Understanding the Mechanism of Chicken Pox

Regardless of language barriers, cultural differences, or upbringing, children worldwide once experienced the same itchy, uncomfortable, and blister-filled rite of passage: chicken pox. From Beijing to Boston, these irritating blisters have affected up to 95 percent of individuals in densely populated regions, as reported by the Public Health Agency of Canada. With blisters numbering anywhere from 30 to 1,500, this widespread ailment leaves its sufferers feverish and desperate to scratch.

Chicken pox, scientifically known as the varicella zoster virus, has troubled humanity for hundreds of years. The virus was first identified in the 16th century by Naples-born Giovanni Filippo Ingrassia, a scholar known for his work on bone structure [source: Ackernecht]. It wasn’t until several centuries later that medical professionals could reliably distinguish chicken pox from smallpox, its more deadly viral relative [source: Centers for Disease Control and Prevention (CDC)].

The varicella virus is highly contagious, spreading effortlessly through the air to unsuspecting individuals. Just how contagious is it? Some medical experts claim that one could contract chicken pox from someone shopping in a different supermarket aisle [source: Rauch]. It primarily affects children under the age of 10, with outbreaks most common during winter and early spring [source: CDC]. Thanks to widespread vaccination efforts in the U.S., the number of cases has significantly declined.

This article explores the reasons behind the widespread prevalence of chicken pox, its effects on the human body, effective treatment methods, and preventive measures.

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What is the chicken pox virus?

A pox is understood as a viral infection causing widespread, eruptive blisters. However, the origin of the term "chicken" in "chicken pox" remains unclear. The Oxford English Dictionary suggests it refers to the mild nature of the infection, implying it is cowardly (or chicken). Others speculate the name comes from the blisters' resemblance to chickpeas or the appearance of being pecked by a chicken.

Having explored its name, let's delve into its lifecycle. Viruses are minuscule particles (approximately one-millionth of an inch) that require host cells to survive and multiply. They infiltrate the body through the nose, mouth, or broken skin. The varicella virus particularly favors entry via the mucous membranes of the eyelids and eyeballs.

Once inside, the varicella virus attaches to host cells in the nasal area and nearby lymph nodes, rapidly multiplying. The newly replicated virus particles then migrate to the liver, spleen, and sensory nerve tissues. After further replication, they infect skin cells, triggering the characteristic chicken pox rash.

The varicella virus typically incubates in the body for 10 to 21 days before the rash appears. This incubation period is the time between infection and the onset of symptoms. Individuals become contagious one or two days before the rash emerges, often unknowingly spreading the virus. This stealthy incubation makes chicken pox highly infectious, with nine out of 10 non-immune household members likely to contract it [source: CDC].

The varicella virus can transfer from one person's bloodstream to another through various means. An infected individual's cough or sneeze can release airborne particles, which others may inhale unknowingly. Additionally, tiny droplets from the blisters can become airborne, or direct contact with the rash before it dries can also transmit the virus.

Having explored how the virus affects the body internally, let's delve into why chicken pox causes the skin to resemble a connect-the-dots pattern.

Chicken Pox Symptoms

Once the replicated varicella virus enters the bloodstream, the immune system identifies it as a foreign threat and initiates a defense after the incubation period. This battle manifests as a fever, typically lasting two to three days. In adults, fever often occurs before the rash, while children usually develop the blistery rash first.

The blisters, known as vesicles, are small sacs filled with clear fluid. They develop on tiny red spots on the skin, measuring about one to four millimeters in diameter [source: CDC]. The fluid inside these vesicles contains a substance that activates nerve cells in the skin, signaling the brain to trigger itching. While uncomfortable, this itching indicates the body's efforts to combat the virus [source: Nemours Foundation]. After three to four days, the itching usually diminishes, and the blisters either burst or form scabs.

The quantity and placement of vesicles can vary based on age, skin health, and vaccination history. Typically, the rash starts on the scalp, face, and abdomen. In unvaccinated individuals, it can spread to produce 250 to 500 blisters, potentially affecting areas like the eyelids, mouth, and genitals. In breakthrough cases, where chicken pox occurs despite vaccination, the number of blisters is usually limited to around 50.

After approximately a week, the blisters crust over and dry out, marking the end of the contagious phase. Until then, individuals should isolate themselves upon the first signs of the rash to prevent spreading the virus. While the visible symptoms fade, the virus becomes dormant but remains in the body's nerve cells. Later in life, it may reactivate as the herpes zoster virus, or shingles, which we'll explore further in the Shingles section.

This timeline of the varicella virus, from infection to dormancy, illustrates the progression of chicken pox:

In rare instances, chicken pox can escalate into more severe health issues, potentially leading to death. In the following section, we'll examine these complications and identify who is most at risk.

Chicken Pox Complications

Chicken pox can pose significant dangers. Prior to widespread vaccinations, approximately 10,600 Americans were hospitalized annually due to varicella-related conditions, with over 100 deaths each year [source: Centers for Disease Control and Prevention (CDC)]. In some cases, chicken pox isn't the sole health challenge, as the virus can lead to a variety of related issues, or complications, especially when it spreads to and infects other areas of the body.

Hover over the chicken pox complications to see their impact on the body.

Most individuals can manage chicken pox at home, as the illness typically resolves within a week. However, the Mayo Clinic advises seeking medical attention if you experience the following symptoms:

While children account for the majority of chicken pox cases, they generally face fewer severe complications. However, it's crucial for kids to avoid scratching the itchy blisters, as approximately one in 20 children may develop an infected rash [source: National Network for Immunization Information]. Bacteria from fingernails can enter the open blisters, leading to secondary infections.

Certain groups of people are at a higher risk of severe complications, which we will explore in the next section.

Chicken Pox Risk Groups

While most chicken pox cases resolve within a week, certain individuals are at higher risk for complications, as noted by the Mayo Clinic:

Infants under one year are especially at risk for complications since they cannot receive the varicella vaccination and may lack sufficient antibodies, the specialized proteins needed to combat the virus. While babies inherit some antibodies from their mothers, these only last between one month and a year. If a mother has never had chicken pox, her baby is more likely to experience a severe outbreak due to the absence of virus-specific antibodies [source: Rauch].

Although adolescents and adults represent only 5 percent of varicella cases, they account for 35 percent of virus-related deaths [source: CDC]. As we age, our immune systems weaken, increasing the risk of severe complications from common infections like varicella.

Routine vaccination against chicken pox can prevent infections and minimize the risk of complications. In the following section, we'll explore the varicella vaccine, its recommended recipients, and the optimal timing for administration.

The Varicella Vaccine: Preventing the Pox

Vaccines act as personal trainers for the immune system, enhancing its ability to combat specific diseases by stimulating the production of antibodies, the proteins that fight infections. Following the FDA's approval of the varicella vaccine (Varivax) in 1995, reported chicken pox cases decreased by 53 to 88 percent nationwide [source: Centers for Disease Control and Prevention (CDC)]. By the 2015-16 school year, all states except Montana mandated the varicella vaccine for elementary school entry [source: Immunization Action Coalition]. Some states also allow proof of prior infection, such as a medical record confirming a previous case of chicken pox, as an alternative [source: CDC].

Since individuals can still contract chicken pox after a single dose of the varicella vaccine, known as a breakthrough case, the Advisory Committee on Immunization Practices (ACIP) advises a second dose, often referred to as a booster shot. With two doses, only one in 10 people may experience a breakthrough case, typically with milder symptoms and an average of 50 blisters [source: CDC].

Once you've had chicken pox, you develop immunity, eliminating the need for vaccination. However, the CDC has identified specific groups of non-immune individuals who should or should not receive the vaccine.

Individuals who should get vaccinated:

Individuals who should avoid the vaccine:

An alternative treatment is available for those exposed to varicella but unable to receive the vaccine. Although costly, varicella zoster immune globulin (VZIG) can provide protection against the virus if administered within 96 hours of exposure.

According to the CDC, the varicella vaccine carries some risks, including pain at the injection site, rash, fever, and seizures. Some also believe vaccines may cause more severe effects in children, such as autism. However, no credible study has confirmed a connection between vaccines and autism. For more on these claims and their validity, read How Vaccines Work.

Since most chicken pox cases don't require medical attention, we'll share home remedies to ease discomfort. Next, we'll explore the soothing effects of oatmeal baths and the calming relief of calamine lotion.

Chicken Pox Treatments: Scratching the Itch

Similar to the common cold, chicken pox has no instant cure. However, there are ways to relieve itching, fever, and pain. Start by trimming your fingernails to minimize scratching and prevent secondary infections. Wearing gloves at night can also help avoid unconscious scratching during sleep.

Another effective remedy is an oatmeal bath, a widely recommended home treatment for itch relief. This isn't the breakfast variety but finely ground colloidal oatmeal. You can purchase ready-made oatmeal bath products or create your own by blending uncooked oatmeal and adding two cups to a warm bath.

For centuries, oatmeal has been used to treat skin conditions due to its unique chemical composition, which offers a triple benefit. Its water-absorbing starches provide hydration, while acidic phenols deliver antioxidant and anti-inflammatory effects. Additionally, saponins, sugar-based compounds found in soaps, offer cleansing and foaming properties.

Third, after stepping out of the bath, apply calamine lotion to the blisters to alleviate itching. Calamine, a pink zinc-based compound, has anti-inflammatory properties that help dry out the fluid inside the pox.

Fourth, over-the-counter pain relievers can reduce fever, but only use non-aspirin options like acetaminophen. Aspirin use during chicken pox has been associated with Reye syndrome, especially in children and teenagers. This rare, non-contagious condition occurs in approximately one in a million cases [source: Nemours Foundation]. Prescription medications for the varicella virus are typically reserved for those at risk of severe complications. For more details on safely managing chicken pox, read Shingles and Chicken Pox In-Depth.

Once you recover from chicken pox, the good news is the itching and blisters are gone. The bad news is the varicella virus stays dormant in your sensory nerve cells and can reappear later in life as shingles. In the next section, we'll explore what happens when the virus returns for a second round.

Shingles: Chicken Pox Part Two

Following a bout of chicken pox, the varicella virus lies dormant in nerve cells. It can later reawaken as the herpes zoster virus, commonly known as shingles. This latency is a hallmark of the herpes virus family, akin to a viral hibernation. After the immune system combats chicken pox, the virus retreats to nerve cells, where it can remain inactive. The exact reasons and mechanisms for the virus reactivating and causing shingles are not fully understood, but factors like stress, aging, illness, medication, and contact with a shingles rash are linked to its resurgence [source: Mayo Clinic].

While shingles can affect younger individuals, those aged 50 and older are most susceptible. According to the Centers for Disease Control and Prevention, half of unvaccinated individuals who reach 85 will develop shingles. Annually, about one million people are affected by this condition.

Symptoms of shingles include:

Shingles begins as a rash on the face or body, with blisters forming and scabbing over three to five days. The rash typically clears within two to four weeks. Medications such as acyclovir (Zovirax), valacyclovir (Valtrex), and famciclovir (Famvir) are effective treatments. For additional remedies, read 10 Home Remedies for Shingles.

When the herpes zoster virus attacks nerve cells, it can cause lasting damage, leading to pain in the rash area that persists long after the rash has healed. This condition, known as post herpetic neuralgia, affects one in five shingles patients, with the risk increasing with age. While there is no definitive cure, early treatment for shingles may help reduce the likelihood of developing this condition [source: Mayo Clinic].

Uncommon complications of shingles include:

In 2006, the Food and Drug Administration approved a shingles vaccine for individuals aged 60 and older. This vaccine is a stronger version of the varicella vaccine. Clinical trials demonstrated a 51 percent effectiveness rate in preventing herpes zoster and reducing symptom severity. Additionally, 66 percent of participants avoided post herpetic neuralgia entirely [source: CDC]. The most frequent side effect was soreness at the injection site. Furthermore, those vaccinated against chicken pox are less likely to develop shingles, though ongoing research is still determining the vaccine's full protective capabilities [source: National Institute of Neurological Disorders and Stroke].