Common Infectious diseases

 

ABOUT COMMON INFECTIOUS DISEASES ……………

Infectious diseases are known as communicable diseases. These diseases are passed on from one person to another that is they are transmitted and are thus said to be infectious, contagious, communicable or transmissible. Diseases that are caused by bacteria, viruses and fungi are commonly referred to as infectious diseases. These are transmitted by way of droplets of liquid (small drops of liquid extruding from sneezing or coughing) in the air, food or water, by sexual intercourse or simply by touching.

Infectious diseases are those caused by other living organisms which invade the body and live parasitically. The following technical terms are of use when discussing infectious diseases.

Causative agent: The organism that causes the disease. 

Source of infection: How the infection occurs.

Incubation period: The period between the original infection and the appearance of signs and symptoms.

Infective period: the time during which a person is capable of passing the disease on to another person.

Carrier: A person who has been infected but develops no symptoms, the carrier can pass disease into another person.

Notifiable disease: A disease that must be reported by doctors to the health authorities due to its seriousness. (E.g. cholera, T.B., polio)

Epidemic: Situation in which a disease spreads rapidly through a large number of people and later disappears again.

Pandemic: an epidemic that spreads across the whole continent.

Endemic describes a disease that is always present at a low level in a given population.

Signs: Visible expression of the disease which can be found by examining a patient. E.g. a rash or a high temperature

Symptoms: An indication of a disease that is not detectable by examination and can only be reported by the patient. E.g. headache, nausea.

Prevention: Measures taken to prevent a person from getting a disease E.g. vaccination, sewage treatment, hygiene.

Treatment: Measures taken to cure a disease

In Sri Lanka, some infectious diseases cause epidemics from time to time. These epidemic diseases are cholera, typhoid, tuberculosis, diphtheria, measles, mumps, poliomyelitis, and hepatitis B. Some of the above diseases such as cholera, typhoid, diphtheria, tetanus and tuberculosis are caused by bacteria. Other diseases such as measles, mumps, poliomyelitis and hepatitis B are caused by a virus.

Cholera is one of the diseases which spread easily in a population and then disappear. Therefore it is an epidemic disease. Actually, it is one of the major five epidemic diseases in the world. The causative agent is Vibrio cholera which is a comma-shaped motile bacterium. The Source of infection is the water contaminated with the faeces of a sufferer or a carrier. A carrier is an individual infected with Vibrio cholera who does not develop typical symptoms of cholera.

It is estimated that only about one infected person in 50 develops the disease, the rest being carriers. Thus the faeces containing Vibrio are a considerable threat when the carriers are free moving in society.

The most common ways of transmission are drinking or washing food or utensils with contaminated water.  Direct contamination of food with faeces as a result of poor hygiene is possible. Once enter the intestine the bacteria multiply after 4 or 4 and 1/2 hours and release a powerful toxin. This will result in violent inflammation of the intestine and the production of watery diarrhoea. World Health Organization in Geneva should be informed to take international action to prevent the spreading of the disease. This can be done by restricting travel into or out of the affected area.

Signs and symptoms of the disease: No fever. The main sign is severe diarrhoea due to irritation of the bowel by toxins from the Vibrio. The liquid of the faeces is so profuse and cloudy that is called “rice-water”. Abdominal pain and vomiting also will be common symptoms among the patients. Skin is deathly cold and damp. Muscle cramps also may develop due to loss of minerals through diarrhoea.

Dehydration is rapid and quickly results in death unless rehydration treatment is given. The prime cause of death is the loss of minerals with its water.

Treatment: should be admitted to a hospital. Cheap and immediate therapy can be done by giving oral rehydration solutions like JEEVANI. Various antibiotics like Chloramphenicol and tetra cycling are effective at destroying the Vibrio.

Prevention and control:

 

• Provision of clean drinking water

 

• Proper sewage disposal methods

 

• High stand of personal hygiene

 

• Health education

 

• Control of flies which act as vectors in transferring the faecal matter to food.

 

• Isolation of patients and hygienic disposal of faeces and vomit from patients.

 

• Identification of carriers and prevention of their working in the food industry.

 

• Immediate examination of diarrhoea diseases for bacterial content.

 

• People in the area should be vaccinated.

 

Typhoid fever: An epidemic disease. The causative agent is a bacterium named

Salmonella typhi.

Source of infection: The bacteria are derived from the faeces of a sufferer from the disease or from a carrier. The disease is spread by water or from contaminated food. Typhoid spread needs only a small number of organisms. That means it has a high infectious rate. Water supplies may be contaminated by human faeces through seepage of sewage into a reservoir. Salmonella can live for about one week in sewage or longer in water that has been diluted with sewage. Food can be contaminated by a carrier or from dirty equipment which has been washed with contaminated water

Incubation period:  When the infecting organisms have been swallowed they migrate to the lymph glands, where they multiply during a 10 day incubation period. Then they enter the bloodstream. Now the patient develops signs like headache and muscular pain. A fever develops reaching its peak after about one week. A paint rash may appear. In the 2^nd week, diarrhoea develops and the patient may have mental confusion. If not treated at the end ulceration and rupturing of the intestine occur. The 3^rd week shows the peak of the illness and the patient deteriorates and may die.

Diagnosis: Blood samples will confirm, after culturing, the presence of antibodies against

Salmonella typhi

Treatment: Chloramphenicol and ampicillin are effective.

Prevention:

·         Patients should be isolated and hygienic disposal of faeces. Sewage disposal should be done properly.

·         Purification of water supplies should be done. Hygienic measures in the food trade and in the home.

·         Control of flies which can be transferred the faecal matter to food.

Diphtheria: An epidemic disease. The causative agent is a rod-shaped bacteria which is known as Corynebacterium diphtheriae and controlled by vaccination at the age of.

Method of infection: Droplet infection through the respiratory system. Bacteria grow on the moist mucous membrane of the upper part of the respiratory tract release toxins. The toxin is spread by blood to all parts of the body.

Symptoms and signs: Slight fever, sore throat, followed by severe damage to heart, nerve cells and adrenal glands.

Prevention:  Vaccination should be given to all children at the age of

Tuberculosis is also an infectious disease that can be seen from time to time in Sri Lanka. The causative agent of this disease is a fungal-like bacterium called Mycobacterium tuberculosis.  (Tubercle bacilli) .This is a rod-shaped bacterium and can be found in the air. Therefore tuberculosis is an airborne disease.

 

Source of infection: Transmission is by inhaling the bacteria into the lungs (droplet infection). It is much less infectious than the common cold and required prolonged contact between people to get the disease. Therefore this is associated with overcrowded living conditions, poor ventilation etc. It is a common disease and can be found in refugee camps, military camps and dormitories. Bacteria can resist drying out and can survive in the air and in the house dust for a longer period. Malnutrition and other infections resulting in a weakened immune system can reduce the resistance to the disease.

The outcome of infection by tubercle bacilli depends on a variety of factors.

 

·         Age of person

 

·         State of nutrition

 

·         Presence or absence of the immunity. (Immunity can be obtained by

 

      vaccination or previous mild infection)

 

Symptoms and signs: The disease starts as inflammation in one lung which develops into a cavity. Then further, cavities may develop, spreading into both lungs. As progressive destruction of the lung occur the symptoms become more dramatic with coughing, the appearance of blood in the sputum, chest pains, shortness of breath, fever, poor appetite and weight loss. The disease consumes the body causing it to waste away.

Treatment and prevention: To prevent the disease a vaccine had introduced by two French scientists named Albert Chalmette and Camille Guerin. So the vaccine has been named after them as BCG. (Bacilli Chalmette Guerin) This Vaccine should be given in the first week of birth. To treat the disease antibiotic Streptomycin can be used. The full course of treatment lasts 6-8 months and requires the consumption of several tablets a day, every day. This gives the combination of at least three or four antibiotics to reduce the chance of a strain multiplying that is resistant to one of the antibiotics. Some patients feel well after a few weeks of treatment so they stop getting treatments. After some time they will get the disease again. Therefore World   Health Organization launched Directly Observed Treatment under Supervision campaigns. With these programmes, the patient is given pills under supervision and watched each time to check the pills are swallowed. This is done over 6 to 8 months.

Measles: This is also a viral disease and Sinhalese think that this has the influence of God. So, they consider the patient as a holy person. They keep the place very clean where the patient is staying and the things he uses. They keep the patient separate from others. They spread Khomba leaves on the patient’s bed. (Actually, these khomba leaves have a germicidal effect.) As this disease is an air-borne disease and the virus enter through the respiratory tract it is rapidly spread from one person to the other. Therefore these habits are very important in controlling the disease.

Symptoms and signs: High fever 104- 105, reddened eyes, dry cough, sore throat, runny nose, watery eyes, cough. After2 or 3 days small white spots koplik’s spots appear inside the mouth on the wall of the cheek. On the 4^th day, the reddish rash will appear on the face then it is spread to the neck and chest. After 3 or 4 days these patches become brown and then the skin will peal out. Recovery will occur after one week. Sometimes viruses may damage kidneys and the brain.

Spreading of the disease: When a patient with the disease sneeze or coughs droplets that contain millions of viruses will be mixed with the air. Then this virus can enter the respiratory tract of another person. This type of infection is called “droplet infection

Prevention and treatment: Patients should be isolated from others. The people who nurse the patients should have to think much about their personal hygiene. They can use a mask to cover the respiratory tract and should keep their hands clean. No special treatment as the disease is a viral disease. Patients should be given more liquid food and if they are coughing medicine should be given. There is a vaccine to prevent the disease. Vaccination should be done at the age of 9 months. With one dose of vaccine one can get immunity for the whole lifetime. A child who did not get the vaccination may get the disease at any age.

Mumps: This is also an airborne viral disease and easily spread from one person to another. Entering the virus into the body occurs via the respiratory system. Parotid glands which are a type of salivary gland are affected by the virus.

Symptoms and signs:

Due to the viral activity parotid glands may be swollen up. Therefore patients feel difficulties in swallowing. Soreness of the throat, mild fever, loss of appetite, body pains may be occurring. Symptoms may last after 10 days. Sometimes viruses will affect the function of the organs brain, pancreas, thyroid, testes and kidneys. The inflammation of the testes after puberty may cause sterility

Prevention and treatment: MMR vaccination. This stands for three diseases are Measles Mumps and Rubella. Children should be vaccinated after 1 and ½ years of age.

Poliomyelitis: Causative agent is poliovirus. Infection is done by droplet infection or via human faeces.

Signs and symptoms: Fever, headache, and feeling of stiffness in the neck and other muscles. Nerve cells to muscles will

Destroy causing paralysis and muscle wasting. Most cases of paralysis occur in children aged 4-12 years but adults may also be affected by the disease.

Hepatitis A:

A causative agent is a virus. Water and food contaminated with the faeces of a patient will cause the disease 

Signs and symptoms: Loss of appetite, vomiting, mild fever. After 3 or 4 days eyes will become yellow colour. After 2 weeks liver may be enlarged. Sometimes liver may be damaged.

Infective period: For two weeks from the beginning of the disease.

Prevention: Personal hygiene should be improved. Food preparation should be done hygienically. Carriers should be avoided in food preparation.

                Now we can see that most of the above diseases can be prevented by following good hygienic habits. Waterborne diseases can be prevented by drinking boiled water. Water should be kept at the boiling point at least for 15 minutes. When breakout of diseases occur strict care have to be taken about the food you eat and drink. Eating from outside will increase the chance of spreading the disease because most of the outside food sellers do not follow hygienic methods in preparing food. Once, a cooking woman of a hotel who had suffered from typhoid fever earlier had caused to spread the disease for hundreds of people because she had acted as a carrier of the disease. Airborne diseases are rapidly spread because we can’t take any measures to keep out of the germs (causative agents). If a person who has such a disease should avoid mixing with other people even in their homes also they should be kept isolated. Especially, school children who are suffered from measles, mumps and chickenpox will help to spread the disease easily throughout a large area.