Chickenpox risk factors

Immunocompromised patients
Immunocompromised persons who get varicella are at risk of developing visceral dissemination (VZV infection of internal organs) leading to pneumonia, hepatitis, encephalitis, and disseminated intravascular coagulopathy. They can have an atypical varicella rash with more lesions, and they can be sick longer than immunocompetent persons who get varicella. The lesions may continue to erupt for as long as 10 days, may appear on the palms and soles, and may be hemorrhagic.

People with HIV or AIDS
Children with HIV infection tend to have atypical rash with new crops of lesions presenting for weeks or months. HIV-infected children may develop chronic infection in which new lesions appear for more than one month. The lesions may initially be typical maculopapular vesicular lesions but can later develop into non-healing ulcers that become necrotic, crusted, and hyperkeratotic. This is more likely to occur in HIV-infected children with low CD4 counts.

Some studies have found that VZV dissemination to the visceral organs is less common in children with HIV than in other immunocompromised patients with VZV infection. The rate of complications may also be lower in HIV-infected children on antiretroviral therapy or HIV-infected persons with higher CD4 counts at the time of varicella infection. Retinitis can occur among HIV-infected children and adolescents.

Most adults, including those who are HIV-positive have already had varicella disease and are VZV seropositive. As a result, varicella is relatively uncommon among HIV-infected adults.

Pregnant women
Pregnant women who get varicella are at risk for serious complications; they are at increased risk for developing pneumonia, and in some cases, may die as a result of varicella.

If a pregnant woman gets varicella in her 1st or early 2nd trimester, her baby has a small risk (0.4 – 2.0 percent) of being born with congenital varicella syndrome. The baby may have scarring on the skin, abnormalities in limbs, brain, and eyes, and low birth weight.

If a woman develops varicella rash from 5 days before to 2 days after delivery, the newborn will be at risk for neonatal varicella. In the absence of treatment, up to 30% of these newborns may develop severe neonatal varicella infection.