Varicella zoster and fever rash surveillance in Lao People's Democratic Republic

BMC Infect Dis. 2019 May 8;19(1):392. doi: 10.1186/s12879-019-3990-7.


Background: In Lao PDR, the epidemiology of varicella infection is uncertain, since it is not a notifiable disease and VZV outbreaks are rarely reported as fever/rash (F/R) diseases.

Methods: We estimated the seroprevalence of VZV (IgG ELISA) in different age cohorts (9 months to 46 years; N = 3139) and investigated VZV and 6 other viruses in patients during F/R outbreaks and in an ad hoc sentinel site in the context of the national reporting system (IgM ELISA, PCR).

Results: At least 80% of the sampled population had evidence of VZV infection before the age of 15. The largest increase in seroprevalence occurred between the age groups 1 to 5 and 6 to 7 year-olds. A VZV outbreak (clade 2) also occurred in this age group mostly during the first year of primary school (median age 6 years, interquartile range 4.0-7.5). During a dengue outbreak, 6% had varicella. At our F/R sentinel site, 14% of children with viral etiology were laboratory diagnosed as varicella and among others, a sizeable number of measles (N = 12) and rubella cases (N = 25) was detected compared to those reported for the whole country (N = 56 and 45), highlighting nationwide a large challenge of underreporting or misdiagnosis of these notifiable diseases because of lack of diagnostic laboratory capacity.

Conclusion: We recommend strengthening the clinical and laboratory diagnosis of VZV, measles and rubella, the surveillance and reporting of notifiable F/R diseases by retraining of healthcare workers and by setting up sentinel sites and enhancing laboratory capacity.

Keywords: Fever-rash; Measles; Serostudy; Surveillance; Varicella.

MeSH terms

  • Adolescent
  • Adult
  • Antibodies, Viral / blood
  • Chickenpox / diagnosis
  • Chickenpox / epidemiology
  • Child
  • Child, Preschool
  • Dengue / epidemiology
  • Dengue / etiology
  • Disease Outbreaks
  • Enzyme-Linked Immunosorbent Assay
  • Exanthema / epidemiology
  • Exanthema / virology*
  • Female
  • Fever / epidemiology
  • Fever / virology*
  • Herpes Zoster / epidemiology
  • Herpesvirus 3, Human / genetics
  • Herpesvirus 3, Human / immunology
  • Herpesvirus 3, Human / isolation & purification
  • Humans
  • Infant
  • Laos / epidemiology
  • Male
  • Measles / diagnosis
  • Measles / epidemiology
  • Middle Aged
  • Rubella / diagnosis
  • Rubella / epidemiology
  • Seroepidemiologic Studies
  • Varicella Zoster Virus Infection / epidemiology*
  • Varicella Zoster Virus Infection / etiology


  • Antibodies, Viral