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# Erythema infectiosum (fifth disease, parvovirus B19)

A mild childhood viral rash caused by parvovirus B19: bright red 'slapped' cheeks, then a lacy rash on the body. Risky in pregnancy and blood disorders.

Updated 2026-11-01

## Structures involved

Tap one to see what it is and open it in 3D.

- [Skin](https://durgical.com/en/anatomy/skin/)

## Microorganisms that cause it

- [Parvovirus B19](https://durgical.com/en/microbiology/parvovirus-b19/)

## Why it happens

- [Fetal hydrops: immune and nonimmune](https://durgical.com/en/general-pathology/fetal-hydrops-immune-and-nonimmune/)
- [Erythropoiesis and erythropoietin](https://durgical.com/en/physiology/erythropoiesis-and-erythropoietin/)
- [The red cell life cycle and the spleen](https://durgical.com/en/physiology/the-red-cell-life-cycle-and-the-spleen/)
- [Hematopoiesis and bone marrow](https://durgical.com/en/histology/hematopoiesis-and-bone-marrow/)

## What it is

A common, usually mild viral exanthem of school-age children caused by human parvovirus B19. After a short prodrome it produces red cheeks and then a lace-like rash on the limbs and trunk. The same virus can stop red-cell production, which matters in people with haemolytic anaemias, immunosuppression or pregnancy.

## Who gets it

Worldwide, with outbreaks in schools in late winter and spring. Most adults have antibodies from childhood infection. It is not a notifiable disease in Colombia, so local data are limited; outbreaks are reported in schools and nurseries across Latin America.

## Causes

- Human parvovirus B19, a small single-stranded DNA virus (genus Erythroparvovirus)
- Spread mainly by respiratory droplets; also by blood products and from mother to fetus across the placenta
- The virus binds the P antigen (globoside) on erythroid progenitor cells in the bone marrow

## Risk factors

- School or day-care attendance, and working with young children
- Household contact with an infected child
- Chronic haemolytic anaemia (sickle cell disease, hereditary spherocytosis, thalassaemia): risk of transient aplastic crisis
- Immunosuppression (leukaemia, transplant, HIV): risk of chronic anaemia
- Pregnancy without prior immunity, especially in the first half

## Pathophysiology

Parvovirus B19 infects and kills erythroid precursor cells, so red-cell production stops for about a week. Healthy children barely notice this, but people whose red cells already live a short time develop sudden severe anaemia. The rash and joint pain appear later and are immune-complex mediated, so by the time the rash shows the child is usually no longer contagious.

## Classification

- Classic erythema infectiosum (children)
- Arthropathy (mostly adult women)
- Transient aplastic crisis (chronic haemolytic anaemia)
- Chronic pure red-cell aplasia (immunocompromised)
- Fetal infection with anaemia and hydrops fetalis

## Symptoms and signs

- Mild prodrome: low fever, runny nose, headache, malaise
- Bright red 'slapped-cheek' rash with relative sparing around the mouth
- A few days later, a lacy, reticular rash on the arms, legs and trunk that may itch
- The rash can fade and reappear for weeks with heat, sunlight or exercise
- Symmetric joint pain and swelling of the hands, wrists and knees, more often in adults
- Many infections cause no symptoms at all

## Red flags

- Pallor, fatigue, tachycardia or breathlessness in a child with sickle cell disease or spherocytosis (aplastic crisis)
- Exposure or rash in a pregnant woman
- Persistent anaemia in an immunocompromised patient
- Decreased fetal movements or a large-for-dates uterus after maternal infection (possible hydrops)

## Diagnosis

**Clinical**
Usually a clinical diagnosis from the slapped-cheek face followed by a lacy body rash in a well child.

**Tests**
Testing is reserved for high-risk patients: parvovirus B19 IgM (and IgG for immunity) in pregnancy, PCR for viral DNA in the immunocompromised, and a blood count with a very low reticulocyte count in aplastic crisis.

**Imaging**
Not needed in children. After infection in pregnancy, serial fetal ultrasound with [middle cerebral artery](https://durgical.com/en/anatomy/middle-cerebral-artery/) Doppler looks for fetal anaemia and hydrops.

## Differential diagnosis

- Rubella and measles
- Roseola (exanthem subitum)
- Scarlet fever
- Drug eruption
- Juvenile idiopathic arthritis or lupus when joint symptoms dominate

## Goal of treatment

Relieve symptoms in healthy children and detect and treat severe anaemia early in high-risk groups.

## Treatment

**Conservative**
Rest, fluids and fever or pain relief with paracetamol or NSAIDs; children may attend school once the rash appears, because they are no longer contagious.

**Acute**
Transient aplastic crisis is treated in hospital with red-cell transfusion as needed and close monitoring of the blood count.

**Medical**
Intravenous immunoglobulin is used for chronic parvovirus anaemia in immunocompromised patients.

**Procedure**
Severe fetal anaemia is managed in a specialised centre with intrauterine blood transfusion.

**Follow-up**
Pregnant women with infection are followed with serial ultrasound for several weeks; patients in aplastic crisis need droplet isolation because they remain contagious.

## Complications

- Transient aplastic crisis in chronic haemolytic anaemia
- Chronic pure red-cell aplasia in immunocompromised patients
- Fetal anaemia, hydrops fetalis and miscarriage
- Self-limited arthritis, mostly in adults

## Prognosis

Excellent in healthy children; the illness clears on its own and gives lifelong immunity. Outcomes in aplastic crisis and fetal infection depend on early recognition and transfusion.

## Prevention

- Hand washing and covering coughs and sneezes
- Pregnant women and people with haemolytic anaemia should avoid outbreak settings and consult early if exposed
- Droplet precautions for hospitalised patients with aplastic crisis or chronic infection

## Test yourself

Think of the answer, then tap the question to see it.

## Which cells does parvovirus B19 infect?

Erythroid progenitor cells in the bone marrow, through the P antigen (globoside).

## Is a child with the slapped-cheek rash still contagious?

Usually not; the rash is immune-mediated and appears after the infectious period.

## What complication does parvovirus B19 cause in sickle cell disease?

Transient aplastic crisis: sudden severe anaemia with a very low reticulocyte count.

## What fetal complication is feared after maternal infection?

Severe fetal anaemia leading to hydrops fetalis, and miscarriage.

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## Related conditions

- [Rubella and congenital rubella syndrome](https://durgical.com/en/conditions/rubella-and-congenital-rubella-syndrome/)
- [Measles](https://durgical.com/en/conditions/measles/)
- [Roseola infantum (exanthem subitum)](https://durgical.com/en/conditions/roseola-infantum/)
- [Scarlet fever](https://durgical.com/en/conditions/scarlet-fever/)
- [Sickle cell disease](https://durgical.com/en/conditions/sickle-cell-disease/)
- [Hereditary spherocytosis](https://durgical.com/en/conditions/hereditary-spherocytosis/)
- [Aplastic anaemia](https://durgical.com/en/conditions/aplastic-anaemia/)

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Fifth disease](https://medlineplus.gov/ency/article/000977.htm) (MedlinePlus (U.S. National Library of Medicine), 2025); [About Parvovirus B19](https://www.cdc.gov/parvovirus-b19/about/index.html) (Centers for Disease Control and Prevention (CDC), 2025).

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/conditions/erythema-infectiosum/