Kamrul Islam

Regional Variation in the Prevalence of E. coli O157 in Cattle: A Meta-Analysis and Meta-Regression

Background Escherichia coli O157 (EcO157) infection has been recognized as an important global public health concern. But information on the prevalence of EcO157 in cattle at the global and at the wider geographical levels is limited, if not absent. This is the first meta-analysis to investigate the point prevalence of EcO157 in cattle at the global level and to explore the factors contributing to variation in prevalence estimates. Methods Seven electronic databases- CAB Abstracts, PubMed, Biosis Citation Index, Medline, Web of Knowledge, Scirus and Scopus were searched for relevant publications from 1980 to 2012. A random effect meta-analysis model was used to produce the pooled estimates. The potential sources of between study heterogeneity were identified using meta-regression. Principal findings A total of 140 studies consisting 220,427 cattle were included in the meta-analysis. The prevalence estimate of EcO157 in cattle at the global level was 5.68% (95% CI, 5.16–6.20). The random effects pooled prevalence estimates in Africa, Northern America, Oceania, Europe, Asia and Latin America-Caribbean were 31.20% (95% CI, 12.35–50.04), 7.35% (95% CI, 6.44–8.26), 6.85% (95% CI, 2.41–11.29), 5.15% (95% CI, 4.21–6.09), 4.69% (95% CI, 3.05–6.33) and 1.65% (95% CI, 0.77–2.53), respectively. Between studies heterogeneity was evidenced in most regions. World region (p<0.001), type of cattle (p<0.001) and to some extent, specimens (p = 0.074) as well as method of pre-enrichment (p = 0.110), were identified as factors for variation in the prevalence estimates of EcO157 in cattle. Conclusion The prevalence of the organism seems to be higher in the African and Northern American regions. The important factors that might have influence in the estimates of EcO157 are type of cattle and kind of screening specimen. Their roles need to be determined and they should be properly handled in any survey to estimate the true prevalence of EcO157.

Comparative genomics of two jute species and insight into fibre biogenesis

Jute (Corchorus sp.) is one of the most important sources of natural fibre, covering ∼80% of global bast fibre production1. Only Corchorus olitorius and Corchorus capsularis are commercially cultivated, though there are more than 100 Corchorus species2 in the Malvaceae family. Here we describe high-quality draft genomes of these two species and their comparisons at the functional genomics level to support tailor-designed breeding. The assemblies cover 91.6% and 82.2% of the estimated genome sizes for C. olitorius and C. capsularis, respectively. In total, 37,031 C. olitorius and 30,096 C. capsularis genes are identified, and most of the genes are validated by cDNA and RNA-seq data. Analyses of clustered gene families and gene collinearity show that jute underwent shared whole-genome duplication ∼18.66 million years (Myr) ago prior to speciation. RNA expression analysis from isolated fibre cells reveals the key regulatory and structural genes involved in fibre formation. This work expands our understanding of the molecular basis of fibre formation laying the foundation for the genetic improvement of jute.

Fecal carriage of multi-drug resistant and extended spectrum β-lactamases producing E. coli in household pigeons, Bangladesh

Antibiotic resistance and ESBL constitute a risk to human and animal health. Birds residing close to humans could mirror the spectrum of human associated antibiotic resistance. Household pigeons were screened in Bangladesh to shed light on human associated, as well as, environmental antibiotic resistance. Escherichia coli from pigeons (n=150) were tested against 11 antibiotics. 89% E. coli isolates were resistant to one or more critically important human antibiotics like ampicillin, cefadroxil, mecillinam, ciprofloxacin, gentamicin and tigecycline. No carbapenamase-producers were detected and the lower ESBL prevalence (5%) in pigeons. ESBL-producing E. coli isolates had blaCTX-M-15 genes. Pigeons shared some bacterial clones and had bird associated sequence types like E. coli ST1408. Fecal carriage of bacteria resistance of critically important human antibiotics, together with examples of shared genotypes among pigeons, indicate the human-birds and bird to bird transmissions are important in the epidemiology of antibiotic resistance.

Seroprevalence of bovine viral diarrhea virus in crossbred dairy cattle in Bangladesh

Aim: The study was conducted to determine the seroprevalence of bovine viral diarrhea virus (BVDV) and hematological features in crossbred dairy cattle in Chittagong, Bangladesh. Materials and Methods: The antibody against BVDV in crossbred dairy cattle serum was detected by indirect enzyme-linked immunosorbent assay. The association of different categorical variables in the prevalence of BVDV has been studied. Blood samples were collected and analyzed to know the hematological variations in the study population. Results: The overall seroprevalence of BVDV in the study area was 51.1% (95% confidence interval [CI], 40.5-61.5). Among different physiological stages of animals, the highest 57.1% (95% CI, 42.2-71.2) prevalence was in case of non-pregnant animals. Aborted cows were found to be significantly (p<0.05) more seropositive 77.8% (95% CI, 52.4-93.6) than the non-aborted cows (77.8%, 95% CI, 52.4-93.6, compared to 44.7%, 95% CI, 33.3-56.6, respectively). Cows having the history of retained placenta were found more positive than without the history of retained placenta (63.2%, 95% CI, 38.4-83.7, compared to 54.7%, 95% CI, 40.4-68.4, respectively). Among the animals of different age groups, BVDV seroprevalence was higher 61.3% (95% CI, 42.2-78.2) in animals of more than 3 years up to 5 years, whereas 32% was in case of 0-1-year-old. Significant variation found in different geographical areas of the study area. Hematological analyses have shown variation between the BVDV positive and negative animals. Conclusion: Seroprevalence of BVDV found to be high in the study area is also economically important and cause significant damage to the production industry. Therefore, it is necessary to conduct effective control measures to reduce the burden of BVDV.

Monitoring the Coastal Groundwater of Bangladesh

The low-lying topography and geographic position makes Bangladesh very vulnerable regarding the anticipated impacts of climate change that likely affects nearly all sectors of socio-economic life, where water sector is the most vulnerable and sensitive among them and country’s coastal areas are at the greatest risk. The primary source of fresh water in the coastal belt is groundwater. But very few studies have been conducted to assess the influence of climate change on this resource. There is also high vulnerability to contamination with salinity due to mixing of pre-existing fresh and saline groundwater accelerated by irrigation pumping and vertical infiltration of salt water from periodic storm surge flooding. Changing climate and population stress might affect various components like recharge, discharge, storage, and water quality. The volume of water which is retained in the top soil is required for agriculture and has a role on the process of evaporation, recharge of groundwater, and innovation of runoff. Tidal saltwater wedge because of rising sea levels would cause to encroach further upstream in rivers, resulting salinity intrusion in aquifers. To know the evidence of changes in the events of hydrologic cycle including groundwater quality and storage is very important in order to adapt with the climate change impacts. The principal source of the irrigation water in Bangladesh is groundwater since decades and is one of the major factors making the nation almost self-dependent in crop production. Bangladesh being a very low-elevated country, where main part of the landform in the coast is up to 2–3 m above mean sea level, sea-level rise can cause increased intrusion of saline water both in surface water and in groundwater system. Inadequate safe water for irrigation and water supply will create more stress on fresh water. Therefore, it is important to map fresh water—saline water distribution in coastal aquifers with other important physico-chemical parameters and predict future changes in this environment due to both climate change and anthropogenic stresses. Considering this, a monitoring network has been established by Bangladesh Water Development Board in 19 coastal districts with monitoring wells at variable aquifer depths down to 350 m. The objective of the project, under the support of Bangladesh Climate Change Trust, is to establish a long-term monitoring network to assess and monitor coastal water resources both on quantitative and on qualitative aspects. This paper focuses on to determine the potential of available fresh water resources and distribution of salinity in aquifers both spatially and vertically, mainly based on the monitoring data, for sustainable long-term use of very scarce fresh water in the region.

Model Impact of Climate Change on the Groundwater Flow and Salinity Encroachment in the Coastal Areas of Bangladesh

The coastal population of Bangladesh has already been suffering from the salinity encroachment both in groundwater and surface water regime. Reduced river discharge, coastal surges, shrimp farming, lowering of groundwater table due to dry season irrigation in a large part of the country accelerate the rate of saline water distribution. In addition, sea level rise, due to the impact of climate change, may contribute to salinity encroachment on coastal freshwater resources, particularly in the shallow alluvial aquifers. Though the groundwater table is within 2–5 m below ground surface, availability of fresh and safe water in the coast is very limited in upper aquifers because of the arsenic contamination and water salinity. For the coastal population, deep (>250 m) tube wells are the main source of drinking water and irrigation water supply is mostly restricted to surface water including rainwater. In monsoon, freshwater pockets are available at the shallow depth (<8 m) from seasonal precipitation but mostly turn to brackish condition during dry period. Therefore, assessment and monitoring of development stress and probable impact of climate change on freshwater resource are utmost important. The main purpose of the study is to assess the impact of climate change and development stresses on the availability of fresh water resources in the coastal area. For that purpose, integrated hydrological model has been prepared describing the subsurface condition both the saturated and unsaturated zone together with the influence of various water components of the hydrological cycle. Groundwater salinity models are developed to simulate salinity transport in the sea, river and through the porous medium of aquifer for a range of existing and possible future conditions. It has been seen from the simulation result of the model that under climate change condition during the month of March and April, the salinity level is highest for all river system within the study area and significant during period from December to June. The climate change scenario illustrates that the groundwater level increases within the range of 0.6–0.8 m under climate change scenario. Movement of salinity is found insignificant from the river to the aquifer. Major rivers in the south central coast there is a considerable interaction between surface water and groundwater due to the tidal effect. On the other hand, there is negligible interaction between the aquifer and adjacent river in the south-eastern coastal plain.

Characterization of hemagglutination activity of emerging Newcastle disease virus in Bangladesh

Aim: Newcastle disease (ND) is an important viral disease for poultry caused by avian paramyxovirus which can be identified by its nature of agglutination activity with red blood cell (RBC) of different species. The study was aimed to characterize the hemagglutinating (HA) activity of ND virus (NDV) at three different temperatures using RBC of five avian species, six mammalian species, and eight different human blood groups. Materials and Methods: The study was conducted from January to December 2014 at Chittagong Veterinary and Animal Sciences University. Five avian and six different mammalian species were selected for the study. In each species, two blood samples were collected aseptically. Eight different blood groups (A+, A−, B+, B−, AB+, AB−, O+, and O−) were studied in human. HA test was performed using two virus strains ND lasota and field isolate of very virulent NDV (VVNDV) with mentioned species of RBC at chilling (4°C), incubating (37°C), and room temperature (24°C). Results: Avian RBC requires less time for agglutination than mammalian RBC. Incubation temperature (37°C) requires lowest time and chilling temperature requires highest time for agglutination of RBC. Duck RBC requires lowest time (17.81 min) while chicken RBC needs highest (57.5 min) time for HA at incubation temperature and at chilling temperature, respectively, against ND lasota virus and with field strain. Goat RBC requires significantly higher time for HA (184.68 min) at chilling temperature than other mammalian species. Human RBC requires almost similar time but O+ and O− blood group do not show any HA activity. Significant variation (p<0.05) found in quail RBC at incubation temperature. In mammalian species, a significant difference (p<0.05) has been observed in goat and horse RBC at chilling; horse and dog RBC at incubation; goat, horse, buffalo, and dog RBC at room temperature. In human, significant variation (p<0.05) has been found in A+, A− and B− blood group in chilling, in B+ blood group at incubation and A+, B+, B−, AB− blood group at room temperature against two virus strains. Conclusion: ND is considered as an economically significant disease which is highly contagious in nature infecting many avian species. The threat of ND outbreak to poultry industry necessitates effective control measures to reduce the burden in commercial and backyard farming in Bangladesh.