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

Abstract

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. Electronic supplementary material The online version of this article (10.1186/s12879-019-3990-7) contains supplementary material, which is available to authorized users.

Susceptibility to Vaccine-Preventable Diseases in Four Districts of Xaysomboun Province, Lao People’s Democratic Republic

“…Seroprotection against rubella in our study was higher than measles in all age groups with 91.2% overall. This is similar to other provinces [ 27 ] and high seroprevalence in children could reflect wild-type rubella circulation [ 32 ], or vaccination—suggesting a difference in immunogenicity between measles and rubella components of the MR vaccine [ 14 , 33 ]. In contrast, the high seroprevalence in adults born before introduction of rubella vaccination in 2011 is likely to be due to rubella virus infection or SIA for younger adults.…”

Population Immunity to Varicella Zoster Virus in the Republic of Belarus

“…Исследования серопревалентности у работников здравоохранения или студентов продемонстрировали колебания уровней серонегативных в диапазоне от < 5% в США до 14 -9% в Саудовской Аравии, 26% -в Индии и около 50% -в Шри-Ланке [15]. В то же время проведенные недавно исследования в Лаосской Народно-Демократической Республике показали, что к возрасту 15 лет более 80% обследованной популяции (3139 человек в возрасте 9 месяцев -46 лет) имели антитела к вирусу Varicella Zoster, наибольшее накопление серопозитивных лиц отмечалось в возрастных группах 1-5 и 6-7 лет [21].…”

Waning of Maternal Antibodies against Measles Suggests a Large Window of Susceptibility in Infants in Lao People’s Democratic Republic

“…From 2016 to 2018, a total of 21 measles cases (8, 3, and 10 respectively) were reported, while a resurgence in 2019 resulted in 1037 confirmed and clinically compatible cases of measles, many of which were in children under five [ 15 , 18 ]. Since measles surveillance and reporting remain suboptimal in Lao PDR, with probably many undetected cases and those suspected not commonly confirmed in the laboratory, these figures may underestimate the real measles burden in the country [ 19 , 20 , 21 ].…”