A 55 y.o. schizophrenic comes to the ED with a rash.

The rash appeared to be pustular

Our patient is not immune compromised but had Varicella zoster proven by a viral  culture of the lesions. The differential includes: chloracne since he worked with chemicals, Sweets syndrome and herpes simplex which can produce very similar lesions

In 2019 a Hong Kong reporter was exposed to dioxin in tear gas and devloped chloracne

Chloracne is caused by exposure to halogenated aromatic compounds, such as dioxins. In 1949 226 workers became ill after a container of herbicide exploded at a Monsanto plant in Nitro West Virginia.  Many were diagnosed with chloracne. 

Sweets syndrome is called acute febrile neutrophilc dermatosis and involves a rash diagnosed on biopsy by infiltrating neutrophils.  It ofter occurs  after an illness or medication.  The treatment is steroids

Often the lesions in Sweets syndrome are raised .

Herpes simplex can produce a very similar rash to Varicella zoster.  Often erythema multiforme are visible as in the picture below.

A patient with a cold sore developed erythema multiforme on the palms from herpes simplex.

Varicella zoster

The original exposure to the virus causes chicken pox.  Following infection, usually in childhood, the virus lies latent in the dorsal root ganglia and can reactivate in later life causing herpes zoster; a rash in a dermatomal pattern.  90% of people are exposed to the virus in childhood but it can occur primarily later in life as in our patient.  While only 2% of the cases occur in adults, they account for 50% of the deaths.  Because of the complications of the disease in adulthood and infancy a vaccine containing a live virus was created. 

The virus was initially obtained from a child with natural varicella, introduced into human embryonic lung cell cultures and propagated in embryonic guinea pig cell cultures.  It was finally propagated in human diploid cell cultures.  Because it is a live virus, it is not recommended for pregnant women, those who have received a blood transfusion in the previous five weeks(this is because of the immunoglobulins in blood which would prevent the vaccine from being effective), immunosuppressed individuals, people taking ASA,  or those with tuberculosis. The herpes zoster vaccine is just a stronger version of the varicella vaccine.

Interestingly,  many countries including England and most of Europe do not vaccinate children for varicella since it is not clear how long the immunity lasts.  They do vaccinate health care workers.  Immunity in some Japanese studies lasted up to 20 years in some but in others it lasted less than six years. It is clear that booster shots will be needed  now, whereas in the past natural immunity was maintained by repeated exposure to children with chicken pox.    

fun fact: guinea pigs are not from Guinea and are not related to pigs. They are from South America

Pergam S, Limaye A, Varicella Zoster 2009. Am J Transplant  Dec:9(Suppl ):S108-S115.

Nguyen H, Jumaan A, Seward J. Decline in mortality due to varicella after implementation of varicella vaccine in the US. 2005. NEJM. 352(5):450-8.

Tugwell B, Lee L , Gillette H, et al. chicken pox outbreak in a highly vaccinated school population. 2004 Pediatrics 113(3 Pt. 1 )455-9. Although 97% of students were vaccinated, those vaccinated more than five years before still got chicken pox.

 Varicella and herpes vaccines WHO position paper June 2014 Releve Epidemiolofique Hebdomadaire 89(25):265-87.