RESUMEN
In February 2016, three influenza B/Victoria/2/87 lineage viruses exhibiting 4- to 158-fold reduced inhibition by neuraminidase inhibitors were detected in Laos. These viruses had an H134N substitution in the neuraminidase and replicated efficiently in vitro and in ferrets. Current antiviral drugs may be ineffective in controlling infections caused by viruses harboring this mutation.
Asunto(s)
Antivirales/farmacología , Farmacorresistencia Viral/genética , Virus de la Influenza B/efectos de los fármacos , Gripe Humana/epidemiología , Gripe Humana/virología , Neuraminidasa/genética , Adolescente , Adulto , Anciano , Sustitución de Aminoácidos , Niño , Preescolar , Femenino , Regulación Enzimológica de la Expresión Génica , Regulación Viral de la Expresión Génica , Humanos , Lactante , Virus de la Influenza B/genética , Laos/epidemiología , Masculino , Persona de Mediana Edad , Adulto JovenRESUMEN
BACKGROUND: Influenza sentinel surveillance in Lao PDR is used to inform seasonal vaccination programs. This analysis reviews epidemiologic and virologic characteristics of influenza virus infection over 8 years, before and after emergence of SARS-CoV-2. METHODS: Data collected for ILI and SARI surveillance during January 2016 through December 2023 were analyzed from nine hospitals. Respiratory specimens from ILI and SARI cases were tested by reverse transcriptase polymerase chain reaction to determine influenza positivity and subtype and lineage. Aggregate counts of outpatient visits and hospitalizations were collected from hospital logbooks. Epidemiologic trends of influenza activity were described, and the proportional contribution of influenza-associated ILI and SARI to outpatient and inpatient loads was estimated. RESULTS: Influenza was detected year-round with positivity peaking during September through January and occurring in most years approximately 1 month earlier in the south than the north. After decreasing in 2 years following the emergence of SARS-CoV-2, influenza positivity increased in 2022 and resumed its typical temporal trend. Influenza-associated ILI contribution to outpatient visits was highest among children ages 5-14 years (3.0% of all outpatient visits in 2023), and influenza-associated SARI contribution to inpatient hospitalizations was highest among children ages 2-4 years (2.2% of all hospitalizations in 2023). CONCLUSIONS: Influenza surveillance in Lao PDR provides clinicians and public health authorities with information on geographic and temporal patterns of influenza transmission. Influenza surveillance data support current vaccination timing and recommendations to vaccinate certain populations, especially young children.
Asunto(s)
Hospitalización , Gripe Humana , Vigilancia de Guardia , Humanos , Laos/epidemiología , Gripe Humana/epidemiología , Gripe Humana/virología , Gripe Humana/prevención & control , Preescolar , Niño , Adolescente , Adulto , Persona de Mediana Edad , Adulto Joven , Lactante , Femenino , Masculino , Anciano , Hospitalización/estadística & datos numéricos , COVID-19/epidemiología , COVID-19/virología , COVID-19/prevención & control , Estaciones del Año , SARS-CoV-2/genética , SARS-CoV-2/aislamiento & purificación , Recién Nacido , Anciano de 80 o más AñosRESUMEN
In March 2021, Lao People's Democratic Republic (Laos) reported an avian influenza A(H5N6) virus infection in a 5-year-old child identified through sentinel surveillance. This was the first human A(H5N6) infection reported outside of China. A multidisciplinary investigation undertook contact tracing and enhanced human and animal surveillance in surrounding villages and live bird markets. Seven Muscovy ducks tested positive for highly pathogenic avian influenza A(H5N6) viruses. Sequenced viruses belonged to clade 2.3.4.4h and were closely related to viruses detected in poultry in Vietnam and to previous viruses detected in Laos. Surveillance and coordinated outbreak response remain essential to global health security.
Asunto(s)
Virus de la Influenza A , Gripe Aviar , Gripe Humana , Animales , Pollos , Preescolar , China/epidemiología , Patos , Humanos , Virus de la Influenza A/genética , Gripe Aviar/epidemiología , Gripe Humana/epidemiología , Laos/epidemiología , Filogenia , Aves de CorralRESUMEN
In May 2012, the first authenticated cases of active chikungunya virus infection were detected in Champasak Province, Southern Laos. Analysis of series of human samples and mosquito specimens collected during the outbreak and over the year that followed the emergence enabled the drawing up of a map of the progression of CHIKV and the establishment of a full genetic characterization of the virus.
Asunto(s)
Aedes/virología , Fiebre Chikungunya/epidemiología , Animales , Biomarcadores/sangre , Fiebre Chikungunya/sangre , Fiebre Chikungunya/patología , Virus Chikungunya/genética , Virus Chikungunya/aislamiento & purificación , Brotes de Enfermedades , Humanos , Laos/epidemiología , Mosquitos Vectores , Filogenia , Estudios SeroepidemiológicosRESUMEN
Although dengue has been a public health problem for several decades in the Lao People's Democratic Republic, the magnitude of the disease burden and epidemiological trends remain poorly understood. We analysed national dengue surveillance and laboratory data from 2006 to 2012 by person, place and time. Between 2006 and 2012, the annual dengue notification rate ranged between 62 and 367 cases per 100 000 population with an apparent geographical expansion of transmission throughout the country in recent years and concurrent co-circulation of all four dengue virus subtypes. An electronic database, called Lao People's Democratic Republic Early Warning Alert and Response Network, was introduced in 2008 to provide automated early warning for outbreaks and epidemics. Village outbreaks continue to be notified primarily through event-based surveillance, whereas the weekly indicator-based system provides systematic assessment of annual epidemic cycles. The dengue case data indicate a high and increasing burden of disease. Efforts now need to focus on using available data to prompt more effective outbreak response and to guide the design and implementation of intervention strategies.
Asunto(s)
Virus del Dengue , Dengue/epidemiología , Brotes de Enfermedades , Vigilancia de la Población , Adolescente , Adulto , Niño , Dengue/prevención & control , Dengue/virología , Femenino , Humanos , Laos/epidemiología , Masculino , Epidemiología Molecular , Especificidad de la Especie , Adulto JovenRESUMEN
BACKGROUND: Information on influenza virology and epidemiology from Lao PDR is limited and the seasonal patterns of influenza have not been previously described. OBJECTIVES: To describe epidemiological and virologic characteristics of influenza in Lao PDR to recommend public health interventions, including improvements in surveillance and response. PATIENTS/METHODS: We performed a descriptive analysis of samples taken from patients with influenza-like-illness (ILI) (fever >38°C with cough and/or sore throat) presenting at seven sentinel hospitals in three regions of Lao PDR, January 2008-December 2010. A nasopharyngeal (NP) swab or combined nasal with oropharyngeal swab was collected from patients with ILI. Samples were tested for influenza by either Luminex RVP, conventional reverse transcriptase PCR (RT-PCR) (January 2008-2009), or by real-time PCR (rRT-PCR) using US CDC reagents (February 2009 onward). RESULTS: Of 2346 samples tested from patients with ILI, 523 (22%) were positive for influenza. The median age of those positive was 12 years (range, <1-60 year). The percentage of samples that were influenza positive was similar over the 3 years (20-23%). Each year 3-4 types/subtypes cocirculated with differing predominant type/subtype. Influenza was detected year-round with the highest proportion of positive specimens in the 3rd and 4th quarter. CONCLUSIONS: Similar to other countries in the region, we found that influenza is present year-round and has a peak activity from July to December. Dominant types or subtypes vary by year. A large proportion of patients with ILI are not influenza positive. ILI surveillance is critical for weighing disease burden, both morbidity and mortality, against the costs of advancing influenza vaccine delivery strategy.
Asunto(s)
Gripe Humana/epidemiología , Gripe Humana/virología , Orthomyxoviridae/aislamiento & purificación , Adolescente , Adulto , Anciano , Niño , Preescolar , Femenino , Humanos , Lactante , Laos/epidemiología , Masculino , Persona de Mediana Edad , Orthomyxoviridae/clasificación , Orthomyxoviridae/genética , Pandemias , Estaciones del Año , Vigilancia de Guardia , Adulto JovenRESUMEN
BACKGROUND: Because of reductions in the incidence of Plasmodium falciparum malaria in Laos, identification of the causes of fever in people without malaria, and discussion of the best empirical treatment options, are urgently needed. We aimed to identify the causes of non-malarial acute fever in patients in rural Laos. METHODS: For this prospective study, we recruited 1938 febrile patients, between May, 2008, and December, 2010, at Luang Namtha provincial hospital in northwest Laos (n=1390), and between September, 2008, and December, 2010, at Salavan provincial hospital in southern Laos (n=548). Eligible participants were aged 5-49 years with fever (≥38°C) lasting 8 days or less and were eligible for malaria testing by national guidelines. FINDINGS: With conservative definitions of cause, we assigned 799 (41%) patients a diagnosis. With exclusion of influenza, the top five diagnoses when only one aetiological agent per patient was identified were dengue (156 [8%] of 1927 patients), scrub typhus (122 [7%] of 1871), Japanese encephalitis virus (112 [6%] of 1924), leptospirosis (109 [6%] of 1934), and bacteraemia (43 [2%] of 1938). 115 (32%) of 358 patients at Luang Namtha hospital tested influenza PCR-positive between June and December, 2010, of which influenza B was the most frequently detected strain (n=121 [87%]). Disease frequency differed significantly between the two sites: Japanese encephalitis virus infection (p=0·04), typhoid (p=0·006), and leptospirosis (p=0·001) were more common at Luang Namtha, whereas dengue and malaria were more common at Salavan (all p<0·0001). With use of evidence from southeast Asia when possible, we estimated that azithromycin, doxycycline, ceftriaxone, and ofloxacin would have had significant efficacy for 258 (13%), 240 (12%), 154 (8%), and 41 (2%) of patients, respectively. INTERPRETATION: Our findings suggest that a wide range of treatable or preventable pathogens are implicated in non-malarial febrile illness in Laos. Empirical treatment with doxycycline for patients with undifferentiated fever and negative rapid diagnostic tests for malaria and dengue could be an appropriate strategy for rural health workers in Laos. FUNDING: Wellcome Trust, WHO-Western Pacific Region, Foundation for Innovative New Diagnostics, US Centers for Disease Control and Prevention
Asunto(s)
Enfermedades Transmisibles/complicaciones , Fiebre/etiología , Enfermedad Aguda , Adolescente , Adulto , Niño , Preescolar , Enfermedades Transmisibles/epidemiología , Femenino , Fiebre/epidemiología , Humanos , Laos/epidemiología , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Estaciones del Año , Adulto JovenRESUMEN
The Lao People's Democratic Republic (PDR) committed to pandemic detection and response preparations when faced with the threat of avian influenza. Since 2006, the National Center for Laboratory and Epidemiology of Lao PDR has developed credible laboratory, surveillance, and epidemiological (human) capacity and as a result was designated a World Health Organization National Influenza Center in 2010. The Lao PDR experience in building influenza capacities provides a case study of the considerable crossover effect of such investments to augment the capacity to combat emerging and re-emerging diseases other than influenza.
Asunto(s)
Gripe Humana/epidemiología , Pandemias/estadística & datos numéricos , Administración en Salud Pública/normas , Líneas Directas/normas , Humanos , Laos/epidemiología , Vigilancia de la Población , Estaciones del Año , Factores de TiempoRESUMEN
Although dengue has been a public health problem for several decades in the Lao People's Democratic Republic, the magnitude of the disease burden and epidemiological trends remain poorly understood. We analysed national dengue surveillance and laboratory data from 2006 to 2012 by person, place and time. Between 2006 and 2012, the annual dengue notification rate ranged between 62 and 367 cases per 100 000 population with an apparent geographical expansion of transmission throughout the country in recent years and concurrent co-circulation of all four dengue virus subtypes. An electronic database, called Lao People's Democratic Republic Early Warning Alert and Response Network, was introduced in 2008 to provide automated early warning for outbreaks and epidemics. Village outbreaks continue to be notified primarily through event-based surveillance, whereas the weekly indicator-based system provides systematic assessment of annual epidemic cycles. The dengue case data indicate a high and increasing burden of disease. Efforts now need to focus on using available data to prompt more effective outbreak response and to guide the design and implementation of intervention strategies.