What is a host and what types of hosts do you know?
What is mycosis?
Fungal infection of an animal is called mycosis (plural: mycoses).
63. What types of mycoses do you know?
Superficial mycoses are limited to the outer layers of the skin and hair. Examples: pityriasis versicolor and superficial dermatophytoses of hair.
Cutaneous mycoses extend deeper into the epidermis, they are restricted to the keratinized layers of the skin, hair, and nails. Unlike the superficial mycoses, they may evoke cellular immune response. Because of this, a variety of pathologic changes may occur in the deeper layers of the skin. Examples: ringworm, favus, onychomycosis.
Subcutaneous mycoses involve the dermis, subcutaneous tissues, muscle and fascia. These infections are chronic and can be initiated by piercing trauma to the skin, which allows the fungi to enter the body. Examples: sporotrichosis, primary subcutaneous blastomycosis.
64. Give examples of diseases caused by fungi.
RINGWORM, SPOROTRICHOSIS, HISTOPLASMOSIS
65. What are protozoa?
Protozoa are microscopic unicellular eukaryotes that have a complex internal structure and carry out complex metabolic activities.
66. What do you know about their structure and metabolic activities?
Protozoa are microscopic unicellular eukaryotes that have a complex internal structure and carry out complex metabolic activities.
67. Why are they named so?
The word protozoa means “little animals”. They are named so because they behave like tiny animals, e.g. they hunt other microbes as food.
68. How can protozoa be classified taking into account type of their nutrition?
Based on the type of nutrition, protozoa can be classified into a) free-living protozoa, which ingest particulates such as bacteria, yeast and algae and b) parasitic protozoa, which get their nutrients from the body fluids of their hosts.
69. What are the main stages in protozoan life cycle?
During its life cycle, a protozoan generally passes through several stages that differ in structure and activity. Trophozoite (Greek for “animal that feeds”) is a general term for the active, feeding, multiplying stage of most protozoa. In parasitic species, this stage is usually associated with pathogenesis. Some protozoa form cysts that contain one or more infective forms. Cysts are stages with a protective membrane or thickened wall. Cysts that are passed in the feces of the host usually have more resistant walls than cysts that form in tissues, allowing the parasite to survive in the outside environment for a period ranging from days to a year, depending on the species and environmental conditions.
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70. How do cysts help the parasite to survive in the outside environment for a long time?
Cysts are stages with a protective membrane or thickened wall. Cysts that are passed in the feces of the host usually have more resistant walls than cysts that form in tissues, allowing the parasite to survive in the outside environment for a period ranging from days to a year, depending on the species and environmental conditions.
71. What are the main groups of protozoa that are recognized on the basis of their locomotion?
amoebae
flagellates
ciliates
sporozoa
72. What do you know about protozoan biodiversity?
Protozoan biodiversity includes some 32,000 living species and another 34,000 extinct species. Of those alive today, some 21,000 species occur as free-living organisms in aquatic or terrestrial environments, whereas the remaining 11,000 species are parasitic in vertebrate and invertebrate hosts. There are approximately 6,900 flagellate species, 11,550 amoebae species, 7,200 ciliate species and 5,600 sporozoan species.
73. Is phylum Arthropoda the largest and most varied in the animal kingdom?
The phylum Arthropoda (meaning “jointed feet”) is the largest and most varied in the animal kingdom.
74. What is the habitat of Arthropods?
Arthropods are found in literally every known marine (ocean-based), freshwater, and terrestrial (land-based) ecosystem, and vary tremendously in their habitats, life histories, and dietary preferences.
75. Do Arthropods share single basic body plan?
Despite the remarkable variety of arthropod species, all share aspects of a single basic body plan.
76. What kind of skeleton do they have?
All arthropods possess a stiff exoskeleton (external skeleton) composed primarily of chitin. In some species lipids, proteins, and calcium carbonate may also contribute to the exoskeleton.
77. How do they breathe?
Some species have gills, while others employ tracheae. The tracheal respiratory system consists of external openings called spiracles.
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78. What gut do they have?
Arthropods also have a complete gut with two openings, the mouth and the anus.
79. Are Arthropods divided into males and females?
In most arthropod species, the sexes are separate.
80. How do they develop during their life cycle?
While some species exhibit direct development, in which eggs hatch as miniature versions of adults, other species pass through an immature larval stage and undergo a dramatic metamorphosis before reaching adult form.
81. How many pairs of legs do Arachnids have?
Arachnids (having 4 pairs of legs)
82. How can you tell Insect from Acari?
Insects include fleas, mosquitoes, flies, botflies, horse-flies, gnats and others. Arachnids include spiders, scorpions and Acari (Acarina).
83. What is the difference between ticks and mites?
Their differences are: their size (ticks are larger than mites). ticks have short bodily hair if any, while mites have long bodily hairs. ... the diseases they spread (ticks spread lyme disease, rocky mountain spotty fever, and babesiosis.
84. What damage can Arthropods cause?
A surprisingly large number of various diseases are transmitted by insects and other arthropods, either mechanically, by carrying infective material on their biting mouthparts, or by the fact that they act as intermediate hosts for the complete development of certain disease- producing organisms.
85. Do Acari bother animals in other ways apart from being vectors?
Apart from being vectors and transmitting significant number of different diseases, both insects and acari bother animals biting or literally eating them. They may cause diseases like mange, dermatitis, gastrophilosis, etc.
86. What is a helminth?
Helminths, also known as parasitic worms, are multicellular eukaryotic invertebrates, which live in the gastrointestinal tract of their host, or may burrow into other organs, such as lungs, heart, kidneys, liver.
87. In what classes are helminthes divided?
Helminths important in veterinary medicine are classified into two phyla: Platyhelminthes and Nemathelminthes. The first group is commonly known as flatworms and is subdivided into cestodes or tapeworms and trematodes or flukes. Nemathelminthes has only one class named nematodes or roundworms.
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88. What are the main features of cestodes, trematodes and nematodes?
Cestodes have tape-like, flattened, segmented bodies. Anatomically, they are divided into a scolex, or head, carrying suckers and/or hooks, a neck and a chain of segments called proglottids. They vary in length from 2 to 3 mm to 10 m, and may have three to several thousand segments. Cestodes lack alimentary system, and nutrients are absorbed through the body covering. Body cavity is absent. Tapeworms are hermaphroditic, it means that they have both male and female reproductive organs in the same individual. The adults of most species live only in the intestinal tract of their hosts.
Trematodes are leaf-shaped, unsegmented worms, ranging in length from a few millimeters to 7 to 8 cm. All of them have an oral sucker around the mouth, and another on their ventral surface. They possess an alimentary canal, but it is incomplete. Except for the blood flukes, trematodes are hermaphroditic. Adults of most trematodes live in the gastro-intestinal system, including the liver, gall bladder and bile ducts. Other species parasitize the lungs, the vascular system or the urinary tract.
In contrast to platyhelminths, nematodes are cylindrical rather than flattened, and vary with species from a few mm to more than 50 cm in length. They possess a relatively well-developed complete alimentary canal, with mouth surrounded by lips and armed with teeth or cutting plates, and anus. Most nematode species form two separate sexes, with male and female individuals, males are usually smaller than females.
89. How do direct and indirect life cycles differ from each other?
The life cycles of helminths are either direct or indirect. The worms with direct life cycles reach maturity and reproduce in a single host that is called definite or final host. Many nematodes have direct life cycles. Typical for flukes and tapeworms indirect life cycles require one or more intermediate hosts in addition to the definite host. Inside these intermediate hosts, the worms complete certain development stages and may reproduce asexually.
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What is a host and what types of hosts do you know?
definite or final host, intermediate host
91. In what forms do helminths exist?
In general, helminths exist in three morphological forms — 1) eggs, 2) larval form and 3) adult form (or the worm).
92. How can helminths influence productivity in livestock?
Some parasitic worms are live threatening for livestock and pets, other species are well tolerated by their hosts without apparent damage. Often helminths are competitors for food, which is virtually “stolen” by the worms living in the host’s digestive system.
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