S. A. Khan

A Strategy To Estimate Unknown Viral Diversity in Mammals

ABSTRACT The majority of emerging zoonoses originate in wildlife, and many are caused by viruses. However, there are no rigorous estimates of total viral diversity (here termed “virodiversity”) for any wildlife species, despite the utility of this to future surveillance and control of emerging zoonoses. In this case study, we repeatedly sampled a mammalian wildlife host known to harbor emerging zoonotic pathogens (the Indian Flying Fox, Pteropus giganteus) and used PCR with degenerate viral family-level primers to discover and analyze the occurrence patterns of 55 viruses from nine viral families. We then adapted statistical techniques used to estimate biodiversity in vertebrates and plants and estimated the total viral richness of these nine families in P. giganteus to be 58 viruses. Our analyses demonstrate proof-of-concept of a strategy for estimating viral richness and provide the first statistically supported estimate of the number of undiscovered viruses in a mammalian host. We used a simple extrapolation to estimate that there are a minimum of 320,000 mammalian viruses awaiting discovery within these nine families, assuming all species harbor a similar number of viruses, with minimal turnover between host species. We estimate the cost of discovering these viruses to be ~

Ebola virus antibodies in fruit bats, bangladesh.

6.3 billion (or ~

Identification of GBV-D, a Novel GB-like Flavivirus from Old World Frugivorous Bats (Pteropus giganteus) in Bangladesh

1.4 billion for 85% of the total diversity), which if annualized over a 10-year study time frame would represent a small fraction of the cost of many pandemic zoonoses. IMPORTANCE Recent years have seen a dramatic increase in viral discovery efforts. However, most lack rigorous systematic design, which limits our ability to understand viral diversity and its ecological drivers and reduces their value to public health intervention. Here, we present a new framework for the discovery of novel viruses in wildlife and use it to make the first-ever estimate of the number of viruses that exist in a mammalian host. As pathogens continue to emerge from wildlife, this estimate allows us to put preliminary bounds around the potential size of the total zoonotic pool and facilitates a better understanding of where best to allocate resources for the subsequent discovery of global viral diversity. Recent years have seen a dramatic increase in viral discovery efforts. However, most lack rigorous systematic design, which limits our ability to understand viral diversity and its ecological drivers and reduces their value to public health intervention. Here, we present a new framework for the discovery of novel viruses in wildlife and use it to make the first-ever estimate of the number of viruses that exist in a mammalian host. As pathogens continue to emerge from wildlife, this estimate allows us to put preliminary bounds around the potential size of the total zoonotic pool and facilitates a better understanding of where best to allocate resources for the subsequent discovery of global viral diversity.

Factors limiting the health of semi-scavenging ducks in Bangladesh

To determine geographic range for Ebola virus, we tested 276 bats in Bangladesh. Five (3.5%) bats were positive for antibodies against Ebola Zaire and Reston viruses; no virus was detected by PCR. These bats might be a reservoir for Ebola or Ebola-like viruses, and extend the range of filoviruses to mainland Asia.

Molecular epidemiology of influenza A (H5N1) viruses, Bangladesh, 2007-2011

Bats are reservoirs for a wide range of zoonotic agents including lyssa-, henipah-, SARS-like corona-, Marburg-, Ebola-, and astroviruses. In an effort to survey for the presence of other infectious agents, known and unknown, we screened sera from 16 Pteropus giganteus bats from Faridpur, Bangladesh, using high-throughput pyrosequencing. Sequence analyses indicated the presence of a previously undescribed virus that has approximately 50% identity at the amino acid level to GB virus A and C (GBV-A and -C). Viral nucleic acid was present in 5 of 98 sera (5%) from a single colony of free-ranging bats. Infection was not associated with evidence of hepatitis or hepatic dysfunction. Phylogenetic analysis indicates that this first GBV-like flavivirus reported in bats constitutes a distinct species within the Flaviviridae family and is ancestral to the GBV-A and -C virus clades.

A survey of gastro-intestinal parasitic infection in domestic and wild birds in Chittagong and Greater Sylhet, Bangladesh.

Duck rearing is well suited to coastal and lowland areas in Bangladesh. It is an important component of sustainable livelihood strategies for poor rural communities as an additional source of household income. An epidemiological study was conducted during January 2005–June 2006 on 379 households in Chatkhil of the Noakhali District, Bangladesh which were using the recently devised “Bangladesh duck model”. The overall objective of the study was to identify factors that significantly contributed to mortality and constrained productivity and to generate sufficient knowledge to enable establishment of a disease surveillance system for household ducks. The overall mortality was 15.0% in Chatkhil, with predation causing a significantly higher mortality compared with diseases (p < 0.001). Common diseases were duck plague and duck cholera. Morbid ducks frequently displayed signs associated with diseases affecting the nervous and digestive systems. Haemorrhagic lesions in various organs and white multiple foci on the liver were frequently observed in dead ducks. Epidemiological analysis with a shared frailty model that accounted for clustering of data by farm was used to estimate the association between survival time and risk factors. The overall mortality rate due to disease was significantly lower in vaccinated than in non-vaccinated ducks in all zones except zone 2 (p < 0.001). Only vaccinated ducks survived in zone 1. In conclusion, duck mortality and untimely sale of ducks appeared to be important constraints for household duck production in Chatkhil. Vaccination against duck plague appears to be an effective preventive strategy in reducing the level of associated duck mortality. A successful network was established amongst farmers and the surveillance team through which dead ducks, with accompanying information, were readily obtained for analysis. Therefore, there is an opportunity for establishing a long-term disease surveillance programme for rural ducks in Chatkhil of the Noakhali District of Bangladesh.

Epidemiology and genetic characterization of Peste des petits ruminants virus in Bangladesh

To investigate the origins, evolution and patterns of spread of HPAI H5N1 outbreaks in Bangladesh, we performed a phylogenetic reconstruction analysis using Bayesian methods. The analysis was conducted using 81 hemagglutinin (HA) gene sequences from the H5N1 viruses isolated in Bangladesh from 2007 to 2011, together with 264 publicly available HA sequences of clade 2.2, 2.3.2 and 2.3.4 retrieved from GenBank. Our study provides evidence that clade 2.2.2 viruses that caused outbreaks in Bangladesh were lineages independent from the viruses introduced earlier into India. Furthermore, the Bangladesh clade 2.2.2 descendents subsequently spread to India and Bhutan. This has implications for avian influenza control in southern Asia suggesting multiple routes of entry of the virus including one pathway that spread to neighboring countries via Bangladesh.

A prevalence of parasites in black bengal goats in Chittagong, Bangladesh

A survey of gastrointestinal parasitic infection as determined by faecal examination was conducted among domestic and wild birds in Bangladesh. Birds were sampled from households, wet markets and wetlands in Chittagong and Greater Sylhet districts during April 2012 to February 2013. Mist nets were used to catch resident wild and migratory birds. The overall prevalence of parasitic infection ranged among locations from 25 to 55% in indigenous domestic ducks (live bird samples=304), 20% in resident wild birds (environmental faecal samples=40) and 40% in migratory birds (live bird samples=35). The prevalence of parasitic infection was significantly higher in indigenous domestic ducks collected during summer (39%) than winter (22%) (p=0.04). In domestic indigenous ducks and Muscovy ducks, both single and multiple types of parasitic infections were found. However, other domestic birds and wild birds often had a single type of parasitic infection. Ascaridia spp. with an average egg load of 50-900, was commonly detected in faecal samples of domestic and wild birds in this study. Other identified parasites were Capillaria spp. and Heterakis spp. both in domestic and wild birds. Improvement of biosecurity measures for household duck farms through educating and motivating household farmers could help mitigate the effects of parasitic infection on production.

Studies on the antidiarrhoeal, antimicrobial and cytotoxic activities of ethanol-extracted leaves of yellow oleander (Thevetia peruviana).

Abstract Peste des petits ruminants (PPR) is an acute, highly contagious disease responsible for high morbidity and mortality rates in susceptible sheep and goats. Adequate knowledge of the diversity of circulating strains of PPR virus will help livestock authorities choose appropriate vaccines. The objective of this study was to describe the epidemiology of PPR and characterize the strains circulating in Bangladesh. Veterinarians enrolled goats showing signs consistent with PPR, including diarrhoea, fever and respiratory distress, from three veterinary hospitals. Post‐treatment follow up was carried out to ascertain health outcomes of the goats. Faecal and throat swab samples were collected from the goats and tested for PPRV RNA using real‐time reverse transcription polymerase chain reaction (rRT‐PCR). Nucleotide sequence‐based phylogenetic analyses of two structural genes, the nucleocapsid (N gene), and the haemagglutinin (H gene) were studied to determine the genetic variations of PPRV strains. Of the 539 goats enrolled, 38% (203/539) had detectable RNA for PPRV. We were able to follow up with 91% (184/203) of the PPRV infected goats; 44 of them died (24%). PPRV was more frequently identified in the summer (45%) than in the rainy season (29%) (Odds ratio = 1.9, 95% confidence interval: 1.3–3.1). Bangladeshi strains were phylogenetically similar to the lineage IV PPRV strains; showing particularly strong affiliation with Tibetan and Indian strains. PPR is a common viral infection of the goats in Bangladesh, with a high case‐fatality rate. This study confirms the circulation of lineage IV PPRV in the country with unique amino acid substitutions in N and H proteins and provides baseline data for vaccine development and implementation.