Etiology of viral respiratory infections in Northern Lao People's Democratic Republic

Abstract

In Lao People's Democratic Republic (PDR), acute respiratory infections overburden the health care system, but viral etiology, genetic diversity, and seasonality, especially in light of the introduction of influenza vaccination in the country, are poorly understood. From August 2010 to April 2011, 309 outpatients were recruited at the Luang Prabang Provincial Hospital covering highland Lao communities. Nasopharyngeal swabs were screened for the presence of 13 respiratory viruses. At least one virus was detected in 69.6% and dual/triple viral infections in 12.9%/1.9% of the patients. Influenza A and B viruses combined were the most frequently detected pathogens, followed by human adenovirus and respiratory syncytial virus (RSV). The other viruses were detected in less than 10% of the patients. Phylogenetic analyses on a representative set of RSV strains revealed that, while otherwise very rare, the RSV-B CB1/THB genotype cocirculated with other common genotypes. A single wave of influenza virus and RSV activity was observed during the rainy season, providing further support to influenza vaccination before the onset of the rains. This study provides recommendations for influenza vaccination that still needs optimization and highlights the need for revised guidelines for treatment and prevention of respiratory infections in Lao PDR, as well as for increased surveillance efforts.

Human influenza viruses in South-East and East Asia: a systematic review of seasonal patterns, viral types/subtypes, and antiviral susceptibility pattern in the past two decades

“…21 This pattern is different from the seasonal peaks observed in other SE-Asia countries. 17,21,22 However, a similar all-year-round transmission has been observed in other countries in the region with a tropical and sub-tropical climate. 21,22 Moreover, in the review, peak influenza infection in East-Asia occurred between March-July which also corresponds with the winter season in the southern hemisphere.…”

“…35 For instance, there are reports of the emergence of the new clade 1.1.2 and 2.3.2.1 reassortant A(H5N1) virus and clade 3c.2a and 3c.3a A(H3N2) virus between 2012-2015. 15,17 Within this same period, other new reassortant clades were detected for influenza A (H3N2) and B viruses in Laos PDR, Taiwan, Malaysia, Myanmar, Thailand, Japan, China and Vietnam. 35,36 The finding implies that there is the need for a sustained approach in the regions periodic update of information provided to the WHO global influenza surveillance response (GISRS) system which is a mechanism designed by the WHO for deciding the antigenic and genetic composition of influenza vaccines used in the different hemispheric zones.…”

“…1,3,4,12,[14][15][16] The most recent pandemic caused by the novel influenza A virus strain A(H1N1) pdm09 which started in 2009 originated from Mexico and America and later spread to over 214 countries including South-East and East Asia causing over 18,449 deaths globally. 1,3,4,16,17 Surveillance data has shown influenza rates of 11-26% in out-patient and 6-14% in hospitalized patients in both regions. 4 However, the majority of Asian countries lie in the northern hemisphere with seasonal influenza patterns varying across the continent and in countries in the southern hemisphere.…”

Current Animal Models for Understanding the Pathology Caused by the Respiratory Syncytial Virus

“…Human respiratory syncytial virus (hRSV) is an enveloped, single-stranded, and negative-sense RNA virus belonging to order Mononegavirales , family Pneumoviridae , genus Orthopneumovirus , species Human orthopneumovirus (Hacking and Hull, 2002; Borchers et al., 2013; Afonso et al., 2016; Snoeck et al., 2018). This virus is a human pathogen that causes a major burden in public health, both in developing and in industrialized countries (Simoes, 2003; Zang et al., 2015; Kuhdari et al., 2018).…”

Epidemiology of acute respiratory viral infections in children in Vientiane, Lao People's Democratic Republic

“…Thus, our data and other surveillance activities revealed two influenza seasons of equal intensities in 2015. This situation contrasts with the overall reported pattern of influenza circulation with low but steady levels of transmission from January to August followed by a period of increased transmission between September and December (Figure ) 2,21 . Current recommendations for seasonal influenza vaccination in April–May in Lao PDR 30,31 seem adequate to protect the population during the main influenza period.…”