Lower back pain (LBP) is one of the most frequent reasons people seek medical attention, and it affects nearly everyone at some point in their lives. The vast majority of these cases are considered mechanical, meaning the pain arises from issues with the physical structure of the spine, such as muscles, ligaments, discs, or joints. However, not all lower back discomfort originates from a structural problem or injury. The body’s response to an infection can sometimes manifest as pain in the lower back, suggesting a virus may be the underlying cause.
How Systemic Inflammation Triggers Muscle Pain
A common way a virus causes lower back discomfort is indirectly, through the body’s coordinated immune response to fight the pathogen. When a person contracts a systemic infection like influenza, the common cold, or COVID-19, the immune system releases chemical messengers known as cytokines. These signaling proteins travel through the bloodstream and help coordinate the attack against the invading virus.
The presence of these circulating cytokines leads to myalgia, or generalized muscle aches, felt throughout the body. Cytokines sensitize pain receptors, increasing the overall perception of discomfort, and this effect is often prominent in large muscle groups like those supporting the lumbar spine. This discomfort is typically a dull, diffuse ache rather than a sharp, localized pain, and it resolves once the acute viral infection subsides.
Viruses That Directly Affect the Spine and Nerves
In certain instances, viruses do not rely on systemic inflammation alone but instead directly target neurological or musculoskeletal tissue near the spine, leading to more localized and severe pain. This direct invasion relies on a virus’s neurotropic capacity, meaning its ability to infect nerve cells. The resulting pain is often distinct from the generalized aches of a common illness.
Varicella-Zoster Virus (VZV)
The Varicella-Zoster Virus (VZV), which causes shingles, is a prime example. After a childhood chickenpox infection, VZV lies dormant in nerve root ganglia near the spinal cord. When the virus reactivates years later, it travels down the nerve fiber, causing radicular pain. This pain can be felt as a sharp, burning sensation in the lower back region before the characteristic rash appears.
Enteroviruses
Enteroviruses, though most often causing mild respiratory or gastrointestinal illness, have the capacity to spread into the central nervous system. In rare cases, this can lead to viral myelitis, which is the inflammation of the spinal cord itself. Poliovirus, a historically significant enterovirus, demonstrates this potential for spinal cord involvement.
Herpes Simplex Virus type 2 (HSV-2)
Another neurotropic virus, Herpes Simplex Virus type 2 (HSV-2), can lay dormant in the sacral root ganglia, located at the base of the spine. Reactivation of HSV-2 can cause sacral radiculopathy, sometimes known as Elsberg syndrome, where the pain is felt in the lumbosacral area. This direct viral attack on the nerve tissue results in pain that is often described as sharp or electric, contrasting with the dull muscular ache of systemic myalgia.
Key Symptom Differences in Viral Lower Back Pain
Distinguishing between viral-induced back pain and common mechanical back pain involves observing the presentation of the symptoms. Mechanical LBP, caused by issues like muscle strain or disc herniation, is typically aggravated by specific movements, such as bending or lifting, and is often relieved by rest or changing position. This type of pain is localized to the lower back and lacks other signs of illness.
Viral LBP, whether systemic or direct, presents with additional indicators that suggest an infection is the source of the discomfort. Pain caused by systemic inflammation is typically accompanied by other signs of illness, such as fever, chills, fatigue, or a sore throat. This pain is often diffuse and constant, meaning it is not relieved simply by lying down or changing position.
In cases where a virus directly affects the nerves, the pain is often localized but has a distinct, neuropathic quality, described as burning, shooting, or tingling, and it may radiate down the leg along a specific nerve path. Inflammatory pain, which includes viral-related discomfort, sometimes feels better with movement and worse after long periods of rest, which is the opposite pattern of mechanical pain.