By Medifit Education.
Typhoid fever, also known as enteric fever, is a potentially fatal multisystemic illness caused primarily by Salmonella enterica, subspecies enterica serovar typhi and, to a lesser extent, related serovars paratyphi A, B, and C.
The protean manifestations of typhoid fever make this disease a true diagnostic challenge. The classic presentation includes fever, malaise, diffuse abdominal pain, and constipation. Untreated, typhoid fever is a grueling illness that may progress to delirium, obtundation, intestinal hemorrhage, bowel perforation, and death within 1 month of onset. Survivors may be left with long-term or permanent neuropsychiatric complications.
S typhi has been a major human pathogen for thousands of years, thriving in conditions of poor sanitation, crowding, and social chaos. It may have responsible for the Great Plague of Athens at the end of the Pelopennesian War. The name S typhi is derived from the ancient Greek typhos, an ethereal smoke or cloud that was believed to cause disease and madness. In the advanced stages of typhoid fever, the patient’s level of consciousness is truly clouded. Although antibiotics have markedly reduced the frequency of typhoid fever in the developed world, it remains endemic in developing countries.
S paratyphi causes the same syndrome but appears to be a relative newcomer. It may be taking over the typhi niche, in part, because of immunological naivete among the population and incomplete coverage by vaccines that target typhi.
Note that some writers refer to the typhoid and paratyphoid fever as distinct syndromes caused by the typhi versus paratyphi serovars, while others use the term typhoid fever for a disease caused by either one. We use the latter terminology. We refer to these serovars collectively as typhoidal salmonella.
Typhoid fever is a bacterial infection that can spread throughout the body, affecting many organs. Without prompt treatment, it can cause serious complications and can be fatal.
It is caused by a bacterium called Salmonella typhi, which is related to the bacteria that cause salmonella food poisoning.
Typhoid fever is highly contagious. An infected person can pass the bacteria out of their body in their stools (faeces) or, less commonly, in their urine.
If someone else eats food or drinks water that has been contaminated with a small amount of infected faeces or urine, they can become infected with the bacteria and develop typhoid fever.
TYPHOID AND PARATYPHOID ENTERIC FEVERS
Typhoid and paratyphoid fevers are infections caused by bacteria which are transmitted from faeces to ingestion. Clean water, hygiene and good sanitation prevent the spread of typhoid and paratyphoid. Contaminated water is one of the pathways of transmission of the disease.
THE DISEASE AND HOW IT AFFECTS PEOPLE
Typhoid fever is a bacterial infection of the intestinal tract and bloodstream. Symptoms can be mild or severe and include sustained fever as high as 39°-40° C, malaise, anorexia, headache, constipation or diarrhoea, rose-coloured spots on the chest area and enlarged spleen and liver. Most people show symptoms 1-3 weeks after exposure. Paratyphoid fever has similar symptoms to typhoid fever but is generally a milder disease.
Typhoid and paratyphoid fevers are caused by the bacteria Salmonella typhi and Salmonella paratyphi respectively. Typhoid and paratyphoid germs are passed in the faeces and urine of infected people. People become infected after eating food or drinking beverages that have been handled by a person who is infected or by drinking water that has been contaminated by sewage containing the bacteria. Once the bacteria enter the person’s body they multiply and spread from the intestines, into the bloodstream.
Even after recovery from typhoid or paratyphoid, a small number of individuals (called carriers) continue to carry the bacteria. These people can be a source of infection for others. The transmission of typhoid and paratyphoid in less-industrialized countries may be due to contaminated food or water. In some countries, shellfish taken from sewage-contaminated beds is an important route of infection. Where water quality is high, and chlorinated water piped into the house is widely available, transmission is more likely to occur via food contaminated by carriers handling food.
Typhoid and paratyphoid fevers are common in less-industrialized countries, principally owing to the problem of unsafe drinking-water, inadequate sewage disposal and flooding.
SCOPE OF THE PROBLEM
The annual incidence of typhoid is estimated to be about 17 million cases worldwide.
Public health interventions to prevent typhoid and paratyphoid include:
- health education about personal hygiene, especially regarding hand-washing after toilet use and before food preparation; provision of a safe water supply;
- proper sanitation systems;
- excluding disease carriers from food handling.
Control measures to combat typhoid include health education and antibiotic treatment. A vaccine is available, although it is not routinely recommended except for those who will have prolonged exposure to potentially contaminated food and water in high-risk areas. The vaccine does not provide full protection from infection.
Prepared for World Water Day 2001. Reviewed by staff and experts from the cluster on Communicable Diseases (CDS) and the Water, Sanitation and Health unit (WSH), World Health Organization (WHO).
Early symptoms include fever, general ill-feeling, and abdominal pain. High fever (103°F, or 39.5°C) or higher and severe diarrhea occur as the disease gets worse.
Some people with typhoid fever develop a rash called “rose spots,” which are small red spots on the abdomen and chest.
Other symptoms that occur include:
- Abdominal tenderness
- Bloody stools
- Difficulty paying attention (attention deficit)
- Fluctuating mood
- Severe fatigue
- Slow, sluggish, lethargic feeling
EXAMS AND TESTS
A complete blood count (CBC) will show a high number of white blood cells.
A blood culture during the first week of the fever can show S. typhi bacteria.
Other tests that can help diagnose this condition include:
- ELISA urine test to look for the bacteria that cause Typhoid fever
- Fluorescent antibody study to look for substances that are specific to Typhoid bacteria
- Platelet count (platelet count may be low)
- Stool culture
HOW IS TYPHOID FEVER TREATED?
Typhoid fever is treated with antibiotics which kill the Salmonella bacteria. Prior to the use of antibiotics, the fatality rate was 20%. Death occurred from overwhelming infection, pneumonia, intestinal bleeding, or intestinal perforation. With antibiotics and supportive care, mortality has been reduced to 1%-2%. With appropriate antibiotic therapy, there is usually improvement within one to two days and recovery within seven to 10 days.
Several antibiotics are effective for the treatment of typhoid fever. Chloramphenicol was the original drug of choice for many years. Because of rare serious side effects, chloramphenicol has been replaced by other effective antibiotics. The choice of antibiotics is guided by identifying the geographic region where the infection was contracted (certain strains from South America show a significant resistance to some antibiotics.) If relapses occur, patients are retreated with antibiotics.
Those who become chronically ill (about 3%-5% of those infected), can be treated with prolonged antibiotics. Often, removal of the gallbladder, the site of chronic infection, will provide a cure.
For those traveling to high-risk areas, vaccines are now available.
CHOOSING A VACCINE
Two main vaccines are available for typhoid fever in the UK:
- Vi vaccine – given as a single injection
- Ty21a vaccine – given as three capsules to take on alternate days
There are also combined typhoid and hepatitis A injections available for people aged 15 to 16 or older.
No vaccine offers 100% protection against typhoid fever, but the Vi vaccine is generally more effective than the Ty21a vaccine. However, some people prefer to have the Ty21a vaccine because it does not require an injection.
As the Ty21a vaccine contains a live sample of Salmonella typhi bacteria, it is not suitable for people who have a weakened immune system (the body’s natural defence against infection and illness), such as people with HIV. It is also not usually recommended for children under six, whereas children can have the Vi vaccine from two years of age.
Ideally, the typhoid vaccine should be given at least one month before you travel, but, if necessary, it can be given closer to your travel date.
Booster vaccinations are recommended every three years if you continue to be at risk of infection.
By Medifit Education.