZ. It has not been demonstrated, however, that either of these effects on the baby can happen as a result of maternal shingles.
Medications include an antiviral drug, such as acyclovir, famciclovir, or valacyclovir, which should be started within 72 hours of the start of your illness, which is why it is vital to get to the doctor at the first sign of trouble. These medications appear to be quite safe during pregnancy. Doctors also give pain medications, such as acetaminophen or paracetamol, which are not considered risky for the fetus. On the other hand, a great deal of concern surrounds opioids, the most potent group of anti-pain medications. Gabapentin is another medication that is effective against pain persists after shingles has resolved. This drug is surrounded by controversy regarding its safety during pregnancy, but you and your doctor may have to weigh the potential for risk against the benefits in controlling your pain. Another group of medications that are given are corticosteroids to confront the inflammation of shingles. Generally, corticosteroids are fairly safe during pregnancy. As for breastfeeding mothers, antiviral medications, such as such as acyclovir, famciclovir, or valacyclovir, are thought to be safe for nursing infants. Also if you need gabapentin for post shingles pain, the risk during breastfeeding is thought to be low.