Publications (11)22.53 Total impact
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Article: Prevalence and clinical impact of Toxocara vitulorum in cattle and buffalo calves in northern Lao PDR.
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ABSTRACT: This study was completed to determine the prevalence and distribution of Toxocara vitulorum infection in cattle and buffalo calves and investigate its clinical impact in northern Lao PDR (Peoples Democratic Republic). The results aim to assist decisions on disease control measures that can contribute to increasing cattle and buffalo productivity within smallholder farming systems in tropical areas. A prevalence survey for T. vitulorum in buffalo and cattle calves aged <3 months was conducted between September 2009 and June 2010 in five provinces of northern Lao PDR using a two-stage sampling technique to select 69 villages and 899 calves, with faecal samples collected and examined for T. vitulorum eggs at a local laboratory. At the time of sampling, data on calf morbidity and anthelmintic treatment was also collected. Factors potentially associated with infection and severity of infection were analyzed at univariable and multivariable levels, using T. vitulorum status (positive/negative) and on the positive calves only, faecal egg count levels as outcome variables. The estimated prevalence of T. vitulorum in northern Lao was 22.6 % (95 % confidence interval [CI], 0.17-0.28), and 76.8 % of villages had at least one positive calf. Province was the only significant (p < 0.05) variable investigated associated with calf infection status. Species (buffalo) was the only variable significantly (p < 0.05) associated with higher egg per gram of faeces levels among infected calves. Prevalence in calves aged 1-21 days, the reported prepatent period, was 17.5 % (CI 0.11-0.24). Treatment levels were very low (8.2 %) and if treatment occurred it was mostly unsuccessful. The high and wide spread infection of T. vitulorum in cattle and buffalo calves identified in this survey is likely to result in suboptimal cattle and buffalo productivity. Improved management of T. vitulorum infection in cattle and buffalo calves in northern Lao PDR is indicated to reduce potential negative production impacts and enable more efficient development of large ruminant livestock industry as a pathway from rural poverty for smallholder farmers in northern Lao PDR. In addition to quantifying this disease problem in calves, the conduct of this applied participatory research study provided an important opportunity to improve animal health services by increasing the parasite, large ruminant handling and research knowledge and capacity of government animal health staff and farmers.Tropical Animal Health and Production 09/2012; · 1.12 Impact Factor -
Article: Seroprevalence of Major Bovine-Associated Zoonotic Infectious Diseases in the Lao People's Democratic Republic.
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ABSTRACT: Abstract Bovine-associated zoonotic infectious diseases pose a significant threat to human health in the Lao People's Democratic Republic (Lao PDR). In all, 905 cattle and buffalo serum samples collected in northern Lao PDR in 2006 were used to determine seroprevalence of five major bovine zoonotic infectious diseases that included Taenia saginata cysticercosis, bovine tuberculosis, Q-fever, bovine brucellosis, and bovine leptospirosis. Five enzyme-linked immunosorbent assays (ELISAs) were used to test for the presence of antibodies to the diseases, except Taenia saginata, for which we tested for the presence of Taenia metacestode circulating antigens. The overall highest prevalence was for T. saginata (46.4%), with lower prevalence for Q-fever (4%), leptospirosis (3%), tuberculosis (1%), and brucellosis (0.2%). Although there were no significant differences in the proportion of seroprevalence between sex and age of the animals sampled, there were significant differences between the provincial distributions. Further studies are required to determine the seroprevalence of these infections in other locations in Lao PDR, as well as other animal species including humans, in order to develop effective prevention and control strategies. This is the first study to investigate the prevalence of bovine zoonotic infectious agents in the Lao PDR. Positivity was demonstrated for all diseases investigated, with the highest prevalence for T. saginata antigen and Coxiella burnetti antibodies. For T. saginata, there were significant differences in the provincial distribution. Approximately 16% seroprevalence of Coxiella burnetti was noted in Xayabuly Province; however, there are no clear reasons why this was the case, and further studies are required to determine risk factors associated with this observation.Vector borne and zoonotic diseases (Larchmont, N.Y.) 05/2012; 12(10):861-6. · 2.61 Impact Factor -
Article: Significant mortality of large ruminants due to hypothermia in northern and central Lao PDR.
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ABSTRACT: An extreme cold exposure event occurred between March 14th and 19th 2011 in northern and central Lao PDR resulting in a major mortality of cattle and buffalo. At least six northern and one central province reported losses, involving 46 districts and 1,384 smallholder farmers, with a total of 7,162 cattle and 3,744 buffalo reported to have died in association with cold weather. Affected animals were observed to shiver, display slow and shallow respiration, lose consciousness and eventually die. Many deaths occurred at night and were recorded in both sexes and all ages of large ruminants. However, mortalities occurred mostly in animals that were free-grazing in the forest and natural grassland, and exposed to the cold weather. Some housed animals that were provided with warmth from shelter and fires and supplementary feed did not die. Samples from dead animals collected for laboratory analysis confirmed that bacterial or viral pathogens were not present. The cause of the mortality was attributed to hypothermia, and the economic losses were estimated at USD 2,463,912.00. Xieng Khouang Province reported the most severe losses with deaths of 4,600 cattle and 1,665 buffalo. At Thong Haihin meteorological station in this province on March 16th and 17th 2011, minimum temperatures recorded were 6.7°C and 7.5°C and rainfall recorded was 36.6 mm and 61.7 mm, respectively. This was the first reported extreme cold event in living memory occurring between the end of dry season and beginning of the wet season in northern Laos. This event is reported in detail as it caused a major loss of wealth for poor smallholder farmers and indicates that strategies to minimise the impact of extreme cold weather events need to be included in livestock development extension programmes.Tropical Animal Health and Production 09/2011; 44(4):835-42. · 1.12 Impact Factor -
Article: Molecular epidemiology of foot-and-mouth disease viruses from South East Asia 1998-2006: the Lao perspective.
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ABSTRACT: Foot-and-mouth disease (FMD) causes sporadic disease outbreaks in the Lao People's Democratic Republic (Lao PDR) and appears to be endemic within a livestock population largely susceptible to infection. As Lao PDR is a major thoroughfare for transboundary animal movement, regular FMD outbreaks occur causing economic hardship for farmers and their families. The dominant serotype causing outbreaks between 1998 and 2006 was type O. Using phylogenetic analysis, type O isolated viruses were divided into two topotypes: South East Asia (SEA) and the Middle East-South Asia (ME-SA). Type A virus was reported only in 2003 and 2006 and type Asia 1 only in 1996 and 1998.Veterinary Microbiology 01/2009; 137(1-2):178-83. · 3.33 Impact Factor -
Article: Development and evaluation of a rapid immunomagnetic bead assay for the detection of classical swine fever virus antigen.
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ABSTRACT: Classical swine fever (CSF) is a highly contagious and severe viral disease of swine resulting in substantial production losses in different farming systems in many regions of the world. The accurate and rapid detection of CSF outbreaks is reliant on sensitive and specific laboratory testing and is a key component of disease control. Specific detection of CSF virus can be achieved by virus isolation in tissue culture, antigen capture or the detection of viral RNA using molecular techniques. In order to reduce the time taken to achieve a diagnostic result and simplify testing methods, an antigen capture ELISA using immunomagnetic beads (IMB) as the solid phase was developed and compared to a microplate-based antigen capture (AC)-ELISA. The IMB-ELISA has up to 64-fold greater analytical sensitivity than the AC-ELISA and initial estimates of diagnostic sensitivity and specificity are 100%. The IMB-ELISA has a highly robust, rapid and stable test format and is simpler to perform than the AC-ELISA. The IMB-ELISA has the added advantage that a result can be sensitively and specifically determined by eye, lending it to the possibility of adaptation to a near-to-field test with minimal equipment or expertise needed.Tropical Animal Health and Production 12/2008; 41(6):913-20. · 1.12 Impact Factor -
Article: A review of taeniasis and cysticercosis in the Lao People's Democratic Republic.
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ABSTRACT: Taeniasis and cysticercosis are important but underreported parasitic zoonoses in the Lao People's Democratic Republic (Lao PDR). Reports of human and pig cysticercosis are rather limited and based largely on anecdotal evidence. To date, no structured surveys of disease prevalence or incidence have been reported. However, one unpublished pilot survey of pig cysticercosis in a slaughterhouse in northern Laos estimated prevalence to be 1.7%, without speciation of parasite cysts. Over the past 20 years, nine surveys of intestinal helminthic infection have been conducted; the prevalence of human taeniasis ranged from 0 to 14.0%. The study designs and sample sizes varied greatly, however a high degree of spatial and age variation in taeniasis prevalence was evident. These results are however inconclusive as the species of tapeworm infecting the people was not determined. To further our knowledge of taeniasis and cysticercosis in Lao PDR, structured community-based surveys in high-risk areas are required in combination with the use of sensitive and specific diagnostic tests capable of identifying the pork tapeworm, Taenia solium. This will enable the development and implementation of control measures that are both appropriate and sustainable if T. solium is shown to be a public health threat.Parasitology International 10/2008; 57(3):252-5. · 2.13 Impact Factor -
Article: Prevalence of hepatitis E virus antibodies in pigs: implications for human infections in village-based subsistence pig farming in the Lao PDR.
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ABSTRACT: We report a high seroprevalence of hepatitis E virus (HEV) in pigs in the Lao PDR. HEV seroprevalence was 51.2% (300/586) amongst abattoir pigs and 15.3% (46/301) amongst village pigs. The age distribution suggested previous in-village HEV pig infections. These findings suggest a zoonotic risk associated with village-based smallholder pig farming.Transactions of the Royal Society of Tropical Medicine and Hygiene 04/2007; 101(3):305-7. · 2.16 Impact Factor -
Article: A simple and inexpensive container for the transport of biological specimens in limited resource situations.
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ABSTRACT: We describe a diagnostic specimen transport container that is appropriate for limited resource or emergency settings. The transport container is constructed from polyvinyl chloride (PVC) plumbing pipe, which is readily available and inexpensive (US$1-2, depending on size) and has wide flexibility of size due to the range of PVC pipe dimensions available. The PVC transporters are durable, water-resistant and may be easily decontaminated. They have been adapted for the transport of blood culture bottles from provincial hospitals in Laos, where, during a 2-year period, 380 PVC tubes containing blood culture bottles were transported without any leakage or breakage. We have found the PVC transporter to be a useful and cost-efficient durable alternative that meets IATA Packing Instruction 650 biological transport container requirements.Transactions of the Royal Society of Tropical Medicine and Hygiene 12/2006; 100(11):1084-6. · 2.16 Impact Factor -
Article: Genetic typing of classical swine fever viruses from Lao PDR by analysis of the 5' non-coding region.
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ABSTRACT: The 5' non-coding region (5'-NCR) of 27 classical swine fever virus (CSFV) isolates from Lao People's Democratic Republic (Lao PDR) during 1997 and 1999 were amplified by RT-PCR. A 150-bp region of the 5'-NCR amplicons was analysed and compared with reference CSFV of European and Asian origin and a phylogenetic dendrogram constructed. Following analysis, all viruses were determined to belong to genogroup 2. Viruses from Lao PDR grouped on a geographical basis with the majority of northern/central isolates falling into subgroup 2.1 and southern/central isolates falling into subgroup 2.2. These results concur with previous studies of CSF viruses from Lao PDR, although this study recognized the first occurrence of subgroup 2.1 in southern Lao PDR.Virus Genes 01/2006; 31(3):349-55. · 1.85 Impact Factor -
Article: Phylogenetic analysis of the E2 gene of classical swine fever viruses from Lao PDR.
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ABSTRACT: The E2 genes of 21 classical swine fever viruses (CSFV) were genetically characterized and compared with reference CSF viruses. The viruses originated from CSF outbreaks that occurred in the Lao People's Democratic Republic (Lao PDR) during 1997 though to 1999. All viruses characterized belonged to genogroup 2 and were members of subgroups 2.1 and 2.2. Results demonstrated a geographic delineation between subgroups 2.1 that was only found in the North-Central region, and subgroup 2.2 that was mostly found in the South-Central regions of Lao PDR. Although it was not possible to determine the origin of these viruses, it is probable that they may have been introduced to Lao PDR following cross-border trade. Alternatively, they have evolved independently of other viruses in the region.Virus Research 09/2004; 104(1):87-92. · 2.94 Impact Factor -
Article: The effect of sample degradation and RNA stabilization on classical swine fever virus RT-PCR and ELISA methods.
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ABSTRACT: Classical swine fever (CSF), also known as hog cholera, is a highly contagious viral infection of swine caused by a member of the genus pestivirus of the family, Flaviviridae. The need for accurate laboratory diagnosis of CSF is particularly important as it is more reliable than clinical diagnosis. CSF is endemic in many tropical countries where the climate is characterized by high ambient temperature and humidity. This study details the effect of sample quality on CSF antigen-capture ELISA (AC-ELISA) and reverse transcriptase-polymerase chain reaction (RT-PCR) methods. RT-PCR assessment of AC-ELISA-positive spleen samples stored in a conventional glycerol/saline buffer demonstrated that the RT-PCR was detrimentally affected by poor sample quality. To provide a more accurate representation of this effect, a 14 days study was performed to determine the effect of tropical ambient conditions on CSF virus-positive spleen samples stored in two transport media; glycerol/saline and a proprietary RNA preservation solution (RNAlater). A protective effect was demonstrated in both assays with RNAlater as samples were positive in both assays until day 14 post-exposure. Samples stored in glycerol/saline were negative at RT-PCR at day 3 post-exposure although AC-ELISA was still positive at day 14 post-exposure.Journal of Virological Methods 07/2004; 118(1):33-7. · 2.01 Impact Factor
