Study of Prevalence and Associated Risk Factors of Bovine Fasciolosis in and Around Ambo District Abattoir and Field Survey Western Ethiopia

Study of Prevalence and Associated Risk Factors of Bovine Fasciolosis in and Around Ambo District Abattoir and Field Survey Western Ethiopia

Introduction

Ethiopia has the largest livestock population in Africa, with a total cattle population of 57.83 million [1]. In spite of the presence of huge ruminant population, Ethiopia fails to optimally exploit resources due to a number of factors such as diseases, poor nutrition, poor husbandry practices and lack of government policies for disease prevention and control [2]. Among the animal diseases that hinder the animal health are parasitic infections that have great economic impact [3]. Among many parasitic problems of farm animals, fasciolosis is a major disease which imposes economic impact on livestock production particularly of cattle and sheep [4]. Fasciola hepatica and Fasciola gigantic are the two liver flukes commonly reported to cause fasciolosis in cattle. The life cycles of these parasites require snail as an intermediate host [5]. Fasciola hepatica has a worldwide distribution but predominates in temperate zones while F. gigantic is found on most continents, primarily in tropical regions [6]. The presence of fasciolosis due to F. hepatica and F. gigantica in Ethiopia has long been known and its prevalence and economic significance has been reported by several workers [7]. However, few attempts have been made to study the epidemiology of this parasitic problem in various parts of the country with the specific aim of determining the parasitic burdens, especially in relation to months of the year, rainfall, temperature, humidity, altitude and other related factors. This information is very important in planning control programs and also estimating the economic burden to the country as the result of this parasite [8]. These Losses from parasitic diseases including fasciolosis expected to be high in tropical countries like Ethiopia where strategic and most effective disease control programs are lacking. Therefore, a study on the prevalence and associated risk factors of the disease is crucial before planning and instituting a control program [9]. Several studies have reported the presence and economic significance of fasciolosis in Ethiopia.

The prevalence of the disease is known to be relatively high causing considerable economic losses in livestock production [10]. The areas around Ambo and peasant association areas are generally considered as one of the most affected and endemic area of fasciolosis in the country region, Veterinary practitioners and animals owners complain of huge annual losses from it. However, there are practically no dependable detailed studies that have been conducted on the prevalence the monthly/seasonal variations in the prevalence rates of the disease and other related parameters so as to design relevant control strategies that can be implemented against the disease in the area. The information regarding the prevalence and associated risk factors of bovine fasciolosis in Ambo area is scanty. Therefore, the aim of this study is to determine the prevalence and associated risk factors of trematode infections, identify the fluke burden and species identification in particular positive livers, and determination of the liver pathology (Lesion) in cattle owned by smallholder farmers located in and around Ambo area, Western Ethiopia.

Materials and Methods

Description of the Study Area

The study was conducted from November 2015 to November 2016 in and around Ambo peasant association. Ambo is located about 115km West of Addis Ababa. It is found at the longitude of 37032’ to 3803’E, at latitude of 8047’ to 9020’N and average altitude of 1900 meters to 2275 above sea level. Ambo has a climatic condition of 23% highland, 60% mid latitude and 17% low land. It has annual rainfall and temperature ranging from 800mm- 1000mm and 200c to 290c respectively. The rain is bimodal with the short rainy season (February to May) and long rainy season from June to September.

Study Animals and Sampling Technique

Study population comprises of indigenous (local) breed of animals of different age, sex, body conditions and origin category found under the extensive grazing system. All Sampled cattle from the selected six peasant association in and around Ambo areas were recorded. In the abattoir study 258 male indigenous animals provided for slaughter from different localities in the West Shoa part of Ethiopia. Simple random sampling technique was the sampling strategy used to collect all the necessary data from fecal samples and abattoir survey of the study animals.

Sample Size Determination

Since there was no previous study in Ambo and around peasant association to establish the prevalence, associated risk factors, fluke burden and species identification in of bovine fasciolosis, the sample size was determined by taking the prevalence of 50% and 5% absolute precision fasciolosis using the formula given by [11]. Accordingly, 384 animals were supposed to be sampled but in order to increase the precession a total of 642 sample size were used. It was also considered both sexes and age. Age was classified as young (< 4 years) and adult (>4years) [12].

Study Design

A cross-sectional investigation of the prevalence of bovine fasciolosis in the six peasant association in and around Ambo was carried out from November 2015 to November 2016.

Corpological Examination

Fecal samples were collected directly from the rectum of each animal and placed in universals bottles and transported to Ambo University collage of parasitological laboratory by preserving with 10% formalin. Sedimentation technique was used to detect the presence or absence of fluke eggs in the fecal sample collected according to [13]. Two grams of faeces was added to 42ml of water in a graduated cylinder. The contents were then mixed thoroughly using a glass rod, and were poured through a tea strainer to remove large debris. The solution was then further passed through a sieve (mesh aperture 210mm) into a conical flask and water was run through the sieve to ensure no eggs remained attached to the sieve. The filtrate was then allowed to sediment for 3 min after which the supernatant was siphoned off taking care not to disturb the precipitated matters. The latter was stained with two drops of methylene blue and the entire sediment placed on slide covered with a cover slip and viewed under a compound microscope (Labomed). Eggs of Fasciola species were identified by their characteristic morphology and colour. To differentiate between eggs of Paramphistomum species and Fasciola species, a drop of methylene blue solution was added to the sediment where eggs of Fasciola species show yellowish colour while eggs of Paramphistomum species stain by methylene blue [14]. Samples that were not processed within 24 hours were stored in a refrigerator at 4°C.

Abattoir Study

Active abattoir survey was conducted based on cross sectional study during routine meat inspection on randomly selected cattle slaughtered at Ambo municipal abattoir. A total of 258 cattle was examined during this study. During ante-mortem examination detail records about the age, sexes, origins and body conditions of the animals were performed. During post-mortem inspection, each liver visually inspected, palpated and incised based on routine meat inspection by [15]. All livers having Fasciola species condemned were registered and flukes were conducted for species identification as described by [16]. Hepatic lesions in Fasciola positive livers were further grouped into lightly, moderately and severe affected base on the severity of damage inflicted by the parasite. The task of categorization was performed based on the criteria forwarded by [17].

Body Condition Scoring

Body condition of the study animals was scored based on the criteria set by [18], which ranged from 0 to 5. Body condition score 0 stands for cows with the poorest body condition while score 5 for cows with the best condition. All cattle under the study their body condition grouped into three groups poor (score 0-1), medium (score 2-3) and good (score 4-5).

Statistical Analysis

The recorded data were entered in to Microsoft excel data base system to be analyzed using SPSS version 20 statistical software. Descriptive statistics was computed. Pearson’s chi square (x2) was used to evaluate the association between the prevalence of fasciolosis and different factors. A 95% confidence interval and P-value less than 0.05 (at 5% level of significance) were considered significant in all analysis.

Results

Coprological Examination

From a total of 384 fecal samples examined from cattle during the study period, 150 (39.06%) samples were found positive for fasciolosis. Infection rate of fasciolosis in poor body condition group was higher than the animals with good body conditions group. However, there was no statistically significant variation among body condition group (x2 = 1.1154; P>0.05). As to the prevalence rates on sex basis, infection rates of 36% and 42% in female and male respectively were observed. Statistical analysis of this result shows no significant variation in infection rate between sex (x2 = 1.1154; P>0.05). When prevalence rate among age groups is considered analysis of data indicates that 42% and 37% in Adult and young respectively. It has statistically significant when get analyzed statistically between age group (x2 = 54.1337; P < 0.05) (Table 1). The severity of egg infestation in three categories in positive animals’ light infestation, medium infestation and severe infestation depending on the number of eggs per gram of faces identified during fecal examination. Out of positive samples 11 samples are severely infested, means EPG level> 1000, 84 samples indicate medium infestation EPG Level> 600-1000, and light infestation 55 samples having EPG level 1-600 (Table 2). From counted eggs the maximum egg count is 1200 and the minimum egg count is 100 with the mean of 486 from the all positive sample EPG count (Table 3).

Prevalence Survey Results: This result revealed that out of 258 slaughtered animals 101 animal’s liver found infected with adult Fasciola hepatica. Classification of liver pathological lesions out of 101 infected livers, 9(9%) were lightly affected, 36(35.6%) moderately affected, and 56 (55.4%) severely affected (Table 4).

Fluke Burden Determination and Species Identification:

Fluke count made on 101 livers taken from each of the three pathological categories light, moderate and severely affected liver revealed that the overall fluke mean is 40 per affected liver, maximum number of fluke 91 and minimum number fluke 8 from the total 101 livers positive for liver fluke parasites (Tables 4 & 6). Out of 258 total sample, F. hepatica is dominant no F. gigantica and mixed infection were found (Table 5).

Discussion

Prevalence rate of 39% in bovine fasciolosis was found in fecal examination in and around Ambo peasant association. This result was in line with [17] and [19], who reported that 32% and 32.6% prevalence of bovine fasciolosis in Adwa municipal Abattoir, North Ethiopia, and Guduru and Abay Chomaan districts, respectively. This result was also similar with report of [20] with 30.02% prevalence around Dangila; [21] 33.42% in North Gonder, [22] 36.72% in and around Bahir Dar, [23] (42.25%) around Assela and [24] 41.41% in and around woreta, Northwestern Ethiopia. On the other hand, the prevalence of bovine fasciolosis reported in current study is higher than the values reported by [25] 19.1% in Zenzelma; [26] 12.4% in Kombolcha; [27] Negesse et al. with 15.9% at Wolega zone 9.1% in Kombolcha town; 15.9% prevalence by [28] at Nekemte veterinary clinic; [29] at Welaita Sodo (12.7% and by [30] Hawi, Tanzania (14.05%). This variation in prevalence of bovine fasciolosis might be due to differences in environmental factors, management system and level of veterinary service. There was statistically significant association among age of the animal and prevalence of fasciolosis (P< 0.05). Similarly, several studies in Ethiopia [31,32,24,5] reported age as one of the important risk factors influencing bovine fasciolosis in cattle. The increased resistance (low prevalence) as age increases is most likely related to the high level of tissue reaction seen in bovine livers, severe fibrosis which impairs the passage of immature flukes, acquired resistance. Stenosis and calcification of bile duct assumed unfavorable site for adult parasites and consequently fast their expulsion [33].

The study showed that there was no significant variation among sex of animals which the same with reported of [11], [34] and [35]. This may be due to management system is similar for both sexes that means they have equal exposures for contaminated grass and in this study area the management and treatment is the same for all animals. Prevalence of bovine fasciolosis was not statistically association with body condition of animals. This result was similar with reports of [35] and it was different from [36] and [37]. The highest prevalence of bovine fasciolosis was recorded in poor body condition animals. This could be due to differences in their resistance for concurrent infection and also fasciolosis itself. Concurrent infection and chronic disease on animals with poor body condition may result the animals to be susceptible for fasciolosis. This shows fasciolosis causing weight loss and is the characteristic sign of the disease. Chronic fasciolosis commonest form of the disease in cattle and one of the sign is weight loss (emaciation) [32]. The prevalence rate of faciolosis observed in the Abattoir survey (39%) and the prevalence rate observed in the coprological examination is much similar. This is because of the fact that most of the animal slaughtered in the Ambo municipal slaughter house came from Ambo and its surrounding woredas, which has the same ecology, climatic and geographical location and the animal slaughtered (slaughtering) in the Ambo Abattoir use the same type of veterinary service (treatment) with that of animal in other parts of Ambo area.

From animals found positive for Fasciola, the egg burden or quantitative examination indicate out of examined animal faces the EPG level lay in moderate infestation (>600-100 EPG) is 84 Fecal sample out of 150 positive samples, 55 samples light egg infestation and 11 sample were severe infestation with Fasciola eggs (>2000 EPG) is identified. The present result observed in bovine fasciolosis is closely similar with reports of [13], [20] and [37], who reported that prevalence of 24.3%, 28% and 24.4% in Mekelle, Kombolcha and Haramaya, Ethiopia, respectively. However, it is lower than that of many other studies from different abattoirs in the country and elsewhere in Africa. [35] reported 90.7% prevalence of fasciolosis in cattle slaughtered at Gondar abattoir, while [30] recorded prevalence of 46.2% at Jimma abattoir. [23] from Zambia and [22] from Zimbabwe reported prevalence of 53.9% and 31.7%, respectively. The variation in agro-ecology, management system and suitability of the environment for survival and distribution of the parasite and intermediate host might play their own role in such differences. According to fluke count made on 101 liver positive for Fasciola, the mean fluke burden per affected liver was found to be 40, the maximum number is 91 and the minimum number is 8 flukes are observed. This amount of fluke burden per affected liver reflect the pathogenic effect produced by the flukes on the host the greater the fluke number in animal has more effect in the production loss. On discussing this, the present result should be stressed that the fluke burden found in this survey is large enough to cause considerable reduction in production of the animals.

An assessment of the relation between hepatic lesion and fluke burden does show significant direct association, in that the average fluke count in severely affected livers exceeds that observed in moderate and lightly damaged ones. Even if this result not make agreement with the idea of [9] the severe fibrosis impede the passage of immature flukes and acquired resistance and calcification of bile ducts results in the expulsion of adult flukes. The species of liver fluke recovered during postmortem examination of livers is dominantly F. hepatica (100%), no F. gigantica and mixed infection is detected, this because of the animal slaughtered in the abattoir were obtained from high lands, may study area comprises an altitude over 1800 meters above sea level, so in such areas the dominant species is F. hepatica [38].

Conclusion and Recommendations

The present study indicated that bovine fasciolosis is the most wide spread and prevalent parasitic disease affecting the health and productivity of animals with an overall prevalence rate of 39%. Fasciolosis is the disease of a primary concern in study area and that is must be remarked in priority list in any animal disease control program to be investigated in the area. The abattoir study demonstrated that bovine fasciolosis is prevalent disease in the study area, causing great economic losses as a result of condemnation of affected livers. This study identified that age of animals was risk factors for bovine fasciolosis.

a) Strategic use of antihelmintics should be performed to reduce pasture contamination with fluke eggs

b) Further study on epidemiology of the disease, the ecology and biology of intermediate host snail should be carried out for better control of disease.

c) Integrated control approach using selected antihelmitics therapy and snail control should be conducted to reduce magnitude of the problem.

Visual Disability in Mexico-https://biomedres01.blogspot.com/2020/05/visual-disability-in-mexico.html

More BJSTR Articles : https://biomedres01.blogspot.com

Visual Disability in Mexico

Visual Disability in Mexico

Opinion

Knowing what level of health, the population of a country has an indicator of wealth, prosperity and well-being. With the population growth and the increase in life expectancy, also with an increase in chronic degenerative diseases, a greater active participation of society in these health problems is required. Disability due to visual diseases is one of the public health problems that is present now days and is taking high importance in the world, this problem presents a big impact in the economy of families and countries in the total population due to its rapidly growing. It is known that visual disabilities 90% occur in developing countries with low incomes and poor health systems and it is also known that 80% of cases of visual disability can be prevented according to the Global Data on visual impairments 2010, World Health Organization 2012 (who/nmh/pbd/12.01).

Mexico has become one of the most populated countries in America with approximately 120 million habitants. Currently 27% of the population is under 15 years and 11% over 60 years. By 2050, a growth of 22% in the population is expected. By then population will increase 45 million, 30% of Mexicans will be over 60 years with an expectation of life of 83 years. The country will face greater visual health challenges than the current ones, with a society that grows and ages in a country of contrasts where inequality in access to education and health services is increasing the challenge of having a good health programs will increase as well creating a virtuous circle. In 2013, the World Health Assembly approved the World Plan of Action 2014-2019 “Universal Eye Health: 2014-2019 Global Plan of Action.” During the 66th World Health Assembly A66/11, March 28, 2013 World Health Organization. The vision of the Plan is to envision a world in which no one suffers from visual disability due to avoidable causes and where people with unavoidable vision loss can reach their full potential by strengthening access to comprehensive ophthalmic care services.

In 2014, with great enthusiasm and interest, they motivated a group of Mexican Ophthalmologists with training in Public Health who decided to join and found the Mexican Center of Preventive Visual Health, A.C. (CMSVP). With the intention of joining the efforts made by the Ministry of Health of Mexico in implementing programs through the National Council for the Prevention and Treatment of Visual Diseases, an area created in 2003 by the federal government with minimal impact on achievements in visual health. Currently the CMSVP is recognized as a High Specialty group of the Mexican Society of Ophthalmology. The mission of the CMSVP is to reduce the prevalence of blindness and avoidable visual disability in Mexico as a challenge in Public Health. The Vision is to live in a Mexico that has a comprehensive system of efficient, accessible and quality visual health care for all, avoiding blindness and visual disability. The CMSVP has identified the main visual health problems that affect Mexicans, such as cataracts, diabetic retinopathy, age-related macular degeneration, glaucoma, retinopathy of prematurity and refractive errors.

Public Health must be get closer to therapeutic medicine, not only focus on treating the disease, but to see and detect the external factors and the environment that causes the visual problem. Public Health invites us to a different culture, we must transmit and educate the population, so they are better informed and better situated in objective reality in the same way prepare medical students, doctors, health professionals and ophthalmologists in training who will be responsible for continuing, improving, transforming or discarding these preventive visual health programs. The actions of the CMSVP are to promote awareness of prevention, early detection and rehabilitation of visual diseases at all levels of medical care. We know that investing in prevention programs benefits the population and generates economic development for them, for their families and for the country. We are interested in collaboration with Educational Institutions, Civil Society, Pharmaceutical Industry, Government, National and International Non-Governmental Organizations to share knowledge, experience and tools that are useful in the generation of public policies that improve visual health and prevent their disability.

Trends of World Cereals and Pulses Following the Human Populations-https://biomedres01.blogspot.com/2020/05/trends-of-world-cereals-and-pulses.html

More BJSTR Articles : https://biomedres01.blogspot.com

Trends of World Cereals and Pulses Following the Human Populations

Trends of World Cereals and Pulses Following the Human Populations

Mini Review

Food is the first priority for the human beings. World food security is a serious and pressing contemporary issue [1]. Cereals (major rice, wheat, and maize, minor sorghum and millets) and pulses (major Chickpea, field pea, lupin, faba bean, lentils, etc) are basic elementary food sources. The plant protein is a key driver of agricultural market. Cereals and pulses are a sustainable and major source of protein, energy and fibre, which human beings particularly rely on. Pulses offer many benefits for nutrition, health and chronic disease prevention. As a result, there has been increased interest from food companies in using pulse for product formulations. Cereal grains have been the critical component of human diet for thousands of years and have played very important role in shaping human civilization. Cereals are important staples critical to daily survival of billions of people. Over 50% of world daily caloric intake is derived directly from cereal grain consumption by the entire human population [2]. It was estimated that there are 1.45 billion vegetarians of necessity and another 75 million of choice, thus approximately 21.8% of the world’s population rely on plant protein as their major protein source [3]. Pulses are a major source of plant protein for vegetarian people.

Figure 1: World Total population from 1961 to 2016.

Pulses have a major role in sustainable agricultural systems. They produce their own fertiliser by fixing nitrogen from the air. This not only has a direct benefit to the cropping system, but also has flow-on benefits through overall energy efficiency compared to other crops as seventy percent of non-renewable energy used in cropping systems is attributable to fertilisers. Plant derived protein is far more water efficient than animal protein: 43 gallons of water is required to produce one pound of pulses, 469 gallons for one pound of chicken, 756 gallons for one pound of pig and 1,857 gallons of water is required for one pound of beef [4]. The world grew significantly in terms of both population and economic development in the period 1961-2016. As a result of the industrial revolution, lifespan and survival rate improved, and the world’s population more than doubled from about 2.5 billion in 1961 to 6.1 billion in 2000, and then up to 7.2 billion in 2016, nearly triple in these 56 years [5] (Figure 1, FAOSTAT). Interestingly, during this period, the production of the grains, cereals was tripled from 877 million tonnes in 1961 to 2.8 billion tonnes in 2016 and pulses was also doubled from 40.8 million tonnes in 1961 to 81.8 million tonnes in 2016. FAO projections are that the human population will be up to 9.3 billion in 2050.

This is another 30% increase in the populations in the next three decades. The booming population will put a great pressure on the food and grain system. According to above pattern of human population’s growth with the production of cereals and pulses, in order to meet the demand from the increased population it will be required that production of the fundamentally basic foods of grains increase another 30% in the next 30 years to feed the growing peoples. The expansion in area and increase in productivity of cereals and pulses have contrasted in the past 56 years [5] (Figure 2, FAOSTAT). The world’s total area of cereals harvested in 1961 was about 648 million ha, and production was 877 million tonnes with an average yield of about 1.35 t ha-1. In 2016, the world’s total cereals harvested area was about 718 million ha, an increase of 10.8% in 56 years. However, production and yield tripled in this period with production of 2.8 billion tonnes and average yield about 3.97 t ha-1 in 2016. These increases in production could be attributed to improved yield as a consequence of the development and application of new technologies such as availability of higher yield of hybrid varieties and application of better agronomy technologies.

Figure 2: World Total Area and Production of Cereals and Pulses from 1961 to 2016.

The total area of pulses harvested in 1961 was 64 million and increased to 82.4 million ha in 2016. This represents an increase of 28.8% which is more than double the percentage increase for cereals and indicates that there is increased interest in growing pulses. Global production of pulses doubled from 40.8 million tonnes in 1961, to 81.8 million tonnes in 2016. The yield of pulses was about 0.64 t ha-1 in 1961, but increased to 1.0 t ha-1 in 2016, an increase of just 55.8% compared to cereals where yield was tripled in the same period. It is highly likely cultivation of pulses will continue to increase as people understand more about the value and contribution to health of pulses, while the relatively low increase in yield of pulses, compared to cereals, suggests that there is significant potential to improve the yield of pulses. Beside the major crops of cereals and pulses, there are some minor cereal and pulse crops classified as nes (not elsewhere specified) [5]. These crops include: cereals nes - Including inter alia: canagua or coaihua (Chenopodium pallidicaule); quihuicha or Inca wheat (Amaranthus caudatus); adlay or Job’s tears (Coix lacryma-jobi); wild rice (Zizania aquatica) and pulses nes - Including inter alia: lablab or hyacinth bean (Dolichos spp.); jack or sword bean (Canavalia spp.); winged bean (Psophocarpus tetragonolobus); guar bean (Cyamopsis tetragonoloba); velvet bean (Stizolobium spp.); yam bean (Pachyrrhizus erosus);. Vigna spp. The data is in Figure 3 (FAOSTAT).

Figure 3: World Total Area and Production of Cereals and Pulses (nes) from 1961 to 2016.

The world cereals harvested area (nes) has three stages of development during the last 56 years. The world cereals harvested area was approximately 2.2 million ha in 1961, and production was about 1.35 million tonnes, it dropped to 1.48 million ha in 1975, with production of 1.08 million tonnes. After that, it gradually recovered. From 1990 to 2016, the cereals (nes) was flying growth in both area and production. Harvested area from 1.5 million hectares to 4.32 million hectares, which was 188% increase. The world pulse (nes) development trend is different to cereals (nes) during these nearly six decades. Its harvested area (nes) was 6.5 million ha in 1961 but dropped slowly to 5.17 million hectares in 1968. After that, it fluctuated between 5.17 million ha in 1973 and 5.98 million ha in 1980 and remained constant from 1980 to 1991. The area continued to decrease and reached the minimum area of 4.1 million ha in 2005 but has subsequently recovered and reached 6.4 million ha in 2013. During these six decades, the total harvested area of these minor pulses was between 4 and 6.5 million ha with production from 2 to 3 million tonnes.

Summary

In general, there has been an increase in demand for food with growth of the human population. The major staple food sources of cereals and pulses have grown with similar trends to the human population. During last six decades, the human population are tripled. The grains included the cereals and pulses are doubled or tripled in production during those periods. As the population is projected to grow to 9.3 billion in 2050 (FAO projected and estimated) which is another approximately 30 % of growth, there is great pressure on food for another 30% of growth, as well as the great demand for grains of cereals and pulses. In order to secure these food sources, every country needs to pay more attention to the agriculture industry development.

The pulses total harvested area increased 28.8% for the period 1961 - 2016, which in percentage terms is twice the increase for cereals. Production of pulses doubled in this period and it is highly likely to continue to increase as people understand more about the value and health benefits of the pulses as food. It is said the cereals yield has already achieved a certain ceiling or plateau [1], which has tripled during last half century. The Agriculture sector need to discover alternative ways to increase the productivity. The yield of pulses has increased just 55.8% in nearly six decades, compared to cereals yields which have tripled in the same period. Hence this is great potential to develop higher yields of pulses crops, but it will require more attention and more input from the world to make this happen.

Review of Feature Extraction from Exhaled Aerosol Fingerprints to Diagnose Lung Structural Remolding-https://biomedres01.blogspot.com/2020/05/review-of-feature-extraction-from.html

More BJSTR Articles : https://biomedres01.blogspot.com

Review of Feature Extraction from Exhaled Aerosol Fingerprints to Diagnose Lung Structural Remolding

Review of Feature Extraction from Exhaled Aerosol Fingerprints to Diagnose Lung Structural Remolding

Introduction

Symptomless development of lung cancer leads to high mortality rates of lung cancer patients. It is expected that the mortality rate can be dramatically reduced if cancer can be detected and treated at its early stage. However, effective methods for early cancer detection are lacking despite years of research [1]. Bronchoscope and percutaneous lung needle biopsy have the capacity of detecting and diagnosing lung cancers but are not used for of screening because of their invasive nature. In recent years, Low-Dose (LD) CT scanning gain popularity in screening lung cancers in senior populations who are or have been heavy smokers and are considered to have a high lung cancer risk. However, the reliability and cost-to-benefit ratio still need to be improved. A large-scale two-year trial (2002-2004) with 53,454 participants demonstrated that LDCT could increase the survival rate of lung cancer by 20% [2]. Moreover, LDCT was known to have a high false positive rate, overdiagnosis, and potential risk from long-term radiation exposure [2].

Previous Work on the Aerosol Diagnosis of Lung Functions

Serval studies have investigated the feasibility of employing aerosols to diagnose respiratory diseases. One example is the method of Aerosol Bolus Dispersion (ABD) [3,4], which measures the temporal concentrations of exhaled aerosols to gauge the lung health. It is noted that the ABD method provides no extra information in comparison to current lung function tests [4]. Recently, we proposed an exhalation breath test that is promising to detect lung diseases as well as their locations. This method was based on persistent exhaled aerosol patterns from a given lung geometry [5-9]. In other words, each lung has a unique exhaled aerosol distribution, which is called the signature “Aerosol Fingerprint (AFP)”, to differentiate from the “gas fingerprint” used in VOC-based breath tests [10]. It is hypothesized that a deviation from the normal AFP pattern will be indicative of lung geometry remodeling or tumorigenesis.

Exhaled Aerosol Profiles (Fingerprint)

The AFP pattern, which resembles an actual human fingerprint, collectively result from the aerosol motions through the lungs. In order to predict lung structure remodeling via exhaled aerosol breath tests, the AFPs should be adequately sensitive to variations in lung geometries. Figure 1 shows the expiratory aerosol patterns at the mouth in the four models that represent one healthy and three diseased airways (carinal tumor, left bronchial tumor, and asthma) [9]. The aerosol sizes were 0.4 μm and 5 μm under a steady breathing condition of 30 L/min. There are large differences in particle distributions between health and disease, as well as among diseases with different sites and level of severity. As the particle size increases from 0.4 μm to 5 μm, such differences become even more pronounced. Figure 2a shows the exhaled aerosol distributions (red) when aerosols were released only from the two constricted bronchi (red particles) of Model D and were superimposed onto the asthma case [9]. The red particles had a clear pattern and could be viewed as a biomarker for that diseased condition. In this sense, these tagged trace particles can be employed to detect the position of the disease and estimate the severity of structural remolding. To compare, the superimposed plot in the normal case (Model A) was shown in Figure 2b, with red particles released from corresponding bronchioles.

Relative Concentration

Although the particle profiles in Figures 1 & 2 are visually distinctive between models, particle overlapping may prevent an accurate quantification of particle concentration. Figure 3 displays the ratio of local aerosol accumulations over the averaged concentration, with blue representing zero and red representing high concentrations [5]. For a given airway model, the exhaled aerosol profile and local relative concentrations appear similar. However, the concentration map can readily pinpoint the sites of peak aerosol localization (red color), which should also be the most susceptible sites for tumorigenesis.

Figure 1: Healthy and diseased airway models and their exhaled aerosol fingerprints: (a) Normal condition, (b) Carina tumor, (c) Left bronchial tumor and (d) Asthma.

Figure 2: Exhaled aerosol profiles at the mouth for airways with asthma in comparison to normal condition.

Figure 3: Local concentration: (a) Normal condition, (b) Carina tumor, (c) Left bronchial tumor and (d) Asthma.

Fractal and Multifractal Feature Extraction

Fractal dimension quantifies the complexity of an image by measuring the space occupied by the particles, while the multifractal spectrum quantifies both the heterogeneity (space vs. particles) and complexity [11-18], as shown in Figure 4 [5]. Human lungs resemble an upside-down tree and can be considered as a fractal structure [19-26] with a fractal dimension of approximately 1.57 [27,28]. Considering that aerosols constantly fill and empty the lung trees, it is expected that exhaled particles also show fractal features and therefore, are suitable for fractal analyses. In contrast to the fractal dimension, a multifractal spectrum captures more features associated with the space-filling nature of the lungs at varying scales and is more suitable to describe the expiratory AFPs [29].

Figure 4: Fractal dimension and multifractal spectrum: (a) Box-counting method, (b) Fractal dimension and (c) Multifractal spectrum.

DMD to Capture Temporal Features

Instead of using FD (global or local) of the image which may suffer information loss [11], aerosol patterns formed by exhaled airflows, together with their temporal dynamic processes, should better capture the progression of airway structural remodeling in deep lungs. To avoid possible information loss, features, or eigenmodes, should be extracted directly from the images (i.e., pixel values). By projecting the aerosol images onto low-dimensional eigenmodes, the underlying physics (fluid-particle transport equations) can be approximated by a dynamical system with fewer degrees of freedom, which can be used for the detection, monitoring, and when combined with targeted pulmonary drug delivery, treatment of the lung diseases.

Great advances were made in extracting temporal-spatial features from numerical simulations and experimental visualizations. Proper Orthogonal Decomposition (POD) [12], Principal Component Analysis (PCA) [13], global eigenmodes [14], balanced modes [15] and Dynamic Mode Decomposition (DMD) [16] have given useful insights on the dynamics of fluid flows. POD decomposes the dynamics into orthogonal modes. It provides a lowrank basis and a hierarchy of features that are most predominant in the system. In recent years, DMD has attracted attention in various fields as an approach for the above purpose that works without explicit knowledge of the governing equations. Although DMD is a data-driven decomposition technique like POD and PCA, it generates modes that are directly linked with the transient dynamics of the data. In this sense, DMD is inherently suitable for studying time-evolution observables that evolve on an attractor (i.e., healthy lungs) with transient oscillators (i.e., diseases of varying severities). Besides analysis of fluid flow and vortex dynamics, successful applications of DMD and its variants have been made in power systems [17], robotic control [18], neuroscience [19], image processing [20], epidemiology [21], financial market [22], and weather broadcasting [23].

Deep Learning

In recent years, deep learning algorithms have become the mainstream with increasing evidence of superiority over traditional machine learning algorithms, such as SVM and random forest, in image classification [24,25]. One particularly appealing feature in deep learning is that feature extraction and classification can be executed at the same time. The ability of Convolutional Neural Network (CNN) model to learn rich features at multiple levels has led to a variety of successful application in medical image analysis [26]. On the other hand, unique challenges present in applying CNN models. It generally requires large datasets for effective model training, while quality medical images are often limited. For instance, a database of 405 images was adequate in SVM and random forest classifications but appeared insufficient for a meaningful deep learning test. Evaluations of the performance of CNN models in analyzing exhaled aerosol images are needed when more image data become available.

Conclusion

The use of multiple feature extraction algorithms is becoming increasingly pertinent when categorizing complex images. Considering the exhaled aerosol fingerprints, the most distinctive deviations presumably arise from the diseased sites, where perturbation in airflow is also the strongest. In this study, we reviewed different methods to quantify the exhaled aerosol images in order to distinguish between healthy and diseased lung models, including concentration disparity, fractal dimension, multifractal analysis, and temporal features. These methods collectively formed a feature vector for the AFP and were promising to disclose the hidden order veiled by the seemingly chaotic aerosol distributions. Future studies that used unsupervised feature extractions, such as deep learning, are needed.

Can Dietary Method Replace the 24 hours Urinary Sodium Excretion Method of Assessing Sodium Consumption at Population Level?-https://biomedres01.blogspot.com/2020/05/can-dietary-method-replace-24-hours.html

More BJSTR Articles : https://biomedres01.blogspot.com