During July 2017, seven paediatric burns patients between the ages of 10 months and 5 years presented with a maculopapular rash at a tertiary hospital in Gauteng, South Africa. Four of these patients were female. The rash was associated with both fever and coryza in four of the cases. The characteristics of the cases involved in this cluster are shown in Table 1. The cluster was reported to the National Institute for Communicable Diseases. Due to a concurrent measles outbreak in the province, measles was initially suspected. The rash subsequently evolved and became vesicular in two of the cases, affecting the limbs and hands in one of the cases (Figure 1). Contemporaneously, an eighth patient presented with a vesicular rash on the trunk and on both upper and lower extremities bilaterally. Of note is that this patient did not initially present with a maculopapular rash. Varicella-zoster became a differential diagnosis. As children are not routinely immunised against varicella in South Africa's public health sector, the cost, availability and resource utilisation of prophylactic varicella immunoglobulins for the cases posed a number of challenges. The natural history in the cases that developed the vesicular lesions was also atypical of the varicella-zoster infection. There was therefore a possibility of administering the immunoglobulins unnecessarily. Other possible diagnoses that were considered included enterovirus and pox infections. An investigation was initiated by the National Institute for Communicable Diseases in order to establish the cause of the illness. A composite case definition that was used to identify other cases in the ward included any patient who was admitted to the unit during July 2017, presenting with a maculopapular or vesicular rash, with or without fever or coryza. The medical records of suspected cases were reviewed using a pre-designed case investigation form. Cases were also examined for any residual or new symptoms. Further information on the history of the illness was also obtained from the caregivers of some of the cases. Blood samples were collected for serological and molecular testing using the following assays: Siemens Enzygnost  measles IgM and rubella IgM EIA (Siemens, Marburg, Germany), Liaison  VZV IgM CLIA (DiaSorin, Saluggia, Italy), HerpeSelect  HSV-1 EIA (Focus Diagnostics, Cypress, California, United States), Genesig  Herpes Simplex Virus type 1 and 2 real-time polymerase chain reaction kit (PrimerDesign Ltd, Southampton, Hampshire, United Kingdom). Vesicular fluid and scab samples were collected and submitted to the National Institute for Communicable Diseases for transmission electron microscopy using negative staining.
Measles, rubella and varicella infections were excluded based on negative serological testing. Viral particles consistent with those of the Herpesviridae family were seen on electron microscopy of the vesicular fluid, while no virions were detected in the scab specimen (Figure 2). Based on these electron microscopy findings, further laboratory testing for herpes viruses was conducted, and HSV1 was confirmed based on serological and molecular testing. The medical record review of other patients in the ward identified two other cases with a documented vesicular rash. A timeline showing the sequence of events in this investigation is shown in Figure 3.
Due to the initial differential diagnosis of measles, cases were given vitamin A, and measles vaccine was administered to all ward contacts below the age of 5 years. All of the cases recovered completely without any complications.