Strengthening Public Health Surveillance and Response to Foodborne Outbreaks in Southern Vietnam

Abstract

Elintarvikevälitteiset epidemiat ovat maailmanlaajuinen kansanterveysongelma, etenkin kehittyvissä maissa kuten Vietnamissa. Epidemioiden havaitsemis-ja seurantajärjestelmät sekä valmiudet niiden torjuntaan ja ehkäisyyn ovat näissä maissa puutteellisia: tutkittua näyttöä epidemioiden ja tautitapausten määrästä sekä niiden terveydenhuoltojärjestelmälle ja yhteiskunnalle aiheuttamasta taakasta on vähän. Vietnamissa ilmoitetaan vuosittain virallisesti noin 200 ruokaepidemiaa, 6000 tautitapausta ja 50 kuolemaa. Todellisuudessa nämä luvut ovat huomattavasti suurempia koska puutteellinen seurantajärjestelmä havaitsee vain pienen osan tautitapauksista, laboratorioilla ei ole valmiuksia taudinmääritykseen eikä valtaosaa epidemioiden aiheuttajista kyetä jäljittämään. Vaikka elintarviketurvallisuuden tulisi kattaa koko tuotantoketjun monitoroinnin ja riskikohtien identifioinnin pellolta pöytään, puutteelliset resurssit rajoittavat tämän toteutumista.

Väitöskirjatutkimuksen tavoite oli ruokaepidemioiden epidemiologisen seurannan ja torjunnan vahvistaminen elintarviketurvallisuuden parantamiseksi Etelä-Vietnamissa. Tutkimus koostuu neljästä ruokaepidemiasta, joiden selvityksestä päätutkija vastasi toimiessaan Vietnamin Kansanterveyslaitoksessa ja kenttäepidemiologian koulutusohjelmassa. Useat epidemiat liittyivät suurien vientiteollisuusyhtiöiden henkilökunnan joukkoruokaloihin. Hyödyntämällä useita epidemiologisia tutkimusasetelmia näissä tutkimuksissa tunnistettiin laajojen ruokaepidemioiden lähteitä, välittäjäelintarvikkeita sekä riskitekijöitä. Lisäksi tutkittiin elintarviketyöntekijöiden ruokaturvallisuuteen liittyviä tietoja, asenteita ja käytäntöjä. Suurien teollisuuslaitosten ruokaloissa todetuilla epidemioilla on merkittäviä taloudellisia vaikutuksia, mm. sairauspoissaolojen kautta. Tutkimuksen tulokset tuottivat tietoa Etelä-Vietnamin kansanterveysviranomaisille tartuntatautien seurantajärjestelmien kehittämistarpeista, epidemiologisten ja laboratoriovalmiuksien vahvistamistarpeista sekä elintarviketyöntekijöiden koulutuksen sisällöstä. Tutkimuksen kansainväliset yhteistyötahot olivat Vietnamin Kansanterveyslaitos (Institute of Public Health), Ho Chi Minh City ja Maailman terveysjärjestö (WHO), Hanoi, Vietnam sekä Tampereen yliopiston Terveystieteiden yksikkö.

Foodborne diseases (FBD) are a global public health concern. The World Health Organization (WHO) estimates that one billion people in developing countries are affected by FBD annually, resulting in significant economic losses. In Vietnam, approximately 200 foodborne outbreaks, 6,000 cases, and 50 deaths are reported annually. The majority of detected foodborne outbreaks have been linked to large factory canteens in industrial zones manufacturing products for export. Whereas almost all reported fatal cases were associated with family meals. Public health statutory surveillance systems rely on outbreak investigation reports, and most outbreaks are only detected when severe cases are admitted to health facilities or when deaths occur. It is therefore clear that these figures are an underestimate. FBD cause a significant public health and economic burden in Vietnam.

In developing countries, public health systems face many challenges in ensuring food safety, including shortages of human resources, laboratory capacity, and financial resources. These shortcomings result in poor surveillance and response systems, which are unable to accurately estimate the burden of FBD, trends, contributing factors, and sources. Principles of food safety and best practices of food production are critical for comprehensive FBD prevention and control. However, capacity to monitor the complete food production chain is limited and outside the jurisdiction of public health. Therefore, studies in this dissertation focus on strengthening surveillance and response systems for foodborne outbreaks to improve food safety.

The five studies (I to V) in this dissertation describe and evaluate the public health surveillance systems and responses to foodborne outbreaks in Southern Vietnam from 2009 to 2013. Studies I to IV aim to identify vehicles, sources, causative agents, and risk factors associated with the outbreaks. These studies use various analytic methods to identify gaps and shortcomings in the surveillance and investigation of foodborne outbreaks. Study V then evaluates food-handlers’ food safety knowledge, attitudes, and practices at large canteens. The main findings of these studies help to identify feasible approaches to build capacity and improve public health practices in resource-poor settings.

We identified likely outbreak vehicles and sources in four outbreak investigations and risk factors contributing to these outbreaks, in particular inadequate personal hygiene and food hygiene practices of food-handlers. Additionally, findings of outbreak investigations showed that only severe cases sought care at hospitals, clinicians alerted public health officials to suspected outbreaks, and that these notifications were usually delayed. The notifiable disease system are generally unable to detect clusters of cases or suspected foodborne outbreaks, and foodborne notification/complaint systems were not set up to receive FBD complaints from the public. Currently, outbreak investigation reports are the only method used to track food safety, but these reports usually contain only limited information. In addition, standard epidemiologic methods were not appropriately applied in most investigations in Southern Vietnam.

In Study V, we conducted a large survey on food safety knowledge, attitudes, and practices (KAP) and on the training needs of food-handlers in large canteens. Of the 909 food-handlers participating in the study, knowledge, attitudes, and practices were considered adequate for 26%, 36%, and 26%, respectively. The number of food-handlers reporting adequate KAP in schools was about twice as high as the number of such food-handlers in factory canteens in industrial manufacturing zones. Food-handlers’ suggestions for training needs included appropriate location of the training venue at the workplace, involvement of managers, fewer trainees per course, more practical exercises, and longer course duration.

In these studies, we found that public health surveillance systems for food safety are mainly based on foodborne outbreak investigations, response capacities to foodborne outbreaks are limited, and food-handlers’ KAP are poor. We therefore recommend the following: i) For public health surveillance and response in resource-poor settings, food safety authorities and policy-makers should consider including syndromic surveillance and notification/complaint systems in food safety systems, based on existing notifiable disease reporting for infectious diseases. ii) The Vietnam Field Epidemiology Training Program should develop a strategy and plan to train outbreak response teams at all administrative levels. iii) Efforts to educate food-handlers, together with supportive supervision conducted by managers, have great potential to improve food-handlers’ KAP, especially among those working in large factory canteens. iv) Further studies should investigate contributing factors in food preparation and foodborne outbreaks, the burden of foodborne diseases, and most important source.