Background Arboviral diseases, including dengue and chikungunya, are major public health concerns in Bangladesh where there have been unprecedented levels of transmission reported in recent years. The primary approach to control these diseases is to control the vector Aedes aegypti using pyrethroid insecticides. Although chemical control has long been practiced, no comprehensive analysis of Ae. aegypti susceptibility to insecticides has been conducted to date. The aim of this study was to determine the insecticide resistance status of Ae. aegypti in Bangladesh and investigate the role of detoxification enzymes and altered target site sensitivity as resistance mechanisms. Methods Eggs of Aedes mosquitoes were collected using ovitraps from five districts across Bangladesh and in eight neighborhoods of the capital city Dhaka, from August to November 2017. CDC bottle bioassays were conducted for permethrin, deltamethrin, malathion, and bendiocarb using 3- to 5-day-old F0–F2 non-blood-fed female mosquitoes. Biochemical assays were conducted to detect metabolic resistance mechanisms, and real-time PCR was performed to determine the frequencies of the knockdown resistance (kdr) mutations Gly1016, Cys1534, and Leu410. Results High levels of resistance to permethrin were detected in all Ae. aegypti populations, with mortality ranging from 0 to 14.8% at the diagnostic dose. Substantial resistance continued to be detected against higher (2×) doses of permethrin (5.1–44.4% mortality). Susceptibility to deltamethrin and malathion varied between populations while complete susceptibility to bendiocarb was observed in all populations. Significantly higher levels of esterase and oxidase activity were detected in most of the test populations as compared to the susceptible reference Rockefeller strain. A significant association was detected between permethrin resistance and the presence of Gly1016 and Cys1534 homozygotes. The frequency of kdr (knockdown resistance) alleles varied across the Dhaka Aedes populations. Leu410 was not detected in any of the tested populations. Conclusions The detection of widespread pyrethroid resistance and multiple resistance mechanisms highlights the urgency for implementing alternate Ae. aegypti control strategies. In addition, implementing routine monitoring of insecticide resistance in Ae. aegypti in Bangladesh will lead to a greater understanding of susceptibility trends over space and time, thereby enabling the development of improved control strategies.

Introduction: In Bangladesh, human sludge from dry pit latrines is commonly applied directly to agricultural lands as manure. This study was conducted to investigate the presence of antibiotic resistance, virulence factors and plasmid contents of E. coli strains isolated from sludge samples. Methodology: E. coli were isolated from human feces from closed pit latrines and identified by culture method. Antibiotic susceptibility patterns of the isolates were determined by Standard Kirby-Bauer disk diffusion method. Pathogenic genes and antibiotic resistance genes of ESBL producing isolates were determined by PCR assay. Results: Of the 34 samples tested, 76.5% contained E. coli. Of 72 E. coli isolates, 76.4% were resistant to at least one of the 12 antibiotics tested and 47.2% isolates were resistant to three or four classes of antibiotics. Around 18% isolates were extended spectrum β- lactamase producing and of them 6 were positive for blaTEM specific gene, 4 for blaCTX-M gene, 1 for blaOXA gene and 2 for both blaTEM and blaCTX-M genes. Moreover, among 72 isolates, 4.2% carried virulence genes of enterotoxigenic E. coli; two isolates were positive for st and one was positive for both st and lt genes. In addition, 59.7% of the isolates contained plasmids (range 1.4 to 140 MDa) of which 19.5% isolates contained a single plasmid and 40.2% contained multiple plasmids. Conclusions: The presence of pathogenic, drug resistant E. coli in human sludge necessitates a regular surveillance before using as a biofertilizer.

Arboviral diseases including dengue and chikungunya are a major public health concern in Bangladesh, with unprecedented levels of transmission reported in recent years. The primary approach to control these diseases is control of Aedes aegypti using pyrethroid insecticides. Although chemical control is long-practiced, no comprehensive analysis of Ae. aegypti susceptibility to insecticides has previously been conducted. This study aimed to determine the insecticide resistance status of Ae. aegypti in Bangladesh and investigate the role of detoxification enzymes and altered target site sensitivity as resistance mechanisms. Aedes eggs were collected using ovitraps from five districts across the country and in eight neighborhoods of the capital city Dhaka from August to November 2017. CDC bottle bioassays were conducted for permethrin, deltamethrin, malathion, and bendiocarb using 3-5-day old F0-F2 non-blood fed female mosquitoes. Biochemical assays were conducted to detect metabolic resistance mechanisms and real-time PCR was performed to determine the frequencies of the knockdown resistance (kdr) mutations Gly1016, Cys1534, and Leu410. High levels of resistance to permethrin were detected in all Ae. aegypti populations, with mortality ranging from 0 – 14.8% at the diagnostic dose. Substantial resistance continued to be detected against higher (2X) doses of permethrin (5.1 – 44.4% mortality). Susceptibility to deltamethrin and malathion varied between populations while complete susceptibility to bendiocarb was observed in all populations. Significantly higher levels of esterase and oxidase activity were detected in most of the test populations as compared to the susceptible reference Rockefeller strain. A significant association was detected between permethrin resistance and the presence of Gly1016 and Cys1534 homozygotes. The frequency of kdr alleles varied across the Dhaka populations, and Leu410 was not detected in any of the tested populations. The detection of widespread pyrethroid resistance and multiple mechanisms highlights the urgency for implementing alternate Ae. aegypti control strategies. In addition, implementing routine monitoring of insecticide resistance in Ae. aegypti in Bangladesh will lead to a greater understanding of susceptibility trends over space and time, thereby enabling the development of improved control strategies.Author summaryGlobally, arboviral diseases including dengue, chikungunya, and Zika are major public health problems. Bangladesh recently experienced its two worst outbreaks of chikungunya and dengue, involving hundreds of thousands of people. The principal vector of these diseases, the Aedes aegypti mosquito, is present throughout Bangladesh, especially in the major cities including the capital, Dhaka. The control of Ae. aegypti in Bangladesh has long been based on space sprays by thermal fogging of pyrethroid insecticides. However, no comprehensive assessment has previously been conducted to understand the insecticide resistance status of Ae. aegypti. We tested Ae. aegypti collected from places of historical arboviral outbreaks to determine their insecticide resistance status, as well as some of the underlying mechanisms causing the resistance. All of the populations tested were highly resistant to permethrin, the key insecticide used by vector control programs in Dhaka, with varying degrees of resistance to deltamethrin and malathion, and full susceptibility to bendiocarb. High levels of esterase and oxidase enzyme activity and the presence of mutations on the voltage-gated sodium channel gene were detected as key mechanisms underpinning the resistance. The findings of this study provide the first comprehensive evidence base for improving Ae. aegypti control strategies in Bangladesh.

Malaria elimination is a Millennium Development Goal. Artemisinins, fast-acting antimalarial drugs, have played a key role in malaria elimination.

Infections by Frog Virus 3 (FV3) and other ranavirus genus members are significantly contributing to global amphibian decline. The Xenopus laevis frog is an ideal research platform upon which to study the roles of distinct frog leukocyte populations during FV3 infections. Frog macrophages (MΦs) are integrally involved during FV3 infection, as they facilitate viral dissemination and persistence but also participate in immune defense against this pathogen. In turn, MΦ differentiation and functionality depend on the colony-stimulating factor-1 receptor (CSF-1R), which is ligated by CSF-1 and iterleukin-34 (IL-34) cytokines. Our past work indicated that X. laevis CSF-1 and IL-34 give rise to morphologically and functionally distinct frog MΦ subsets, and that these CSF-1- and IL-34-MΦs respectively confer susceptibility and antiviral resistance to FV3. Because FV3 targets the frog kidneys and establishes chronic infections therein, presently we examined the roles of the frog CSF-1- and IL-34-MΦs in seeding and maintaining these chronic kidney infections. Our findings indicate that the frog CSF-1-MΦs result in more prominent kidney FV3 infections, which develop into greater reservoirs of lingering FV3 marked by infiltrating leukocytes, fibrosis, and overall immunosuppressive states. Moreover, the antiviral effects of IL-34-MΦs are short-lived and are lost as FV3 infections progress.

Introduction: The persistent increase of resistance to existing antimalarials underscores the needs for new drugs. Historically, most of the successful antimalarial are derived from plants. The leaves of the S. cymosum is one of the plant materials used by traditional healers in malaria-endemic areas in Bangladesh for treatment of malaria. Here, we investigated the crude extract and its fractions against chloroquine (CQ)-sensitive 3D7, CQ-resistant Dd2, and artemisinin (ART)-resistant IPC 4912 Mondulkiri strains of Plasmodium falciparum. Methodology: The antimalarial activities were tested using HRP II based in-vitro antimalarial drug sensitivity ELISA described by WWARN and half inhibitory concentrations (IC50) were calculated by non-linear regression analysis using GraphaPad Prism. The cytotoxicity of the crude methanolic extract was assessed using the MTT assay on Vero cell line. Results: The methanolic crude extract revealed promising activity against 3D7 (IC50 6.28 µg/mL), Dd2 (IC50 13.42 µg/mL), and moderate activity against IPC 4912 Mondulkiri (IC50 17.47 µg/mL). Among the fractionated portions, the chloroform fraction revealed highest activity against IPC 4912 Mondulkiri (IC50 1.65 µg/mL) followed by Dd2 (1.73 µg/mL) and 3D7 (2.39 µg/mL). The crude methanolic extract also demonstrated good selectivity with the selectivity indices of > 15.92, > 7.45, and > 6.91 against 3D7, Dd2, and IPC 4912, respectively when tested against Vero cell line. Conclusions: This is the first report on S. cymosum for its putative antimalarial activity, and is imperative to go for further phytochemical analyses in order to investigate possible novel antimalarial drug compound(s).

The global amphibian declines are compounded by ranavirus infections such as Frog Virus 3 (FV3), and amphibian tadpoles more frequently succumb to these pathogens than adult animals. Amphibian gastrointestinal tracts represent a major route of ranavirus entry, and viral pathogenesis often leads to hemorrhaging and necrosis within this tissue. Alas, the differences between tadpole and adult amphibian immune responses to intestinal ranavirus infections remain poorly defined. As interferon (IFN) cytokine responses represent a cornerstone of vertebrate antiviral immunity, it is pertinent that the tadpoles and adults of the anuran Xenopus laevis frog mount disparate IFN responses to FV3 infections. Presently, we compared the tadpole and adult X. laevis responses to intestinal FV3 infections. Our results indicate that FV3-challenged tadpoles mount more robust intestinal type I and III IFN responses than adult frogs. These tadpole antiviral responses appear to be mediated by myeloid cells, which are recruited into tadpole intestines in response to FV3 infections. Conversely, myeloid cells bearing similar cytology already reside within the intestines of healthy (uninfected) adult frogs, possibly accounting for some of the anti-FV3 resistance of these animals. Further insight into the differences between tadpole and adult frog responses to ranaviral infections is critical to understanding the facets of susceptibility and resistance to these pathogens.

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