Boston exanthem disease

Boston exanthem disease, also known as Boston fever or sixth disease, is a viral infection primarily affecting children. Characterized by its distinctive rash, fever, and flu-like symptoms, it is caused by the human herpesvirus 6 (HHV-6) and, less commonly, human herpesvirus 7 (HHV-7). This disease is part of the group of illnesses commonly referred to as the exanthematous diseases, which also includes measles, rubella, and roseola, among others.

Etiology

Boston exanthem disease is primarily caused by two closely related viruses: human herpesvirus 6 (HHV-6) and human herpesvirus 7 (HHV-7). These viruses are part of the Herpesviridae family, which includes other viruses responsible for conditions such as genital herpes, chickenpox, and mononucleosis. HHV-6 is further divided into two variants: HHV-6A and HHV-6B, with the latter being more commonly associated with Boston exanthem disease.

Symptoms

The initial presentation of the disease often includes a high fever that lasts for three to five days, followed by a sudden rash as the fever subsides. The rash is typically pink or red and may have small flat spots or raised lesions. It usually starts on the trunk and then spreads to the limbs and neck but rarely affects the face. Other symptoms may include irritability, mild diarrhea, coughing, and swollen lymph nodes.

Transmission

Boston exanthem disease is contagious and can be spread through direct contact with saliva, nasal secretions, or the tears of an infected person. It can also be transmitted via airborne droplets from coughs or sneezes. Mothers can transmit the virus to their infants during childbirth. The disease is most contagious during the febrile phase before the rash appears.

Diagnosis

Diagnosis of Boston exanthem disease is primarily based on the clinical presentation of fever followed by a rash. Laboratory tests, including serology and polymerase chain reaction (PCR), can confirm the presence of HHV-6 or HHV-7. However, these tests are not routinely performed unless complications arise or the diagnosis is uncertain.

Treatment

There is no specific antiviral treatment for Boston exanthem disease. Management focuses on symptomatic relief, such as fever reduction with acetaminophen or ibuprofen and ensuring adequate hydration. Antiviral therapy may be considered in severe cases or for immunocompromised patients.

Complications

While most children recover without any long-term effects, complications can occur, especially in immunocompromised individuals. Complications may include encephalitis, hepatitis, and, rarely, a condition known as hemophagocytic lymphohistiocytosis (HLH), which is a severe systemic inflammatory syndrome.

Prevention

There is currently no vaccine available for the prevention of Boston exanthem disease. Good hygiene practices, such as regular handwashing and avoiding close contact with infected individuals, are the best methods to reduce the risk of transmission.

Epidemiology

Boston exanthem disease is a global disease, with cases reported in various parts of the world. It primarily affects infants and young children, with the majority of infections occurring in those under two years of age. Most children have been exposed to HHV-6 by the age of three.

History

The disease was first identified in Boston in the 1940s, hence the name Boston exanthem disease. It was initially thought to be a form of rubella or measles due to the similar rash. The viral cause, HHV-6, was not identified until the 1980s.