Parasitic Diseases of Goats

Goats are livestock, which is very popular among the poor people of developing countries who cannot afford to raise large ruminants. However, small ruminant producers face significant economic threats due to parasitism. Both ecto- and endo-parasites cause significant damage to the animals that either reduces the performance or may cause death of animals. These parasites are either single-cell, protozoa or multicellular, helminths and arthropods. They enter into the host by various means, such as foods, water, penetration of the skin, from mother to foetus via placenta and/or milk, etc. A number of parasites affect the goats, leading to different kinds of diseases. Some are very serious in nature, while others cause mild to moderate kinds of diseases. Furthermore, the severity of the disease depends upon different factors associated with the animals, like age, sex, and breed, parasites like species/strain, quantum of infection, virulence, and environment factors like temperature, humidity, soil type, food, management, etc. Management of parasites is somewhat challenging in the extensive system, while it can be well managed in the intensive system of animal rearing by following the good practices of management.

Goats, being hardy and prolific in their growth, play a crucial role in cultural and socioeconomic life of rural poor under privileged people by providing meat, milk, wool and hide to them. Gastrointestinal parasitic infections are worldwide problem in ruminants. They results considerable loss in them causing mortality and poor production. Various gastrointestinal parasites like trematodes, cestodes, nematodes and protozoa are prevalent in different climates and geographical regions depending on rearing systems, intermediate host’s availability and management practices. Epidemiology of gastrointestinal parasites, though variable at times, is determined by various factors like treatment, climate and poverty (socio-economic and traditional practices). The diseases like Fasciolosis, Dicrocoelosis, Amphistomosis in trematodes, Monieziosis, Avitellinosis in cestodes, Haemonchosis, Trichostronglylosis, Oesophagostomosis, Trichuriosis, Strongyloidosis in nematodes and coccidiosis in protozoa were still serious challenges in the region threatening the small ruminant production. 

Goats are an important part of the agrarian economy in different parts of the world. They are known as poor man’s cows. Some of the parasitic infections can lead to a reduction in performance and reproductive failures in goats. Toxoplasma gondii is one among them, and only one reported parasite affecting the urogenital tract of goats. Goats usually harbor the intermediate stages of this organism in different body tissues. It causes abortion in goats if pregnant goats are infected during any stage of pregnancy. This lead to great economic loss to the farmer. However, abortions in goats may not always attributed to Toxoplasma infections alone. In most cases, it may be due to coinfections with other abortifacient parasites like Neospora caninum. The problem with this infection lies mainly in the lack of facilities for early diagnosis or treatment of this condition. Even though many serologic tools like IFA, ELISA and MAT can be used for its diagnosis, a confirmative diagnosis is not possible. Biotechnological tools like PCR and Genotyping have been reported to produce better results. In addition to the problems caused by Toxoplasma infections in livestock, this parasite possesses a significant public health status as it is a highly potent zoonotic agent. Worldwide, onethird of the human population is chronically infected with this parasite. This chapter dealt in detail with all aspects of this parasitic infection.

Goats play an important role in providing supplementary income in a landless farming system. Nowadays, goat farming has converted into a profitable industry. Goats suffer from various diseases, especially parasitic diseases, that adversely impact this industry. The cardiovascular system is a very important system for communication between different parts of the body in all animals. Several parasites, which are found in the cardiovascular system, cause morbidity and mortality in the goat population. These parasites may cause myocarditis, pericarditis and cardiomyopathy, which are the major causes of heart failure in goats. Some other protozoan and rickettsial parasites found in blood produce severe harm to goats. The present chapter elaborates on the various parasites of the goat's cardiovascular system. This chapter helps to understand the morphological identification, life cycle, pathogenesis, clinical signs, diagnostic methods, treatment and control aspects of parasites in the cardiovascular system of goats.

The ectoparasites that affect the skin, such as ticks, mites, fleas, and lice, are integumentary parasites. Diseases spread by various ectoparasites are distinguished by their distinctive morphology, while symptoms are caused by interactions between the parasite and the host. Parasites from outside the body eat bodily surface tissues like skin, blood, and hair. Ectoparasite wounds, as well as skin irritation, cause animal discomfort and irritability and function as an attractant for myiasis by blood-sucking flies. As they impair animal health, growth, and productivity, these ectoparasites have a substantial economic impact on goat farmers. In general, it is impossible to effectively handle infected livestock. Since there is a strong correlation between the climate, management techniques, and the prevalence of ectoparasitism in animals, it is imperative that biological control agents rather than chemical treatments should be used to control flies. 

The nervous system may be the primary or secondary site of parasitic infection; parasitic diseases may occur as opportunistic infections or arise in immunecompetent hosts. Parasitic infections cause a major economic impact on the farm goats industry, especially the infected central nervous system, as they cause a group of neurological diseases and constitute the biggest single and only challenge for veterinarians. The neurological health problems caused by these parasites affect goats as an outbreak in an endemic area or as sporadic cases in no endemic areas because of a decrease in good management, and immunosuppression caused by different stress as (transportation, grassing, pregnancy, and other risk factors). Parasites are a diverse group of organisms that can be broadly classified into single-celled organisms (i.e. protozoa) or multicellular helminthes (i.e. metazoan). Parasites can cause disease by physical disruption of tissue as they migrate, inflammatory response, provoking an intense, and often eosinophilia, some helminthic larvae can be very large, causing disease because of their expanding mass. A relatively large number of parasites are zoonotic and transmitted to humans, sometimes migrating through or lodging in tissues, including the CNS. Some parasites regularly cause symptomatic disease, while others cause asymptomatic diseases. Most goats through the word carry worms. However, the extent of their effect on goats in terms of deaths, loss of productivity, and the cost of control depends on the severity of the infestation and the species of the parasite, where goats are less able to develop natural immunity compared with other livestock species. Most common parasites have two stages of development: the larval stage, which may develop on pasture or tissue of goats as intermediate host, and the adult parasitic stage, which occurs in the intestine of goats or another definitive host.

The goat (Capra hircus) is the most important domesticated animal due to its importance in various parts of the world since it produces wool, meat, milk, fertilizer, draught power, and leather. There are numerous ways through which parasitic illnesses restrict goat industry production. Parasites outside the body survive on blood, skin, and hair. These parasites cause sores and skin inflammation, which makes the animal uncomfortable and irritated. Diseases can be spread by parasites from ill to healthy animals. These can reduce milk production and weight gain. Livestock that is infested cannot typically be managed well. The eyes and ears are the main organs of any animal, which serve as windows to the outside world and help to find food and shelter and defend them. The eyes and ears of goats are frequently affected by parasitic infections, which are characterized by blindness, severe lacrimation, conjunctivitis, corneal opacity, keratitis, abscesses in the eyelid, photophobia, and deafness. Amongst several species of external parasites that infect the goat include ticks, mites, fleas, flies, and lice. Out of these, ticks are ranked the uppermost in terms of causing infections. There are several genera of ticks that are present on the ear surface, ear canal, and body surface of goats, which are responsible for the transmission of various tickborne diseases, tick worry, metabolic debilitation, tick-toxicosis, and also anemia. Ticks are also considered the second vector in the world after mosquitoes in the transmission of different diseases.  

Goats are susceptible to a variety of respiratory illnesses. Lungworms primarily affect young goats with severe parasitic bronchitis. Coughing, dyspnoea, nasal discharge, weight loss, lethargy, and occasionally fever are some of the symptoms that may be present in animals infected with lungworms. This chapter will deal with parasitic cestodes, nematodes, and arthropods affecting the goats' respiratory systems. Here, parasites have been described according to the region of the respiratory system they affect. Parasitic nematodes such as Dictyocaulus and Protostrongylus commonly infect the trachea and bronchi, Muellerius spp. and metacestode stages of Echinococcus granulosus infest the lung parenchyma, while larvae of the dipteran fly Oestrus ovis infest the nasal passages. The symptoms of pulmonary parasitic diseases can be made worse by secondary bacterial or viral infections, which can lead to bronchitis, bronchiolitis, or pneumonia.

Goats are important in the economy of a country like India. In India, a vast majority of small-scale farmers depend on sheep and goat rearing as their livelihood. They can be completely utilized in different forms, such as milk, meat, skin, and manure. Researchers suggest that the goat sector contributes 8.4% to India’s livestock GDP. A multitude of different species of parasites make goats their hosts, some of which can cause significant diseases. A systematic way to identify them is by examining the organs in which they inhabit. Parasites infecting the liver and pancreas of goats include Fasciola hepatica, F. gigantica, Fascioloides magna, Dicrocoelium dendriticum, Ehinococcus granulosus (intermediate stage hydatid cyst occurs in the liver), Stilesia hepatica, Taenia hydatigena, Eurytrema pancreaticum, etc. Most of them cause severe damage to liver parenchyma, which, in turn, results in the loss of production and in some cases, fatality of farm animals. They can also cause internal bleeding and anemia. These parasites require an intermediate host (mostly snails of the genus Lymnea, Planorbis, etc) to complete their life cycle. This chapter describes in detail various parasites affecting the liver and pancreas of goats, their predilection site, pathogenesis, clinical signs, treatment, and control. Control of intermediate hosts, especially snails, is an important part of the control of the majority of these parasites. Hence, due importance is given to the various snail control methods in this chapter. Recent trends in this aspect are discussed in detail, which will be helpful for the scientific community.

This chapter discusses some of the important parasites affecting or found in the musculoskeletal system of goats. Among them, many are zoonotic in nature. Toxoplasmosis is a worldwide occurring zoonotic disease belonging to the phylum Apicomplexa. Toxoplasma stages are found in different parts of goats, including the musculoskeletal system. Transmission of toxoplasma from goat meat to humans in India is of low importance as the meat is properly cooked before consumption. However, it can spread to cats if they are fed with improperly cooked infected meat. Also, carcasses infected with toxoplasmosis will lose their infectivity very shortly after the death of the animal. Similarly, sarcocystosis is a silent zoonotic parasitic disease caused by obligatory intracellular protozoa of the genus Sarcocystis. The main factor that helps in the control of sarcocystosis in goats is to avoid dogs and cats in the animal sheds. Besnoitia caprae is found in goats. To date, Besnoitia caprae has not been assigned with any definitive host and or intermediate hosts. This parasite has a close resemblance with other species of Besnoitia. Hammondia causes a transient myositis that may be present in the skeletal muscles of infected goats. In areas of high endemicity of Oestrus ovis, humans are at high risk of zoonosis and the parasite may cause ophthalmic infections. Wohlfahrtia magnifica causes traumatic myiasis in the flesh of goats. Coenurus is treated mainly by the treatment of infected dogs and proper disposal of intermediate host carcasses. In many countries, trichinellosis is an emerging disease in goats.

Parasitic infections in goats adversely affect health and productivity and are a major concern worldwide, leading to severe economic losses to the goat industry. The use of anti-parasitic drugs has been proven to be effective in the prevention and control of parasitic load in small ruminants. However, accurate diagnosis of parasitic infection is of utmost importance, which helps in the selection of the most suitable therapeutic agents and reduces the indiscriminate use of anti-parasitic drugs. The conventional diagnostic methods, such as microscopic examination of excretions, secretions, and blood smear for parasites, even nowadays are considered to be “gold standard” techniques in diagnosis, whereas the advancement in clinical diagnostic methods with rapid screening procedures and introduction of molecular biology tools without sacrificing sensitivity, value-added tests, and point-of-care tests overcome the issues related with these conventional methods. Recent diagnostic evaluation of parasitic diseases is performed by serology-based tests, parasite DNA-based molecular methods and proteomic technology. Serology-based tests/ assays are helpful for screening of large number of goats at a time, whereas the parasite DNA-based molecular methods are found helpful for the diagnosis of parasite with very high sensitivity and specificity. Recently, the use of proteomic technology with host or parasite protein as a biomarker opens a new horizon for parasite disease diagnosis. The current chapter discusses the detailed conventional methods and alternative approaches for the diagnosis of parasite disease. 

Goats act as a crucial source of meat, milk, and wool for humans worldwide. Due to their browsing and foraging activity, their health and production constantly suffer from the threat of helminth infection and ectoparasitic infestation. However, there is limited and scattered information on the therapeutics and control of parasites in goats. The information available for the sheep and cattle industry is often reinforced in the goat industry without any safety and efficacy trials of particular formulations in goats. This chapter emphasizes the fact that goat metabolism differs widely from other small ruminants. Therefore, the therapeutic dosage regimen of anthelmintics and other oral medications in goats differs significantly from other animals. Secondly, refugia must be maintained in the animal farms to maintain the efficacy of available drugs. The emergence of anthelmintic and acaricide resistance can be delayed by using integrated parasite management practices. Prudent implication of available therapeutics in light of available scientific literature can significantly impact the livelihood of farmers engaged in the goat industry.