akinohanayuki ブログ

学位を持っても、センスのない、感染制御専門薬剤師のブログ.  I have Ph.D. but less sense ID pharmacist.


UpToDate より


Primary varicella infection in children is generally a mild disease compared to more severe presentations in adults or immunocompromised patients of any age. The incidences of infection, hospitalizations, and mortality have all declined since the introduction of the varicella vaccine in 1995.

Chickenpox is highly contagious, with secondary household attack rates of >90 percent in susceptible individuals. Transmission occurs in susceptible hosts via contact with aerosolized droplets from nasopharyngeal secretions of an infected individual or by direct cutaneous contact with vesicle fluid from skin lesions.
The clinical manifestations of varicella generally develop within fifteen days after the exposure and typically include a prodrome of fever, malaise, or pharyngitis, followed by the development of a generalized vesicular rash. 
Complications of varicella in children can include bacterial superinfection while pneumonia is more common in adults. 
Patients with a history of underlying malignancy, steroid use or immunosuppressive therapy, HIV infection, or solid organ transplantation are susceptible for disseminated varicella due to impaired cellular immunity.
Primary infection with varicella-zoster virus (VZV) causes chickenpox, with fever and a characteristic vesicular rash. Although varicella is usually a mild, self-limited illness, it can be associated with morbidity and mortality, particularly among immunocompromised hosts and pregnant women.
VZV infection causes two clinically distinct forms of disease: varicella (chickenpox) and herpes zoster (shingles).
●In general, the risk of transmission of VZV infection is higher after exposure to persons with primary varicella compared with herpes zoster. The period of contagiousness is estimated to begin approximately one to two days before the onset of rash during primary varicella. Persons with either illness are not infectious once the lesions have crusted over. 
Essential factors to consider prior to providing post-exposure prophylaxis include assessment of the exposure itself, risk of severe infection, and the patient’s susceptibility to VZV infection. Evidence of immunity can include written documentation of vaccination, prior laboratory evidence of immunity, birth in the United States before 1980, or a prior diagnosis of varicella or herpes zoster illness by a health care provider. 
Whether active immunization (varicella vaccine) or passive immunization (varicella specific antibodies; VariZIG) is offered to a susceptible person with a history of varicella exposure will depend on the host. Varicella vaccine, which contains live attenuated virus, should not be given to patients with altered immunity.
●Immunization with the varicella vaccine is associated with both prevention of infection among susceptible persons and lessening of disease severity in those who do become infected. We recommend varicella vaccine for postexposure prophylaxis in healthy VZV-nonimmune children and adults (Grade 1B). Persons who have a history of only one dose of vaccine should be offered a second dose of vaccine for completion of their series, as long as three months have passed since their first dose. 
●We recommend immunoprophylaxis with VariZIG after VZV exposure for patients who are not candidates for varicella vaccine (eg, pregnant women, infants, and immunocompromised patients) (Grade 1B). 
●When indicated, VariZIG should be administered as soon as possible. The efficacy of VariZIG has only been studied within 10 days of varicella exposure; the efficacy of passive immunization after this time interval is unknown. 
●Patients who receive VariZIG for post-exposure prophylaxis should be monitored for varicella for 28 days after exposure since passive immunization may prolong the incubation period. Patients who develop varicella infection despite prophylaxis should be treated with antiviral therapy.
●Any patient who receives VariZIG should also receive varicella vaccine, provided vaccine is not contraindicated (eg, pregnant females, immunocompromised hosts). Varicella vaccine should be delayed until five months after receipt of VariZIG. 
●Patients with varicella typically develop a fever and a vesicular rash that is pruritic. Many patients require supportive care to manage these symptoms.
●For healthy children ≤12 years, varicella is typically self-limited and we suggest not administering antiviral therapy (Grade 2C). However, we suggest antiviral therapy for immunocompetent children and adolescents who are at increased risk of developing complications from varicella (eg, unvaccinated patients ≥13 years old, individuals with chronic cutaneous or pulmonary disorders, those taking chronic salicylates or inhaled steroids) (Grade 2B). 
●For immunocompetent adults with uncomplicated varicella infection, we suggest oral antiviral therapy in addition to supportive care rather than supportive care alone (Grade 2B). Antiviral therapy can reduce the severity of symptoms and may decrease the risk of complications. We initiate antiviral therapy, regardless of the individual’s vaccination status. We typically administer oral valacyclovir because it can be given in fewer doses compared with acyclovir and has equivalent activity.
●For immunocompromised individuals who present with varicella, we recommend antiviral treatment in addition to supportive care rather than supportive care alone (Grade 1B). For most patients, we suggest initial therapy with intravenous acyclovir rather than oral agents (Grade 2C). Treatment should be administered for 7 to 10 days. 
●For pregnant women who develop uncomplicated varicella, we suggest oral antiviral therapy rather than supportive care (Grade 2C). The management of pregnant women with varicella is discussed elsewhere. 
●For individuals who present with complications related to varicella, intravenous acyclovir should be initiated. Antiviral therapy should be continued for 7 to 10 days.