Strategies for describing myxozoan pathogens, dreadful fish diseases in aquaculture

Myxozoans are obligate endoparasites, cosmopolitan in distribution with both vertebrate and invertebrate hosts. Their myxospores consist of shell valves, polar capsules with coiled polar tubules that are extrudible, and infective amoeboid germs. Myxozoan parasites are most abundant, and due to their increasing number in recent years, they can pose an emerging threat to the fish industry worldwide. Hence, the immediate need is to devise a strategy to understand and detect parasites and parasitism. They may proliferate to different organs with the advancement of infection. This all warrants the development/devising of strategies and results of integrative studies in order to identify these dreadful parasites and resolve taxonomic issues. Different methods whether classical methods including gross morphology or advanced methods such as electron microscopy (SEM, TEM, STEM), Confocal laser scanning microscopy (CLSM), histopathological studies, site preference, host and tissue specificity, a molecular approach using new markers can be clubbed for identification because these parasites are hidden and are difficult to recognize. This group was earlier classified only on the basis of myxospores morphology, but due to the high structural variability of this group advanced methods and approaches have to be implied which can minimize the problems in assigning new species.

Breaking the resistance of Escherichia coli: Antimicrobial activity of Berberis lycium Royle

The antimicrobial activity of root bark of Berberis lycium and its principal component berberine was tested against a panel of microbial strains using agar well diffusion test and further analyzed using micro-broth dilution method. Preliminary analysis, on the basis of zone of Inhibition (ZOI) showed that the methanolic extract of B. lycium was highly effective against Escherichia coli (ZOI 41 ± 1 mm). Among the bacterial strains E. coli was found to be most susceptible and among fungi Candida albicans was the most susceptible for berberine as well as the crude methanolic extract of the plant. Methanolic extract of the plant was more effective for E. coli (MIC 1.7 ± 1.18; MBC 2.4 ± 1.18) than berberine (MIC 3.5 ± 0.57) (p < 0.05), whereas berberine was more effective than crude extracts for C. albicans. In addition, E. coli showed the development of resistant colonies after 72 h when tested with berberine but the development of such colonies was not observed with the methanolic extract of the plant. This could be due to the presence of resistance breaking molecules in the crude methanolic extract of B. lycium. Also the MIC index of crude methanolic extract was 1.39 for E. coli, which showed the mode of action to be bactericidal. HPLC analysis revealed the presence of berberine at highest concentration in methanolic extract of the plant, followed by aqueous extract. Potentiation of this berberine by resistance breaking molecules in the crude extract could be a possible explanation for its strong effectiveness.

A field survey on the status of gastrointestinal helminth parasites in hangul (Cervus elaphus hanglu) in Dachigam National Park of Kashmir

One year crossectional survey was carried out to determine and describe the prevalence and intensity of gastrointestinal parasite infections in hangul (Cervus elaphus hanglu) in Dachigam National Park of Kashmir through faecal examinations. Out of 153 faecal samples examined, 82 (53.59 %) were found infected with GIT helminthes. In present study seven helminth species were found, including five nematode [Haemonchus contortus (55.39 %), Trichuris ovis (39.75 %), Dictyocaulus viviparus (28.4.00 %), Oesophogostomum circumcincta (13.7 %) and Chabertia ovina (4.02 %)] one trematode [Fasciola hepatica (17.3 %)] and one cestode species [Moneizia expansa (6.05 %)]. Based on the severity of infection 81.7 % of hangul positive samples were severely infected (epg > 1,500), 8.3 % heavily infected (epg = 1,100-1,500), 3.8 % moderately infected (epg = 800-1,000) and 7.2 % mildly infected (epg = 500). Season, sex and age were the factors that influenced the epidemiological prevalence of GIT helminths in hangul in the present study. The maximum helminth infection was observed in summer season and lowest in winter (P = 0.003). Lower age groups were more infected than adult animals (P > 0.05). Prevalence was higher in males than females (P > 0.05). The present study will initially be of great significance to add to existing knowledge of the epidemiology of GIT helminth of hangul which is the pioneering study on this animal in the valley and the findings will be quite helpful to devise the appropriate control and prophylactic strategies for GIT helminthiasis of hangul in the Dachigam national park.

A report on the incidence of Trichodina heterodentata from fishes of Jammu, J&K India

The present study was aimed at screening for the presence of protozoan's among Cyprinid fishes collected from various fish ponds and farms in Jammu division of Jammu and Kashmir (J and K) state. Out of 75 fishes collected from local water bodies of Jammu division, only 35, (49.6 %) were infested with Trichodina. Trichodina infestations were studied in the period from November to February. In light infestation Trichodina was usually present on gills, fins and skin of apparently healthy fish. Clinical signs of Trichodiniasis appeared on fish with heavy infections and in presence of one or more stress factors including, rough handling during transportation from ponds, over crowdedness, malnutrition, high concentration of free ammonia and low oxygen concentration. Clinical signs of Trichodiniasis in fish such as sluggish movement, loss of appetite, black colouration, necrosis and ulcer on different parts of the body, detached scales and excessive accumulation of mucous in gill pouches were also observed.

[A comparative analysis of various antigenic proteins found in Haemonchus contortus--a review]

Many innovative researches on the development and introduction of recombinant vaccines against many economically important parasites were carried out in the 20th century. Research continues to hold promise with the development of immunological and molecular approaches for control of these parasites and in this regard it has already been seen that blood-sucking parasites such as Haemonchus contortus and Ostertagia ostertagi are susceptible to control by vaccines containing "novel" or "concealed" antigens. Haemonchus contortus is primarily pathogenic to sheep and its blood-feeding behaviour causes effects ranging from mild anaemia to mortality in young animals. Current means of control which are dependent on repeated treatment with anthelmintics are responsible for the increasing drug resistance of this parasite. Together with the growing concern of residual chemicals in the environment and food chain, this has led to attempts to better understand the biology of the parasite with an aim to develop alternate means of control, including the development of molecular vaccines. More problematic and also important is the formulation and delivery strategy to induce expulsion of this parasite, using vaccines containing recombinant "conventional" antigens. Tremendous progress has been made in the last decade in identifying several antigens from Haemonchus contortus which in their native form stimulate useful levels of protective immunity. Vaccines have been developed against H. contortus using 'novel' gut antigens from the parasite, but variable responsiveness of the host sheep has resulted in varying degrees of protection which are stimulated by these vaccines. Computer models have also been used to simulate vaccine efficacy in worm control and have yielded good results. This review will try to summarise the protective efficacy and also the molecular properties of principal candidate antigens which are expressed by this parasite. The review will try to cover the aspirations, current success, limitations and problems faced by researchers in the control of this economically important parasite.

First record of protozoan parasites in cyprinid fish, Schizothorax niger Heckel, 1838 from Dal lake in Kashmir Himalayas with study on their pathogenesis

Trichodina heterodentata Duncan, 1977 and Ichthyophthirius multifiliis Fouquet, 1876 obtained from gills during a parasitological survey conducted for the protozoan parasitic fauna of Schizothorax niger a snow trout in Dal Lake, Kashmir, India during the period October 2013 and March 2015. Thirty out of 180 fish were found infected with protozoan parasites. During the study of their pathogenecity the most common deteriorating signs observed in gill tissue were necrosis, hypertrophy, hyperplasia and fusion of secondary lamellae. Prevalence of infection was found to be 16.66%. This is the first record of the protozoan fauna of the schizothoracines from Kashmir valley, India.

Synergistic approach for treatment of chicken coccidiosis using berberine--A plant natural product

Despite the advent of anticoccidial drugs and vaccines, coccidiosis continues to result in substantial economic losses to the poultry industry. Berberine, a natural alkaloid is well known in studies involving synergistic approaches, thereby reducing the dosage of principal drugs. Therefore, a study was designed to see whether a synergistic anticoccidial effect could be obtained between amprolium and berberine, in vivo using broiler chicken. Anticoccidial activity was measured in comparison to the reference drug amprolium on the basis of oocyst output reduction, mean weight gain and feed conversion ratio. Oocyst output was measured using Mc-Masters counting technique. Different combinations of berberine and amprolium were tested and out of which 1:1 ratio was the most effective for controlling these parasites. Oral gavaging of 100(50 + 50) mg/kg body weight of 1:1 ratio of amprolium and berberine caused the equivalent reduction in number of oocysts (38.85 ± 9.61) one day prior to that of standard drug amprolium (49.95 ± 16.65) as well as pure berberine (44.4 ± 9.61) used in the study. Weight gain of birds was also highest in the synergistic group (1547.43 ± 12.86) among all the infected groups. Besides feed conversion ratio in the synergistic group was also better (1.387 ± 0.026). The results of this study proved the effectiveness of both amprolium and berberine and revealed synergism between amprolium and berberine against coccidian oocysts, confirmed by significant reduction in the number of coccidian oocysts shed in the feces, leading to better weight gain and improved feed conversion ratio. The study deep-rooted the synergistic potential of berberine, a natural bioactive compound for controlling a protozoan parasite and the results of this study corroborate with its use for treatment of severe diarrhoea, amoebiasis and intestinal infections.

Does alteration in biodiversity really affect disease outcome? - A debate is brewing

How changes in biodiversity alter the transmission of infectious diseases is presently under debate. Epidemiologists and ecologists have put a lot of effort to understand the mechanism behind biodiversity-disease relationship. Two important mechanisms, i.e. dilution and amplification theories have in some manner made it clear that biodiversity and disease outcome have an intimate relationship. The dilution effect theory seems to answer some overarching questions, but paucity of information about many disease systems is a real obstacle for its acceptance. Also, there is hardly any agreement on host population threshold and critical community size vis-à-vis wild life diseases. We suggest a multidimensional approach whereby the same disease system needs to be studied in different ecological zones and then the effect of biodiversity on disease outcome needs to be ascertained. Nonetheless, caution is to be taken while jumping to any conclusion as biodiversity-disease relationship is a multifactorial process.

In vivo anticoccidial activity of berberine [18, 5,6-dihydro-9,10-dimethoxybenzo(g)-1,3-benzodioxolo(5,6-a) quinolizinium]--an isoquinoline alkaloid present in the root bark of Berberis lycium

Coccidiosis, caused by various Eimeria species, is a major parasitic disease in chicken. However the increasing resistance of these parasites to currently used anticoccidial drugs has stimulated the search for new methods of control. As part of this effort we investigated the root bark of Berberis lycium (barberry) as a potential source of compounds with anticoccidial activity. In the present study anticoccidial activity of different solvent extracts of the root bark of B. lycium and berberine was evaluated in vivo using broiler chicken. Results of the study demonstrated equipotent efficacy of pure berberine in comparison to that of standard drug amprolium on the basis of reduction in coccidian oocyst output, body weight gain of chicken and feed conversion ratio. Among the extracts crude methanolic extract showed highest anticoccidial activity tested at 300 mg/kg body weight which could be due to the presence of alcohol-soluble active ingredients in root bark of B. lycium. Toxicological studies revealed that B. lycium extracts as well as berberine were not lethal up to dosage of 2000 mg/kg body weight. LD(50) was not determined as mortalities were not recorded in any of the five groups of chicken. From the present study it can be concluded that root bark of B. lycium has the immense potential to contribute to the control of coccidian parasites of chicken. Our results corroborate the use of berberine for treatment of severe diarrhoea, amoebiasis and intestinal infections and could justify its use in folk medicine for treatment of haemorrhagic dysentery.

Seasonal changes in infrapopulations of Diplozoon kashmirensis Kaw, 1950 (Monogenea: Diplozoidae) along a eutrophic gradient

Seasonal population dynamics of the monogenean, Diplozoon kashmirensis Kaw, on the gills of two cyprinid fish species, Schizothorax niger Heckel and Carassius carassius (Linnaeus), was investigated in three limnologically distinct trophic habitats located along the flood plain of River Jhelum in Kashmir from June 2006 to May 2008. The parasite infrapopulations exhibited a marked seasonal regime in infestation pattern as the infection indices increased to a much higher plateau during summer season at all the lakes, while the lows were recorded in winter. The heterogeneity in infection pattern indicates that water temperature is an important determinant of the seasonality of infrapopulations at all the localities. Furthermore, the results of our work clearly indicate that the parasite infrapopulations increased proportionally with eutrophication level and, as such, the highly eutrophic habitat, Anchar Lake, was significantly more favourable for parasite infrapopulations than the less eutrophic ones. However, the lakes presented no significant interlake differences in water temperature. Therefore, we could argue that interlake differences in the infestation pattern of parasite can be safely attributed to respective water quality in the lakes rather than water temperature. We propose that infrapopulations of the diplozoid studied herein do respond to differences in water quality of lakes and, thus, could qualify as simple and reliable indicator species in short-term comparative assays by lake managers.

Infection level of monogenean gill parasite, Diplozoon kashmirensis (Monogenea, Polyopisthocotylea) in the Crucian Carp, Carassius carassius from lake ecosystems of an altered water quality: What factors do have an impact on the Diplozoon infection?

Monogeneans are of great interest to the ecologists because of their simple life cycle and are considered as one of the important and sensitive parasites to any changes in water quality. The monogenean gill parasite, Diplozoon kashmirensis of the Carassius carassius was examined with the aim to evaluate the infection level and the factors influencing the infection. Our results showed that highest prevalence (34.22%) of D. kashmirensis was in the lake having high trophic status and least prevalence (10.90%) in the lake having least trophic status. Infection levels were significantly higher at the basins/sites having deteriorated water quality in comparison to the basins/sites having better water quality. The combined effect of pollutants and eutrophication showed decrease in intensity of D. kashmirensis in one of the polluted/hypertrophied site in the hypertrophic lake (Anchar Lake), while as synergistic effect (i.e. increase) on prevalence and intensity was observed in one of the polluted/hypertrophied site in the eutrophic lake (Dal Lake). Sex was not an important factor influencing the D. kashmirensis in three lakes. The study showed that condition factor was significantly higher in the hypertrophic lake and in an uninfected fish. In addition microhabitat influenced the Diplozoon infection. Most preferable site for the D. kashmirensis was middle sector of the gill. Furthermore, the gill parasite showed significantly positive correlation (r(p)=0.6, P<0.05) with water temperature in the hypertrophic lake, thus showing the impact of water temperature on this parasite. It was concluded that intra lake differences, season, condition factor, microhabitat and water temperature influenced the infection of D. kashmirensis. It seems from the data that eutrophic and hypertrophic habitats were favourable for the D. kashmirensis. The D. kashmirensis showed both antagonistic and synergistic response to the combined effect of pollution and eutrophication.

Infection level of the Asian tapeworm (Bothriocephalus acheilognathi) in the cyprinid fish, Schizothorax niger, from Anchar Lake, relative to season, sex, length and condition factor

Various studies have shown that the Asian fish tapeworm, Bothriocephalus acheilognathi causes great economic loss in hatcheries, fish farms as well as in lakes. In order to understand the seasonal variation of infection in a nutrient-enriched lake, parasitological investigation was carried out in the indigenous cyprinid fish, Schizothorax niger Heckel 1838 from September, 2008 to August, 2009. Overall, this study revealed definite seasonality of infection (p < 0.05), with greater infection in summer (prevalence = 39.5%) and lesser in winter (prevalence = 8.1%). The prevalence among different seasons revealed significant differences (p < 0.05). Sex was not an important factor influencing the prevalence of the Asian tapeworm. A strong positive correlation (Pearson's correlation, r = 0.7; p = 0.02) between total length of S. niger and number of Asian fish tapeworms was observed. Similarly, a strong positive correlation existed between weight of fish and number of tapeworms (Pearson's correlation, r = 0.7; p = 0.005). Prevalence and mean abundance were positively and significantly correlated with water temperature (r = 0.8, p < 0.01 and r = 0.8, p < 0.01, respectively). Thus seasonal dynamics, total length and weight of the host significantly influenced the tapeworm infection. The above findings will be useful in devising the appropriate control strategies for the Asian tapeworm in wild fish in Kashmir valley as well as in similar climatic zones of other parts of the world. Also, information from this study will be used to assess the spread and extent of B. acheilognathi which is a potential threat to the indigenous fish fauna of Anchar Lake.

Anthelmintic activity of extracts of Artemisia absinthium against ovine nematodes

The increasing prevalence of anthelmintic resistant strains of helminths, drug residues in animal products and high cost of conventional anthelmintics has created an interest in studying medicinal plants as an alternative source of anthelmintics. Artemisia absinthium Linn. (Tethwen) is used traditionally by people as a vermifuge in addition to its other livestock uses. The objective of this study was to evaluate the anthelmintic efficacy of crude aqueous extracts (CAE) and crude ethanolic extracts (CEE) of the aerial parts of A. absinthium in comparison to albendazole against the gastrointestinal (GI) nematodes of sheep. To fulfill the objectives, the worm motility inhibition assay was utilized in order to investigate the direct effects of plant extracts on the survival of the adult nematodes under in vitro conditions and faecal egg count reduction assay to investigate the effects on faecal egg output of GI nematodes under in vivo conditions. Significant anthelmintic effects of CAE and CEE on live adult Haemonchus contortus worms (P < 0.005) were observed in terms of the paralysis and/or death of the worms at different hours post-treatment (PT), however, CEE were more efficacious than CAE. The oral administration of the extracts in sheep was associated with significant reduction in faecal egg output by the GI nematodes. The CEE was as effective as the reference drug-albendazole and demonstrated faecal egg count reduction (FECR) of 90.46% in sheep at 2.0 g kg(-1) body weight on day 15 PT followed by 82.85% FECR at 1.0 g kg(-1) bw on day 15 PT. The CAE showed less activity and resulted in maximum of 80.49% FECR at 2.0 g kg(-1)bw. Dosage had a significant (P < 0.05) influence on the anthelmintic efficacy of A. absinthium. The better activity of CEE can be attributed to the greater concentration of alcohol soluble active anthelmintic principle/s and a more rapid transcuticular absorption of the CEE into the body of the worms when compared with the CAE. The results of the present study suggest that A. absinthium extracts are a promising alternative to the commercially available anthelmintics for the treatment of GI nematodes of sheep.