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- Herausgeber: Bentham Science Publishers
- Kategorie: Fachliteratur
- Sprache: Englisch
Handbook of Poultry Parasites offers critical insights into the etiology, pathology, diagnosis, and prevention of parasitic diseases affecting poultry. With poultry production being a cornerstone of global food security, understanding the impact of parasites is essential for sustaining flock health, productivity, and economic viability. This volume brings together expert contributions that systematically examine the biology, clinical manifestations, and control of parasites in poultry, making it an indispensable reference for students, researchers, and professionals in veterinary and animal sciences. The book begins with general aspects of poultry parasitology, covering seasonal disease dynamics, principles of parasitism, pathological and immunological responses, diagnostic methodologies, and therapeutic strategies including vaccines, drug resistance, and One Health approaches. The second section focuses on organ- and species-specific parasitic diseases, addressing infections caused by flukes, roundworms, tapeworms, protozoa, ticks, fleas, mites, and lice. Each chapter emphasizes disease mechanisms, clinical signs, and effective preventive and treatment measures. Key Features: Examines principles of parasitism, immunopathology, and disease pathogenesis in poultry Explores diagnostic approaches, therapeutic strategies, and the role of vaccines in parasite control Evaluates organ-specific parasitic infections with detailed clinical and pathological insights Addresses challenges of drug resistance and highlights sustainable management strategies Features contributions by experts offering global perspectives on poultry parasitology.
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Veröffentlichungsjahr: 2025
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FOREWORD
Poultry production is one of the most significant sectors in the global agricultural economy, providing an essential source of protein through meat and eggs. As the demand for poultry products continues to grow, so does the need to understand and address the challenges that threaten the health and productivity of poultry flocks. Among these challenges, parasitic infections stand out as a persistent and pervasive problem that affects poultry worldwide, with substantial impacts on animal welfare, food safety, and economic sustainability.
The “Handbook of Poultry Parasites” is an indispensable resource that addresses this critical issue with clarity, depth, and scientific rigor. This book provides comprehensive insights into the various parasites that infect poultry, including their biology, epidemiology, diagnosis, control, and management. It covers a wide range of parasites, from protozoa and helminths to ectoparasites, each of which poses unique threats to poultry health.
What sets this handbook apart is its balanced approach, combining foundational knowledge with practical applications. It serves not only as a reference for veterinarians, poultry health specialists, and researchers but also as a practical guide for poultry producers and farm managers. The book emphasizes integrated pest management strategies, highlighting the importance of prevention, monitoring, and judicious use of treatments to minimize the impact of parasites while reducing the risk of resistance.
In an era marked by increasing concerns over antimicrobial resistance, food safety, and sustainable agriculture, this handbook is timely and relevant. It provides the tools and knowledge needed to develop effective, sustainable, and science-based strategies for managing parasites in poultry, ensuring that poultry production remains both profitable and responsible.
I commend the authors and contributors for their dedication to this project and for their valuable contributions to the field of poultry health. This handbook is a testament to their expertise and commitment to advancing our understanding of parasitic infections in poultry and their management.
I am confident that this book will become a vital reference for all those involved in poultry health and production. It will undoubtedly contribute to improving poultry welfare, enhancing productivity, and ensuring the sustainability of poultry farming around the world.
PREFACE
POULTRY generally suffers from many parasitic diseases, and the object of this book is to present to poultry-keepers the information about life histories of these pests, so that protection may be successfully ensured. Poultry products are valuable protein sources throughout the globe and the poultry commercial industry, especially Commercial Production Systems (CPS) gained continuous growth during 20-30 years. On the other hand, the traditional scavenging rural systems are also exploited with low growth and serious nutritional, management, and constraints of diseases. The parasite can cause harm in poultry developing countries with the declined productivity of backyard poultry. The handbook describes useful updated information on the pathogenic parasites of economic consequences and also elaborately describes the procedure as well as techniques for the epidemiological study, diagnosis, treatment, and control. The book is structured interestingly for routine application in research institutes, field laboratories, and universities. The book describes the characteristics and habits of the parasites in relation to the occurrence of many diseases. The book guides poultry-breeders, and fanciers in distinguishing and coping with poultry parasites that can cause them serious loss. As most of the birds are grown in more concentrated/confinement areas, new disease problems may appear and old ones sometimes reoccur simultaneously. Proper treatment, management, and sanitation can reduce disease or parasite problems at an early stage. The book is an invaluable resource for both veterinarians in training and in practice for gathering knowledge about the parasitic diseases of poultry. The contributors are well-specialized in their knowledge for writing the individual chapter. This book is especially intended for farmers, industry specialists, practitioners, academics, researchers, veterinarians, and DVM graduate students engaged with a special interest in poultry health, and management. It is assumed that a wide circulation of the handbook can accelerate the standardization and enhancement of diagnostic capacity, treatment, and effective disease control programmes. I hope that this book serves as a new paradigm for the stimulus to further research in clarifying the pathomechanisms, diagnosis, and treatment of parasitic diseases of poultry. I expect that the reader will observe this book interestingly with updated information about the diseases. The book can utilize the knowledge in research and teaching to the new generation. I always welcome constructive feedback and encouragement from my veterinarian colleagues all over the world.
ACKNOWLEDGEMENTS
I would like to convey my regards and sincere gratitude to the Hon’ble Vice Chancellor, West Bengal University of Animal & Fishery Sciences, Kolkata, India for providing me an opportunity to edit the book. I am also extremely grateful to all contributors who helped me by submitting their respective chapter/s at the proper time. I also convey my warmest thanks to all departmental colleagues for giving me wonderful thoughts, extreme energy, and bits of knowledge for editing the book. This book could not have been written without the understanding and support of Bentham Science Publishers. Therefore, a big “thanks” to all of the people at Bentham who worked as a team to get it into the final form. I am really grateful to the clients who have confidence in my abilities to allow me to treat poultry. I also acknowledge and thank all veterinary practitioners, researchers, and academicians whose works are highly cited profusely throughout the text of the book. Last, but not the least, I am indebted to my family for the expanse of time spent on editing of the book.
List of Contributors
Introduction
Sirigireddy Sivajothi1,*,Tanmoy Rana2,Bhavanam Sudhakara Reddy1,Nanga Divyasree1,Yellay Praneetha1Abstract
Poultry now constitutes 30% of global meat consumption, with a rising demand observed worldwide. However, parasites pose a significant challenge in both large-scale commercial poultry operations and small backyard flocks, leading to considerable economic losses. Nematode and cestode worm infections in chickens can result in decreased egg production, weight loss, growth impediments, and weakness. Parasitic infestations in poultry are widespread, regardless of the rearing method used, and can severely affect production outcomes. In confinement systems, parasites have short life cycles and routes of direct transmission, such as Heterakis gallinarum, Ascaridia galli, Eimeria spp., and Capillaria spp. thrive more easily. On the other hand, free-range or backyard rearing creates opportunities for parasites that depend on intermediate hosts to complete their life cycles. It is important to understand that parasitism in poultry impacts the entire flock, and the health of an individual bird is of less economic significance compared to the overall impact on flock productivity.
INTRODUCTION
Various factors, including infectious agents, toxins, and nutritional deficiencies, significantly influence farm performance, thereby affecting the local poultry industry [1]. In addition, poultry is vulnerable to a variety of common diseases, including endoparasites, ectoparasites, infectious bronchitis, Marek's disease, fowl cholera, salmonellosis, infectious coryza, fowl pox, avian encephalomyelitis, among others. These health challenges can significantly impact poultry production and the sustainability of the industry. Controlling infectious diseases is essential for preserving poultry health, and diagnostic methods are critical for identifying disease causes and evaluating the effects of pathogens on the host [2].
Although the core principles of disease diagnostics remain consistent, the landscape of poultry diseases is continually evolving, with new pathogens being discovered and deeper insights gained into epidemiology and disease mechanisms. At the same time, innovative technologies have emerged to detect and characterize infectious agents [3]. However, traditional methods, such as pathogen isolation and characterization through functional assays and studies, remain essential in the diagnostic process. These classical approaches complement new technologies, providing a more complete understanding of poultry health and disease management.
In poultry medicine, the diagnostic approach has shifted from focusing on individual birds to evaluating the health of entire flocks [4]. Flocks are considered “healthy” when they perform according to their genetic potential and show no clinical signs of disease [4]. On-farm diagnostic activities involve regular sampling and investigations as part of health control programs, often aligned with national or international efforts targeting specific parasitic diseases. Samples collected on-site may be tested immediately using rapid antigen tests or sent to laboratories for further analysis, including ELISA and PCR. Field veterinarians play a key role in diagnostic surveillance, and gathering epidemiological data to support flock management. Routine sample collection, such as feces, serum, and mucosal swabs, focuses on confirming flock health status and monitoring vaccine effectiveness [5]. The data generated through these diagnostic processes enable informed decision-making to optimize both flock health and production outcomes.
In field settings, diagnostic procedures are initiated promptly when flock health is compromised, typically indicated by rising morbidity or mortality rates. Investigations begin with the collection of a detailed case history, including relevant information about the flock, management practices, and the characteristics of the infection or disease [6]. This involves recording details such as the type and origin of the birds, their age, routine medications, vaccination protocols, history of diseases, husbandry practices, and standard operating procedures for feeding, watering, ventilation, and lighting systems. Additionally, hygiene and biosecurity measures are documented [7]. In addition, production parameters, morbidity and mortality statistics, the duration of observed signs or problems, and any epidemiological links to other production sites are carefully documented. This comprehensive information serves as the basis for the next diagnostic steps, enabling a systematic approach to identifying and resolving flock health issues [8].
On the farm, diagnostic procedures begin with the clinical examination of both flocks and individual birds at various disease stages, as well as their products, such as feces and eggs. These assessments are carried out by experienced poultry workers and veterinarians who have a deep knowledge of what defines a healthy flock and environment. While clinical evaluations are thorough, they can be time-consuming and labor-intensive. Unfortunately, they may not always identify diseases, particularly subclinical infections, which can be difficult to diagnose accurately [9]. The manifestation of infectious diseases can vary greatly, ranging from subtle subclinical symptoms to severe clinical illness. This variability is influenced by factors such as the causative agent, host characteristics, and environmental conditions, making diagnosis more challenging. Common clinical signs often include non-specific indicators like apathy, ruffled feathers, and decreased appetite, which can be associated with a wide array of diseases [10]. Specific signs may also be present, indicating particular disorders, such as enteric, respiratory, or neurologic issues. In certain cases, signs may be pathognomonic, serving as unique indicators of a specific disease, such as those observed in histomonosis [11].
Post-mortem investigations, whether performed on the farm or in a laboratory, are essential diagnostic procedures designed to identify gross pathological changes in organs and tissues. These investigations assist in determining a tentative cause of impaired performance and clinical signs. By integrating a detailed case history, a comprehensive assessment of clinical signs, and careful post-mortem examinations, the range of presumptive diagnoses can be narrowed. This process lays the groundwork for selecting suitable laboratory methods to further confirm and refine the diagnosis [12].
Protozoa
The primary protozoa are predominantly from the phylum Apicomplexa, encompassing genera such as Eimeria spp., Leucocytozoon spp., Haemoproteus spp., Toxoplasma spp., Sarcocystis spp., and Cryptosporidium spp. Additionally, flagellates like Histomonas spp., Trypanosoma spp., Trichomonas spp., Chilomastix spp., and Hexamita spp., as well as amoeba including Entamoeba spp.and Endolimax spp., are commonly found. Recently, a microsporidian known as Encephalitozoon cunicule has also been reported in chickens [13].
Coccidiosis
Coccidia unquestionably stands out as the most significant parasite affecting poultry, with widespread distribution, high frequency of occurrence, and substantial economic repercussions [14]. Although mortality from coccidiosis is effectively managed with anticoccidial medications, the poultry industry continues to face significant losses due to reduced weight gain, decreased feed efficiency, and treatment costs. To highlight the economic sensitivity of the industry, even a slight improvement in feed efficiency, such as a reduction of 0.01 kg of feed required per kg of gain, could save the U.S. poultry sector over $70 million, based on recent production figures [15].
Coccidiosis, caused by the protozoan Eimeria spp., is a prevalent ailment in poultry. Nine distinct species of Eimeria (Fig. 1 and Table 1) have been identified as infecting chickens: Eimeria acervulina, Eimeria brunetti, Eimeria maxima, Eimeria mitis, Eimeria necatrix, Eimeria praecox, Eimeria tenella, Eimeria mivati, and Eimeria hagani. The impact of infection can range from weight loss to high mortality, depending on the species or strain involved [16]. Each Eimeria species presents different levels of severity and unique clinical characteristics, highlighting the importance of accurately identifying the species impacting the flock. Precise identification is essential for effective monitoring and control of coccidiosis, as well as for determining the most suitable treatment strategies [17].
Fig. (1)) Different regions of the digestive tract of poultry affected by nine Emieria spp.Avian coccidia from the genus Eimeria displays notable host specificity, with pheasants, chickens, Japanese quail, turkeys, and bobwhite quail each hosting distinct species. Poultry producers are primarily focused on the potential issues that any species can cause when present in large numbers. Some species may require higher inoculation doses to cause significant problems [18].
All avian Eimeria species lead to weight loss, increased feed conversion ratios, loss of skin pigmentation, and reduced egg production. The widespread presence of coccidia in poultry production units of all sizes is due to the remarkable reproductive capacity of these intracellular parasites. Each ingested oocyst can produce hundreds of thousands of infective oocysts in the feces within 7 to 12 days [19]. Transmission between farms is facilitated by the movement of personnel and equipment, and new farms can harbor the parasite within weeks of introducing poultry [20].
The Digestive Tract of other Protozoa
Among the protozoa that affect the digestive tract (Fig. 2), Histomonas meleagridis infections can occasionally become a significant economic concern, particularly in turkeys, but also in chickens and, on rare occasions, game birds. The role of the earthworms and cecal worm, Heterakis gallinarum in transmission, along with the necessity of specific bacterial flora for pathogenicity, is well documented [21]. Mortality rates can be significantly high, particularly in turkeys, chukar partridge, and ruffed grouse. Cryptosporidium presents serious challenges in certain poultry species [22], with C. meleagridis infections in turkeys leading to diarrhea and mild mortality [23]. Another species, C. baileyi, infects both the respiratory tracts and digestive of turkeys and chickens [24].
Blood and Tissue Protozoa
These blood parasites (Table 2) are primarily prevalent among birds inhabiting tropical regions. In chickens, the most significant genera of haemoparasites include Haemoproteus spp., Leucocytozoon spp., and Plasmodium spp.. Leucocytozoon spp., which infects the tissue cells and blood of internal organs, with transmission facilitated by various dipteran intermediate hosts like simuliid flies and Culicoides midges in areas of residency. Infection rates can reach up to 100% in some regions [25]. The primary species include L. simondi (found in ducks and geese), L. caulleryi (in chickens), and L. smithi (in turkeys), although additional species have been identified [26]. L. smithi notably led to the failure of a large-scale turkey production endeavor in South Carolina's sandhill areas and coastal plains [27].
Fig. (2)) Digestive tract of poultry.120 species of Haemoproteus have been discussed from birds, they generally pose minimal problems [28]. Sarcosporidiosis can be a significant concern in waterfowl, and many bird species are susceptible to Toxoplasma infections. With limited or no effective medications available for these infections, prevention remains the primary control method. Although over 65 species of Plasmodium have been cited in birds, avian Plasmodium species primarily develop in mosquitoes from the Culex and Aedes genera, with occasional development in Anopheles. Among the most pathogenic for domestic fowl are Plasmodium gallinaceum, P. juxtanucleare, and P. durae, which can lead to mortality rates exceeding 90% [29].
Nematodes
Nematodes stand out as the predominant and consequential helminth species found in poultry, with over 50 distinct species identified [30]. Among these, a majority inflict pathological harm upon their hosts. Belonging to the phylum Nemathelminthes and the class Nematoda, these parasitic worms in poultry exhibit a characteristic unsegmented, cylindrical body shape. Their exterior may feature various textures, such as circular annulations, smoothness, longitudinal striations, or cuticular ornamentations like plagues or spines [31]. All nematodes have an alimentary tract and display distinct sexes. Their life cycles can be direct or indirect, with the latter often involving intermediate hosts [2]. Among breeders, nematodes, or roundworms (Table 3), reign as the most prevalent internal parasites. This group comprises Ascaridia galli (found in the intestine), Heterakis gallinarum (residing in the ceca), and various Capillaria species (occupying the crop and intestine), which traverse the digestive tract. Additionally, the Syngamus trachea, commonly known as the gape worm, resides in the lungs and trachea. These nematodes typically have elongated spindle shapes and range in color from off-white to creamy yellow [5]. Distinct species further define their habitats within the avian body. Capillaria contorta infests the crop, while Capillaria obsignata targets the intestine. Ascaridia galli primarily inhabits the jejunum, whereas Heterakis gallinarum resides in the cecum. Tetrameres americana, a spherical nematode measuring 3 mm, resides beneath the mucosa of the proventriculus. Meanwhile, Cheilospirura hamulosa, a 2.5 cm long nematode, is found beneath the mucosa, specifically within the koilin layer of the ventriculus [7, 9].
Cestodes
Tapeworms, belonging to the phylum Platyhelminthes and class Cestoda, are internal parasites commonly found in poultry. These hermaphroditic organisms have flat, elongated bodies made up of segments and lack both an alimentary tract and a body cavity. Poultry tapeworms can reach lengths of 30 to 50 cm [22, 24]. They have a distinct scolex, or head, followed by a neck. The rest of the body, known as the strobila, is made up of numerous proglottids, or segments, that develop from the neck. Each segment contains a set of reproductive organs, with the number varying among species. As these segments mature, the ones furthest from the neck detach from the body. Gravid segments, filled with numerous eggs, release their contents into the environment through the host's feces [17, 18].
Poultry raised in free-range environments are vulnerable to cestode (tapeworm) infections. These tapeworms have indirect life cycles that depend on intermediate hosts, such as earthworms, beetles, flies, ants, or grasshoppers, to complete their development. As a result, infections are rare in indoor systems. The extensive diversity of tapeworms affecting domesticated poultry and wild birds includes over 1,400 species; however, the pathogenicity of most of these species remains unclear. Many are benign or cause only mild pathogenic effects, while only a few induce severe reactions in the host [5, 9].
The most frequently identified cestodes in diagnoses include:
Davainea proglottina: A 4 mm cestode residing in the duodenum.Choanotaenia infundibulum: A 25 cm cestode found in the distal duodenum and jejunum.Raillietina tetragona: A 25 cm cestode inhabiting the distal jejunum.Raillietina echinobothridia: A 30 cm cestode located in the jejunum, leading to the formation of nodular granulomas and catarrhal enteritis [6, 9].Cestodes (Table 4) depend on intermediate hosts such as insects, crustaceans, earthworms, or snails to complete their life cycle (Fig. 3). In poultry farming, various types of birds, including floor layers, breeders, and broilers, can contract Raillietina cesticillus by ingesting its intermediate host, small beetles that breed in the contaminated litter. In unscreened houses, cage layers may ingest Choanotaenia infundibulumvia house flies, which serve as its intermediate host. Additionally, litter beetles nearby can also act as intermediate hosts. Notably, there have been recorded instances of over 3,000 microscopic tapeworms of the species Davainea proglottina found in a single bird [8].
Fig. (3)) Lifecycle of Cestodes.Many species of slugs and snails serve as intermediate hosts for cestode parasites, with reports indicating that over 1,500 infective parasites can be recovered from a single slug [12]. While the gastrointestinal tract of domestic fowl offers a favorable environment for various cestode parasites, those belonging to the genus Raillietina are the most widely distributed avian helminth parasites globally. Among them, R. echinobothrida is particularly significant due to its prevalence and pathogenicity, especially in domestic fowl, Gallus domesticus [17].
The cestode infests the small intestine, leading to stunted growth in young chickens, emaciation in adults, and reduced egg production in hens [14]. A high prevalence and significant variation in cestode infections were found particularly in indigenous poultry compared to exotic breeds [12]. They attributed this discrepancy to potential shortcomings in the management practices of indigenous layers. Various cestode parasites, including Raillietina tetragona, R. echinobothrida, R. cesticillus, and Choanotaenia infundibulum, were encountered [17]. Among them, Hymenolepis carioca emerged as the most prevalent, while R. cesticillus was the least common.
Other Helminths
Acanthocephalans, also known as spiny-headed worms, and trematodes, commonly referred to as flukes, are rarely found in poultry. In many instances, acanthocephalans appear in their larval forms, indicating accidental infections and the resulting pathology is typically mild. While more than 500 species of trematodes have been documented in birds, approximately 20 are considered potentially hazardous to poultry. Most trematode species exhibit broad host specificity, so diagnosticians may encounter either adult or larval metacercaria in various tissues or cavities, particularly in poultry from backyard flocks or pet birds [30, 31]. One of the more commonly encountered trematodes is Prostogonimus spp., known as the oviduct fluke. This fluke relies on two intermediate hosts: snails and dragonflies. Once it reaches adulthood in the oviduct, it significantly reduces egg production [9, 17].
Ectoparasites
Various arthropods are the primary ectoparasites affecting poultry (Table 5), including bugs, lice, mites, fleas, and ticks. The extent and nature of these infestations are greatly influenced by the production methods employed. In the United States, modern high-density production units have resulted in a notable prevalence of the northern fowl mite, Ornithonyssus sylviarum, in breeder and layer houses [12]. However, these production systems have also decreased the occurrence of lice infestations (due to fewer bird ages on the same farm) and chicken mites (because of reduced hiding places). In contrast, in countries like Denmark, such production methods have led to increased infestations of Dermanyssus gallinae. Detecting ectoparasites is generally easier for those that live directly on the bird, such as northern fowl mites, lice, hard ticks, and stick-tight fleas, compared to those that only feed on the bird temporarily, such as bedbugs, chicken mites, and soft ticks [19].
Insects
Among ectoparasites, only chewing lice (Fig. 4) of the order Mallophaga are known to infect birds. Domestic birds have reported over 40 species, with relatively low host specificity. However, lice can pose significant pathogenic risks, particularly in young birds. The sticktight flea, Echidnophaga gallinacea, is found across a wide range of birds and mammals. Its adults typically cluster on the host's head, with groups numbering up to 100. This flea is distinctive among poultry fleas because its mouthparts are deeply penetrated in the skin, rendering the adult sessile. In contrast, other adult fleas of mammals and birds intermittently feed on poultry [25].
The common human bedbug, Cimex lectularius, is known to infest poultry, sometimes in significant numbers, resulting in detrimental effects on production. While numerous Diptera species, such as midges, mosquitoes, gnats, and stable flies, feed on poultry, a few are typically considered significant by parasitologists, as they act as intermediate hosts for other parasites [12].
Black flies, belonging to the family Simuliidae, play a crucial role in transmitting Leucocytozoon spp. to poultry, including ducks and turkeys. Biting midges, such as Culicoides spp., act as intermediate hosts for Haemoproteus nettionis, which infects domestic ducks in Canada. Various genera of mosquitoes are also capable of transmitting avian Plasmodium spp. Additionally, the pigeon fly, known as the hippoboscid fly or louse fly (Pseudolynchia canariensis), poses significant threats to nestling pigeons and transmits Haemoproteus columbae, that causes a malarial-like exhibition of disease in pigeons. Notably, this fly has an unusual life cycle, with larvae maturing inside the female and pupating immediately upon being ejected [17].
Fig. (4)) Lice infestation in poultry.Arachnids
The northern fowl mite is the most prevalent and important ectoparasite affecting poultry [11]. In severe infestations, feathers may darken, particularly around the vent area. In warmer regions worldwide, the tropical fowl mite often replaces the northern fowl mite, exhibiting similarly severe pathology. Although the chicken mite, also known as the red mite or roost mite (Dermanyssus gallinae), is relatively rare in caged-layer operations in the U.S., it is common on breeder farms and is found in 60% of layer systems in Denmark. Mite infestations can lead to reduced egg production and may increase feed costs by 1 to 6 cents per dozen eggs laid. Furthermore, mite infestations can be fatal to both young and adult birds. Additionally, during heavy infestations, mites may leave the birds to attack poultry workers or infest nearby dwellings [22].
Various mites can be found on or within the respiratory system, quills, air sacs, and subcutaneous tissue of poultry. Among these, larval chiggers are particularly notable due to their economic impact. In turkeys, these larvae are attached to the skin, often in clusters, resulting in prominent abscesses. This can lead to downgrading during processing, as the skin lesions should be trimmed. Soft-bodied ticks of the genus Argas are the primary concern among poultry ticks, although various species of hard ticks may also intermittently feed on poultry [5, 7]. Blood loss caused by the feeding activities of soft tick larvae and nymphs can lead to fatal anemia. Furthermore, the fowl tick has been associated with the transmission of various diseases, including spirochetosis, piroplasmosis, rickettsial infections, and other bacterial diseases, which are of significant concern worldwide.
