Dataset Information

Diphtheria in Lao PDR: Insufficient Coverage or Ineffective Vaccine?

ABSTRACT: During late 2012 and early 2013 several outbreaks of diphtheria were notified in the North of the Lao People's Democratic Republic. The aim of this study was to determine whether the re-emergence of this vaccine-preventable disease was due to insufficient vaccination coverage or reduction of vaccine effectiveness within the affected regions.A serosurvey was conducted in the Huaphan Province on a cluster sampling of 132 children aged 12-59 months. Serum samples, socio-demographic data, nutritional status and vaccination history were collected when available. Anti-diphtheria and anti-tetanus IgG antibody levels were measured by ELISA.Overall, 63.6% of participants had detectable diphtheria antibodies and 71.2% tetanus antibodies. Factors independently associated with non-vaccination against diphtheria were the distance from the health centre (OR: 6.35 [95% CI: 1.4-28.8], p = 0.01), the Lao Theung ethnicity (OR: 12.2 [95% CI:1,74-85, 4], p = 0.01) and the lack of advice on vaccination given at birth (OR: 9.8 [95% CI: 1.5-63.8], (p = 0.01) while the level of maternal edu-cation was a protective factor (OR: 0.08 [95% CI: 0.008-0.81], p = 0.03). Most respondents claimed financial difficulties as the main reason for non-vaccination. Out of 55 children whose vaccination certificates stated that they were given all 3 doses of diphtheria-containing vaccine, 83.6% had diphtheria antibodies and 92.7% had tetanus antibodies. Furthermore, despite a high prevalence of stunted and underweight children (53% and 25.8%, respectively), the low levels of anti-diphtheria antibodies were not correlated to the nutritional status.Our data highlight a significant deficit in both the vaccination coverage and diphtheria vaccine effectiveness within the Huaphan Province. Technical deficiencies in the methods of storage and distribution of vaccines as well as unreliability of vaccination cards are discussed. Several hypotheses are advanced to explain such a decline in immunity against diphtheria and recommendations are provided to prevent future outbreaks.

SUBMITTER: Nanthavong N

PROVIDER: S-EPMC4409043 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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Diphtheria in Lao PDR: Insufficient Coverage or Ineffective Vaccine?

Nanthavong Naphavanh N Black Antony P AP Nouanthong Phonethipsavanh P Souvannaso Chanthasone C Vilivong Keooudomphone K Muller Claude P CP Goossens Sylvie S Quet Fabrice F Buisson Yves Y

PloS one 20150424 4

<h4>Background</h4>During late 2012 and early 2013 several outbreaks of diphtheria were notified in the North of the Lao People's Democratic Republic. The aim of this study was to determine whether the re-emergence of this vaccine-preventable disease was due to insufficient vaccination coverage or reduction of vaccine effectiveness within the affected regions.<h4>Methods</h4>A serosurvey was conducted in the Huaphan Province on a cluster sampling of 132 children aged 12-59 months. Serum samples, ...[more]

PMID: 25909365

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Project description:BackgroundTargeted malaria elimination (TME) in Lao PDR (Laos) included three rounds of mass drug administrations (MDA) against malaria followed by quarterly blood surveys in two villages in Nong District at Savannakhet Province. The success of MDA largely depends upon the efficacy of the anti-malarial drug regimen, local malaria epidemiology and the population coverage. In order to explore the reasons for participation in TME, a quantitative survey was conducted after the completion of the three rounds of MDA.MethodsThe survey was conducted in two villages with a total of 158 households in July and August 2016. Among the 973 villagers eligible for participation in the MDA, 158 (16.2%) adults (> 18 years) were selected, one each from every household for the interviews using a quantitative questionnaire.Results150/158 (94.9%) respondents participated at least in one activity (taking medicine or testing their blood) of TME. 141/150 (94.0%) respondents took part in the MDA and tested their blood in all three rounds. 17/158 (10.7%) were partial or non-participants in three rounds of MDA. Characteristics of respondents which were independently associated with completion of three rounds of MDA included: attending TME meetings [AOR = 12.0 (95% CI 1.1-20.5) (p = 0.03)], knowing that malaria can be diagnosed through blood tests [AOR = 5.6 (95% CI 1.0-32.3) (p = 0.05)], all members from household participated [AOR = 4.2 (95% CI 1.3-14.0) (p = 0.02)], liking all aspects of TME [AOR = 17.2 (95% CI 1.6-177.9) (p = 0.02)] and the perception that TME was important [AOR = 14.9 (95% CI 1.3-171.2) (p = 0.03)].ConclusionComplete participation in TME was significantly associated with participation in community engagement activities, knowledge that the blood tests were for malaria diagnosis, family members' participation at TME and perceptions that TME was worthwhile. A responsive approach to community engagement that includes formative research and the involvement of community members may increase the uptake of the intervention.

Project description:BackgroundDiphtheria is a vaccine-preventable disease. When vaccination coverage and population immunity are low, outbreaks can occur. We investigated a diphtheria outbreak in Lao People's Democratic Republic that occurred during 2012-2013 and highlighted challenges in immunization services delivery to children in the country.MethodsWe reviewed diphtheria surveillance data from April 1, 2012-May 31, 2013. A diphtheria case was defined as a respiratory illness consisting of pharyngitis, tonsillitis, or laryngitis, and an adherent tonsillar or nasopharyngeal pseudomembrane. To identify potential risk factors for diphtheria, we conducted a retrospective case-control study with two aged-matched neighborhood controls per case-patient in Houaphan Province, using bivariate analysis to calculate matched odds ratio (mOR) with 95% confidence intervals (CI). Reasons for non-vaccination among unvaccinated persons were assessed.ResultsSixty-two clinical cases of diphtheria and 12 diphtheria-related deaths were reported in seven of 17 provinces. Among case-patients, 43 (69%) were <15years old, five (8%) reported receiving three DTP doses (DTP3), 21 (34%) had received no DTP doses, and 35 (56%) had unknown vaccination status. For the case-control study, 42 of 52 diphtheria case-patients from Houaphan province and 79 matched-controls were enrolled. Five (12%) case-patients and 20 (25%) controls had received DTP3 (mOR=0.4, CI=0.1-1.7). No diphtheria toxoid-containing vaccine was received by 20 (48%) case-patients and 38 (46%) controls. Among case-patients and controls with no DTP dose, 43% of case-patients and 40% of controls lacked access to routine immunization services.ConclusionSuboptimal DTP3 coverage likely caused the outbreak. To prevent continued outbreaks, access to routine immunization services should be strengthened, outreach visits need to be increased, and missed opportunities need to be minimized. In the short term, to rapidly increase population immunity, three rounds of DTP immunization campaign should be completed, targeting children aged 0-14years in affected provinces.

Dataset Information

Diphtheria in Lao PDR: Insufficient Coverage or Ineffective Vaccine?

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Diphtheria in Lao PDR: Insufficient Coverage or Ineffective Vaccine?

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