Health is described as the state of complete physical, mental and social well being. Being healthy is far more than just being free from disease. Disease is a condition of disturbed functioning of the body caused by infection, defective diet, heredity, environment or deprived condition of brain. Health is a state of complete physical, mental and social well being.
Disease may be a response to :
• Environmental factors (as malnutrition, industrial hazards or climate)
• Specific infective agents (as worms, protozoans, fungi, etc)
• Inherent defects of the organism (as genetic anomalies.)
• Combination of these factors
Causes of Diseases/Disease Agents
Disease agent is organism, substance or force which causes disease due to its excessive presence, deficiency or absence.
Pathogens/Biological Agents:
They are biological entities which cause infectious diseases, e.g., viruses (mumps, chicken pox, small pox), mycoplasma (e.g, bronchitis, acute leukemia), chlamydia (e.g, trachoma), bacteria (e.g. cholera, tetanus), fungi (ringworm, thrush, moniliasis, pulmonary aspergillosis), protozoa (e.g. giardiasis, sleeping sickness), helminths (e.g., filariasis, ascariasis, taeniasis), other organisms (e.g., scabies).
• Nutrient Agents: Deficiency of vitamins (e.g., beriberi, scurvy, night blindness), minerals (e.g., anaemmia, rickets), carbohydrates, fat and proteins (e.g., kwashiorkar, marasmus), or excess of food (e.g., obesity).
• Chemical Agents: Endogenous Agents– Excess presence of uric acid, reduced secretion of ADH (diabetes insipidus) or insulin (diabetes mellitus). Exogenous Agents- Pollutants (e.g., pneumoconiosis), allergens (allergy).
• Physical Agents: Heat (e.g., stroke), cold (frost bite), radiations, sound (impaired hearing), humidity, etc.
• Mechanical Agents: Fractures, sprains, dislocation, injury, chronic friction.
• Genetic Agents: Excess or deficiency of chromosomes, mutations, harmful alleles, e.g, colour blindness, albinism, haemophilia, Turner’s syndrome.
• Degeneration: They include old age change like peptic ulcers, hypertension, atherosclerosis.
Types of Disease
1. Congenital diseases: Congenital disorders can be due to fault in the chromosome structure or damage inflicted to the development embryo. These could be caused by radiations, diseases contracted by the mother (German measles), use of certain drugs, excessive smoking and alcohol intake by the pregnant mother; for example, Hare-lip, club foot and Mongolism.
2. Hereditary Diseases: Diseases that are transmitted from parent to offspring from generation to generation are termed hereditary diseases. E.g., Haemophilia and colour blindness.
3. Acquired diseases: Acquired diseases develop in an individual after birth.These are of two kinds –
(I) Communciable diseases: These are caused due to the entry of disease-causing germs called pathogens into the body and are easily transmitted from person to person by direct or indirect contact or through a carrier which is called vector, e.g., mosquito (Anopheles) is a vector of malaria. Indirect contact may be through clothes, beddings, utensils, etc.
Communicable diseases are further classified into several types depending on the types of causative agents:
(i) Viral (ii) Bacterial, (iii) Protozoan (iv) Helminthic (v) Fungal.
(II) Non-Communicable diseases: These are restricted to the persons suffering and they are of the following types:
(a) Degenerative Diseases: These diseases are due to degeneration of tissues in old age, that is, diseases caused due to decline in the ability of the body to repair its tissues. It leads to malfunctioning of the heart, lungs and central nervous system E.g., Parkinson’s disease, cataract and arteriosclerosis.
(b) Cancer: It is caused due to uncontrolled growth of tissues in any part of the body. This disease has become a challenge to medical science as it is incurable in later stages.
(c) Allergies: These are caused due to hypersensitivity of the body to certain foreign substances called as Allergens. E.g., Hay fever, asthama, nettle rash.
DISEASES IN NEWS
Rotavirus
Rotavirus is a most common virus that contaminates the bowels. It causes diarrhoea among infants and children throughout the world and causes over 450,000 deaths worldwide annually inclusive of 110,000 deaths in India which is accounts for 22 per cent of the estimated global deaths from diarrhoea-causing rotavirus.
Symptoms
• Rotavirus affects the body in many ways and multiple infections can be noticed.
• Vomiting
• Low grade Fever
• Watery diarrhoea
• Nausea
What is Rotavirus vaccine?
• Rotavirus vaccine prevents diarrhoea virus to enter the body which causes death
• RotaShield is a Rotavirus vaccine by Wyeth was licensed in 1998 in the United States
• In 1999, however the manufacturer withdrew it from the market risking bowel obstruction in one of every 12,000 vaccinated infants
• The vaccine was under trial for 8 years since the withdrawal. After efficient research Rotarix by GlaxoSmithKline and RotaTeq by Merck were manufactured which is effective and safe
Zika Virus
• Zika virus infection is caused by the bite of an infected Aedes mosquito. It is spread by mosquitoes of the Aedes genus (Aedes aegypt) which can breed in a pool of water as small as a bottle cap and usually bite during the day. The Asian tiger mosquito, Aedes albopictus, is also known to transmit the virus.
Symptoms
a) The illness is usually mild with symptoms lasting for several days to a week.
b) The most common symptoms of Zika are fever, rash, joint pain, or conjunctivitis (red eyes). Other common symptoms include muscle pain and headache. The incubation period (the time from exposure to symptoms) for Zika virus disease is not known, but is likely to be a few days to a week.
c) There are concerns that pregnant women who become infected with Zika virus can transmit the disease to their unborn babies, with potentially serious consequences. Reports from several countries, most notably Brazil, demonstrate an increase in severe foetal birth defects and poor pregnancy outcomes in babies whose mothers were infected with Zika virus while pregnant.
d) The new born infants are suffering from Microcephaly. It is a rare condition where a baby has an abnormally small head. This is due to abnormal brain development of the baby in the womb or during infancy. Babies and children with microcephaly often have challenges with their brain development as they grow older.
Transmission
a) Zika virus is transmitted to people primarily through the bite of an infected Aedes species mosquito (A. aegypti and A. albopictus). These are the same mosquitoes that spread dengue and chikungunya viruses.
b) These mosquitoes typically lay eggs in and near standing water in things like buckets, bowls, animal dishes, flower pots and vases.
c) Mosquitoes that spread chikungunya, dengue, and Zika are aggressive daytime biters. They can also bite at night.
d) Mosquitoes become infected when they feed on a person already infected with the virus. Infected mosquitoes can then spread the virus to other people through bites.
e) It is possible that Zika virus could be passed from a mother to her baby during pregnancy. Studies are going on how some mothers can pass the virus to their babies.
f) To date, there are no reports of infants getting Zika virus through breastfeeding. Because of the benefits of breastfeeding, mothers are encouraged to breastfeed even in areas where Zika virus is found.
g) Spread of the virus through blood transfusion and sexual contact has also been reported.
Prevention
a) No vaccine exists to prevent Zika virus disease (Zika). Hence prevention and control relies on reducing mosquitoes through source reduction (removal and modification of breeding sites) and reducing contact between mosquitoes and people.
The World Health Organization has recently declared the Zika virus and its suspected link to birth defects as an international public health emergency, a rare move that signals the seriousness of the outbreak and gives countries new tools to fight it.
India’s Health Ministry issued health advisory, appointing National Centre for Disease Control (NCDC); as the nodal agency for investigation of outbreak. Integrated Disease Surveillance Programme (IDSP) through its community and hospital based data gathering mechanism would track clustering of acute febrile illness and seek primary case, if any, among those who travelled to areas with ongoing transmission in the 2 weeks preceding the onset of illness.
Ebola Virus
Ebola virus disease (EVD), formerly known as Ebola hemorrhagic fever, is a severe, often fatal illness in humans.
The virus is transmitted to people from wild animals and spreads in the human population through human-to-human transmission. Fruit bats of the Pteropodidae family are considered to be the natural host of the Ebola virus.
Ebola is introduced into the human population through close contact with the blood, secretions, organs or other bodily fluids of infected animals.
In Africa, infection has been noticed among those handling infected chimpanzees, gorillas, fruit bats, monkeys, forest antelope found ill or dead or in the rainforest. Ebola then spreads in the community through human-to-human transmission, with infection resulting from direct contact (through broken skin or mucous membranes) with the blood, secretions, organs or other bodily fluids of infected people, and indirect contact with environments contaminated with such fluids.
Health-care workers have frequently been infected while treating patients with suspected or confirmed EVD when infection control precautions are not strictly practiced.
Signs and symptoms:
EVD is a severe acute viral illness often characterized by the sudden onset of fever, intense weakness, muscle pain, headache and sore throat. This is followed by vomiting, diarrhoea, rash, impaired kidney and liver function, and in some cases, both internal and external bleeding. The incubation period, that is, the time interval from infection with the virus to onset of symptoms, is 2 to 21 days.
In the absence of effective treatment and a human vaccine, raising awareness of the risk factors for Ebola infection and the protective measures individuals can take is the only way to reduce human infection and death.
World Health Organisation (WHO) has approved the ReEBOV Antigen rapid test kit for Ebola virus disease (EVD).
Middle East Respiratory Syndrome virus
MERS stands for Middle East Respiratory Syndrome virus.
It was first seen in Saudi Arabia in 2012. It’s a coronavirus – a family of viruses that usually cause common colds and that can infect both animals and people. It’s a relative of SARS, the Severe Acute Respiratory Syndrome virus that swept around the world, infecting more than 8,000 people globally and killing 774 before it was stopped in 2004.
MERS can cause fever, cough, shortness of breath, diarrhea, body aches, nausea and, in the most serious cases, pneumonia and kidney failure, according to the U.S. Centers for Disease Control and Prevention. Its incubation period is usually 5 or 6 days, but people can be contagious for up to 14.
The virus kills by causing respiratory or kidney failure, or septic shock, an infection that overwhelms the body’s defenses.
The South Korean outbreak of MERS began in May 2015 when a traveler returned from Saudi Arabia, and infected many people before officials realized he had the disease. So far, around 180 people have been infected in South Korea, and nearly 30 have died.
Swine Flu
Swine flu (swine influenza) is a respiratory disease caused by viruses (influenza viruses) that infect the respiratory tract of pigs and result in nasal secretions, a barking cough, decreased appetite, and listless behaviour.
The virus spreads by tiny droplets that are released when a person coughs or sneezes. The droplets reach a distance of about one metre (3ft). These droplets remain suspended in the air for a short duration, and then settle on a surface. The virus suspended in airborne droplets can infect a person, if the person inhales the contaminated droplet.
Common objects such as door handles, remote control, hand rails and computer keyboards can get contaminated with the virus when the droplet settles on these surfaces. If a person touches these surfaces and places the contaminated hands on their mouth or nose he or she can get the infection.
They can spread it further by touching other things. If the droplets land on a hard surface the virus can survive for about 24 hours, and on a soft surface it survives for about 20 minutes.
• Symptoms of swine flu are similar to most influenza infections: fever (100 0F or greater), cough, nasal secretions, fatigue, and headache, with fatigue being reported in most infected individuals. Some patients also get nausea, vomiting, and diarrhea.
Some patients develop severe respiratory symptoms and need respiratory support (such as a ventilator to breathe for the patient). Patients can get pneumonia (bacterial secondary infection) if the viral infection persists, and some can develop seizures. Death often occurs from secondary bacterial infection of the lungs; appropriate antibiotics need to be used in these patients.
H1N1 swine flu virus is sensitive to the antiviral drugs Tamiflu and Relenza. These antiviral drugs are most effective when taken within 48 hours of the start of flu symptoms. It’s resistant to older flu drugs. A third antiviral drug, peramivir, can be used only in hospitalized patients with severe flu.
In 2015 the states of Gujarat and Rajasthan are the worst effected by Swine Flu.
