Typhoid fever is a life threatening illness caused by the bacterium salmonella thyphi. It affects about 21.5 million persons each year in developing countries like ours and causes about 3 million death/year in this part of the world. It occurs all year round especially in the rural part of these countries.
HOW DO PATIENTS GET TYPHOID
Typhoid fever is contracted by the ingestion of the bacteria in contaminated food or water. Patients with acute illness can contaminate the surrounding water supply through stool, which contain a high concentration of the bacteria. Contamination of the water supply can in turn taint the food supply. About 3-5% of patients become carriers of the bacteria after the acute illness. Some patients suiffer a very mild illness that goes unrecognized. Those patients can become long term carriers of the bacteria. The bacterium multiplies in the gall bladder, bile duct or liver and passes into the bowel. The bacteria can survive for weeks in water or dried sewage. The chronic carriers may have no symptoms and can be the source of the new outbreak of typhoid fever for many years.
HOW DOES THE BACTERIA CAUSE DISEASE
After the ingestion of contaminated food or water, the salmonella bacteria invade the small intestine and enter the blood stream temporary. The bacteria are carried by the white blood cells in the liver, spleen and bone marrow. The bacteria then multiply in the cells of these organs and re-enter the blood stream. The bacteria invade the gall bladder, biliary system and the lymphatic tissue of the bowel. Here, they multiply in high number.
WHAT ARE THE SYMPTOMS OF TYPHOID FEVER?
The incubation period is usually one to two weeks and the duration of the illness is about six weeks. The patient experiences poor appetite, headache, generalized aches and pains, fever, lethargy and diarrhea. People with typhoid fever usually have a sustained fever as high as 39-C. Chest congestion develops in many patients and abdominal pain and discomfort are common. The fever becomes constant. Improvement occurs in the third and four week in those without complication. About 10% of patients have recurrent symptoms or relapse after feeling better for one to two weeks. Relapses are more common in individuals treated with antibiotics.
HOW DOES TYPHOID FEVER SPREAD?
Salmonella thyphi lives only in humans. Persons with typhoid fever carry the bacteria in their bloodstream and intestinal tract. In addition, a small number of persons called carriers recover from the illness but continue to carry the bacteria. Both ill persons and carriers shed salmonella typhi in their faeces (stool). Typhoid fever is contracted and spread if a food or drink beverage that have been handled by a person that is shedding S. Typhi is consumed or if sewage contaminated with the bacteria gets into the water used for drinking or washing food. Therefore, typhoid fever is more common in areas of the world where hand washing is less frequent and water is likely to be contaminated with sewage. Once S. typhoid bacteria are ingested, they multiply and spread into the blood stream. The body react with fever and other signs and symptoms.
Specimens for the isolation of Salmonella Typhi include blood, faeces, urine, vomit, joint aspirates. Faeces is one of the common specimen requested for the isolation of salmonella typhi.
The organism is present in the faeces in large numbers only during the secondary entry into the intestine. This is about the second week of infection. The isolation of the organisms from faeces is not as valuable as blood culture in diagnosis. This because the organism can be recovered in the faeces of carriers.
Widal test is the most widely used serological test for salmonella which measure the O and H antibodies in typhoid in patient’s Sera. In this test, known antigens are used against unknown antibodies in the patient serum. It is a confirmatory test for salmonellosis.
HOW CAN TYPHOID FEVER BE AVOIDED?
Two basic actions can prevent you from typhoid fever which includes avoiding risky foods, drinks and vaccination against typhoid fever. Watching what you eat and drink when you travel is as important as being vaccinated. This is because the vaccines are not completely effective. It also gives protection against diarrhea, cholera, dysentery and hepatitis A. Ensure that wells are not sited near sewage containers. Also peel, boil and cook food before eating.
Typhoid fever is treated with antibiotics which kill the salmonella bacteria. Prior to the use of antibiotics, the fatality rate was 20%. With antibiotics and supportive care, mortality has been reduced to 1-2%. With appropriate antibiotic therapy, there is usually improvement within one or two days.