Prapan Jutavijittum

Possible new hepatitis B virus genotype, southeast Asia.

We conducted a phylogenetic analysis of 19 hepatitis B virus strains from Laos that belonged to 2 subgenotypes of a new genotype I. This emerging new genotype likely developed outside Southeast Asia and is now found in mixed infections and in recombinations with local strains in a geographically confined region.

High genetic diversity including potential new subtypes of hepatitis C virus genotype 6 in Lao People's Democratic Republic

Sera from 105 anti-HCV-positive first-time blood donors collected in 2004, 2005 and 2008 in different provinces in Laos were investigated by PCR. Forty-five samples were positive for HCV (42.86%); two belonged to subtype 1b (2/45, 4.4%) and all others to genotype 6 (43/45, 95.6%), including subtypes 6b, 6h, 6k, 6l, 6n and 6q. Three groups of sequences were not clearly attributable to any genotype 6 subtype, two of which may be regarded as candidates for new subtypes of genotype 6. Two samples were mixed infected with different subtypes or clusters of genotype 6 viruses.

A High Variability of Mixed Infections and Recent Recombinations of Hepatitis B Virus in Laos

In Lao PDR, where more than 8% of the population are chronic carriers of HBsAg, multiple genotypes and subgenotypes co-circulate and are prone to generate recombinant viruses. Phylogenetic analyses of multiple clones per donor revealed mixed infections of subgenotypes B1, B2, B4, C1, C5, I1 and I2 in almost 6% of HBsAg positive rejected blood donors. Recombination analyses and distance calculations furthermore showed that about 65% (17/26) of the mixed infected donors showed recombinations in the S-gene alone, involving the predominant genotypes B and C. These results suggest that, at least in Laos, hepatitis B virus (HBV) mixed infections lead to frequent recombinations. In many donors with recombinant strains, the recombinant fragment and a non-recombinant strain of the same genotype co-existed (127/185 analysed recombinant fragments). For a large proportion of these (60/127), the most closely related known virus was found, although not always exclusively, in the same donor. Recombinant virus strains are largely distinct. This is reflected in an unexpected diversity in recombination breakpoints and the relatively rare recombinations with identical recombination patterns of the same genotypes in different donors. Recent recombination events would explain the limited spread of each of the recombinants. Using a published mutation rate of 4.2×10−5 mutations per site and year, the observed minimum genetic distances of 0–0.60% between parent strain and recombinant fragment would correspond to 0–71 years of evolution from a most recent common ancestor (MRCA). Thus several lines of evidence are suggestive of recent independent recombination events, a proportion of these even occurring within the same donors. In conclusion, our analyses revealed a high variability of mixed infections as a very probable breeding ground of multiple variable recombination events in Laos that so far have not led to new dominant strains.

Clinicopathologic Study of Hepatic Penicillium marneffei in Northern Thailand

CONTEXT Penicillium marneffei, an opportunistic fungus, is endemic in Southeast Asia, especially in human immunodeficiency virus-infected individuals living in northern Thailand. OBJECTIVE We present the results of a clinicopathologic study of hepatic penicilliosis among human immunodeficiency virus/acquired immunodeficiency syndrome patients. DESIGN A search of liver biopsies in one institution from 1998 to 1999 identified 30 cases of penicilliosis. RESULTS Histologically, hepatic lesions could be classified into 1 of 3 patterns: diffuse, granulomatous, and mixed. The diffuse pattern showed a diffuse infiltration of foamy macrophages that contained numerous P marneffei. The granulomatous pattern showed a formation of multiple granulomata with various degrees of inflammatory cell infiltration. The mixed pattern showed features intermediate between the diffuse and granulomatous patterns. Liver function tests of the 3 pathologic pattern groups were evaluated, but there were no statistically significant differences in aspartate aminotransferase, alanine aminotransferase, or alkaline phosphatase levels among the various histologic groups. CONCLUSION To our knowledge, this is the largest series to date that documents the liver pathology that results from this pathogen. We hypothesize that the histologic patterns seen on biopsy reflect the level of the hosts immunity. Hence, in addition to a diagnosis of penicilliosis, a liver biopsy may also provide an assessment of the hosts immune status, whereas liver function tests do not.

Occult hepatitis B infections among blood donors in Lao PDR

In Lao Peoples Democratic Republic, hepatitis B virus is highly endemic. However, blood donations are only screened for HBsAg, leaving a risk of transmission by HBsAg‐negative occult infected donors. Here, we characterized first‐time blood donors to assess prevalence of hepatitis B virus infections and occult infected donors.

Immunity levels to poliovirus in Lao children and adults before the vaccine-derived poliovirus outbreak: A retrospective study

In 2015, several provinces in Lao Peoples Democratic Republic (Lao PDR) experienced a vaccine-derived poliovirus outbreak. This survey was conducted (i) to evaluate the vaccination coverage in different settings and cohorts using the seroprevalence of anti-poliovirus (PV) antibodies as a surrogate measure, and (ii) to explore the usefulness of an ELISA in a country with limited resources and a specific epidemiological setting. IgG antibodies were assessed by ELISA in Lao children (n = 1216) and adults (n = 1228), including blood donors and health care workers. Protective antibody titers against the 3 vaccine serotypes were determined by microneutralization (VNT) in a subset of participants. More than 92% of the children had anti-poliovirus antibodies, regardless of nutritional status or access to health care, highlighting the success of the vaccination outreach activities in the country. In contrast, anti-poliovirus seroprevalence reached only 81.7% in blood donors and 71.9% in health care workers. Participants born before the introduction of poliovirus vaccination in Lao PDR were considerably less likely to be seropositive. These findings align with the epidemiology of the outbreak. Neutralizing antibodies against at least one of the 3 poliovirus serotypes were detected in all children (99/99) and 93/99 had antibodies against all serotypes. Similarly, all health care workers had neutralizing antibodies against at least one and 92/99 against all serotypes. The comparison of both assays shows an acceptable underestimation of vaccine coverage in children by ELISA, but a low sensitivity of the ELISA in the adults. We show that the ELISA is a reasonable alternative to the VNT in particular in vaccinated children, that an improved version should be serotype specific, and that negativity thresholds should be revisited for optimal sensitivity and specificity. Thus, polio-free countries with an uncertain vaccination coverage and limited laboratory capacity, that are at risk of vaccine-derived poliovirus outbreaks or of re-importation of wild poliovirus may benefit from an improved ELISA for cohort studies to evaluate their immunization program in children.

Etiology of viral respiratory infections in Northern Lao People's Democratic Republic: SNOECK et al.

In Lao Peoples 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.

High prevalence of mumps in Lao People’s Democratic Republic

In the Lao Peoples Democratic Republic (PDR), mumps is not a notifiable disease and mumps vaccine is currently not included in the routine childhood immunization programme. In order to assess the burden of disease, we investigated the seroprevalence of mumps-specific IgG antibodies across four provinces. In addition, we genetically characterized mumps viruses from the past 3 years from several outbreaks and single cases. Blood and/or throat swabs from suspected cases were investigated for specific IgM antibodies or viral RNA. Mumps cases occurred between March and November in 2011-2013 and 5- to 15-year-olds were most affected. Four sequences from an outbreak in the north of Lao PDR in 2011 were identical and belonged to genotype G. Eight sequences from two outbreaks and two individual cases from 2012 and 2013 belonged to genotype J. In addition, sera collected from 2379 healthy infants and school pupils aged between 9 months and 19 years and from pregnant women aged between 16 and 46 years were investigated for mumps-specific IgG. Overall, 58.2% were positive, 39.5% were negative and the remaining 2.3% were equivocal. The seropositivity increased with age, with the lowest percentage found in <1-year-old infants (9.1%) and the highest in the cohort of pregnant women (69.2%). More female subjects than male subjects were seropositive (60.4 vs. 54.9%). There were some differences between the locations. Mumps should be a notifiable disease in Lao PDR in order to get more accurate case numbers and cost estimates for public health-care, and vaccination of children and high-risk groups should be considered.