Introduction

A rash is anything that changes the appearance or feeling of the skin. This may include a colour change in the skin (most commonly the skin becomes red), or the texture may feel bumpy or scaly. Many types of conditions may present with a rash, such as autoimmune disorders, allergies, bacterial infection, fungal infection, or viral infection, of which chickenpox is an example. It is important to be able to distinguish between different types of rashes to allow for correct treatment plans, to avoid any more serious complications.

Chickenpox

Chickenpox is a viral infection caused by the varicella-zoster virus that often infects people during childhood. Infection in previously unexposed adults is also possible, but this means they are more likely to experience it more severely than those infected during childhood. There is an effective vaccine against chickenpox, usually administered to children but is also encouraged for unvaccinated adults, who did not get infected as a child.¹

Symptoms

The most noticeable and distinguishing symptom of chickenpox is the rash, which is widespread throughout the body. The rash has three stages:

1. The beginning stage is usually a red and bumpy rash
2. Which then progresses to blisters filled with a cloudy white pus
3. These blisters tend to burst, forming scabbing, which is the last stage of the rash

With chickenpox, the rash is also extremely itchy, which is a very characteristic chickenpox symptom.

Along with the rash, other more systemic symptoms may be observed, such as fever, fatigue, headache, and stomach discomfort.

Transmission

Those with chickenpox may be contagious even two days before they start to show symptoms and are infectious up to when the blisters have scabbed. During this time, the virus may be spread through direct contact or the air. Direct contact transmission involves touching someone with the rash or any of the fluids excreted by them during the disease, whether that's pus from the blisters or excretions from the eyes, nose, or mouth. Alternatively, airborne transmission involves breathing in contaminated droplets excreted by the infected person when they sneeze or cough.¹

Complications

Although chickenpox is usually self-limiting, there is a possibility of complications, especially in vulnerable individuals. These individuals include people who are immunocompromised, whether that is due to immune disorders, chemotherapy, HIV, or an organ transplant. Adults and pregnant women are also considered to be higher-risk groups. The complications that may arise from a chickenpox infection include bacterial skin infections, which may progress to sepsis, encephalitis (swelling of the brain), pneumonia, problems with blood clotting, and dehydration.¹

Comparison with other common rashes

Measles

Measles is a skin condition also caused by a virus, but in this case, the measles virus is the origin. It is an extremely contagious infection, which has an airborne spread and occurs most commonly in children.²

• Symptoms

For measles, the rash only develops a few days after the first symptoms show.

• The first symptoms are typically a cough, runny nose, red eyes and Koplik spots (white spots inside the mouth).
• The rash then appears as flat, red spots that begin at the head and then move down the body all the way to the extremities
• Differences
  • The differences between the two can easily be spotted in the rash itself. For measles, the rash does not blister or scab. Furthermore, measles presents unique symptoms that do not occur in chickenpox, like Koplik spots.²

Impetigo

Impetigo is a bacterial infection of the skin most commonly caused by Staphylococcus aureus. It is transmitted by direct contact with those infected, therefore, those most at risk of contracting this infection are those living in crowded conditions, participants in sports that involve skin-to-skin contact like wrestling, and young children. There are two types of impetigo, which have different symptoms: bullous and nonbullous.³

• Symptoms
  • Nonbullous impetigo first involves the formation of a pustule
  • This pustule will then burst and scab over, forming a crusty yellow scab
  • This type of impetigo does not usually present with systemic symptoms like a fever
  • Bullous impetigo begins with fluid-filled blisters, where the fluid may be clear or yellow
  • With time, the fluid will darken, and the blister will rupture. Once ruptured, the blister will present with scaly surrounding skin. This type of impetigo will present with systemic symptoms like fever
• Differences
  • The most obvious difference between impetigo and chickenpox rashes is the colour
  • For nonbullous impetigo, there will be a yellow crust, which does not occur in chickenpox
  • For nonbullous impetigo, the colour will be more brown
  • The crusting/scabbing will also be larger than the chickenpox scabs
  • Furthermore, impetigo is more limited to certain body parts like the face, neck, and limbs, whilst chickenpox is widespread³

Ringworm

Ringworm, also known as tinea, is a fungal skin infection. Unlike the name suggests, it is not caused by a worm. Similarly, to impetigo, it is also caused by direct contact and is more likely to occur in people who partake in sports involving skin-to-skin contact, like wrestling. People who often use public sports centres and shower facilities, as well as those who have increased contact with animals are also at risk.³

• Symptoms
  • The most common symptom is the rash it causes
  • The ringworm rash is distinct due to its circular, ring-shaped plaques, hence the name
  • The plaques tend to be flat, with the surrounding ring being slightly raised
  • The rash may also cause itching and, depending on if it is present on the scalp, may cause hair loss
• Differences
  • The main difference between ringworm and chickenpox rashes is the flat, circular, ring shape of the tinea rash. Furthermore, ringworm often does not present with any systemic symptoms; it is skin-limited, unlike chickenpox, which may present with a fever, headache, or stomach ache⁴

Psoriasis

Psoriasis is a non-communicable disease, meaning it does not spread from person to person. It is caused by immune system dysregulation that leads to overly rapid division of skin cells. It is caused mainly by genetic factors, but environmental factors may also contribute, such as certain infections, obesity, smoking, and particular medications.⁵

• Symptoms
  • The most common type of psoriasis is plaque psoriasis, which causes a rash involving red and raised patches of skin covered by white/silvery scales. These may crack, causing itching and bleeding. Other symptoms may also occur, such as rigged or pitted nails and sleep quality issues
• Differences
  • The main difference from chickenpox is that the psoriasis rash does not blister. Also, with chickenpox, there tends not to be any changes in the nails or scaling on the skin⁵

Eczema

Eczema is another non-communicable disease that causes a rash. There are many factors that cause eczema, such as immune dysregulation, genetic factors, exposure to an irritant, and stress.

• Symptoms
  • Eczema rash is usually described as itchy, dry and inflamed skin. The skin may also appear leathery
• Differences
  • Unlike eczema, chickenpox does not involve patches of dry or leathery skin but rather it shows us as spots. Furthermore, in eczema, there are no blisters, unlike in chickenpox⁶

Allergic reactions

A rash may appear as part of an allergic reaction to something a person has ingested or touched. Hives are a common rash that occurs in response to exposure to an allergen. 

• Symptoms
  • Hives tend to present with skin-coloured or reddish bumps that often become pale in the centre when pressed. These bumps are also itchy and may appear with further swelling. During an allergic reaction, hives may also be accompanied by other symptoms like swelling of the eyes, lips, and throat
• Differences
  • The main difference between hives and chickenpox is the appearance of the rash. With hives, there are no blisters or scabbing, only raised bumps. Furthermore, the symptoms which accompany hives are different to those which accompany chickenpox in that with chickenpox, there usually isn't any swelling of the eyes, lips, or throat⁷

Summary

Chickenpox is a viral disease that presents with a distinctive rash. It is important to be able to distinguish it from other common rashes so you can treat it effectively.  Rashes may be caused by bacteria, fungi, immune conditions, allergies, as well as viruses, so it is key to target the treatment correctly to prevent any further serious complications or to avoid the unnecessary use of medication.