Stan Fenwick

Highly pathogenic avian influenza H5N1 has resulted in large losses to the Indonesian poultry sector. Evidence suggests that live bird markets (LBMs) play an important role in the epidemiology of the disease. Knowledge of the frequency and type of contact between the various poultry market players should allow animal health authorities to develop a better understanding of factors influencing virus transmission between Indonesian villages. A questionnaire-based cross-sectional survey was conducted in 17 LBMs on the neighbouring Indonesian islands of Bali and Lombok to investigate the movement patterns of poultry to and from markets. Using social network analyses, a network of contacts was created for each island from a total of 413 live poultry traders and 134 customers. Individual nodes with high degree and/or betweenness were identified in each network. The Lombok network was more dense and connected than the Bali network indicating that disease transmission would be more efficient in the Lombok network. Our findings indicate that whilst live poultry are typically transported over relatively short distances of approximately 10 km, it is not uncommon for traders and customers to travel in excess of 100 km to buy or sell poultry, which may facilitate the spread of disease over a large geographical area. This study highlights the different roles markets play in poultry movement networks and their potential for disease dissemination. The identification of highly influential market nodes allows authorities to target HPAI surveillance activities to locations where disease is more likely to be present, which is crucial in low-resource settings.

A rickettsial organism harboured by Amblyomma triguttatum ticks on Barrow Island, Western Australia, was discovered after reports of possible rickettsiosis among local workers. Subsequent isolation of this rickettsia (strain BWI-1) in cell culture and analysis of its phylogenetic, genotypic and phenotypic relationships with type strains of Rickettsia species with standing in nomenclature suggested that it was sufficiently divergent to warrant its classification as a new species. Multiple gene comparison of strain BWI-1 revealed degrees of sequence similarity with Rickettsia raoultii, its closest relative, of 99.58, 98.89, 97.03, 96.93 and 95.73% for the 16S rRNA, citrate synthase, ompA, ompB and sca4 genes, respectively. Serotyping in mice also demonstrated that strain BWI-1T was distinct from Rickettsia raoultii. Thus, we propose the naming of a new species, Rickettsia gravesii sp. nov., based on its novel genotypic and phenotypic characteristics. Strain BWI-1T was deposited in the ATCC, CSUR and ARRL collections under reference numbers VR-1664, CSUR R172 and RGBWI-1, respectively.

Coxiella burnetii, the causative agent of Q fever, was first discovered in Australia in 1937. However, little is known about the strains of C. burnetii present in this country. In this study, six published genotyping methods were applied to 42 isolates from Australian patients with acute (n = 39) and chronic (n = 3) Q fever. All the isolates contained the plasmid QpRS and lacked the acute disease antigen A (adaA) gene. Two methods of genotyping based on single nucleotide polymorphisms (SNPs) also failed to discriminate between the isolates. However, results from the method based on SNPs within the multi-spacer sequence typing (MST) loci determined a novel MST genotype, with the Australian isolates forming a unique phylogenetic clade. Multi-locus variable number of tandem repeats (VNTR) analysis (MLVA) determined 14 genotypes, all of which were novel compared with those previously identified in strains from other countries. Many of these were single locus variants, differing from each other at just one of the 15 loci tested. Our results show that the Australian isolates exhibit significant diversity from previously characterised strains, but are genetically closely related to each other, supporting a model of evolution by clonal expansion in a geographically isolated location.

Influenza A viruses pose a major public health threat worldwide, especially due to the potential for inter-species transmission. Farmers could be among the first people to be infected with a novel reassortant virus in a pig herd and may serve as a source of the virus for their communities. In this study, the pig production systems of smallholders in rural Thailand were examined to qualitatively evaluate the potential risks that may contribute to the spread of influenza A viruses. The investigation was based on questionnaire interviews regarding pig farmers' practices and trading activities. We found that extensive pig-human contacts, commingling of pigs and chickens and suboptimal biosecurity practices adopted by farmers and traders may constitute substantial risks for inter-species influenza virus transmission, thereby posing a threat to pig populations and human public health. The regular practices of using manure as field fertilizer, hiring boars from outside and trading activities could contribute to the potential spread of influenza viruses in the local community. To mitigate the potential risks of influenza A virus transmission and spread in the local community, it is recommended that appropriate public health strategies and disease prevention policies for farmers and traders should be developed including improving biosecurity, encouraging separation of animals raised on farms and minimizing the exposure between pigs and humans. Furthermore, surveillance systems for pig diseases should be targeted around the festival months, and on-farm identification of pigs should be promoted.

This study assessed the ability of three adjuvants (aluminum hydroxide, Essai (microparticle) and Phema (nanoparticle)) to enhance the immune response of chickens to an H6N2 avian influenza DNA vaccine. No hemagglutination inhibition (HI) antibody was detected following two intramuscular immunizations with the adjuvanted and non-adjuvanted pCAG-HAk vaccine, which has previously been shown to induce moderate H6 HA antibody response in SPF chickens. Following virus challenge, neither the vaccinated group without adjuvant nor the Essai adjuvanted group showed a statistically significant reduction in virus shedding in oropharyngeal and cloacal swabs compared with the naïve control group. However, the aluminum hydroxide and Phema adjuvanted groups significantly reduced the frequency of virus shedding in oropharyngeal swabs, indicating that these adjuvants appeared to further enhance the vaccine potency. Aluminum hydroxide holds promise as an adjuvant for enhancing DNA-induced immune response in chickens owing to its low price and safety record.

This study analysed the available data of seroprevalence to human influenza viruses in pigs in Cambodia using generalized linear mixed models in order to improve understanding of factors underlying the spread of human influenza viruses in Cambodian pigs. The associations between seroprevalence against seasonal H1N1 influenza virus in pigs and the population density of humans and pigs were not significant. However, a positive association between anti-H3 antibodies in pigs and the human population density was identified. In contrast, there was a negative association between seroprevalence of H3N2 in pigs and the pig population density. Our study has highlighted the difficulty in identifying epidemiological risk factors when a limited data set is used for analyses. We therefore provide recommendations on data collection for future epidemiological analyses that could be improved by collecting metadata related to the animals sampled. In addition, serosurveillance for influenza A viruses in pigs in high-risk areas or at slaughterhouses is recommended in resource-limited countries.

Worldwide there are few isolate collections of the intracellular bacterium Coxiella burnetii, due to the difficulties associated with working with the organism and the scarcity of suitable samples from which to attempt isolation. Particularly lacking are isolates from acute Q fever patients. The aim of this study was to evaluate whether the serum samples taken from patients with confirmed acute Q fever during the early stage of their disease represented a potential source of viable C. burnetii. Isolation was attempted from 65 of these samples by inoculation of the serum into Vero cell culture and was successful in 36 cases (55%). This high success rate was likely due to extended incubation of up to twelve weeks of the inoculated cultures, allowing the growth of the organism to levels detectable by PCR. Retrospective analysis of the time the sera was stored prior to inoculation into culture demonstrated that C. burnetii remained viable for 224. days in samples stored refrigerated and 371. days in samples stored frozen at - 20. °C. These results demonstrate that standard serum samples taken from acute Q fever patients are a valuable source of new isolates of C. burnetii, with no special handling of the specimens required to maintain the organism's viability.

A total of 1,136 samples from 289 households in four provinces in northern Laos were subjected to Japanese encephalitis virus (JEV) and dengue virus hemagglutination inhibition (DENV HI). Overall, antibodies to JEV were detected by HI in 620 (54.6%) of 1,136 people; of which 217 (19.1%) had HI activity against JEV only. Antibodies to DENV4 were detected by HI in 526 (46.3%) of 1,136 people; of which 124 (10.9%) had HI activity against DENV4 only. Antibodies to DENV1-3 were detected by HI in 296 (26.1%), 274 (24.1%), and 283 (24.9) of 1,136 people, respectively; of which 7, 1, and 0, respectively, had HI activity against DENV1-3 only. JEV was the most prevalent Flavivirus in Oudomxay, Luangprabang, and Huaphan provinces and DENV4 was the most prevalent in Xiengkhouang province. Seroprevalence for JEV increased with increasing age and wealth and was higher in villages where rice was cultivated in paddy fields and highest for people of Lao-Tai ethnicity.

Highly Pathogenic Avian Influenza (HPAI) has been prevalent in Indonesia since 2003 causing major losses to poultry production and human deaths. Live bird markets are considered high risk areas due to the density of large numbers of mixed poultry species of unknown disease status. Understanding trader knowledge and perceptions of HPAI and biosecurity is critical to reducing transmission risk and controlling the disease. An interview-administered survey was conducted at 17 live bird markets on the islands of Bali and Lombok in 2008 and 2009. A total of 413 live poultry traders were interviewed. Respondents were mostly male (89%) with a mean age of 45 years (range: 19–81). The main source of AI information was TV (78%), although personal communication was also identified to be an important source, particularly among female traders (60%) and respondents from Bali (43%). More than half (58%) of live poultry traders interviewed knew that infected birds can transmit HPAI viruses but were generally unaware that viruses can be introduced to markets by fomites. Cleaning cages and disposing of sick and dead birds were recognized as the most important steps to prevent the spread of disease by respondents. Two thirds (n = 277) of respondents were unwilling to report sudden or suspicious bird deaths to authorities. Bali vendors perceive biosecurity to be of higher importance than Lombok vendors and are more willing to improve biosecurity within markets than traders in Lombok. Collectors and traders selling large numbers (>214) of poultry, or selling both chickens and ducks, have better knowledge of HPAI transmission and prevention than vendors or traders selling smaller quantities or only one species of poultry. Education was strongly associated with better knowledge but did not influence positive reporting behavior. Our study reveals that most live poultry traders have limited knowledge of HPAI transmission and prevention and are generally reluctant to report bird deaths. Greater efforts are needed to engage local government, market managers and traders in education and awareness programs, regulatory measures and incentive mechanisms. Understanding and evaluating the social responses to such an integrated approach could lead to more effective HPAI prevention and control.

The microscopic examination of Phytophthora cinnamomi in plant tissues is often difficult as structures such as hyphae, chlamydospores and oospores are frequently indistinguishable from those of other fungi and oomycetes, with histological stains not enabling species differentiation. This lack of staining specificity makes the localization of P. cinnamomi hyphae and reproductive structures within plant tissues difficult, especially in woody tissues. This study demonstrates that with the use of a species-specific fluorescently labelled DNA probe, P. cinnamomi can be specifically detected and visualized directly using fluorescent in situ hybridization (FISH) without damage to plant or pathogen cell integrity or the need for subculturing. This approach provides a new application for FISH with potential use in the detailed study of plant–pathogen interactions in plants.