Haitham Mohammed

Texas A&M University | TAMU · Department of Rangeland, Wildlife, and Fisheries Management

The pathogen Nocardia seriolae is responsible for causing chronic granulomatous disease, known as fish nocardiosis, which has been observed in more than 40 species of fish cultured in marine and freshwater environments. Therefore, it is imperative to perform research to address and eradicate this substantial threat to the aquaculture industry. Howe...

Aquaculture is now the main source of seafood in human diets and is one of its fastest-growing industries worldwide. However, the industry is facing several difficulties, including infectious diseases, the most significant limiting factor for aquaculture expansion. The impact of diseases on aquaculture growth, fecundity, mortality rates, and market...

Background Ultrasonography had diagnostic importance in the evaluation of different diseases in buffaloes, including cardiovascular diseases. Aim The current work describes the normal echocardiographic findings in healthy buffaloes, along with establishing reference values for echocardiographic dimensions for both sides of the heart, i.e., left an...

Objective: The first objective of the study aimed to detect the presence of Lactococcus petauri, L. garvieae, and L. formosensis in fish (n = 359) and environmental (n = 161) samples from four lakes near an affected fish farm in California during an outbreak in 2020. The second objective was to compare the virulence of the Lactococcus spp. in Rain...

Background The post-parturient period in goat had marked changes in an animal’s endocrine and metabolic status as well as by reduction in feed intake when the nutrient demand for impending lactogenesis was increasing. The current study aimed to monitor the residues of oxytetracycline in Baladi goat milk and their hazards on public health as well as...

Background According to reports, the majority of domesticated species exhibited uterine torsion. It was occasionally noted as a cause of dystocia in buffaloes. The uterus might twist more frequently late in pregnancy because of certain animal traits. The current research monitored the clinical findings and laboratory assays associated with uterine...

The present study investigated the effects of dietary supplementation of nanocurcumin (NCur = 150 ppm) in African catfish feed for 15 days along with two doses of florfenicol—a therapeutic dose (FFC1 = 10 mg/kg.BW) and a high dose (FFC2 = 30 mg/kg.BW). Serum biochemical parameters and histopathological changes in liver and kidney tissues were deter...

Background: Organic egg is among the most common organic foods offered for sale in Egyptian markets in recent years, and consumers buy them at a higher price because they believe organic eggs are safer and have superior nutritional value than conventional eggs. Aim: The present work aimed to monitor antimicrobial residues in brown table eggs, wh...

Flavobacterium columnare causes columnaris disease in freshwater fish in both natural and aquaculture settings. This disease is often lethal, especially when fish population density is high, and control options such as vaccines are limited. The type IX secretion system (T9SS) is required for F. columnare virulence, but secreted virulence factors ha...

Twenty-two unidentified Gram-positive, rod-shaped organisms were recovered from the conjunctival surface of apparently healthy horses and subjected to a polyphasic taxonomic analysis. Based on cellular morphology and biochemical criteria, the isolates were tentatively assigned to the genus Corynebacterium, although they did not match any recognized...

The dinoflagellate Amyloodinium ocellatum is an important pathogenic parasite infecting cultured marine and brackish water fishes worldwide. This includes cultured Florida pompano (Trachinotus carolinus), which is one of the most desirable marine food fish with high economic value in the USA. A. ocellatum infects fish gills and causes tissue damage...

Piscine lactococcosis is an emergent bacterial disease that is associated with high economic losses in many farmed and wild aquatic species worldwide. Early and accurate detection of the causative agent of piscine lactococcosis is essential for management of the disease in fish farms. In this study, a TaqMan quantitative polymerase chain reaction (...

Flavobacterium columnare causes columnaris disease in wild and cultured freshwater fish and is a major problem for sustainable aquaculture worldwide. The F. columnare type IX secretion system (T9SS) secretes many proteins and is required for virulence. The T9SS component GldN is required for secretion and for gliding motility over surfaces. Genetic...

Flavobacterium psychrophilum causes bacterial cold-water disease in wild and aquaculture-reared fish, and is a major problem for salmonid aquaculture. The mechanisms responsible for cold-water disease are not known. It was recently demonstrated that the related fish pathogen, Flavobacterium columnare , requires a functional type IX protein secretio...

Flavobacterium columnare is a Gram-negative, aquatic bacterium that causes columnaris disease in wild and aquaculture-reared freshwater fish, including ecologically and economically important species. The mechanisms responsible for columnaris disease are not understood and little is known regarding F. columnare virulence. Iron acquisition from the...

Columnaris disease, caused by Flavobacterium columnare, is characterized by ectopic pathogenesis resulting in ulcerative skin lesions, frayed fins, and gill necrosis, triggering high mortality rates and extensive economic losses. The disease impacts almost all U.S. freshwater finfish aquaculture industries. The pathogenic mechanisms of F. columnare...

Myxozoa (phylum Cnidaria) are a diverse group of metazoan parasites that predominately infect fish. Little is known regarding the composition and physiology of their myxospore life stage. The objective of this work was to investigate the composition of myxospores and extrasporogonic stages of nine myxozoan species infecting various teleost fish usi...

Columnaris disease is a major problem for the aquaculture industry worldwide and results in substantial mortality and economic loss. The pathogenesis of the disease is poorly understood, and the existing control measures are ineffective. Flavobacterium columnare causes columnaris disease in wild, farmed, and ornamental freshwater fishes. Challenge...

Background The equine conjunctival microbiota has often been reported to be dominated by Gram‐positive species such as Staphylococcus sp., Bacillus sp., and Corynebacterium sp. However, traditional culture‐based methods can only recover a fraction of the bacterial species present in the sample. Objectives This pilot study aimed at exploring the di...

Flavobacterium columnare causes columnaris disease worldwide in freshwater fish, including many economically important aquaculture-reared species. Columnaris disease causes high mortality rates in aquaculture systems. The mechanisms of columnaris disease are poorly understood, and adequate vaccines are lacking. The type IX protein secretion system...

Flavobacterium columnare, a member of the phylum Bacteroidetes, causes columnaris disease in wild and aquaculture-reared freshwater fish, including ecologically and economically important species. The mechanisms responsible for columnaris disease are not known and little is known regarding F. columnare virulence factors. Many members of the phylum...

Flavobacterium columnare causes columnaris disease worldwide in freshwater fish, including many economically important aquaculture-reared species. Columnaris disease causes high mortality rates in aquaculture systems. The mechanisms of columnaris disease are poorly understood, and adequate vaccines are lacking. The type IX protein secretion system...

Flavobacterium columnare causes columnaris disease in freshwater fish, including many economically important aquaculture-reared species in Wisconsin. The mechanisms of this disease are unknown, although a type IX secretion system (T9SS) has been shown to be required for virulence. Material secreted by wild type and T9SS mutant cells was analyzed by...

Flavobacterium columnare, a member of the phylum Bacteroidetes, causes columnaris disease in wild and aquaculture-reared freshwater fish, including ecologically and economically important species in Wisconsin. The mechanisms responsible for columnaris disease are not known and little is known regarding the virulence factors produced by F. columnare...

Henneguya adiposa is one of ten known, closely related myxozoan species that parasitize a variety of tissue sites in the channel catfish, Ictalurus punctatus. Reported to specifically target the adipose fin, H. adiposa is not associated with morbidity or mortality, although detailed descriptions of its associated histologic pathology are lacking. T...

White bass (Morone chrysops), striped bass and their interspecific hybrid are important game fishes, whereas the hybrid striped bass is an important aquaculture species in the US. Numerous state, federal and private hatcheries, therefore, rear these species for stocking purposes as well as for food fish. Although striped bass populations (both wild...

Aeromonas hydrophila is one of the most widespread bacterial pathogens affecting freshwater fish and an emerging pathotype of A. hydrophila has severely impacted the catfish industry over the last decade. In this study, we evaluated the effect of treatment with kaolin (Al2Si2O5(OH)4), an inert clay, on the chemotaxis and adhesion (two important ste...

We evaluated a Saccharomyces cerevisiae fermentation product (Diamond V Original XPC) in hybrid catfish (Ictalurus furcatus x I. punctatus) for its potential effects on growth, blood parameters, and disease resistance. The trial featured four levels of inclusion that were added to a commercial 32% protein floating catfish ration. Following six week...

The gut microbial community is considered an additional ‘organ’ due to its vital functions to the host. It is composed of pathogenic and non-pathogenic microorganism living in a dynamic but balanced symbiosis with their host. Once this equilibrium is disrupted, dysbiosis occurs and could lead to unbalanced physiological functions and even an increa...

An outbreak occurred in a floating in-pond raceway system (IPRS) stocked with hybrid catfish (Ictalurus furcatus x Ictalurus punctatus) during the summer (May-July) of 2017. The IPRS consists of 12 rectangular-shaped units constructed in a 8 hectare earthen sport-fishing pond (pond S6) located at the E. W. Shell Fisheries Center in Auburn, AL and h...

Description: Infectious diseases are one of the main factors limiting aquaculture productivity. Flavobacterium columnare, the causative agent of columnaris disease, is one of the leading causes of fish mortality for US catfish farmers. Mortality rates varied but can reach up to 90% in fingerlings. F. columnare is a ubiquitous bacterium in freshwate...

Unusual persistent natural mortality occurred in a floating in‐pond raceway system intensively stocked with channel and hybrid catfish beginning in early November 2016 up until March 2017. The temperature during the period of outbreak ranged from 7.2 to 23.7°C. Gross examination of freshly dead and moribund fish revealed pale gills, slight abdomina...

Until 2012, the genus Edwardsiella was composed by three species Edwardsiella tarda, Edwardsiella hoshinae and Edwardsiella ictaluri. In 2013, Edwardsiella piscicida, compiling fish pathogenic strains previously identified as E. tarda was described, and more recently a new species isolated from diseased eel was reported, namely Edwardsiella anguill...

The Florida bass (Micropterus floridanus) is a species endemic to peninsular Florida that is held in high esteem by bass anglers for its tendency to attain a larger maximum size and aggressiveness relative to that of its sister taxon, the Northern largemouth bass, Micropterus salmoides. Hatchery rearing and stocking of Florida bass outside of their...

Rhamnose-binding lectins (RBLs) are crucial elements associated with innate immune responses to infections and have been characterized from a variety of teleost fishes. Given the importance of RBL in teleost fishes, we sought to study the diversity and expression profiles of RBLs in an important cultured fish, Nile tilapia (Oreochromis niloticus) f...

A recently developed attenuated vaccine for Flavobacterium columnare has been demonstrated to provide superior protection for channel catfish, Ictalurus punctatus, against genetically diverse columnaris isolates. We were interested in examining the mechanisms of this protection by comparing transcriptional responses to F. columnare challenge in vac...

An emerging pathotype of Aeromonas hydrophila (vAh) has been responsible for widespread farm losses in the US catfish industry over the last decade. While our genetic and biochemical understanding of vAh has been greatly enhanced in this time frame, our ability to reliably induce the disease in the laboratory has remained limited. Taking cues from...

3. Purpose. The equine conjunctival microbiota has often been reported to be dominated by Gram-positive species such as Staphylococcus sp., Bacillus spp. and Corynebacterium spp, however, traditional culture-based methods detect only a fraction of the microbiota. This pilot study aimed to explore the true diversity of the equine conjunctival microb...

Columnaris disease, caused by Flavobacterium columnare, is an emerging problem in the rainbow trout (Oncorhychus mykiss) aquaculture industry of Idaho. All F. columnare isolates taken from disease outbreaks in the rainbow trout producing region of southern Idaho, and for rainbow trout, are all genomovar I.Virulence phenotyping of 11 genomovar I and...

A recently developed attenuated vaccine (17-23) for Flavobacterium columnare has been demonstrated to provide superior protection for channel catfish, Ictalurus punctatus, against genetically diverse columnaris isolates. First, we were interested in elucidating the host responses generated by a virulent (BGSF-27) or attenuated (17-23) isolate utili...

The external microbiome of fish is thought to benefit the host by hindering the invasion of opportunistic pathogens and/or stimulating the immune system. Disruption of those microbial communities could increase susceptibility to diseases. Traditional aquaculture practices include the use of potent surface-acting disinfectants such as potassium perm...

A recently developed attenuated vaccine (17-23) for Flavobacterium columnare has been demonstrated to provide superior protection for channel catfish, Ictalurus punctatus, against genetically diverse columnaris isolates (Mohammed et al. 2013; Vaccine). We were interested in examining the mechanisms of this protection by comparing transcriptional re...

Columnaris disease, caused by Flavobacterium columnare, continues to inflict substantial losses among freshwater, cultured species almost one hundred years after it was first described. In fact, experimental and anecdotal evidence suggests an expanded range and rising virulence for columnaris worldwide correlated with warming climate conditions. In...

Columnaris disease, caused by the bacterium Flavobacterium columnare, is currently the most frequently reported bacterial disease affecting farm-raised channel catfish in the USA. Common treatments against the disease include the use of medicated feed that has led to emergent antibiotic resistant strains of F. columnare. Nigella sativa (Black cumin...

In this dissertation, I explored the intraspecies genetic heterogeneity within Flavobacterium columnare isolates collected during particularly severe columnaris outbreaks observed at the E.W. Shell Fisheries Center, Aquatic Experiment Research Station at North Auburn, AL, USA. These outbreaks affected both farmed and sport fish species that were ra...

Columnaris disease, caused by Flavobacterium columnare, is currently one of the most important bacterial disease affecting farm-raised channel catfish (Ictalurus punctatus) around the world. Conventional therapy for columnaris outbreaks is often through administration of medicated feeds with antibiotics, however, the excessive use of antibiotics in...

Columnaris disease is a widespread acute to chronic bacterial infection, caused by the fish pathogen Flavobacterium columnare, affects all species of cultured and wild freshwater fish. Typically, columnaris disease is an external infection, attacking primarily the fins, skin and gills of fish resulting in fin erosion, skin lesions and gill necrosis...

Columnaris disease is currently the most important bacterial diseases affecting both wild and cultured freshwater fishes including commercially raised channel catfish (Ictalurus punctatus). Despite the worldwide and the far-reaching negative impacts of columnaris disease, safe and effective preventatives and curatives are not yet available. Convent...

In the southeastern USA, columnaris disease (caused by Flavobacterium columnare) typically affects catfish raised in earthen ponds from early spring until late summer. Recently, unusually severe outbreaks of columnaris disease occurred at the E. W. Shell Fisheries Center located in Auburn, AL, USA. During these outbreaks, catfish and other aquacult...

Edwardsiella tarda es un patógeno bacteriano con capacidad para infectar multitud de organismos incluyendo peces, anfibios, mamíferos marinos e incluso al hombre. La enfermedad causada por este bacilo, edwardsielosis, constituye un serio problema en el cultivo de rodaballo a nivel mundial pudiendo afectar al cultivo de lenguado. Tradicionalmente E....

Columnaris disease, caused by the fish pathogen Flavobacterium columnare, is one of the most important bacterial diseases affecting cultured and wild freshwater fishes including channel catfish. Columnaris disease typically courses as an external infection affecting primarily gill and skin epithelia. Healthy skin microbiota is thought to maintain h...

Flavobacterium columnare, the etiologic agent of columnaris disease, is one of the most significant bacterial pathogens of freshwater wild and cultured fishes both in the US and worldwide. However, the epizootiology of columnaris disease in fish ponds has not been extensively studied. Recently, we have observed abnormally rigorous outbreaks of colu...

This study investigated the impacts of bacterial DNA extraction methodology on downstream analysis of fish gut microbiota. Feces and intestine samples were taken from three sympatric freshwater fish species with varying diets. Samples were processed immediately (approximately 4 h after capture; fresh), stored at -20°C for 15 days or preserved in RN...

Due to the strong influence of the gut microbiota on fish health, dominant bacterial species in the gut are strong candidates for probiotics. This study aimed to characterize the gut microbiota of channel catfish Ictalurus punctatus, largemouth bass Micropterus salmoides, and bluegill Lepomis macrochirus to provide a baseline for future probiotic s...

Columnaris disease, a bacterial infection caused by Flavobacterium columnare, is one of the main diseases affecting freshwater aquaculture worldwide. In the US, columnaris disease negatively impacts catfish aquaculture causing great economic losses annually. Although F. columnare is one the main bacterial pathogens limiting the profitability of the...

Edwardsiella tarda is a gram-negative bacterial pathogen of fish, reptiles, amphibians, marine mammals and other warm-blooded animals. The septicaemia caused by this rod in fish is a serious problem for several aquaculture species worldwide. Although traditionally considered a homogenous species by morphological, physiological and biochemical analy...

Flavobacterium columnare, the causative agent of columnaris disease, is a highly diverse species comprised by three genomovars. Genomovar II strains are more virulent toward catfishes than genomovar I isolates. The objective of this study was to compare the vaccine efficacy of avirulent mutants derived from genomovars I and II using a rifampicin-re...

Flavobacterium columnare is the causal agent of columnaris disease, currently, the most important bacterial disease of freshwater fish affecting both wild and cultured fish species. However, little is known about the epidemiology of F. columnare in fish ponds. Fish are vulnerable to columnaris following stressful situations. Sudden variations in wa...

Flavobacterium columnare, the causative agent of columnaris disease, is pathogenic to most species of freshwater fish in the USA and worldwide. Columnaris disease is the second highest killer of farmed catfish and is currently the most prevalent illness in farm-raised channel catfish, Ictalurus punctatus (Rafinesque), which constitutes the largest...

Flavobacterium columnare is the causative agent of columnaris disease that affects many species of freshwater fish and has a worldwide distribution. Second only to enteric septicaemia, columnaris disease is a leading killer of commercially raised channel catfish, Ictalurus punctatus. Flavobacterium columnare is divided into three different genetic...

Antibiotics are commonly administered to animals and humans as therapeutic agents against bacterial infections. Antibiotic residues in water have been increasing over the years resulting in more aquatic bacteria acquiring resistance mechanism to those antibiotics. In aquaculture, the use of antibiotic is limited with only three approved antibiotics...

This study was conducted to investigate the pathogenesis of columnaris disease in African sharptooth catfish, Clarias gariepinus. Flavobacterium columnare infections were detected in 33 (22.9%) fish out of 144 fish collected and examined over a year, in Assiut, Egypt. The present study demonstrated that parasitic infestation increases the susceptib...

The aim of my study was to investigate the infection of African sharptooth catfish, Clarias gariepinus with Flavobacterium spp. The study was carried out using 144 C. gariepinus collected (12 fish / month). The period of survey extended from May, 2006 till April 2007. Collected fish were divided according to their body weight into two groups. First...