- 1 Fifth’s disease medical definition
- 2 If this is fifths disease, is there a first, second, third and fourth disease as well?
- 2.1 A little about parvovirus B19
- 2.2 Why do parvoviruses specifically attack the red blood cells?
- 2.3 How is Parvovirus B19 virus spread from one person to another?
- 2.4 How common is fifths disease?
- 2.5 What are the signs and symptoms of Fifths disease?
- 2.6 The other features of erythema infectiosum include:
- 2.7 How is fifths disease diagnosed?
- 2.8 What is the treatment for Fifths disease?
- 2.9 How can you prevent Fifths disease?
Fifth’s disease medical definition
Fifths disease is a viral infection that produces a rash on the body. This disease is also known as Erythema infectiosum and is caused by Parvovirus B19. The transmission of this virus is via the respiratory route, presumably via the spread of large airborne droplets when an infected person coughs or sneezes. Infections with Parvovirus B19 are common and occur worldwide. It most commonly occurs in the school aged children. the patients develop a red rash on the face known as the slapped cheek rash. This rash is the most characteristic feature of Fifths disease and is most commonly seen in children than in adults. The diagnosis of fifths disease is a clinical one.
What is fifths disease in toddlers?
Fifths disease is a viral infection that produces a rash on the body. The virus which is responsible for this condition is known as Parvovirus B19. This disease is also known as Erythema infectiosum. It got its name as fifths disease because this disease was listed as the fifth in a list of classification of common skin rashes made in the past. Erythema infectiousum or the fifths disease is a common infection which is commonly seen in children, especially those of the school age. However, it can occur in adults as well.
If this is fifths disease, is there a first, second, third and fourth disease as well?
Of courses, yes! As mentioned earlier, this condition got its name from a historical classification of common skin rashes. These are also known as viral exanthems. Since Erythema infectiousum was classified as the fifth in that list, it is known as Fifths disease. There are other conditions in the first, second, third, fourth and the sixth places as well. These common 6 classical exanthems as put in the historical classification include:
- First disease – Measles (Rubeola)
- Second disease – Scarlet fever
- Third disease – German measles also known as Rubella
- Fourth disease – A variant of scarlet fever known as Duke’s Fillatow disease
- Fifth disease – Erythema infectiousum
- Sixth disease – Roseola also known as Erythema subitum.
Even though this classification shows only six of the common skin rashes, there is more than this. All the other exanthems are broadly described as atypical exanthems.
A little about parvovirus B19
Fifths disease is a viral condition and is caused by a virus known as the Parvovirus B19. Parvovirus is group of viruses that include a number of animal pathogens. The parvovirus is a small, single stranded DNA virus. This group of viruses are common infectious agents of a variety of animal species such as mammals, birds and insects. These viruses can infect humans too but out of the many parvoviruses, only 4 different types of parvoviruses are known to infect humans. These 4 types include:
- Adeno associated virus (AAVs)
- Parvovirus B19 (B19)
- Human Boca virus (HBoV)
- Parvovirus 4
Out of these 4, onlyParvovirus B19 and Human Boca virus are pathogenic to humans. Out of the 2 pathogenic ones, parvovirus B19 is the most well studied and clinically important human parvovirus.
The parvovirus B19 is composed of a protein capsid but does not have an envelope. They are single stranded DNA viruses. They have specific properties such as heat and solvent resistance which gives them a chance to survive. The parvovirus B19 does not have a DNA polymerase enzyme within themselves which is an essential structure needed for the replication of these viruses. Therefore the Parvovirus B19 cannot replicate on its own. They have to get inside a host cell to replicate properly. These viruses replicate effectively in the erythroid progenitor cells which are derived from:
- Human bone marrow
- Umbilical cord blood
- Peripheral blood
The target cell of the Parvovirus B19 is the erythroid cells. These are the cells that ultimately give rise to red blood cells. Viral infection of these erythroid cell lines will lead to lysis of these cells and therefore the erythroid precursors will deplete and hence the number of red blood cells. As a result there will be a drop in the hemoglobin level and therefore anemia pursues. The process of red blood production is known as erythropoiesis. During an infection with the Parvovirus B19, erythropoiesis also arrests transiently which also contributes to the development of the anemia in these patients.
Why do parvoviruses specifically attack the red blood cells?
The erythroid cell line consists of a P blood group antigen on their cell membranes. This is the place where the parvoviruses attack. This is why they mainly attack the cells of the erythroid cell line. However, these P antigens are also found on the cell membranes of the endothelial cells, placental cells and the fetal myocardial cells. Therefore they can attach these cells as well but the most commonly affected cell type is the red blood cell.
How is Parvovirus B19 virus spread from one person to another?
The transmission of this virus is via the respiratory route, presumably via the spread of large airborne droplets when an infected person coughs or sneezes. They spread through the respiratory secretions such as such as saliva, sputum, or mucus secreted from the nose. The transmission rate is about 15% to 30%.
Although the primary mode of transmission of this virus is via the respiratory route, transmission can also occur through blood and blood products. Knowing that these viruses have a property of solvent resistance, there is a possibility that these viruses will transmit via fomites as well. However, this mode of transmission has not been established.
Once the patient develops the rash, they are less likely to be contagious and therefore it is safe for the patient to go to school or work. However, if this infection occurs in patients with a weakened immune system, then they are more likely to be more contagious for a longer period of time compared to the others. This is because of the fact that these immunocompromised patients have a weakened immune system and therefore are not competent enough to produce antibodies against these viruses as effectively as the other individuals with a healthy immune system.
The good news about this is that once you recover from the infection by a parvovirus B19, you will develop immunity against this infection and will protect you from the parvovirus B19 infection in the future.
How common is fifths disease?
Infections with Parvovirus B19 are common and occur worldwide. It most commonly occurs in the school aged children. 70% of the cases of Parvovirus B19 infection occur in patients between the ages of 5 and 15 years.
Seasonal peaks also have been identified, where the fifths disease seems to have a higher incidence during the late winter and spring. However, sporadic infections can occur though out the year.
What are the signs and symptoms of Fifths disease?
The signs and symptoms of fifths disease usually occurs within 4 to 28 days after the infection with the Parvovirus B19 virus. This is known as the incubation period. This disease occurs in two phases and in each of the phase give rise to different signs and sympotms.
The first phase is known as the prodromal phase and this phase is usually mild and may include:
- A mild low grade fever
- Symptoms of an upper respiratory tract infection such as a runny nose.
Following this phase is the phase with the characteristic rash. This rash appears in three different stages. During stage 1, the patients develop a red rash on the face known as the slapped cheek rash. The reason why this name is given is because this red rash on the face looks as if someone has slapped on the face and hence the name slapped cheek appearance. This rash is the most characteristic feature of Fifths disease and is most commonly seen in children than in adults. During the second stage of this phase which occurs a few days later, the rash spreads to the trunk and the proximal extremities. The rash on the trunk and the proximal extremities appears as a diffuse macular erythema. The rash is more prominent over the extensor surfaces of the arms and legs that is the posterior surface of the upper limbs and the anterior surface of the lower limbs. However, this rash typically spares the palms and the soles.
During stage 3, the rash slowly begins to disappear. It starts with a central clearing of the macules giving it a lacy reticular appearance. The rash usually spontaneously disappears over 1 to 3 weeks without desquamation of the skin. However, the skin rash can recur if you are exposed to sunlight, heat, exercise and stress. Older children and young adolescents may complain of a mild pruritus of the rash.
A minor group of patients can present with other features such as:
- A petechial rash
- Atypical popular, purpuric, vesicular rash
- Lymph node enlargement (lymphadenopathy)
The other features of erythema infectiosum include:
- Joint pains and swelling. This feature is commonly complained by the adults and the older adolescents. There seems to be a tendency where females are more affected with arthropathy compared to males. These patients often complain of a diffuse multiple involvements of the joints associated with morning stiffness. This is known as the poly arthropathy syndrome.
Any joint can be involved but the most commonly affected joints are those of the hands, wrists, knees and the ankles. This joint pain is also self-limiting and usually resolves within 2 to 4 weeks. However, in rare cases, this joint pain can sometimes last for months or longer than that even.
- Papular purpuric gloves and socks syndrome (PPGSS)
This cutaneous manifestation is a rare occurrence and is characterized by the following signs and symptoms:
- Painful edema
- Erythema in the distal extremities showing a gloves and socks distribution.
This condition is also self-limiting meaning that it will disappear spontaneously without the need for any treatment. It usually takes a few weeks for these features to resolve.
- Foetal infections
If mothers who are pregnant get infected with parvovirus B19, their foetuses can also get this infection. Why is this? This is because this virus has the ability to cross the placenta and infect the red blood cells of the foetus. Since the red blood cell production of the foetus commences from the 6th week of period of gestation onwards, they tend to get infected after the 6th week of gestation. Therefore the foetuses can also develop anaemia while inside the uterus. Although the parvovirus B19 is not teratogenic, it can cause anaemia in the foetus and in severe cases can lead to high output heart failure and eventually death. This is why women who are pregnant are advised to be extremely careful of infections and also to take the necessary immunisations before pregnancy is planned.
How is fifths disease diagnosed?
The diagnosis of fifths disease is a clinical one. The mot characteristic feature of this disease is the slapped cheek appearance that these patients develop which helps the health care provider to diagnose Fifths disease instantaneously. There are not many specific tests available to diagnose fifths disease. However, there is a blood test that can be done to study the viral DNA’s which will be helpful to diagnose this condition in cases where the disease is not certain. This is especially true in pregnant women who may have been exposed to the parvovirus B19 virus. In cases where there is foetal death of unknown cause, these viral DNA studies can be done to diagnose this condition.
During serology, what we specially look for is the immunoglobulins produced against the Parvovirus B19 virus. In case of an acute or recent infection, the levels of anti B19 IgM will be raised whereas in a case of a past infection or immunity, the levels of anti B19 IgG will be raised.
What is the treatment for Fifths disease?
Fifth disease usually does not require any treatment. It is a mild infection and usually disappears on its own. This is especially true for healthy children and adults. They recover completely. The only treatment that is given for patients with Fifths disease is symptomatic treatment where the treatment mainly targets on relieving symptoms such as fever, itching and joint pain and swelling.
How can you prevent Fifths disease?
There is not vaccine or drug per se available to prevent the development of a Parvovirus B19 infection. However, there are ways in which you can reduce the chance of developing this infection and these include:
- Wash your hands with soap and water especially after having contact with fomites belonging to an infected person.
- Cover your mouth and nose if you are sneezing or coughing.
- Do not touch your eyes, nose or mouth as these can be potential ports of entry for these organisms.
- Stay away from close friends or relatives who may have this infection. Avoid close contact with them.
- If you have any other infection¸ it is best that you stay at home until you recover.
Once the patient develops the rash, they are less likely to be contagious and therefore it is safe for the patient to go to school or work. However, if this infection occurs in patients with a weakened immune system, then they are more likely to be more contagious for a longer period of time compared to the others.