Analysing the characteristics of a measles outbreak in Houaphanh province to guide measles elimination in the Lao People’s Democratic Republic

Introduction: In recent years, the incidence of measles has declined in the Lao People’s Democratic Republic. However, an outbreak was reported in August 2014 in Houaphanh province, which was the biggest outbreak in the country since 2008. We describe the characteristics of this outbreak and outline critical interventions for the Lao People’s Democratic Republic to achieve measles elimination. Methods: Fever and rash cases in the Khouan and Samtai districts with an onset date from 1 September to 25 October 2014 were investigated. Active case finding and health facility record reviews were carried out. Appropriate samples from the individuals with suspected measles were tested to confirm the diagnosis. Results: A total of 265 suspected cases including 12 deaths were reported from eight villages in the Khouan and Samtai districts. Forty-five individuals tested positive for measles IgM. Most of the confirmed patients were male (n = 28, 62%), less than 5 years old (n = 23, 51%) and from the Hmong ethnic community (n = 44, 98%). The majority of the people with suspected measles (n = 213, 80%) and all the confirmed ones were unvaccinated. A measles vaccination campaign conducted in the eight affected villages resulted in 76% coverage of the targeted population. Discussion: Low routine coverage and measles occurrence among unvaccinated individuals indicate underimmunized areas. The geographical and sociodemographic characteristics of this outbreak highlight the need for tailored vaccination strategies to close the immunity gap. A sensitive surveillance system that is able to detect, notify, investigate and guide response measures, including a second measles dose in the routine immunization schedule, will be essential for the Lao People’s Democratic Republic to attain its measles elimination status

Hidden varicella outbreak, Luang Prabang Province, Lao People's Democratic, December 2014 to January 2015

Background: In January 2015, the Lao People’s Democratic Republic Ministry of Health received a report of 34 cases of fever and rash with one laboratory-confirmed measles case in Houitone village, Pakseng District of Luang Prabang Province. Between 21 and 27 January, we conducted a field investigation to determine the etiology, magnitude and severity of this outbreak. Methods: We conducted active case findings in Houitone and neighbouring villages and collected information on age, location, date of rash onset, symptoms and measles vaccination status. We collected serum samples from cases with rash onset of less than 28 days and tested for measles and rubella IgM using enzyme-linked immunosorbent assay. Results: Between 22 December 2014 and 23 January 2015, 190 fever and rash cases were identified in seven villages in Pakseng District with the majority of the cases in Houitone village. The most affected age group was between 1 and 9 years. The majority of the rashes were vesicular. Of the additional 43 serum samples collected, no samples tested positive for measles or rubella IgM. The clinical manifestation and epidemiology of the disease suggested a varicella outbreak. Conclusion: The rapid response to a single laboratory-confirmed measles case did not identify a measles outbreak but suggested a varicella outbreak. Low measles vaccination coverage led us to recommend a routine catch-up vaccination campaign. We also recommend collecting information of rash types and photos of rashes in future fever and rash outbreaks to better differentiate potential etiologies

Molecular Subtyping in Cholera Outbreak, Laos, 2010

A cholera outbreak in Laos in July 2010 involved 237 cases, including 4 deaths. Molecular subtyping indicated relatedness between the Vibrio cholerae isolates in this and in a 2007 outbreak, uncovering a clonal group of V. cholerae circulating in the Mekong basin. Our finding suggests the subtyping methods will affect this relatedness

Clinical details of the 11 patients with blood samples, all survived.

<p>N/A: data not available.</p

Neighbour-Joining tree of 2,199 dengue 1 envelope gene sequences.

<p>Tree produced using Mega 5.05 software with Kimura-2 model. Bootstrap values (in percentage), generated by using 500 replicates, are only indicated for the nodes that define the genotypes, and for clades inside genotype 1. The sequences from the Latsavang outbreak are indicated by red dots. The other Lao strains from this study are indicated by light blue dots while a dark blue dot is used for the 1996 Lao strain. The sequences from Vientiane are indicated by ‘VTE’, the ones from Luang Namtha by ‘LNT’, and the ones from Salavan by ‘SV’; all followed by year of collection.</p

Map of Lao PDR.

<p>Locations of the hometowns of the patients whose dengue viruses were sequenced are in grey (Luang Namtha, Latsavang (indicated by a star), Vientiane and Salavan).</p

Dengue assay results.

<p>ELISA results: hl.IgG: High Level IgG; ‘+’: for NS1, IgM or IgG, positive according to the manufacturer's instruction; ‘−’ for negative result; ‘N/A’: no sample available; ‘Inter’: Interpretation, ‘Den’: for evidence of dengue infection. PCR results: ‘Den’: dengue All; ‘Den1’: dengue 1; ‘PF’: panflavivirus; ‘nPF’: heminested panflavivirus; ‘Seqce’: sequencing result of PF or nPF PCR product; ‘+’ in case of dengue genome amplification; ‘−’ in case of no detection of dengue or <i>Flavivirus</i> genome.</p

Genotype 1 subtree with genome sequences.

<p>Genotype 1 subtree, 843 sequences, from tree performed with the 39 Lao dengue 1 envelope sequences produced in this study aligned with the 1,318 DENV-1 almost complete sequences (>10,000 bases) downloaded from HFVdb. Evolutionary branches that do not include 2007–2010 Lao DENV-1 strains are not shown to increase the legibility. Origin, country (ISO 3166 code) and year of strains within these branches are indicated. The sequences from the Latsavang outbreak (XB) are indicated by red dots. The sequences from Luang Namtha (LNT) are indicated by squares, the one from Salavan (SV) by triangles and the ones from Vientiane (UI) by lozenges. Sequences from 2007 are in yellow, the ones from 2008 (except the ones from Latsavang) are in purple, the ones from 2009 in blue and the ones from 2010 in green. Groups of sequences supported by a high bootstrap value (>90) that contain at least one of Lao sequence are designated as cluster (1 to 7).</p