HUMAN DISEASES: TYPHOID (ENTERIC FEVER)

· Enteric fever includes both typhoid and paratyphoid fever.
· Typhoid is a foodborne disease of the intestine.
· The word typhoid is derived from the typhus meaning cloud or reference to delirium.
· Marry Mallon nicknamed Typhoid Mary (1906AD) was a historical chronic carrier of typhoid. She was a cook by profession and was a typhoid carrier who continued to spread typhoid for several years through the food she prepared.


Distribution (Occurrence)
· It is worldwide in distribution (cosmopolitan) and most common in such areas having poor sanitation, contaminated drinking water.
· Nowadays, typhoid is very common in developing and underdeveloped countries including Nepal but rare in developed countries.


Causative Organism or Pathogen
· Bacteria Salmonella typhi and Salmonella paratyphi A and B are rod-shaped, motile, gram-negative bacteria measuring about 1-3 ┬Ám in length.
· The movement of bacterium is by the help of flagella.
· It lives in the intestines of human beings.
· Paratyphoid fever is caused by Salmonella paratyphi A and B.
· Symptoms are less severe than typhoid, the individual becomes an asymptomatic carrier, excreting the microbes in urine and faeces.
· Other two species of Salmonella are Salmonella typhimurium and Salmonella enteridis.


Sources or Reservoir of Infection
· Urine and stool of the infected person and contaminated food, vegetables, water etc. by Salmonella typhi.


Mode of Infection or Transmission
· Through contaminated food, water, milk, raw fruits and vegetables.
· Sometimes flies also serve as vectors to transmit the bacteria from contaminated food and vegetables.
· In the carrier stage, Salmonella lives in the gall bladder or cystic duct or biliary tract.
· It is transmitted by five Fs- flies, food, fingers, faeces and fomites (dish or article contaminated with infectious organisms).


Incubation Period
· It is the time period between the infection by bacteria and appearance of first symptoms which is variable, usually 10-14 days (average 2 weeks).
· During the incubation period, microbes invade the payer’s patches and then enter the blood vessels and spread to the liver, spleen and gall bladder.


Symptoms
1) Constant or enteric high fever that lasts for 1-3 weeks.
2) Malaise (weakness and fatigue), headache, anorexia (loss of appetite), cough, sore throat, constipation, sometimes diarrhoea
3) Enlargement of the spleen (Splenomegaly), abdominal distension, bradycardia (slow heartbeat rate, about 50 times/minute), affects Peyer's patches of ileum so causes ulceration of overlying mucosa of Peyer's patches.
4) Intestinal lesions, haemorrhage, ulceration, pneumonia, bone and joint pain. Gall bladder infection is seen at the end of 2nd week.
5) Red spots on the skin of the chest and upper abdomen.
6) Liver and kidney damage
7) Typhoid Cholecystisis: in which microbes multiply in the gall bladder and are excreted in bile, reinfecting the intestine
8) Reduced resistance to other infections, especially of the respiratory tract, Example: Laryngitis, Bronchitis, Pneumonia etc
9) Delirium- A mental state in which we are confused and not able to think or speak clearly because of fever or some other illness


Diagnosis
· Serological test (Widal test) of blood and urine and stool culture from the infected person.
Also, Remember: BASU
B- Blood culture (First week)
A- Antigen-antibody test (Second week)
S- Stool test (Third week)

U- Urine culture (Fourth week)


Treatment

· Antibiotics like Chloramphenicol and Ampicillin were used before but nowadays Ciprofloxacin is a drug of choice.
· Alternative drugs are Cotrimoxazole, Amoxycillin, Bumoxycilin etc.
· The patient needs rest and a nutritious diet.


Prophylaxis (Prevention)
1. Proper sanitation in surroundings, water sources, toilet, bathroom, kitchen (environmental sanitation).
2. Sanitary disposal of human excreta and avoid defecation in the open field, nearby sources of water etc.
3. Protection, purification, filtration and chlorination of public water supply.
4. Protection of food, milk, vegetables from contamination. Faecal carriers are more common than urinary.
5.  Control of flies by insecticides.
6. Proper washing of raw fruits and vegetables before eating.
7. Public awareness or health education.
8. Immunization by typhoid vaccine (TAB i. e. Typhoid and Paratyphoid A and B) which provides immunity for 1-3 years.
9. One should take care of four Fs- Food, fly, filth (dirt) and faeces.


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