Good progress has been made towards achieving the goal of the project to improve the management of zoonotic diseases associated with pig production and pork consumption in Laos. In establishing the prevalence and distribution of pig associated zoonoses (Objective 1), the project team was able to develop a detailed understanding of the pig supply chain and the associated qualitative risks of zoonotic disease along the chain. The supply chain survey was also able to demonstrate that animals entering slaughterhouses in each district are representative of the pig population in the age group being slaughtered. Meat inspection and sample collection training was provided to provincial and district staff to undertake the slaughterhouse surveys, in total 18 field staff have received training in these techniques. A slaughterhouse survey was carried out in six districts in four provinces with approximately 800 pigs sampled. Prevalence of the nematode worm Trichinella was around 3% with some variation between provinces, all isolates have been Trichinella spiralis. The dominant taeniid cysticerci infecting pigs was found to be the dog tapeworm, Taenia hydatigena, with 15-30% of pigs positive on inspection. Only a small number of pigs were positive for Taenia solium or Taenia asiatica cysticerci based on inspection. Serological investigation for cysticercosis in pigs has not yet been completed due to delays in obtaining reagents from collaborators in Belgium. Serological testing for other zoonotic diseases has not been completed. Analysis of faecal samples from pigs at slaughter indicates that pigs may be an important reservoir of the zoonotic liver fluke, Fasciola. Balantidium coli, a protozoan potentially causing severe human disease was also found in 19% of pigs. During a subsequent community level survey, farmers were interviewed to assess their knowledge of pig-human transmission of disease. Initial analysis of the data suggests that most villagers understand that people can get disease from pigs but have limited understanding of how infections are acquired. Surveys of humans were conducted in 24 villages and ~330 households in four provinces (Houaphan, Xiengkhouang, Luangprabang and Oudomxay) from January to March 2009 to determine the risks associated with human and pig transmission (Objective 2). The surveys were undertaken in close collaboration with the Lao Department of Hygiene and Prevention, Ministry of Health (MOH). The questionnaire and laboratory results of this survey are currently being analysed and will be reported in the second annual report. Initial analysis, however, suggests that prevalence of partially cooked or uncooked pork is substantially lower than consumption of partially cooked or uncooked beef and there is evidence of variation between different ethnic groups. This will have important implications for the food-borne transmission of pig-associated zoonoses and suggests that certain risk factors are associated with specific cultural practice.
Two project-related articles have been published in the international scientific literature with regards to taeniasis and cysticercosis in Lao PDR (Objective 4). These review papers provide an important Lao perspective on cysticercosis and highlight the importance of this project from a regional and international point of view. Before the next report the project team will have held a mid-term review meeting and it is anticipated that the project team will have had an opportunity to report on outputs at a regional meeting, thereby contributing to regional policy and action to contain zoonotic diseases. Possible venues would be the 6th Seminar on Food- and Water-borne Parasitic Zoonoses or the Joint International Tropical Medicine Meeting, both to be held in Bangkok in December 2009.
Within a relatively short time period, the project has been able to achieve substantial scientific, capacity and community level impacts. Through the training of national laboratory staff and provincial and district agriculture staff, the project has been able to substantially strengthen capacity for the detection and surveillance of pig-associated zoonotic diseases. These efforts have contributed to MOH public awareness campaigns to promote caution in pork consumption following detection of Trichinella in pigs in Xiengkhouang province.

Substantial progress has been made to better understand the epidemiology and scope of pig-associated zoonoses in Laos. Objectives 1 and 2 are very closely linked and seek to establish the evidence base of pig associated zoonoses and understand the risk factors causing disease in humans and pigs The community survey of ~1430 humans in 24 villages in northern Laos confirmed the presence of cysticercosis, 30 people (2.1%) had detectable antigen to Taenia solium. Taking into account test characteristics, this equates to an estimated true prevalence of 3.6%. Initial risk factor analysis indicates that Oudomxay province and Khmu people are at high risk compared to other groups and that the poorest people in the survey population are also at increased risk. Testing indicates that 18.7% of the survey population have been exposed to Trichinella. Initial analysis indicates that groups at higher risk of infection are lowland Lao loum ethnic groups, males, people in the higher wealth categories and there is an increased serological prevalence in older age groups. Ethnicity and poverty status were found to be important determinants of disease outcome One hundred and seven people were treated for tapeworm infection and expelled tapeworms were tested to identify the species, Taenia saginata (the beef tapeworm) was detected in the majority of cases and Taenia solium was detected but at a very low level. No Taenia asiatica cases were detected. In addition to taeniasis, hookworm worm was detected in almost half of the population and work is ongoing to determine if the hookworm are zoonotic species.
A slaughter slab survey indicated that Taenia hydatigena (dogs are the natural host of the adult worm) is the dominant Taeniid species infecting pigs and that this parasite may actually be able to act as a natural vaccine for T. solium cysts in pigs through cross-species immunological interactions. The prevalence of T. solium in pigs was much less than expected and this is reflected by the low prevalence of T. solium adult tapeworms in people. The Taeniid parasite ecology in Lao shows T. solium is being out-competed in humans by T. saginata and out-competed by T. hydatigena in pigs. to be the dominant species infecting humans and that T. Japanese encephalitis (JE) virus was detected in three-quarters of the pig population tested by hemagglutination inhibition (HAI). Peak prevalence was seen in young animals indicating that impacts on pig reproductive performance in Lao is limited. IgM antibodies to JEV (indicative of a recent infection) were detected in the early wet-season months indicating that the mosquito vectors responsible for JE virus transmission are most active at the start of the wet season. Hepatitis E virus was also highly prevalent in the pig population. No serological evidence of Nipah virus or epidemic H1N1 swine influenza virus was detected in the pig survey population. There was, however, evidence of a low level of swine influenza H3N2. A subsequent survey of village pigs younger than 6 months of age showed pigs harbouring Hepatitis E virus genotype 4.
During the period, the Lao Project Leader undertook a John Dillion Fellowship study tour in Australia and received project management training and invaluable insight into the management and operations of world class Australian research institutes. In addition the Lao project leader travelled to Perth for the mid-term review meeting to discuss various issues, but high on the agenda was the delays in laboratory testing and getting results analysed and disseminated.
Socio-economic modelling of pig zoonotic disease impacts has been delayed due to the need for good quality laboratory data to feed into the models. Two experts from the University of Queensland's School of Population Health have been engaged to conduct the economic assessments. The outputs of this economic modelling will be reported in the next annual report.
The results so far demonstrate that population level prevalence of human cysticercosis is lower than one might have expected. We believe, however that prevalence amongst the poorest people of Lao in remote and high-risk areas will be substantially higher and the impacts greater. The number of Taenia solium tapeworm carriers is very low and detecting them will be akin to finding a needle in a haystack. We propose the need for validated methods to first identify what hay bale to look in. Control measures for priority diseases such as cysticercosis will always be limited by the ability to detect Taenia solium taeniasis cases. We have begun developing a non-invasive method of identifying high-risk areas based on key informant interviews. This work has just begun and early results show promise, success in developing these methodologies will be critical to long-term disease control and the outputs of the economic modelling will provide insights into the most cost effective disease control initiatives.