Ringworm (erythema infectiosum) (synonyms: erythema infektiosum; exanthema variegatum; fifth-disease; fifth disease; parvovirus B19 infection; ICD-10-GM B08.3: erythema infectiosum [fifth disease]) is an infectious disease caused by human parvovirus B19 (B19V). Human parvovirus B19 infection.
Occurrence: The infection occurs worldwide. The contagiousness (infectiousness or transmissibility of the pathogen) is very high, but not as highly contagious as measles or varicella (chickenpox). It exists even before clinical symptoms appear! Ringworm viruses are resistant to most disinfectants (resistant). Epidemiologically, endemic cycles are observed every 3-4 years. Seasonal accumulation of the disease: Ringworm occurs more frequently in spring and winter. Transmission of the pathogen (route of infection) occurs via droplets produced by coughing and sneezing and absorbed by the other person through the mucous membranes of the nose, mouth and possibly the eye (droplet infection) or aerogenically (through droplet nuclei containing the pathogen (aerosols) in the exhaled air) or by smear infection or contact with body fluids such as saliva or blood.Parvovirus B19 can also be transmitted with breast milk. The incubation period (time from infection to onset of disease) is usually 6-18 days. Peak incidence: The disease occurs predominantly in young children and schoolchildren, between 6 and 15 years of age. Up to 50% of children and adolescents have antibodies to human parvovirus B19 (in their blood). In the elderly, the rate of contamination increases to 80%. Seroprevalence (percentage of patients tested serologically positive) is approximately 40-60% depending on age; 95% in those over 75 years of age. Women of childbearing age have a seroprevalence of 69-72 %. Parvovirus B19 is responsible for several different diseases. These include:
- Erythema infectiosum (ringworm).
- Transient anemia – temporary reduction of red blood cells in the blood.
- Transient arthritis – temporary inflammation of the joints.
- Transient arthralgia – temporary joint pain.
The duration of infectivity (contagiousness) persists until the exanthema (skin rash) becomes visible and probably for several days after. 5 days after the onset of exanthema, children can be allowed back into community settings. The disease leaves lifelong immunity. Course and prognosis: In children with functioning immune systems, the disease is asymptomatic (without obvious symptoms) in more than one-third of infections. Occasionally, there are severe courses associated with myocarditis (inflammation of the heart muscle) and encephalitis (inflammation of the brain). The course is more severe in adults compared to children. Usually, the course is good in otherwise healthy individuals. After 10-14 days, the exanthem (rash) subsides spontaneously (by itself). For pregnant women who have not yet formed antibodies against the virus (i.e. have not had contact with parvovirus B19), the risk of complications is increased in the event of infection. This is mostly abortions (miscarriages) in early pregnancy.From 20 + 0 weeks of pregnancy, the fetal risk of complications decreases.Even a primary infection of the mother in the third trimester (third trimester of pregnancy) can still affect postnatally (after birth) in the first days of life of the newborn. Note: Parvovirus B19 (B19V) is neither embryotoxic (“toxic to the embryo“) nor teratogenic (effects that can cause malformations in the unborn child). From the 20th week of pregnancy onwards, sonographic progress controls are carried out weekly for 8 (-12) weeks, which serve in particular to diagnose fetal anemia. This ensures adequate therapy such as an intrauterine transfusion or a scheduled delivery by means of caesarean section if necessary. A vaccination against ringworm is not yet available.
