eChapters

A. Answer the following.

Q.1.     How many types of polio virus are there ?
Ans.    There are 3 serotypes of polio virus namely polio virus type 1, 2 and 3.

Q.2.     Who first developed inactivated polio vaccine ?
Ans.    Jonas Salk.

Q.3.     Who first developed attenuated oral polio vaccine ?
Ans.     Sabin.

Q.4.     What are the different inactivating agents used to inactivate viruses in preparing vaccines ?
Ans.    Formaldehyde, b-propiolactone and ethylenimines.

One of the greatest achievements in science is the development of vaccines. Vaccines have been revolutionary for the prevention of infectious diseases. They have prevented a large number of deaths caused, every year, by dreadful diseases like smallpox, polio, hepatitis etc. Diseases like smallpox and polio have been successfully eradicated by vaccination.

One of the greatest achievements in science is the development of vaccines. Vaccines have been revolutionary for the prevention of infectious diseases. They have prevented a large number of deaths caused, every year, by dreadful diseases like smallpox, polio, hepatitis etc. Diseases like smallpox and polio have been successfully eradicated by vaccination. Normally, when the body encounters a microbe, both humoral and cytotoxic immune responses are induced to neutralize its effect. In addition to eliminate the invader, body forms memory cells which help the body to protect itself from the same pathogen, in future. Vaccines not only function to kill the pathogens but they also stimulate the body to form memory cells which provide immunity against a specific pathogen

Histology

Cell: Structural and functional unit of an organism

M. Schleiden & Theodor Schwan – proposed cell theory

- All living being made up of cell

Tissue: Group of cell and their extracellular product organized to perform a particular function

M. Malpighii – Father of histology

1665 Robert Hooke had successfully invented the microscope. Because of this discovery, Robert Hooke was the first one to have a close look of a cell appears to be. His description of these cells was published in Micrographia. However, the cell walls observed by Hooke gave no indication of the nucleus and other organelles found in most living cells.

1674 Anton van Leeuwenhoek witnessed a live cell (plant) under a microscope.

1775 Antoine Lavoisier first proposed a mechanism for photosynthesis, a process wherein plants plants take in carbon dioxide and release oxygen. Lavoisier was also the first to investigate cell respiration in animals.

1777-83 Chemistry became dominated by the phlogiston theory, or the hypothetical principle of fire wherein all the combustible material was part composed. In this principle, burning (oxidation) was caused by liberating phlogiston, with ash as the dephlogistigated substance.

1836 The proponent of the cell theory in Biology, Theodore Schwann, proposed that the process of fermentation is solely limited to living yeast cells in 1836. Liebig did not agree to this and instead, he proposed another alternative theory of fermentation.

1856 Louis Pasteur opposed Liebig’s chemical theory. In his experiment, he showed that fermentation depends highly on the physiological functions that occur in bacteria and in living yeast cells. This work of Pasteur in 1856 received general recognition.

1860s The view on the chemistry of life highly different from the chemistry of nonliving things. During this period, the view is that the gelatinous and homogenous form of matter in organisms or more commonly known as the protoplasm carries out all the intracellular processes. These include respiration, biosynthesis of molecules, and the breakdown of matter.

Embry Transfer Technology (ETT)

Definition: The process of removing one or more embryos from the reproductive tract of a donor female and transferring them to one or more recipient females.

Foot-and-Mouth Disease

Loeffler and Frosch in 1897. Apthovirus of Picornaviridae. Strain O, A, C, Asia-1, SAT-1, 2, 3.

Cattle as Indicator host, Pig as amplifier, Sheep as maintenance host.

Musculature of heart in calves will have striped appearance termed as TIGER HEART.

Panting is common feature or sequel following FMD due to disturb endocrine function.

Preferred cell line for virus isolation in BHK-21.

Our general environment is loaded with tiny invisible living things that influence us consistently. Microbiology is a specialized area of science that deals with living things typicallytoo little to be seen without magnification. Suchmicroscopic life forms are collectively referred to as microorganisms. Microbial kingdom incorporates the study of bacteria, rickettsiae, viruses, fungi, algae and protozo a. Virology the study of viruses, mycology study of fungi and protozoology deals with protozoa.Credit for prologue to microbial world goes to ‘Antony van Leeuwenhoek’ and to vistas of microbial activities to ‘Louis Pasteur’ and ‘Robert Koch’. This period is reffered as the “Golden Era” of microbiology on account of the significant discoveries viz: microbial fermentations, discovery of various disease-causing agents, microbes’ cultivations, differences in metabolic activities, development of attenuated strains and their use as immunoprophylactic agents. The techniques used to study bacteria and different microorganisms embody direct microscopic examination, cultivation, biochemical tests, animal inoculation, serological reactivity and recent molecular biological techniques.Definitive evidence for the cause of a given infection is established by Koch that are still used to this day to definitively prove that a microorganism causes a particular disease. Koch’s four postulates are:

This chapter explores the essential techniques used in veterinary parasitology to collect, identify, and diagnose parasitic infections. These methods are crucial for understanding general animal health, the complex relationships between parasites and their hosts and for tracking disease outbreaks, that will ultimately allow the development of effective control strategies. Whether in a research lab or a clinical setting, the techniques discussed here are widely used to detect and study parasites that impact both domestic and wild animals.
2.1 Collection of Specimens for Parasitological Examinations
Different species of parasites affects almost all parts of the host. These organisms can inhabit virtually every organ system of the host animal, from the brain and lungs to the digestive tract and skin. Therefore, a thorough examination of both living animals and post-mortem cases is essential for collecting parasites and determining cause of death (when applicable). When collecting from live animals, samples should be collected after through exanimation of the animals and following the standard procedure. The collection of correct samples, use of appropriate transport media and proper handling of specimens are crucial factors that directly influence diagnostic accuracy.
The type of specimen collected depends on the methods of identification and diagnosis. For example, diagnosis of blood parasites requires specific types of samples: peripheral blood smears for microscopic examination of hemoprotozoans, serum or plasma for ELISA and other serological tests, and unclotted whole blood for molecular diagnostic methods such as PCR and qPCR.

Parasite- The word parasite is derived from the Greek. Para- beside and sitos- food. Parasites are those living organism which reside on or inside the body of some other species of living organism.

Host- Those organisms which provide food shelter and conducive environment to parasite for their growth, development and reproduction. e.g. Tape worm in small intestine of man and animals.

Disease = dis + aise (see + ease) old French word

Transmission- Movement of biological agents (Virus, Bacteria, Rickettsial, Fungi & Parasites) from one place to another place via vector or vehicle/ tools

Vector- Latin word- bearer

Vector is a living organism (usually an arthropod) which transfers infective forms of a parasite from one host to the other.

Pathology is derived from Greek word (Pathos=disease + logos=study). It is study of structure and function of body in disease.

Veterinary Pathology is the study of anatomical, chemical and physiological alterations in comparison to normal due to disease in animals. Pathology has responsibility to forms a vital bridge between preclinical sciences (Anatomy, Physiology, Biochemistry) and clinical branches of medicine and surgery.

General Pathology deals with the basic alterations of tissues as a result of disease. e.g. fatty changes, thrombosis, amyloidosis, embolism, necrosis etc.

Systemic Pathology is related to the alterations in tissues/organs of a particular system. e.g. respiratory system, genital system etc.

Special Pathology is the application of the basic reactions of gene general pathology to various specific diseases.

Gross or Macroscopic Pathology is the examination of tissue without the help of a microscope.

Chemotherapy

Chemotherapy is branch of pharmacology that deals with study of chemical substance intended to kills or inhibits the growth of invading microorganism or foreign cell without harm to host cells. Paul Ehrlich coined the term chemotherapy and is known as father of chemotherapy. Gerhard Johannes Paul Domagk discovered sulphonamide (sulfonamidochrysoidine). First commercially available sulphonamide marketed in the form of Prontosil dye, for which he received the 1939 Nobel Prize in Physiology or Medicine. SelmanAbraham Waksman discover streptomycin and several other antibiotics from soil actinomycetes and actinomycetes is called treasurer house of antibiotics.

α-lactam antibiotics- includes penicillins, cephalosporins, carbapenems, monobectum and beta-lactamase inhibitors. It inhibits bacterial cell wall synthesis due to inhibition of transpeptidation reaction thus inhibits peptidoglycan synthesis. Penicillins contain 6-animopenicillanic acid (((lactam ring + thiazolidine ring) eg. natural penicillins, beta-lactamase-resistant agents, aminopenicillins, carboxypenicillins, and ureidopenicillins. Discovery of penicillin was done by Alexender fleming from penicillium mold in 1928 from Penicillium notatum. Now a day’s Penicillium chrysogenum mold is a major source of penicillin production. Benzathine penicillin G is a repository salt of penicillin. Probenicid competitively inhibit renal tubular secretion of penicillin and increase the half- life of penicillin. Procaine penicillin G should not administer by i.v. route due to adversely affect the cardiac conducting system. Beta-lactamses inhibitors are calvulenic acid (Streptomyces clavuligerus), salbactum, tazobactam. They are called suicidal /progressive inhibitors. Main adverse effect associate with penicillin is immediate type of hypersensitivity reaction due to Antigen+ IgE antibody reaction.

Veterinary physiology deals with the study of normal functions of animal systems. It includes the study of how animals work and the physical and chemical processes that occur within animals. The examples of various biological processes in animals include gas exchange, blood and circulation, osmoregulation, digestion, nervous and muscle systems, respiration, growth, reproduction, endocrine function and how animals behave and function in different environmental conditions. This also includes the possible manipulation of the reproductive processes by means of hormone manipulation techniques for more efficient livestock and poultry production.

Zoonoses

Zoonoses are those diseases and infections which are transmitted between vertebrate animals and humans under natural conditions. The emergence of a pathogen into a new host species is called disease invasion or “disease emergence”.

Anthrax is a notifiable disease and primarily occurs in herbivores but it is a type of bio-terrorism agent and called as malignant pustule, malignant edema, woolsorters disease, ragpickers disease, maladi charbon, splenic fever etc. Causative agent is Bacillus anthracis contains vegetative spore and lethal dose is 2,500 to 55,000 spores.

Brucellosis is one of the world’s most widespread zoonoses caused by the genus Brucella. In human it is called Malta fever, Undulant fever, Mediterranean fever, Rock Fever of Gibraltar and Gastric Fever while in animals it is called Bang’s disease, Enzootic abortion, Epizootic abortion, Slinking of calves, Ram epididymitis and Contagious abortion etc. it is also called occupational disease.

Leptospirosis is a disease of animal sand humanbeings caused by genus Leptospira and called as Weil’s syndrome, Canicola fever, Canefield fever, 7-day fever, Rat Catcher’s Yellows, Autumn fever, black jaundice). Fletcher’s EMJH media is used to culture the organism.

Veterinary surgery: The surgery which is practiced on animals. It deals with the treatment of deformities, injuries, or disease conditions by manipulation with the hands. The term “Surgery” is derived from a Greek word – Chirurgia (Cheir – Hand, Ergon – work).

The papyri of Egypt contained information on treatment of fractures and superficial wounds.

In Vedic era, Salihotra and Palakapya were the greatest ancient Indian veterinarians. Salihotra treated horses and Palakaya elephants.

“Susruta Samhita’ is the earliest known work dealing with the medical science especially surgery.

Hobday wrote first comprehensive text on surgical diseases of the dog and cat.

The theory and practice of asepsis was introduced by Joseph Lister.

W.S. Halsted introduced the principles of surgery and use of rubber gloves.

Introduction
Vibrios are Gram-negative, rigid, curved rods that are actively motile by means of a polar flagellum. The name ‘Vibrio’ is derived from the characteristic vibratory motility (from vibrare, meaning to vibrate). They are asporogenous and noncapsulated. Vibrios are present in marine environments and surface waters worldwide. The most important member of the genus is Vibrio cholerae, the causative agent of cholera. It was first isolated by Koch (1883) from cholera patients in Egypt, though it has been observed earlier by Pacini (1884) and others.
Natural Habitat
Vibrio spp. can be present in both freshwater and seawater as well as in the alimentary tracts of animals and man. At least five Vibrio spp. are human pathogens including V. cholerae, the cholera bacillus, and V.parahaemolyticus which causes food poisoning. Only V. metschnikovii is associated with disease in domestic animals. It causes a cholera-like disease in chickens and other birds but its geographical distribution is very limited. V. anguillarum causes infections in many species of fish especially in salt or brackish water. It causes high mortality in salt water eels.
Vibrio Cholerae
Morphology
The cholera vibrio is a short, curved, cylindrical rod, about 1.5 × 0.2-0.4 mm in size, with rounded or slightly pointed ends. The cell is typically comma shaped (hence the old name V comma) but the curvature is often lost on subculture. S-shaped or spiral form may be seen due to two or more cells lying end to end. Pleomorphism is frequent in old cultures. In stained films of mucus flakes from acute cholera cases, the vibrios are seen arranged in parallel rows,

Viruses can be cultivated only in living cells. Laboratory animals, embryonated avian eggs and cell cultures are three systems available for this purpose. These three systems are used for the basic procedures of isolation and identification of viruses, maintenance of stock cultures and production of vaccines.
Cultivation of Viruses in Laboratory Animals
Animal inoculation helps to confirm the infectious nature of the disease. Laboratory animals used for many kinds of virological works such as clinical studies, pathogenicity of viruses, epizootiology, potency tests on vaccines and production of diagnostic and prophylactic antisera.

An ideal experimental animal is one that is
1. Uniformly and fully susceptible to the virus under study
2. Free from intercurrent infection and adventitious lesions and
3. Inexpensive purchase and maintain
If possible it is better to use germ free, specific pathogen free or colostrums deprived animals for experimental purpose. The same species of animals or atleast closely related species of the natural host is selected for inoculation, wherever possible. For example in case of swine fever, which shows a high degree of host specificity, the same species should be used for inoculation. in others such as in case of rabies with low host specificity, the causative virus will grow in a wide range of animals.

Virus can be defined as a genetic element containing either DNA or RNA that replicates in host cells as intracellular parasites but is characterized by having an extracellular state.

Virus can use the metabolic machinery of the host cell and can modify the genetics of the host cell. Virus has both extracellular and intracellular state.

Extracellular State

Outside the host cell, the virus is a minute particle containing nucleic acid surrounded by protein, which is referred as virions or virus particles. Virions are inert and have no biosynthetic and metabolic functions. Extracellular state or virus particle is the perfect stage of virus to study the morphology and chemistry.

Intracellular State

The active state in which the virus replicate in the host cell. When the virus nucleic acid is introduced to host cell and replication starts, the process is referred as infection. The cell in which infection of virus and replication takes place is referred as host cell.