1. Typhoid fever Widal test
Microbiology labratory
Typhoid fever Widal test
Infectious
Disease

2. Definition
An infectious feverish disease caused by the bacterium Salmonella typhi(Salmonella enterica Serovar Typhi ) and less commonly by Salmonella paratyphi.
Acute generalized infection of the
reticulo endothelial system,
intestinal lymphoid tissue, and the gall bladder.
The infection always comes from another human, either an ill person or a healthy carrier of the bacterium. The bacterium is passed on with water and foods and can withstand both drying and refrigeration.

3. Causes 1. Caused by the bacterium Salmonella Typhi .
2. Ingestion of contaminated food or water.
3. Contact with an acute case of typhoid fever.
4. Water is contaminated where inadequate sewerage systems and poor sanitation.
6. Eating food or drinking beverages that handled by a person carrying the bacteria.
7. Salmonella enteriditis and Salmonella typhimurium are other salmonella bacteria,
cause food poisoning and diarrhoea.

4. Salmonella Entrica Member of the genus Salmonella.
Rod shaped, flagellated, aerobic,
Gram negative bacterium.
Large number of fimbrial and non-fimbrial adhesins
are present, mediate biofilm formation and contact to host cells.
Secreted proteins involved in host cell invasion and intracellular proliferation.
Infects cattle, poultry, domestic cats, hamsters, humans etc.
Pasteurizing and food irradiation kill Salmonella for commercially-produced foodstuffs containing raw eggs such as ice cream.
Foods prepared in the home from raw eggs can spread salmonella if not properly cooked before consumption.

5. The organisms causing enteric fever possesses two major antigens namely somatic antigen (O) and a flagellar antigen (H) along with another surface antigen, Vi. During infection with typhoid or paratyphoid bacilli, antibodies against flagellar antigen of S. typhi (H), S. paratyphi A (AH), S. paratyphi B (BH) and Somatic Antigen of S.typhi (O) usually become detectable in blood, 6 days after the onset of infection.

6. Ingestion of contaminated food or water
Salmonella bacteria
Invade small intestine and enter the bloodstream
Carried by white blood cells in the liver, spleen, and bone marrow
Multiply and reenter the bloodstream

7. Bacteria invade the gallbladder, biliary system, and the lymphatic tissue of the bowel and multiply in high numbers
Then pass into the intestinal tract and can be identified for diagnosis in cultures from the stool tested in the laboratory

8. Symptoms
No symptoms - if only a mild exposure; some people become "carriers" of typhoid.
Poor appetite,
Headaches,
Generalized aches and pains,
Fever, Lethargy (Lethargy is a state of tiredness, weariness, fatigue, or lack of energy. It can be accompanied by depression, decreased motivation, or apathy
Diarrhea,
Have a sustained fever as high as 103 to 104 degrees Fahrenheit (39 to 40 degrees Celsius),
Chest congestion develops in many patients, and abdominal pain and discomfort are common,
Constipation, mild vomiting, slow heartbeat.

9. Aches and pains Rose spots High fever Diarrhea Chest congestion
Typhoid Meningitis

10. Time frame
Occurs gradually over a few weeks after exposure to the bacteria. Sometimes children suddenly become sick.
The condition may last for weeks or even a month or longer without treatment.
First-Stage Typhoid Fever
The beginning stage is characterized by high fever,fatigue, weakness, headache, sore throat, diarrhea, constipation, stomach pain and a skin rash on the chest and abdominal area. According to the Mayo Clinic, adults are most likely to experience constipation, while children usually experience diarrhea.

11. Second stage Typhoid State
Second-stage typhoid fever is characterized by weight loss, high fever, severe diarrhea and severe constipation. Also, the abdominal region may appear severely distended.
Typhoid State
When typhoid fever continues untreated for more than two or three weeks, the effected individual may be unable to stand and move, and the eyes may be partially open during this time. At this point fatal complications may emerge.

12. Diagnosis Blood, bone marrow, or stool cultures test Widal test
Diagnosis of typhoid fever is made by
Blood, bone marrow, or stool cultures test
Widal test

13. Prevention Two main typhoid fever prevention strategies:
1. Vaccination
First type of vaccine:
Contains killed Salmonella typhi bacteria.
Administered by a shot.
Second type of vaccine:
Contains a live but weakened strain of the Salmonella bacteria that causes typhoid fever.
Taken by mouth. 

14. Medication Antibiotics
Antibiotics, such as ampicillin, chloramphenicol Amoxicillin ..etc used to treat typhoid fever.

15. Serology
Serology: the study of blood serum, with emphasis on testing of antibodies in the serum
Antigen: A substance which stimulates the body to produce antibody; usually a ‘foreign’ substance
Antibody: A protein molecule produced by the body’s immune system in response to a specific antigen. The antibody combines with the antigen and disables it.
Also called Immunoglobulins (e.g. IgG, IgM, IgA, IgE)
Referred to as anti-(name of antigen), e.g. anti-HCV, anti-HAV

16. Widal test
" A test involving agglutination of typhoid bacilli when they are
mixed with serum containing typhoid antibodies from an
individual having typhoid fever; used to detect the presence
of Salmonella typhi and S. paratyphi."

17. Procedure :
Bring all reagents to room temperature and mix well.
Add 1 drop of test sample (25µl) into each reaction circle labeled as O, H, AH, BH according to given antigen solution.
Add 1 drop of positive control (25µl) into the circle marked as PC and 1 drop of negative control (25µl) into the reaction circle marked as NC.
Add antigen solutions of Salmonella typhi ‘O’, Salmonella typhi ‘H’, Salmonella paratyphi ‘AH’ and Salmonella paratyphi ‘BH’ to circles labeled as O, H, AH, BH respectively in which test samples has been added.
Mix it thoroughly with the aid of applicator stick and rotate the slide gently.
Observe for agglutination.