scholarly journals Trypanotolerance Sheko cattle: an option for sustainable control of bovine trypanosomiasis

2021 ◽  
Vol 2 (1) ◽  
pp. 81-90
Author(s):  
Dereje Tulu Robi ◽  
Beksisa Urge Hurrisa ◽  
Benti Deresa Gelalcha
Keyword(s):  
Drug Resistance ◽  
Agricultural Development ◽  
Antigenic Variation ◽  
Control Method ◽  
Cattle Breed ◽  
Tsetse Fly ◽  
Control Measures ◽  
Natural Resistance ◽  
Southwestern Ethiopia ◽  
Trypanocidal Drugs

Abstract Trypanosomiasis is an impediment to cattle production and other agricultural development in tsetse-infested areas. It is a severe parasitic disease that causes loss in the production and performance of cattle. Hence, the aim of this paper is to review trypanosomiasis control options with emphasis on the use of trypanotolerant Sheko cattle breed for sustainable management of bovine trypanosomiasis in tsetse infested areas. Several methods have been used to control trypanosomiasis through the use of trypanocidal drugs and the management of the vector, tsetse fly. Tsetse fly controls require expensive insecticides and have adverse environmental consequences. Trypanocidal drugs are commonly used and considered a practical trypanosomiasis control method. However, the rise in trypanocidal drug resistance has rendered this option ineffective. The possibility of developing and using a vaccine against trypanosomiasis currently remains out of reach as Trypanosoma periodically undergo antigenic variation. In the absence of a vaccine, presence of trypanocidal drug resistance, and the lack of sustainable tsetse fly control measures demand the need to use trypanotole-rant cattle breeds. The Sheko breed which is found only in southwestern Ethiopia displays considerable natural resistance to tsetse-transmitted trypanosomiasis. This genetic resource provides sustainable solution for challenges related to trypanosomiasis. These cattle have a low level of parasitemia and are able to maintain a good packed cell volume (PCV) compared to other indigenous breeds. As several trypanosomiasis control methods are ineffective, the use of trypanotolerance cattle like Sheko breed in tsetse-fly-challenged areas was suggested.

scholarly journals Farmer perceptions and willingness to pay for novel livestock pest control technologies: A case of tsetse repellent collar in Kwale County in Kenya

2021 ◽  
Vol 15 (8) ◽  
pp. e0009663
Author(s):  
Beatrice W. Muriithi ◽  
Nancy G. Gathogo ◽  
Gracious M. Diiro ◽  
Michael M. Kidoido ◽  
Michael O. Nyanganga ◽  
...  
Keyword(s):  
Rural Communities ◽  
Willingness To Pay ◽  
Clinical Signs ◽  
Field Trials ◽  
Tsetse Fly ◽  
Control Measures ◽  
Tsetse Flies ◽  
Control Approach ◽  
Household Heads ◽  
Trypanocidal Drugs

Tsetse-transmitted Animal African Trypanosomosis (AAT) is one of the most important constraints to livestock development in Africa. Use of trypanocides has been the most widespread approach for the management of AAT, despite the associated drug resistance and health concerns associated with drug metabolites in animal products. Alternative control measures that target tsetse fly vectors of AAT, though effective, have been hard to sustain in part because these are public goods applied area-wide. The International Centre of Insect Physiology and Ecology (icipe) and partners have developed and implemented a novel tsetse repellent collar (TRC) applied on animals to limit contact of tsetse flies and livestock, thereby reducing AAT transmission. The TRC has now advanced to commercialization. A household-level survey involving 632 cattle keeping households, was conducted in Shimba Hills region of Kwale County, where field trials of the TRC have been previously conducted to assess farmers’ knowledge, perception, and practices towards the management of tsetse flies, their willingness to pay (WTP) for the TRC, and factors affecting the WTP. Almost all the respondents (90%) reported that tsetse flies were the leading cattle infesting pests in the area. About 22% of these correctly identified at least four AAT clinical signs, and even though many (68%) used trypanocidal drugs to manage the disease, 50% did not perceive the drug as being effective in AAT management (50%). Few respondents (8%) were aware of the harmful effects of trypanocidal drugs. About 89% of the respondents were aware of icipe TRC, and 30% of them were using the field trial collars during the survey. Sixty-three (63%) of them were willing to pay for the TRC at the same cost they spend treating an animal for AAT. On average farmers were willing to pay KES 3,352 per animal per year. Male educated household heads are likely to pay more for the TRC. Moreover, perceived high AAT prevalence and severity further increases the WTP. Wider dissemination and commercialization of the herd-level tsetse control approach (TRC) should be encouraged to impede AAT transmission and thus enhance food security and farm incomes among the affected rural communities. Besides the uptake of TRC can be enhanced through training, especially among women farmers.

Candida auris and Nosocomial Infection

2020 ◽  
Vol 21 (4) ◽  
pp. 365-373 ◽  
Author(s):  
Sweety Dahiya ◽  
Anil K. Chhillar ◽  
Namita Sharma ◽  
Pooja Choudhary ◽  
Aruna Punia ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Pathogenic Fungus ◽  
Control Measures ◽  
Whole Genome Sequence ◽  
Whole Genome ◽  
Drug Resistant ◽  
Candida Auris ◽  
Preventive Control ◽  
Identification Techniques ◽  
Sensitivity Profile

The existence of the multi-drug resistant (MDR) pathogenic fungus, Candida auris came to light in 2009. This particular organism is capable of causing nosocomial infections in immunecompromised persons. This pathogen is associated with consistent candidemia with high mortality rate and presents a serious global health threat. Whole genome sequence (WGS) investigation detected powerful phylogeographic Candida auris genotypes which are specialized to particular geological areas indicating dissemination of particular genotype among provinces. Furthermore, this organism frequently exhibits multidrug-resistance and displays an unusual sensitivity profile. Identification techniques that are commercialized to test Candida auris often show inconsistent results and this misidentification leads to treatment failure which complicates the management of candidiasis. Till date, Candida auris has been progressively recorded from several countries and therefore its preventive control measures are paramount to interrupt its transmission. In this review, we discussed prevalence, biology, drug-resistance phenomena, virulence factors and management of Candida auris infections.

scholarly journals Tackling resistance: emerging antimalarials and new parasite targets in the era of elimination

F1000Research ◽  
2018 ◽  
Vol 7 ◽  
pp. 1170 ◽  
Author(s):  
Emily S. Mathews ◽  
Audrey R. Odom John
Keyword(s):  
Drug Resistance ◽  
Malaria Elimination ◽  
Large Scale ◽  
Therapeutic Targets ◽  
Control Measures ◽  
Multi Drug Resistance ◽  
Development Projects ◽  
Combination Therapies ◽  
The Past ◽  
Antimalarial Compounds

Malaria remains a significant contributor to global human mortality, and roughly half the world’s population is at risk for infection with Plasmodium spp. parasites. Aggressive control measures have reduced the global prevalence of malaria significantly over the past decade. However, resistance to available antimalarials continues to spread, including resistance to the widely used artemisinin-based combination therapies. Novel antimalarial compounds and therapeutic targets are greatly needed. This review will briefly discuss several promising current antimalarial development projects, including artefenomel, ferroquine, cipargamin, SJ733, KAF156, MMV048, and tafenoquine. In addition, we describe recent large-scale genetic and resistance screens that have been instrumental in target discovery. Finally, we highlight new antimalarial targets, which include essential transporters and proteases. These emerging antimalarial compounds and therapeutic targets have the potential to overcome multi-drug resistance in ongoing efforts toward malaria elimination.

Antigenic variation in its biological context

1984 ◽  
Vol 307 (1131) ◽  
pp. 27-40 ◽  
Keyword(s):  
Salivary Glands ◽  
Antigenic Variation ◽  
Tsetse Fly ◽  
Mammalian Host ◽  
Full Understanding ◽  
Anamnestic Response ◽  
Insect Midgut ◽  
The Relationship ◽  
Biological Context

The biology of antigenic variation is discussed, and the problems that must be solved to provide a full understanding of antigenic variation are considered. These are (i) the induction of v.s.g. synthesis in the salivary glands of the tsetse fly; (ii) the nature of the restriction on v.s.g. genes that allows only some of them to be expressed in the salivary glands; (iii) the nature of ‘predominance’ in v.s.g. expression in the mammalian host, and the mechanism by which it operates; (iv) the repression of v.s.g. synthesis in the insect midgut; (v) the anamnestic response that produces expression of the ingested variant in the first patent parasitaemia in the mammalian host; (vi) the mechanism by which only one v.s.g. gene at a time is expressed; (vii) the relationship if any ofv.s.g. structure to v.s.g.-associated differences in growth rate and host range; (viii) the role of v.s.g. release within the life cycle and to pathogenesis.

An experimental evaluation of conventional control measures against the sheep tick, Ixodes ricinus (L.) (Acari: Ixodidae). II. The dynamics of the tick-host interaction

1985 ◽  
Vol 75 (3) ◽  
pp. 501-518 ◽  
Author(s):  
Sarah E. Randolph ◽  
Gordon M. Steele
Keyword(s):  
Ixodes Ricinus ◽  
Control Method ◽  
Control Strategies ◽  
Stocking Density ◽  
Experimental Manipulation ◽  
Control Measures ◽  
Effective Control ◽  
Contact Rate ◽  
Host Interaction ◽  
Questing Ticks

AbstractThe experimental manipulation of separate, but originally identical, populations of Ixodes ricinus (L.) by applying three conventional tick control measures in different enclosures on naturally infested moorland in Wales allowed the elements of the tick-host interaction to be analysed quantitatively and the effectiveness of the control methods to be compared. From the relationship between the sheep stocking density and the numbers of questing ticks picked up by fortnightly blanket-dragging in each enclosure, the death rate of ticks during their activity season and the rate of contact between sheep and ticks were calculated. From this, it was possible to investigate the effect of different stocking densities on the feeding success of ticks. A major factor determining the much lower contact rate for larvae than for nymphs was the different spatial distribution of questing ticks, clumped for larvae and random for nymphs. The non-random use by sheep of the three different vegetation zones in the paddock resulted in the highest contact rate between sheep and ticks in the pasture area, but tick survival was apparently highest in the bog area. Combining these factors resulted in the prediction that the bracken area was the least favourable habitat for ticks. In the two enclosures where the sheep were not treated with acaricide the mean tick loads on the sheep were similar, but the lower overall use of the pasture by the sheep in the low stocking density enclosure (2/ha) resulted in slightly lower tick loads there compared with those in the high stocking density enclosure (4/ha). The numbers of ticks counted in the second year showed that pasture spelling was the most effective control method, acaricide treatment was less effective, and the benefits of halving the stocking density were marginal. The implications of these results for control strategies are discussed.

scholarly journals Identifying Cattle Breed-Specific Partner Choice of Transcription Factors during the African Trypanosomiasis Disease Progression Using Bioinformatics Analysis

Vaccines ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 246 ◽  
Author(s):  
Abirami Rajavel ◽  
Felix Heinrich ◽  
Armin Otto Schmitt ◽  
Mehmet Gültas
Keyword(s):  
Disease Progression ◽  
Neuronal Degeneration ◽  
Cattle Breed ◽  
Tsetse Fly ◽  
Partner Choice ◽  
Sub Saharan Africa ◽  
Economic Losses ◽  
Intermittent Fever ◽  
Cattle Breeds ◽  
Animal Trypanosomiasis

African Animal Trypanosomiasis (AAT) is a disease caused by pathogenic trypanosomes which affects millions of livestock every year causing huge economic losses in agricultural production especially in sub-Saharan Africa. The disease is spread by the tsetse fly which carries the parasite in its saliva. During the disease progression, the cattle are prominently subjected to anaemia, weight loss, intermittent fever, chills, neuronal degeneration, congestive heart failure, and finally death. According to their different genetic programs governing the level of tolerance to AAT, cattle breeds are classified as either resistant or susceptible. In this study, we focus on the cattle breeds N’Dama and Boran which are known to be resistant and susceptible to trypanosomiasis, respectively. Despite the rich literature on both breeds, the gene regulatory mechanisms of the underlying biological processes for their resistance and susceptibility have not been extensively studied. To address the limited knowledge about the tissue-specific transcription factor (TF) cooperations associated with trypanosomiasis, we investigated gene expression data from these cattle breeds computationally. Consequently, we identified significant cooperative TF pairs (especially D B P − P P A R A and D B P − T H A P 1 in N’Dama and D B P − P A X 8 in Boran liver tissue) which could help understand the underlying AAT tolerance/susceptibility mechanism in both cattle breeds.

Trypanosome sociology and antigenic variation

Parasitology ◽  
1989 ◽  
Vol 99 (S1) ◽  
pp. S37-S47 ◽  
Author(s):  
K. Vickerman
Keyword(s):  
Trypanosoma Brucei ◽  
Antigenic Variation ◽  
Growth Characteristics ◽  
Tsetse Fly ◽  
Antigenic Specificity ◽  
Surface Coat ◽  
Humoral Immune ◽  
Variable Antigen ◽  
Minority Variants ◽  
Stimulation Of

SUMMARYSurvival of the trypanosome (Trypanosoma brucei) population in the mammalian body depends upon paced stimulation of the host's humoral immune response by different antigenic variants and serial sacrifice of the dominant variant (homotype) so that minority variants (heterotypes) can continue the infection and each become a homotype in its turn. New variants are generated by a spontaneous switch in gene expression so that the trypanosome puts on a surface coat of a glycoprotein differing in antigenic specificity from its predecessor. Homotypes appear in a characteristic order for a given trypanosome clone but what determines this order and the pacing of homotype generation so that the trypanosome does not quickly exhaust its repertoire of variable antigens, is not clear. The tendency of some genes to be expressed more frequently than others may reflect the location within the genome and mode of expression of the genes concerned and may influence homotype succession. Differences in the doubling time of different variants or in the rate at which trypanosomes belonging to a particular variant differentiate into non-dividing (vector infective) stumpy forms have also been invoked to explain how a heterotype's growth characteristics may determine when it becomes a homotype. Recent estimations of the frequency of variable antigen switching in trypanosome populations after transmission through the tsetse fly vector, however, suggest a much higher figure (0·97–2·2 × 10−3switches per cell per generation) than that obtained for syringe-passed infections (10−5–10−7switches per cell per generation) and it seems probable that most of the variable antigen genes are expressed as minority variable antigen types very early in the infection. Instability of expression is a feature of trypanosome clones derived from infective tsetse salivary gland (metacyclic) trypanosomes and it is suggested that high switching rates in tsetse-transmitted infections may delay the growth of certain variants to homotype status until later in the infection.

High frequency of antigenic variation inTrypanosoma brucei rhodesienseinfections

Parasitology ◽  
1989 ◽  
Vol 99 (1) ◽  
pp. 67-75 ◽  
Author(s):  
C. M. R. Turner ◽  
J. D. Barry
Keyword(s):  
High Frequency ◽  
Antigenic Variation ◽  
Bloodstream Infections ◽  
Tsetse Fly ◽  
Cell Generation ◽  
Switching Rate ◽  
Parental Stock ◽  
Variable Antigen ◽  
Growth Chambers ◽  
Systemic Infections

SUMMARYRates at whichTrypanosoma bruceirhodesiense trypanosomes switch from expression of one variable antigen type (VAT) to that of another have been determined in cloned populations that have been recently tsetse-fly transmitted. Switching rates have been determined between several, specific pairs of VATs in each population. High rates of switching were observed in 2 cloned trypanosome lines, each derived from a separate cyclical transmission of the same parental stock and each expressing a different major VAT. Five estimates of the switching rate between one particular pair of VATs were consistently high (approximately 1 × 103switches/cell/generation). These high switching rates were similar both in bloodstream populations of mice and in populations confined to subcutaneously implanted growth chambers in mice, thus indicating that the interaction of the bloodstream population with other trypanosome populations in the lymphatics or extravascular sites in systemic infections did not influence the estimates of the rate of switching. Fourteen estimates were made of VAT-specific switching rates in bloodstream infections involving 8 combinations from among 6 VATs. Switching rate estimates were VAT-specific and showed considerable variation between different combinations of VATs — from 1.9 × 10−6to 6.9 × 10−3switches/cel/generation. The rates of switching to different metacyclic-VATs were, however, very similar. Summation of between 3 and 5 VAT-specific switching rate values in each of 4 experiments conducted in bloodstream infections has provided minimum estimates of the overall rate of antigenic variation: 2.0−9.3 × 10−3switches/cell/generation. These values are between 20 and 66000-fold higher than previously published estimates. It is likely that at least 1 in every 100 trypanosomes switches its VAT expression every generation.

Temperature Control Measures and Feedback Analysis in Rapid Construction of Guandi RCC Dam

2012 ◽  
Vol 594-597 ◽  
pp. 1979-1982
Author(s):  
Wei Zhou ◽  
Xiang Yang Jing ◽  
Xing Hong Liu
Keyword(s):  
Temperature Control ◽  
Control Method ◽  
Dynamic Control ◽  
Cooling Water ◽  
Control Measures ◽  
Obvious Effect ◽  
Feedback Analysis ◽  
Cooling Water Temperature ◽  
Rcc Dam ◽  
Rapid Construction

Due to the shortcomings of conventional methods, the temperature control in rapid construction of Guandi dam is less effective. Then improved measures are designed and implemented based on the dynamic control method of pipe cooling, which depends on the real-time adjustment of five factors affecting pipe cooling (beginning time of cooling, lasting time of cooling, water temperature, rate of flow and direction of flow). The monitoring and feedback calculation are conducted. It is found that the newly-designed measures have obvious effect, and that there are no harmful cracks in the whole construction of Guandi dam. The conclusion is that it can effectively solve the problem of temperature control and crack prevention of high RCC dam via these measures, and provide some guide and reference to other similar projects.

The Adaptive Control of Grinding Force of CNC Cam Grinder Based on Neural Network

2012 ◽  
Vol 217-219 ◽  
pp. 2051-2055
Author(s):  
Ming Li Xie ◽  
Ling Lu
Keyword(s):  
Neural Network ◽  
Adaptive Control ◽  
Control Method ◽  
Metal Removal ◽  
Removal Rate ◽  
Grinding Force ◽  
Control Measures ◽  
Numerical Control ◽  
Grinding Wheel ◽  
Grinding Process

In the process of cam grinding, the fluctuation of grinding force can lead to the abnormal wear of the grinding wheel, the decrease of the grinding surface quality and even the damage of the grinding process system. The paper took the grinding process of numerical control cam grinding machine as research subject, the grinding force mathematical model was built, the indirect test and control measures were researched and an adaptive control method based on neural network was proposed and applied to the grinding force control of the cam grinding process. At last, the controller was designed and the grinding simulation was performed with MATLAB, which proved that the system could solve the fluctuation of grinding force during the process of cam grinding and the controller was equipped with good dynamic characteristic. The results indicate that the method can realize the purpose of optimal metal removal rate and enhance the grinding quality of cams.

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