The physical signs of measles are nearly the same as those of smallpox, but nausea and inflammation is more severe. The rash of measles usually appears at once, but the rash of smallpox spot after spot . .
Chickenpox has become much less common since the introduction of the varicella vaccine in 2000 and its inclusion on the National Immunisation Program in 2005, because of both individual and herd immunity.1 Prior to this, nearly all children acquired it (<80% of the Australian population were seropositive by their teens). Chickenpox has a complication of only 1%, and is often thought of as not being a serious disease—which mostly it isn’t—but because it was so common prior to the vaccine’s introduction it resulted in 1500 hospital admissions and 7–8 deaths a year.1
Chickenpox is a highly contagious infection caused by the varicella zoster virus, a DNA virus within the herpes virus family. Primary infection causes chickenpox (varicella), with the virus establishing latency in the dorsal root ganglia. Reactivation leads to herpes zoster (shingles), which is relatively uncommon in children and can be more difficult to diagnose as it often presents with only a few lesions.
Note: shingles can happen in childhood.
The clinical features of varicella are shown in TABLE 93.1 and the complications in TABLE 93.2. Children are not normally very sick but tend to be lethargic and have a mild fever. Adults have an influenza-like illness. The typical distribution is shown in FIGURES 93.1 and 93.2.
Table 93.1Clinical features of varicella |Favorite Table|Download (.pdf) Table 93.1 Clinical features of varicella
Children: no prodrome
Adults: prodrome (myalgia, fever, headaches) for 2–3 days
Centripetal distribution, including oral mucosa (see FIG. 93.1)
Lesions can become infected
‘Cropping’ phenomenon: vesicles, papules, crusting lesions present together
Degrees of severity
Number of vesicles can vary from fewer than 10 to thousands (usually 200–500)1
Mild cases can be missed
More severe in adults and the immunocompromised
Viral pneumonia rare in children, uncommon in adults
Death rare except in the immunocompromised and neonates with congenital varicella
Table 93.2Complications of varicella |Favorite Table|Download (.pdf) Table 93.2 Complications of varicella
Bacterial infection of cutaneous lesions (usually staphylococcal or streptococcal); can take form of cellulitis or bullous impetigo
Can leave pitted scars
Birth defects with neonatal infection
Acute cerebellitis (ataxia, normal mental state)
Varicella (chickenpox) in a 12-year-old girl showing a maculopapular vesicular rash with a centripetal distribution