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- Herausgeber: Bentham Science Publishers
- Kategorie: Fachliteratur
- Sprache: Englisch
Organ-specific Parasites in Cattle explores parasitic diseases affecting various organs in cattle, offering a deep dive into their diagnosis, treatment, and prevention. The book provides valuable insights into the etiology, symptoms, and pathophysiology of parasitic infections across critical organ systems, including the gastrointestinal tract, urogenital system, circulatory system, and more. With an emphasis on the latest research, it highlights advanced diagnostics, histopathological techniques, and the development of antiparasitic drugs and vaccines. Readers will gain a thorough understanding of host-parasite interactions, resistance mechanisms, and effective control strategies, all presented with detailed explanations and visual aids. Designed to serve as a key reference, this book is essential for students, researchers, veterinary practitioners, and academicians aiming to deepen their knowledge in parasitology and animal health. Key Features: - Comprehensive coverage of organ-specific parasitic diseases in cattle - Detailed focus on diagnosis, treatment, and preventive strategies - Latest advancements in anti-parasitic drugs and vaccines Readership: Ideal for graduate and postgraduate students, researchers, and veterinarians
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Veröffentlichungsjahr: 2025
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FOREWORD
The well-being and health of livestock constitute crucial pillars for implementing sustainable agricultural practices within the intricate domain of animal husbandry and agriculture. Cattle, recognized as key components of global agriculture, play an essential role in supplying meat, milk, and other indispensable by-products. Despite their significance, various challenges often undermine the optimal productivity of cattle, and among these concerns, parasitic infections emerge as a noteworthy issue.
The book titled "Organ-specific Parasites of Cattle" delves into the intricate realm of parasitism, centering its attention on those elusive organisms that target specific organs within the host bovine. This thorough inquiry, undertaken by a team of experts in parasitology, veterinary medicine, and animal health, seeks to elucidate the intricacies of the biology, impacts, and control measures associated with these organ-specific parasites.
This groundbreaking publication provides valuable perspectives for cattle farmers contending with the persistent challenge of parasite-related diseases, while also serving as a repository of information for veterinary professionals, researchers, and students. The book's concentration on organ-specific parasites contributes to a deeper understanding of the intricate dynamics between hosts and parasites, enriching our comprehension of these complex interactions.
The pages that follow are evidence of the contributors' unwavering commitment as they have painstakingly collected and synthesized the most recent findings from research and field observations and practical experiences. We sincerely hope that this compilation will prove to be a useful tool, promoting a more thorough understanding of the intricacies related to organ-specific parasites and, in the process, aiding in the creation of more robust and long-lasting control methods.
"Organ-specific Parasites of Cattle" serves as a beacon in the constantly changing field of agriculture and animal health, pointing the way toward a more sophisticated and all-encompassing strategy for reducing the negative effects of these parasitism on the well-being and output of the bovine species. In the continuous search for the welfare of cattle and the resilience of our agricultural systems, may this work serve as an inspiration for more research, creativity, and cooperation.
PREFACE
Parasitic infections, a major global concern, adversely affect cattle health as well as production by losing the economic status of the farmers significantly in terms of declined milk production, inferior meat quality, depreciation of hide, loss of manure production, and draught power. A significant pinpoint evaluation of diseases as well as confirmatory diagnosis is required for specific treatment of both ecto- and endo-parasites. In addition, morphological identification of parasites is a basic important tool for the standard methods for diagnosis. Histopathological analysis of parasitic diseases may play an important role in the diagnosis as well as in providing knowledge of the severity of complications of parasitic diseases. It also provides insights into the interactions between parasites and animal hosts and their impact on infected animals. Interestingly, parasites in cattle can cause delayed growth rates, poor physical development and fertility, serious health-related issues, and death in infected cattle. Besides, several parasites may infect both animals and humans, causing public health concerns. The pathological changes are also observed through toxic, subtractive, inflammatory, allergic, obstructive, traumatic, necrotic, and immunosuppressive pathogenic mechanisms caused by parasites in cattle in a wide diverse host/parasite relationships. Parasites may also have the ability to cause tumors or tumor-like lesions in infected cattle.
The present book is organized with the aim to provide a comprehensive approach used in the identification of various images of parasites, the diagnosis of parasites, and prevention and control strategies to counteract parasitic diseases of cattle. It also provides knowledge of its distribution, epidemiology, lifecycle, morphology, clinical manifestations, diagnosis, prophylaxis, and therapeutic measures of parasitic diseases of cattle. The book also covers numerous informative tables and color images for the easy identification of parasites, their induced diseases, and updated information on suitable prevention and control measures. The book is well acceptable as both a textbook and a reference guide for students, academicians, researchers, field veterinarians, veterinarian nurses, laboratory staff, farm managers and also livestock owners. The book is systematically arranged and provides high-quality literature of international standards on organ-specific parasites and parasitic diseases in cattle and their diagnosis and therapeutic management. The book serves as a useful basic resource for all researchers, academics, and postgraduates wishing to gather knowledge on parasitic diseases, diagnosis, treatment, and prevention of cattle parasites and parasitic diseases with an aim to develop new antiparasitic drugs.
List of Contributors
Introduction
Sirigireddy Sivajothi1,*,Bhavanam Sudhakara Reddy1,Syed Afreen1,Tanmoy Rana2Abstract
Bovine parasitism presents a complex and variable disease condition affecting grazing cattle, encompassing both internal and external parasites. Internal parasites reside within the animal, while external parasites inhabit the animal's exterior. Both types can significantly impact cattle health. Understanding internal parasites and their control in natural field conditions necessitates awareness of external parasites and their role in cattle production cycles. The economic significance of different parasitic worms in cattle hinges on factors such as parasite species, the damage they cause, and parasite numbers within the animals at any given time.
INTRODUCTION
Livestock is a crucial part of the agricultural sector, significantly contributing to the rural economy, especially for small and marginal farmers. Parasites are organisms that inhabit or feed on another species, known as the host, for sustenance. Typically, helminths and protozoa are endoparasites, residing within the host's body, while ectoparasites present over the host's external surface (Fig. 1) [1, 2]. Haemoparasites, on the other hand, inhabit the host's bloodstream, often causing clinical or subclinical parasitic infection.
The impact of internal parasites (Table 1) on cattle is influenced by factors such as the severity of infection, the age of the animal, and its stress levels. Typically, younger animals and those experiencing stress are more prone to displaying signs of parasitic infection. Mature cows tend to develop a degree of immunity against parasites residing in the lower gastrointestinal tract. However, parasite burdens
can be particularly detrimental to mature cows nearing parturition due to suppressed immunity during this critical period [3, 4]. Parasitism's effects can be categorized into two types: subclinical and clinical. Subclinical effects encompass losses in animal productivity such as reduced milk production, weight gain, altered carcass composition, and conception rates. On the other hand, clinical effects manifest as visible disease-like symptoms including roughness of coat, anemia, edema, and diarrhea. The subclinical effects hold significant economic importance for producers. In dairy animals, subclinical gastrointestinal parasitic infections represent the primary health challenges limiting productivity [5, 6]. and is considered one of the major challenges in the development of dairy cattle globally [7, 8]. Subclinical infections result in illness and death among young animals, along with significant production losses in adults. While parasitic infections may not always manifest as apparent diseases, they lead to decreased production, including stunted growth, decreased appetite, and poor feed efficiency. The severity of the disease depends on factors such as the type of parasite or the number of parasites present [9, 10]. It is undeniable that, whether mild or severe, the disease causes infected animals to experience slower growth rates, preventing them from reaching their full growth potential. This inevitably results in economic losses for producers [11, 12]. Calf diarrhea stands out as a prevalent animal health issue among dairy farmers, with high mortality rates observed within the first year of life. In numerous cases, gastrointestinal parasite infections are a leading cause of this mortality. The economic impact of calf diarrhea can reach up to a 20% loss, significantly reducing dairy net profits by 38% [13, 14]. The repercussions extend to the loss of future breeding stock and dairy cows, ultimately affecting milk production. It is estimated that the cattle industry invests approximately USD 2.5 billion in pharmaceutical products for parasite control [15, 16].
Fig. (1)) Types of parasites and location.More than 2000 years ago, Hippocrates proposed that “all disease begins in the gut.” While modern science has revealed this statement to be not entirely accurate, substantial evidence supports the significant association between many diseases and the intestine. Cattle can contract infections from various internal parasites, including roundworms (nematodes), tapeworms (cestodes), and flukes (trematodes) (Fig. 2). Protozoans, such as coccidia, represent another category of internal parasites [17, 18].
Fig. (2)) Types of internal parasites.Roundworms are widely recognized as the most economically impactful internal parasites affecting livestock. While cattle may also suffer from tapeworm infections, their impact on animal performance is relatively minor compared to roundworms. Challenges with flukes typically arise in environments conducive to snail populations, such as poorly drained pastures and stagnant water bodies like ponds or ditches within pasture areas. Snails play a crucial role in the life cycle of flukes [19, 20].
Nematodes
Nematodes (Table 2) are cylindrical worms with bilateral symmetry and tapered ends. They have an outer cuticle layer, lack circular muscles, and contain a pseudo coelom that houses all major systems, including the digestive, excretory, nervous, and reproductive systems. In cattle, trichostrongyles are the most common nematodes, comprising several genera that inhabit the abomasum, small intestine, and large intestine [21, 22]. The genera that produce the trichostrongyle type of eggs are Bunostomum, Chabertia, Cooperia, Haemonchus, Oesophagostomum, Ostertagia and Trichostrongylus sp. They have similar life cycle and produce oval, thin-shelled eggs.
Life Cycle of the Nematode
Fig. (3) illustrates the life cycle of the nematode. Within the host animal, adult nematodes lay eggs, which are then excreted from the host via feces, subsequently contaminating the pasture. From the egg, a first-stage larva emerges, which undergoes two molts before developing into a third-stage larva. At this stage, the larva gains the ability to migrate from dung pats and soil onto moist grass. Larvae can persist on pasture for up to a year [23, 24]. Infection occurs when the third-stage larvae are ingested with the grass. Inside the host's gastrointestinal tract, the larvae complete their life cycle. Once they reach adulthood, reproduction takes place, beginning the cycle again [25, 26]. In contrast to other nematodes, the medium stomach worm has the ability to enter a state of hypobiosis, akin to hibernation, during part of its parasitic life cycle. This phase typically commences in the spring, with the “hibernating” larvae remaining dormant until summer before emerging.
Fig. (3)) Life cycle of nematodes.Lungworms
Parasitic bronchitis, commonly known as husk, stands as a significant parasite infection affecting the bovine respiratory tract, caused by the nematode Dictyocaulus viviparus (Fig. 4). While primarily impacting cattle, this species has also been documented in other ruminants, such as deer. The parasite is widespread, with higher infection rates observed in wetter regions, particularly in the western areas of the British Isles. Severe lungworm outbreaks in growing cattle can result in average losses ranging from £50 to £100 per head, while lost milk production in adults may reach up to £3 per cow per day [27, 28]. Similar to numerous other parasitic nematodes, infection with lungworms is acquired through the ingestion of infective larvae from contaminated pasture. The epidemiology of this infection is intricate, with outbreaks frequently proving unpredictable. Symptoms typically manifest in first-year grazing cattle during late summer and autumn, although they can also occur earlier in the year and affect older animals. The hallmark clinical sign of lungworm infection is widespread coughing within a herd, and mortality may occur in cases of heavy infections [29].
Fig. (4)) Endoparasites.Trematodes
Trematodes, also known as flukes, possess a dorsoventrally flattened, unsegmented, leaf-like body structure. They are equipped with suckers, hooks, or clamps to attach to the host. With the exception of Schistosoma, trematodes are hermaphrodites. Among the common trematodes affecting cattle are Paramphistomes, colloquially referred to as 'rumen flukes'. These flukes have an oral sucker at the front and a large ventral sucker at the rear. While adult flukes are generally non-pathogenic, their pathogenicity stems from the migration of their juvenile forms within the small intestine [30].
Fasciolosis
The condition is caused by the flukes Fasciola hepatica and Fasciola gigantica, which affect various mammalian hosts, including families such as Bovidae, Cervidae, Capridae, Equidae, and others. These flukes can also infect humans. F. hepatica is common in temperate regions worldwide, while Fasciola gigantica is primarily found in tropical and subtropical areas. In India, Fasciola gigantica is mainly prevalent in cattle [31].
The fluke's life cycle necessitates two hosts: cattle and snails. Adult flukes inhabit the bile ducts of cattle, where they lay eggs expelled with the feces. Upon hatching, larval stages infect snails, undergoing asexual reproduction within them. Certain juvenile fluke stages depart from the snail and encyst on aquatic vegetation. When cattle consume the vegetation, they become infected. Subsequently, the fluke migrates to the liver, infects the bile duct, and matures into an adult [32].
Cestodes
Cestodes, commonly known as tapeworms, have a ribbon-like shape characterized by a flat body that lacks a body cavity or alimentary canal. They are hermaphroditic, and the adult tapeworm consists of a series of egg-producing segments called proglottids. Nutrients are absorbed through the worm's integument. Moniezia expansa and Moniezia benedeni are the most common cestodes, primarily infesting the small intestine of cattle, especially calves. The proglottids resemble cooked rice grains [33].
Taeniasis
Taeniasis is a true zoonosis in which humans act as the definitive hosts and spread the infection, while cattle serve as intermediate hosts. The adult tapeworm Taenia saginata resides in the small intestine of humans, measuring approximately 5 to 12 meters in length. Eggs or gravid segments are excreted with feces onto the ground. Cattle become infected by ingesting these eggs while grazing, leading to the development of the larval stage Cysticercus bovis in their skeletal and cardiac muscles. Transmission from humans to animals can occur either directly or indirectly, although direct transmission is rare [34]. Transmission can also occur when hands contaminated with Taenia eggs are used to feed or handle calves. However, the most common mode of transmission is indirect, involving the contamination of food, soil, and sewage, as well as transmission by birds or flies. Sewage plays a significant role in spreading Taenia infections between humans and animals. Additionally, human habits, behaviors, religious practices, and beliefs influence dietary choices and cooking methods, affecting the transmission dynamics between animals and humans. Taeniasis is more prevalent in areas where people consume inadequately cooked or smoked meat or where open defecation is practiced [35].
Protozoan Infections
Coccidiosis
Coccidiosis is one of the most pathogenic intestinal diseases, caused by various species of Eimeria within the phylum Apicomplexa [36]. The disease primarily affects confined animals raised under intensive husbandry practices and is more common in housed animals than in those on pasture. When combined with other enteropathogens, coccidia has been recognized as a major contributor to diarrhea in calves (Fig. 4) [12].
Cryptosporidiosis
Cryptosporidium is a widely distributed intracellular apicomplexan protozoan parasite that can infect a variety of hosts, including humans, domestic animals, wild animals, birds, rodents, and reptiles. In cattle, the earliest reported cases of Cryptosporidium infection date back to the early 1970s [15]. However, because of its association with other viral or bacterial enteropathogens, the status of Cryptosporidium species as primary enteropathogens remained uncertain until 1980, when Tzipori et al. reported an outbreak of neonatal diarrhea attributed solely to Cryptosporidium infection. Bovine cryptosporidiosis is common among newborn calves and is characterized by acute gastrointestinal disturbances, including mucoid or hemorrhagic watery diarrhea, along with symptoms such as fever, lethargy, anorexia, and weight loss. These symptoms result in significant economic losses in farm animals and increased neonatal morbidity in cattle. Shedding intensity is notably higher in calves with diarrhea. Furthermore, Cryptosporidium parvum, an emerging zoonotic protozoan parasite affecting calves, is associated with diarrhea in children (Muraleedharan 2009). Cryptosporidium infection rates have been observed to be notably elevated in urban slum areas [1, 32] and in patients with diarrhea [3]. Cryptosporidium parvum has been documented as the predominant parasite found in individuals who test positive for human immunodeficiency virus (HIV) [8]. In Sheather’s sucrose flotation method, the oocysts appear as round or oval-shaped, refractile bodies with a thin cytoplasmic membrane. In contrast, when using modified Ziehl-Neelsen staining, the oocysts exhibit a spherical to ellipsoidal shape and are stained pink to red, containing four sporozoites against a pale green background.
Giardiasis
Giardiasis in dairy cattle stems from the flagellate protozoa Giardia duodenalis (also known as G. lamblia or G. intestinalis), belonging to the Class Mastigophora and Family Hexamitidae. It ranks among the most prevalent enteroparasites globally and has been recognized under the WHO's neglected disease initiative [10]. The disease is most commonly found in developing countries and areas with poor sanitation and hygiene practices. The parasite has two distinct morphological forms: the vegetative trophozoite and the thin-walled cyst. The cyst, which is the infective stage, encysts immediately upon being released into feces. Giardia cysts can spread directly between hosts or through various fomites, including contaminated water and food. Trophozoites are released from ingested cysts in the small intestine, where they multiply. In cattle, Giardia infection often presents as subclinical or asymptomatic; however, symptoms such as anorexia, watery and foul-smelling diarrhea, reduced weight gain, and poor health may occasionally occur in young calves. Infections are associated with a reduced microvillus surface area, decreased intestinal enzyme activity, and increased intestinal transit, ultimately resulting in malabsorptive diarrhea [23].
Neosporosis
Neospora caninum, a protozoan parasite, is emerging as a significant infectious agent causing weak calves and abortion in cattle. Reported infections span most parts of the world, with estimates indicating that 12-45% of aborted fetuses from dairy cattle are infected with the organism. A distinctive characteristic of the disease is abortion occurring at 4-6 months of gestation, a timeframe unique among infectious causes of bovine abortion. N. caninum demonstrates highly efficient transmission rates, with infection rates reaching up to 90% within certain herds. Cows acquire this parasite through two primary routes: 1) “Horizontal” transmission, by consuming feed or water contaminated with eggs (oocysts) from infected dogs and other canids, or 2) “Vertical” transmission, from cow to fetus during pregnancy. Once infected, N. caninum establishes a lifelong infection in adult cows, bulls, calves, or fetuses. Infected cows can transmit the organism to their calves through the placenta in every pregnancy, with the vast majority of congenitally infected calves (95%) appearing normal but remaining infected for life. Heifer calves born with the infection can pass it on to the next generation when they become pregnant, thus perpetuating the infection within the herd. While vertical transmission is the primary mode of transmission in cattle, both horizontal and vertical transmission are crucial for parasite survival [21, 27].
Echinococcosis (Hydatidosis)
Echinococcosis/hydatidosis is acknowledged as the foremost helminth zoonosis, bearing profound economic and public health implications, especially in developing countries [8, 11]. Echinococcosis is caused by a small taeniid tapeworm from the genus Echinococcus. This genus includes four recognized species: E. granulosus, E. multilocularis, E. oligarthrus, and E. vogeli. Their infective larval stages, known as metacestodes, form large cysts - either hydatid or alveolar cysts - in various mammalian hosts, including humans. The eggs of these tapeworms are usually found on the surface of dog feces and can accumulate in the perianal region of dogs. Dogs may carry these eggs on their tongues and snouts to various parts of their bodies. Direct contact with infected dogs is a significant mode of transmission to humans; however, consuming vegetables and water contaminated with infected dog feces can also lead to infection. It is important to note that humans serve as accidental intermediate hosts and are not capable of transmitting the disease.
Haemoprotozoan Parasites
Haemoprotozoan parasites present significant challenges to improving livestock production. The primary haemoprotozoan diseases affecting livestock in our country are trypanosomiasis, theileriosis, babesiosis, and anaplasmosis, all of which lead to substantial economic losses for livestock owners. Among these, babesiosis, theileriosis, and anaplasmosis are transmitted through ticks and are commonly referred to as tick-borne diseases (TBD). These diseases have been prevalent in our country for a considerable period. However, with the introduction of exotic breeds of cattle to enhance the productivity of indigenous stock and improve milk yield, the significance of these diseases has increased. Losses attributed to haemoprotozoan diseases include mortality, reduced milk yield, weight loss, abortion, infertility, diminished draft power, and the cost of treating affected animals [25]. The estimated annual loss due to tick-borne diseases (TBD) reaches 364 million USD, impacting approximately 1.3 million cattle through mortality. Theileriosis is responsible for 68% of these losses. Mortality-related costs comprise 49% of the overall losses, while chemotherapy expenses account for 21%, and the use of acaricides contributes 14% to the estimated annual losses from TBD. Additionally, infection and treatment methods account for 1% of the total losses, with reduced milk production and weight loss contributing 6% and 9%, respectively [31]. It is important to highlight those asymptomatic infections constituted a substantial portion (50.8%) of these costs. Among subclinical infections, those linked to anemia caused the highest losses in live weight. Disease cases contributed to 23.64% of the losses, with mortality being the most significant factor [29].
Babesiosis
In cattle, it is caused by two species affecting cattle: Babesia bovis and Babesia bigemina, which have a wide distribution and are particularly significant in Africa, Asia, Australia, and Central and South America. Vectors for Babesia transmission, with Boophilus microplus being the principal vector for B. bigemina and B. bovis, prevalent in tropical and subtropical regions. B. bovis generally exhibits greater pathogenicity compared to B. bigemina or B. divergens. Infections typically manifest with elevated rectal temperature, absence of feed intake, neurological signs and circulatory shock, occasionally accompanied by nervous signs due to the sequestration of infected erythrocytes in cerebral capillaries. In acute cases, the maximum parasitemia (percentage of infected erythrocytes) in circulating blood is usually less than 1% for B. bovis infections. In contrast, B. bigemina infections often exhibit parasitemia exceeding 10%, sometimes reaching as high as 30%, with major signs including fever, haemoglobinuria, and anaemia. Unlike B. bovis, intravascular sequestration of infected erythrocytes does not occur with B. bigemina infections. The parasitemia and clinical presentation of B. divergens infections resemble those of B. bigemina infections to some extent [27].
Oriental Theileriosis
Theileria are obligate intracellular protozoan parasites that infect both wild and domestic Bovidae worldwide, with some species also affecting small ruminants. They are transmitted by ixodidae ticks and have complex life cycles involving both vertebrate and invertebrate hosts. In India, bovine tropical theileriosis is primarily caused by Theileria annulata, which is also prevalent in large parts of the Mediterranean coast of North Africa, extending to northern Sudan, southern Europe, southeastern Europe, the Near and Middle East, China, and Central Asia. The parasite group referred to as the T. sergenti/ T. buffeli/ T. orientalis complex is now recognized to consist of two species: T. sergenti, found in the Far East, and T. buffeli / T. orientalis (commonly referred to as T. buffeli) with a global distribution. The infective stage of T. annulata is the sporozoite stage, which is transmitted by various species of Hyalomma ticks while feeding on bovine hosts. Several species of Hyalomma, including H. anatolicum anatolicum (found in Eurasian countries including India and African countries), H. dromedarii (found in Central Asia), H. marginatum (found in India and the Middle East), and H. detritum (found in North Africa and Russian countries), are responsible for the transmission of T. annulata [22].
Anaplasmosis
Anaplasmosis, also known as gall sickness, yellow bag, or yellow fever, is an infectious parasitic disease that affects cattle, caused by the microorganism Anaplasma marginale. This obligate intraerythrocytic parasite belongs to the order Rickettsiales, family Anaplasmataceae, and genus Anaplasma. It primarily targets red blood cells, resulting in severe anemia, weakness, fever, loss of appetite, depression, constipation, decreased milk production, jaundice, abortion, and, in severe cases, death. The incubation period for the disease varies from 2 weeks to over 3 months, with an average duration of 3 to 4 weeks [27]. Adult cattle are more susceptible to infection than calves. The disease generally presents as mild in calves under one year of age, is rarely fatal in cattle up to two years old, can be fatal in animals up to three years old, and is often fatal in older cattle. After recovering from the infection, whether naturally or through standard treatment, animals typically become lifelong carriers of the disease. While carriers may not exhibit symptoms, they can transmit the infection to other susceptible cattle. Occasionally, some animals may spontaneously clear the infection completely and regain susceptibility to the disease. Anaplasmosis is prevalent in tropical and subtropical regions worldwide [21].
EXTERNAL PARASITES
External parasites (Fig. 5) are parasites that live on the outside of an animal's body. They can attach to the skin of the animal and feed on its blood. External parasites can be very irritating and can cause serious skin problems or disease.
Fig. (5)) Types of external parasites.Some Examples of External Parasites Include
Fleas, Ticks, Mites, Lice, Stable flies, House flies, Horn flies, Face flies, Mosquitoes.
Blood-Sucking Flies
Black Flies
Black flies are small, dark, stout-bodied insects with a distinctive humpbacked appearance. Adult females primarily feed on blood during daylight hours and are not particular about their hosts. They often hover around the eyes, ears, and nostrils of animals, landing to inflict irritating bites by puncturing the skin. When bitten in large numbers, animals may experience weakness due to blood loss, anaphylactic shock, or even death. The life cycle of black flies begins with the deposition of eggs on logs, rocks, or other solid surfaces in the eddies of flowing streams. Larvae attach themselves to rocks or vegetation using a posterior sucker or threads. The duration of the larval stage varies significantly depending on the species and environmental conditions. Once pupation is complete, adults emerge and display strong flying abilities, capable of traveling distances of 7 to 10 miles from their breeding sites.
Horn Flies
The horn fly stands out as one of the most significant pests affecting cattle, inflicting pain, irritation, and disruption to their normal activities. This persistent biter pierces the skin to feed on blood, causing discomfort to the host. During periods of high summertime populations, horn flies contribute to weight loss and reduced milk production in cattle. Additionally, their presence may lead to the formation of open sores on the head and underline, increasing the risk of secondary infections. These flies tend to congregate at specific sites on the host, particularly the withers and back [20].
Horn fly populations reaching 50 or more per animal are considered economically significant, although there have been reports of counts as high as 10,000 to 20,000 per animal. In such extreme cases, considerable blood loss can occur. Eggs are laid exclusively in fresh cattle manure, typically within 10 minutes of deposition. Larvae hatch within approximately 18 hours and feed on the dung, progressing through three stages over 3 to 5 days. The pupal stage lasts 3 to 5 days before adults emerge, with a preoviposition period of 3 days. Mating occurs on the host, and females can lay about 200 eggs throughout their lifetime. The entire life cycle, from egg to adult, typically spans 10 to 14 days [28].
Adult horn flies feed intermittently, typically around 20 times a day, and remain on the host continuously throughout both day and night, except during oviposition. This behavior makes them susceptible to chemical control methods. When used consistently, dust bags provide optimal control of horn flies, although sprays, ear tags, and dips can also be effective. While back rubbers and pour-on treatments may offer some control, they are generally less effective. Larval control can be achieved with feed additives; however, adult populations may not see a significant decrease in fly migration and continue to sustain high infestation levels [30].
Horse and Deer Flies
Horse flies and deer flies, also known as Tabanids, are robust insects known for their strong flying abilities. Similar to mosquitoes, only female flies bite. They are typically active during the daytime and are known for their aggressive biting behavior. Their attacks can lead to reduced weight gain and decreased milk production in affected animals. Due to the painful nature of their bites and the frequency of their attacks, horseflies often induce frenzied behavior in their hosts, sometimes prompting them to run long distances in an attempt to evade the flies [6].
Tabanids inject an anticoagulant into the wound when they bite, causing blood to ooze. These wounds create favorable conditions for secondary invasion by other insects and diseases, potentially leading to further blood loss. Due to their intermittent feeding pattern, tabanids can act as significant mechanical vectors for diseases such as anthrax, tularemia, and anaplasmosis. Most tabanid species are aquatic or semi-aquatic during their immature stages, while some develop in moist soil, leaf mold, or decaying logs. Typically, eggs are laid in layers on vegetation, objects above water, or in moist areas that promote larval growth. Eggs hatch within 5 to 7 days, after which the larvae descend to the water's surface or moist areas to begin feeding on organic matter [2].
Many species of horse and deer flies feed on insect larvae, crustaceans, snails, and earthworms. Once the larvae reach the pupal stage, they migrate to drier soil, usually one to two inches below the surface. The pupal stage typically lasts 2 to 3 weeks before the adults emerge. The duration of the life cycle varies significantly among species, ranging from 70 days to 2 years.
In Florida alone, there are over 122 species of horse and deer flies, with some present throughout most of the year. These flies present significant challenges for pest control. While daily mist applications can provide protection for animals, they are often impractical for most cattle farmers to implement [8].
Sand Flies and Biting Midges
Sand flies, also referred to as punkies, no-see-ums, or biting midges, are small biting flies. They breed in wet or aquatic habitats, making them difficult, if not impossible, to control. These flies are primarily a nuisance and can cause significant irritation. In large numbers, they may even lead to suffocation. One species of sand fly is recognized as a vector for the bluetongue virus in cattle, while some species act as intermediate hosts for helminths. However, there is limited knowledge regarding the life cycle of sand flies that affect livestock [11].
Stable Flies
The stable fly, also known as the dog fly, shares similarities with the house fly in size and color, but it can be distinguished by its bayonet-like mouthparts. Unlike other discussed flies, both male and female stable flies are aggressive biters. They are capable of flying long distances from their breeding sites.
Stable flies cause irritation and weakness in animals, leading to significant blood loss in severe cases. Bite wounds can also become sites for secondary infections. These flies are easily disturbed while feeding and can mechanically transmit diseases such as anthrax and anaplasmosis. In 2012, their economic impact on the US cattle industry was estimated to exceed $2.2 billion annually.
Stable flies breed in areas with soggy hay, grain, or feed, fermenting weed or grass cuttings, spilled green chop, peanut litter, seaweed deposits along beaches, and manure mixed with hay. When depositing eggs, females often crawl into loose materials to lay eggs in small pockets. A single female may lay up to 500 to 600 eggs in four separate batches. Eggs hatch within 2 to 5 days, and the newly emerged larvae bury themselves, feed, and mature within 14 to 26 days. While the average life cycle is around 28 days, this duration can vary from 22 to 58 days depending on weather conditions [25].
Adult stable flies can remarkably fly up to 80 miles from their breeding sites. When there are more than 10 flies per animal, it is considered economically detrimental, indicating significant fly breeding in the area. Effective control of stable flies primarily depends on cultural control measures. Since the larvae thrive in moist breeding environments, it is essential to identify and eliminate these breeding sources to promote drying. Animal treatments are limited to insecticide applications through fogging or misting to reduce fly populations [4].
Non-Blood Sucking Flies
Cattle Grubs
The common cattle grub typically lays its eggs on the hair of cattle, attaching clusters of 5 to 15 eggs to a single hair. The process of oviposition does not inflict pain on the host animal. In the spring months (February, March, April, May), cattle may exhibit frenzied behavior, running for water or shade to escape the northern cattle grub, often known as “gadding.” This behavior seems to be triggered by the bee-like sound produced by the fly in flight.
Eggs hatch within about 4 days, and the newly hatched maggots burrow into the skin. The first-stage larvae of the common cattle grub migrate through connective tissue, aided by enzyme secretion, and usually settle in the mucous membrane of the gullet. In contrast, the larvae of the northern cattle grub are typically located in the spinal cord. During the early fall months in Florida (October to November), the migrating first-stage larvae begin to reach the backs of cattle. At this point, they create a breathing hole by cutting or digesting through the skin, resulting in a distinctive warble [7].
After molting in the warble formed on the host's back, the first-stage larvae transition to the second stage within 3 to 4 days. The second-stage larva then undergoes another molt to become the third stage, during which it experiences rapid growth. The larva feeds on pus, necrotic cells, and secretions from the wall of the warble or cyst, spending approximately one to two months inside the warble to reach full development. Once fully grown, the grub exits through the breathing hole in the skin and falls to the ground to pupate. Pupation occurs within 2 to 3 days, and the pupal stage lasts between 20 to 60 days, depending on ambient temperature. The entire life cycle takes about one year. The larvae cause two types of injury to the host. First, there is irritation from the larval migrations within the host's body, followed by irritation when the larva emerges from beneath the skin. Second, the larva's exit from the warble leaves an open, oozing wound that is persistent and susceptible to secondary infection [9].
However, the economic losses are considerably greater. Milk production can drop by 10 to 20 percent, and the animals' frantic attempts to escape from the flies can lead to significant weight loss. Furthermore, the carcass value diminishes substantially, as the flesh takes on a greenish-yellow, jelly-like appearance at the sites where the grubs are located, making it unfit for consumption. Additionally, the value of the hide decreases due to the holes created in the skin [30].
During the treatment period, which begins after the egg hatch has ceased and continues until the larvae have moved up to, but not into, the back or gullet region, various methods can be employed for cattle grub control. These methods include sprays, dips, feed additives, and pour-on, with pour-on generally yielding the most effective results.
Infestations of Fly Maggots (Myiasis)
Myiasis refers to the infestation of living tissue by fly larvae in a host. While several types of maggots can invade the wounds of warm-blooded animals, the primary screwworm is the only species that exclusively feeds on live flesh. Efforts to eradicate the primary screwworm from the Southeast, such as releasing sterile male flies, have been successful; however, the risk of reinfestation persists [2].
Other species, such as the secondary screw-worm and certain blowflies, can also infest wounds. These species typically lay their eggs on the carcasses of deceased animals and occasionally on dead tissue within open wounds. While they primarily feed on dead flesh and wound secretions, their presence can result in additional tissue damage, leading to further necrosis, which they subsequently feed upon [7].
Differentiating between primary screwworms and other fly larvae is not straightforward. Samples of eggs and maggots should be preserved in a container filled with 70% alcohol. Wounds should be treated with insecticidal ointments, sprays, or dusts to prevent and manage infestations.
Lice
Lice are generally permanent ectoparasites, meaning they spend their entire life cycle on the host animal. Both immature and adult lice stages are parasitic, requiring them to remain on their host to survive. Each species of louse typically prefers a specific host, although some may infest multiple breeds of cattle. However, lice species that affect cattle are usually not found on other animals, such as swine or horses. Additionally, most sucking lice are specific to certain areas on the host's body [11].
In Florida, cattle are vulnerable to five types of sucking lice and one type of biting louse. The sucking lice, which feed on blood, include the long-nosed cattle louse and the short-nosed cattle louse, both found on the head, neck, and brisket during winter to early spring. The cattle tail louse is primarily found in the tail brush as adults, while immatures can be located on various body parts during the summer to late fall, and sometimes year-round. The biting louse, known as the cattle biting louse, feeds on skin and hair, causing itching, irritation, and hair loss. This louse can become a significant problem during the fall, winter, or spring.
Lice populations experience seasonal fluctuations largely influenced by the condition of the host animal. The biting louse and most sucking lice typically start to proliferate in the fall, reaching their peak populations in late winter or early spring. During the summer, louse populations are usually minimal, often resulting in no noticeable symptoms. Several factors related to the host's environment - such as skin temperature, moisture levels, hair thickness, oil content on the skin, and grooming habits - can significantly affect the size of the louse population. Additionally, animals under stress are generally more susceptible to harboring larger louse populations compared to those in normal conditions [12].
Lice are typically transmitted between animals through direct contact. Transmission from one herd to another usually occurs when carrier animals are introduced, although some lice may hitch a ride on flies (phoresy) and move from place to place.
Feeding lice irritate host animals, and infestations can be detected through changes in behavior. Sucking lice pierce the skin to draw blood, while biting lice use their chewing mouthparts to feed on hair particles, scabs, and skin secretions. This feeding irritation causes animals to rub and scratch, resulting in raw areas on the skin and hair loss. Nervousness and inadequate nutrition may lead to weight loss, and affected animals may appear listless. In severe cases, blood loss from sucking lice can result in anemia and even abortion [15].
Female lice attach their eggs to the hair of the host, near the skin surface. These eggs hatch within 8 to 12 days, depending on the species and environmental temperature. The nymphs undergo three stages of development and reach maturity in approximately three weeks. The typical duration from egg to adult capable of laying eggs is about 25 to 28 days.
Controlling louse infestations is essential whenever animals excessively scratch and rub. However, louse control is challenging because most pesticides do not effectively kill louse eggs. Since eggs usually hatch 8 to 12 days after pesticide application, retreatment is necessary approximately two weeks after the initial treatment. To prevent new louse infestations, it is crucial to treat any new animals introduced into the herd [17].
Cattle tail lice present a distinct challenge, as their eggs can remain viable and hatch up to 40 days after being laid. To effectively manage this issue, it is advisable to wait three weeks between treatments to ensure that most eggs have hatched by the time the second application is given. Cattle tail lice are particularly problematic during the summer and fall seasons. The most effective method for controlling lice is the use of forced dust bags. Additionally, residual sprays, dips, and pour-on treatments can also provide satisfactory control.
Follicular mites, on the other hand, are microscopic, cigar-shaped organisms that live within the skin, specifically in the hair follicles. All life stages of these mites occur within the follicles, leading to the formation of nodular lesions on the skin. These lesions can sometimes rupture, resulting in holes in the hide and making the skin susceptible to secondary infections. Controlling follicular mites is challenging due to their deep penetration into the skin [19].
Mosquitoes
Mosquitoes are tiny insects equipped with piercing-sucking mouthparts and characteristic scales on their wings. Although female mosquitoes are known for feeding on blood, they do not always need it for the initial egg-laying process. Many mosquito species target livestock, causing painful bites that result in discomfort, reduced vitality, and, in severe cases, potential suffocation or significant blood loss. Furthermore, their relentless attacks can lead to weight loss and decreased milk production in affected animals.
