A varicella outbreak in B-cell lymphoma patients receiving rituximab-containing chemotherapy

Varicella, characterized by a vesicular rash, occurs primarily in young children. Although older individuals can also be affected or vaccinated, outbreaks among adults are rare. We investigated a small outbreak of varicella in B-cell lymphoma patients for elucidation of risk factor of the disease. We experienced four cases of varicella after an index herpes zoster case. All varicella cases were confirmed varicella zoster virus (VZV) infection by PCR. All varicella cases occurred in diffuse large B-cell lymphoma patients receiving rituximab-containing chemotherapy. On the other hand, only three of the 18 non-varicella patients in the same room were receiving rituximab-containing chemotherapy (P = 0.005). All varicella patients had detectable serum anti-varicella zoster virus IgG antibodies before chemotherapy. Even in the presence of neutralizing antibodies to the virus, lymphoma patients treated with rituximab-containing chemotherapy can possibly become re-infected with varicella. These findings suggest that zoster patients should be strictly isolated in hematology and oncology ward, and prophylactic acyclovir should be considered for such patients when exposed to zoster/varicella.