The Novel Coronavirus disease is an infectious disease caused by a newly discovered coronavirus (COVID-19). In humans, coronaviruses cause respiratory tract infections that can range from mild (common cold) to lethal (SARS, MERS, and COVID-19) and recover without requiring any special treatment. This particular infectious disease can even found in birds and mammals. People with medical problems like diabetes, chronic respiratory diseases, cardiovascular diseases, and cancer and other chronic diseases and also in elder are more likely to develop serious illness which can cause to death. At present, no specific treatment is there for this disease caused by a novel coronavirus.

A bacterial infection is a rapid growth of a harmful strain of bacteria on or inside the body. Harmful bacteria can cause a few illnesses like pneumonia, meningitis, and food poisoning. Bacterial infections are one of the main causes of foodborne illness. Common symptoms include nausea, vomiting, diarrhoea, fever, chills, fatigue and abdominal pain. Most of the sexually transmitted diseases (STDs) are caused by harmful bacteria. Most of the times they may not related to any symptoms of the disease but still can cause significant damage to the reproductive system. Bacterial skin infections are generally caused by gram-positive strains of bacteria such as Streptococcus and Staphylococcus. Some of the bacterial infections include boils, impetigo, and folliculitis. Viruses are like hijackers. This can slaughter, damage, or change the cells and make sick. Different viruses attack certain cells in the body such as the liver, respiratory system, or blood.

The most recurrent causes of food, air, and water-borne illnesses are bacteria, viruses, and parasites. The airborne disease can proliferate when a contagious person coughs, sneezes, or talks, spewing nasal and throat secretions into the air. When you inhale airborne pathogenic organisms, they take up residence inside you. You can also pick up microbes when you touch an infected surface, and then touch your own eyes, nose, or mouth. Because these illnesses travel in the air, they’re hard to control. Food- or water-borne diseases are not transmitted from casual contact with another person. A person can come into exposure with food- or water-borne bacteria by eating or drinking something that has bacteria in it. Many diseases are spread through the air are: The common cold, Influenza, Chickenpox, Mumps, Measles, Whooping cough, Tuberculosis, Diphtheria.

In order to work out the cause of sickness, Cytopathology, a diagnostic technique is being employed to examine cells from varied body sites. Pap test was the primary test of cytopathology developed that has is widely utilized within the last fifty years in order to identify and screen the cervical cancer and its precursors. The Pap test is taken into account the foremost economical screening test in medical history. Histopathology is the study which deals with morbid tissue, as an example, breast lumps or the specimens of gut that is removed from the suspected cancer, as well as examining under the microscope. Histopathologists inspect the tissues that are removed from patients within the clinic or throughout an operation. They use a spread of scientific ways to get if a sickness is present and what course of action has to be taken. The tissue is first examined with the eye to appear any visible abnormalities and also to pick out the items in order to look at in additional detail. Immunopathology is the branch of medicine that deals with the immune responses related to sickness. It includes the study of the pathology of an organism, organ system, or sickness with relevancy to the immune system, immunity, and immune responses.

Paediatric infectious diseases, also known as childhood infectious diseases are the infectious diseases that mainly are caused in children of different age groups. Paediatric infectious diseases experts deal with the infections occurring in children and the treatment method fluctuates from children to adults. Common paediatric infections include Pneumonia- diagnosed in nearly 2% of infants < 1 year and in 4% of children aged 1 to 5 years. It is estimated that 90% of paediatric pneumonia are caused by viral agents. Other infections also include Otitis Media which is caused in children who live with the adults who smoke.

From the past several years, the development of molecular diagnostic techniques and its applications had made a revolution in the diagnosis and monitoring of several infectious diseases. Molecular diagnostics are generally used to identify infectious diseases such as chlamydia, influenza virus and tuberculosis. Genetic identification can be made for example a loop-mediated isothermal amplification test diagnoses the malaria parasite in the many developing countries. But despite these advances in genome analysis, in 2013 infections are still more often identified by other means like proteome, bacteriophage, or chromatographic profile. Molecular diagnostics is used to understand the specific strain of the pathogen—for example by detecting the drug resistance genes it possesses and hence which therapies to avoid.

The neurological infections are the disorders of the central nervous system. The examples of neurological disorders are paralysis, muscle weakness, pain, altered level of consciousness, etc. The main cause of neurological problems can be alter and can cover genetic disorders, congenital abnormalities, infections or environmental health. Neuropathology is the study of disease related to nerve tissues, generally in the forms of either a small surgical biopsies or as whole-body autopsies. Neuropathologists are the ones those who works in a department of anatomic pathology, but can also work closely with the clinical disciplines of neurology, and neurosurgery, which often depends upon neuropathology for a diagnosis. Neuropathology can also be related to forensic pathology because brain disease or brain injury can result in death. The term Neuropathology should not get confused with neuropathy, which refers to disorders of the nerves themselves.

Gastrointestinal infections are the most frequently encountered infections in primary care caused by virus, bacteria and parasites. The gastrointestinal infections include gastroenteritis or the inflammation of the gastrointestinal tract involving both the stomach and the small intestine. Gastrointestinal infections are caused by a large number of microorganisms like Adenovirus, Campylobacter, Clostridium difficile, Escherichia coli, Rotavirus, Salmonella etc. All the age groups are affected by the gastrointestinal infections. The management of gastrointestinal infection is done by rehydration, antiemetic medications, antibiotics, other anti-motility agents etc. Born out of increasing awareness on the subspecialty gastrointestinal pathology services, increased and developed marketing efforts by the gastrointestinal pathology related companies and also increased patient awareness on laboratory errors, there is an increasing trend towards referral of tissue specimens to the surgical pathologists with special interest in gastrointestinal pathology.

Pulmonary pathology is the sub specialty that includes a large spectrum dealing with the diagnosis of both neoplastic and non-neoplastic diseases which affect the lung thoracic pleura. Many of these are a result of the unusual relationship of the lung with the outside environment. Every breath that a human takes brings the outside world into the body in the form of infectious agents, organic and inorganic particles, and noxious agents of all types. Pulmonary pathology that is reported in association with primary biliary cirrhosis mainly includes lymphocytic bronchitis and bronchiolitis, OP, and chronic interstitial pneumonia, including LIP. Rare reports have also appeared in describing pulmonary haemorrhage and glomerulonephritis, or microscopic polyangiitis, in individuals with primary biliary cirrhosis.

Dermatopathology is a joint subspecialty of dermatology and pathology which mainly focuses on the study of cutaneous diseases at a microscopic and at a molecular level and also involves analyses of the potential causes of skin diseases. The dermatological infection is defined as the skin infections that are caused by bacteria, fungi and other microorganisms. In the past decade the infectious disease diagnosis on a molecular level is developing notably. The dermatologic disease diagnosis mainly involves different new and advanced techniques such as transcription-mediated amplification, nucleic acid sequence based amplification, polymerase chain reaction, ligase chain reaction etc. The operating cost of these techniques is decreasing with time as well as acquiring the approval of the U.S. Food and Drug Administration and getting easier and more effective to use. In the future, it has been expected that these techniques will be able to provide the fast and accurate diagnosis of infectious diseases in a single clinical visit.

Mycobacterial infections are caused by the bacteria Mycobacteriacease. The most common type of mycobacterial infection is Tuberculosis. Tuberculosis is usually caused by bacteria Mycobacterium tuberculosis. These bacteria usually attack the lungs but they can also damage the other body parts. The symptoms of TB are cough, weight loss, fever, coughing of blood, loss of apetite. Other mycobacterial diseases are:

Rare diseases are caused by causative agents rather than genetic or some environmental factors. Generally a very small percentage of the population are affected by some rare disease. In some parts of the world, an orphan disease called a rare disease in which rarity means there is a lack of a market large enough to gain a support and resources to discover treatments for it that are excepted by the government granting economically advantageous conditions to create and sell such treatments. Globally, nearly one-third of the population deaths are attributable to these infections. In addition, the non-infectious causes of death are often having a mysterious infectious etiology.

Epidemiology involves the study of patterns, causes and the effects of health and other disease conditions. It is the cornerstone of the public health and informs all policy decisions and evidence based practice by identifying all the potential risk factors for disease and the targets for preventive healthcare. Epidemiologists help with the study design, data collection and statistical analysis of data, interpretation and dissemination. Epidemiology mainly helps to develop methodology that is used in clinical research, public health studies and to a lesser extent basic research in the biological sciences.

Clinical microbiology laboratories use a number of rapid tests in order to detect the specific microbial antigens or nucleic acids in the primary nontissue specimens. For example, Cryptococcus antigen testing can be performed on cerebral spinal fluid (CSF), and antigen testing for respiratory viruses can be performed on nasopharyngeal specimens. Molecular techniques that are being used increasingly in clinical laboratories detect the pathogen-specific nucleic acids and have most notably been applied to virologic diagnosis. The introduction and rapid expansion of molecular techniques, especially nucleic acid detection methods such as polymerase chain reaction (PCR)/DNA amplification, to the detection of infectious agents requires clinicians to be familiar with the properties of some newly introduced diagnostic tests as they enter common use. Laboratory tests may identify organisms directly or indirectly.

Antimicrobial/ antibiotic/ antibacterial resistance is the ability of the microorganisms such as bacteria, fungi and other germs to resist the effects of drugs which means the diseases causing germs do not get killed and also their growth is not stopped. Antibiotic resistant infections are of a greater risk that cannot be avoided completely. Infections with resistant organisms are considered difficult to treat. Antibiotic resistance is said to have the potential to affect people at any stage of life, as well as the healthcare, veterinary, and agriculture industries, making it one of the world’s public health problems.

Nosocomial infections/ hospital acquired infections/ health care associated infections are the type of infections that are contracted from the environment or the staff of a healthcare facility. Such infections mainly include fungal and bacterial infections and are aggravated by the reduced resistance of the individual patients. Noscomial Infections or Health care associated infections spread in the hospital environment, nursing home environment, rehabilitation facility and clinics or other clinical settings.

Personal hygiene is generally how a human cares for his body and health. Personal hygiene practices include bathing, washing your hands and body, brushing and cleaning teeth, and more. Every day, we come into contact with millions of germs and viruses and other microorganisms. They can linger on your body and hands as they may make you sick at some cases. Many sufferers of mental sicknesses like dementedness or depression might have some additional support and encouragement with their personal hygiene. It means that being careful to not to cough or sneeze on others, cleansing things that simply bit if you're unwell, some golf stroke things like tissues (that could have germs) into a bin, associate degree victimisation protection like gloves or condoms. Personal hygiene practices can help you and the people around you prevent illnesses and also help to feel good about your appearance.

Infectious diseases have represented a huge threat to human lives since the beginning of the human existence. Many infectious diseases have been conquered through the discovery of antibiotics and antiviral agents. In recent times, natural products or herbal medicine have been playing a wide role in treating several clinical diseases. Most chemical drugs that are widely used today have been isolated from the natural products, and thus these natural products will continue to be important raw materials for the production and development of new drugs. Currently, various scientific experiments are being conducted in order to fill this gap by evaluating the efficacy of natural product which may include infection by multidrug-resistant bacteria, viral influenza, coccidiosis, leishmaniasis, infectious septic shock, and biofilm formation.

The acquired immunity to infectious diseases can be expressed by a primarily humoral or a cellular mechanism or the combination of two. The living or dead vaccines are used in our body for stimulating the acquired immunity. The many different types of immunizations are developed for the resistance against infectious diseases. The innate immune system recognizes the infections by retrieving the information either from long-term, short-term or working memory and matching it with the information from stimuli to activate adaptive immunity. A vaccine is a biological preparation which provides active acquired immunity to a particular disease or infection.

Infections that are caused by germs or other microorganisms which may infect any part of the body are called infectious diseases. Infectious diseases prevention and control is helpful to prevent and control the transmission of infections. Aseptic technique is usually applied for preventing the infections caused by different means or germs. Sterilization is another process or technique of killing microorganisms by the application of heat. Disinfection is also the process of killing harmful microorganisms. Some of the infectious diseases can be prevented by avoiding direct contact with the contagious person. Many harmful infections can also be controlled and prevented by creating public awareness on various infectious diseases and their outbreaks.

Infectious diseases also known as contagious diseases are diseases caused by pathogenic organisms, such as viruses, microscopic organisms, bacteria or parasites. Numerous organisms live in and on our bodies. When exposed to infected animal, humans that possess a pathogenic organism also becomes infected. Microorganisms are tiny living things that are found everywhere - in air, soil and water. Microorganisms that cause disease are together called pathogens. Infectious diseases vaccines are the vaccines which prevent the infectious diseases like Haemophilus influenza, Diphtheria, hepatitis b, measles, meningitis, serotype b infection, tetanus, rubella, tuberculosis, yellow fever are preventable through immunizations. An infectious disease for which an effective preventive vaccine exists is called vaccine-preventable disease. If a person procures a vaccine-preventable disease and if he dies from it then the death is considered a vaccine-preventable death.

Immunization/Vaccination is one of the most cost-effective public health interventions to date, saving millions of lives and protecting countless children from illness and disability. As a direct result of immunization, polio is on the verge of eradication. Immunization has not yet realized its full potential, however. As of end-2013, 21.8 million children under 1 year of age worldwide had not received the three recommended doses of vaccine against diphtheria, tetanus and pertussis containing vaccine (DTP3), and 21.6 million children in the same age group had failed to receive a single dose of measles-containing vaccine. Given an estimated annual cohort of 133.6 million surviving infants, an additional 11.2 million children would need to have been reached during 2013 to attain 90% DTP3 coverage globally.

Emerging infectious diseases are a significant burden on the global economies and public health and their development is believed to be driven to a huge extent by financial, ecological and environmental elements, Global resources to counter disease emergence are inadequately assigned, with most of the scientific and surveillance effort concentrated on nations from where the following significant EID is to the least extent liable to begin. An Infectious disease whose occurrence has increased in the past years or threatens to increase is termed as emerging. These particular diseases include new infections, previously unrecognized infections and other old infections reappearing due to antimicrobial resistance, public health issues and unhygienic conditions.