Human Suis and Pig Diseases in Northern Vietnam

Study Overview
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Brief Summary
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This study aim to test the hypothesis that human S.suis infections are associated in time and space with outbreaks of Porcine Reproductive and Respiratory Syndrome (PRRS) virus or other diseases in pigs.

Detailed Description
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Streptococcus suis is a zoonotic agent which can cause severe systemic infection in humans exposed to infected pigs or pig derived products. Over 700 cases have been reported worldwide, most of them were in China and Vietnam in the last few years. In Vietnam, S. suis infection in adults is common, and patients with S.suis are often admitted to the National Hospital for Tropical Diseases (NHTD), a tertiary referral hospital for infectious diseases in northern Vietnam. In 2007, 50 laboratory confirmed cases with S.suis were reported at this hospital, and in 2010, 65 laboratory confirmed S.suis cases have been identified by September. Pig breeding and pork consumption is popular in Vietnam, with the majority of pigs and meat supply channelled from small-scaled un-controlled farmers and slaughterhouses, which pose a great potential health risk to people involved in the chain. A case-control study conducted in southern Vietnam showed that occupational exposure, raising pigs at home and consuming high-risk dishes from pigs significantly increased the risk of S. suis infection. It has been suggested that the incidence of human S. suis cases is possibly linked to the occurrence of Porcine Respiratory and Reproductive System (PRRS) virus outbreaks in northern Vietnam. In 2010, the disease has spread to over 30 provinces over the country, with many outbreaks reported in northern provinces in the period from April to July. Field observations in other countries showed that PRRS virus infection increased pig's susceptibility to S. suis infection, including serotype 2 and 7. Therefore, PRRS virus outbreaks might have increased the risk of S. suis transmission to humans through exposure to pigs with PRRS virus infection and concomitant S. suis disease. Nevertheless, sufficient data are not available to confirm or refute this hypothesis. Knowledge of spatial and temporal relationships between human S.suis infections and disease outbreaks in pigs can increase our understanding of risk factors for human S.suis infection and support disease prevention and preparedness in the community.

Official Title
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Spatial and Temporal Associations Between Human Streptococcus Suis Infections and Pig Diseases in Northern Vietnam, 2010

Conditions
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Streptococcus Suis Infection

Participation Criteria
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Eligibility Criteria
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Group 1: cases Inclusion Criteria: Date of specimen (blood or CSF sample) collection is between 01/01/2010 to 31/12/2010; and S.suis infection confirmed by either CSF or blood culture or PCR; or Meet the criteria for a probable case as above (in absence of laboratory confirmation). Exclusion Criteria: - Unable to collect patient's spatial data at commune level. Group 2: controls Inclusion Criteria: Diagnosis as sepsis at hospital admission (based on clinical symptoms or laboratory evidence) Admission date between 01/01/2010 and 31/12/2010 Exclusion Criteria: Symptoms of meningitis Clinically a high suspicion of S. suis infection (culture and PCR negative) as determined by doctor. Laboratory culture or PCR result positive for S.suis infection HIV infection Unable to collect patient's spatial data at commune level
Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| S.suis cases<br>This group consists of human cases with S.suis infection (confirmed or probable) admitted to National Hospital for Tropical Diseases in 2010. | |
| Sepsis controls<br>This group consists of hospital controls diagnosed with sepsis (not caused by S.suis) admitted to National Hospital for Tropical Diseases in 2010. | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Temporal proximity to the nearest pig outbreak of human cases versus human controls | The number of days separating identified nearest pig outbreak and identified human cases of S. suis versus the number of days separating identified nearest pig outbreak and human controls. | Up to 1 year | 
| Spatial proximity to the nearest pig outbreak of human cases versus human controls | The number of kilometers separating the identified nearest pig outbreak and identified human cases of S. suis versus the number of kilometers separating the identified nearest pig outbreak and human controls. | Up to 1 year | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Number of human S. suis cases | Total number of human S.suis cases recorded at NHTD in 2010. | One year | 
| Number of pig disease outbreaks | Total number of pig outbreaks identified within 2010 in the Northern region. | One year | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Pig disease, Streptococcus suis, Sepsis, Porcine Respiratory and Reproductive System virus, Epidemiology