Typhoid fever

Typhoid fever, also known as typhoid, is a common worldwide. Typhoid fever is an acute illness associated with fever. transmitted by the ingestion of food or water contaminated with the feces of an infected person, which contain the bacterium Salmonella enteric a. The bacteria then perforate through the intestinal wall and are phagocytes by macrophages. The bacterium grows best at 37°C / 98.6°F – human body temperature.

This fever received various names, such as gastric fever, abdominal typhus, infantile remittent fever, slow fever, nervous fever, pathogenic fever, etc. The name of "typhoid" comes from the neuropsychiatry symptoms common to typhoid and typhus (from Greek τῦϕος, "stupor").

The impact of this disease fell sharply with the application of modern sanitation techniques.

The incidence of typhoid fever in the United States has markedly decreased since the early 1900s. Today, approximately 400 cases are reported annually in the United States, mostly in people who recently have traveled to endemic areas. This is in comparison to the 1920s, when over 35,000 cases were reported in the U.S. This improvement is the result of improved environmental sanitation. Mexico and South America are the most common areas for U.S. citizens to contract typhoid fever. India, Pakistan, and Egypt are also known high-risk areas for developing this disease. Worldwide, typhoid fever affects more than 13 million people annually, with over 500,000 patients dying of the disease.

If traveling to endemic areas, you should consult with your health-care professional and discuss if you should receive vaccination for typhoid fever.

Prevention

1939 conceptual illustration showing various ways that typhoid bacteria can contaminate a water well (center)

Sanitation and hygiene are the critical measures that can be taken to prevent typhoid. Typhoid does not affect animals and therefore transmission is only from human to human. Typhoid can only spread in environments where human feces or urine are able to come into contact with food or drinking water. Careful food preparation and washing of hands are crucial to preventing typhoid.

There are two vaccines currently recommended by the World Health Organization for the prevention of typhoid these are the live, oral Ty21a vaccine (sold as Vivotif Berna) and the injectable Typhoid polysaccharide vaccine (sold as Typhim Vi by Sanofi Pasteur and Typherix by GlaxoSmithKline). Both are between 50% to 80% protective and are recommended for travelers to areas where typhoid is endemic.

Boosters are recommended every 5 years for the oral vaccine and every 2 years for the inject able form. There exists an older killed whole-cell vaccine that is still used in countries where the newer preparations are not available, but this vaccine is no longer recommended for use, because it has a higher rate of side effects.

Treatment

The rediscovery of oral dehydration therapy in the 1960s provided a simple way to prevent many of the deaths of diarrhea diseases in general.
Where resistance is uncommon, the treatment of choice is such as ciprofloxacin otherwise, a third-generation cephalosporin such as ceftriaxone or cefotaximeis the first choice. Cefixime is a suitable oral alternative.

Typhoid fever in most cases is not fatal. Antibiotics, such as ampicillin, chloramphenicol,trimethoprim-sulfamethoxazole, amoxicillin and ciprofloxacin, have been commonly used to treat typhoid fever in developed countries. Prompt treatment of the disease with antibiotics reduces the case-fatality rate to approximately 1%.

When untreated, typhoid fever persists for three weeks to a month. Death occurs in between 10% and 30% of untreated cases. In some communities, however, case-fatality rates may reach as high as 47%.

Resistance

Resistance to ampicillin, chloramphenicol, trimethoprim-sulfamethoxazole and streptomycin is now common, and these agents have not been used as first line treatment now for almost 20 years. Typhoid that is resistant to these agents is known as multi drug-resistant typhoid (MDR typhoid).

Ciprofloxacin resistance is an increasing problem, especially in the Indian subcontinent and Southeast Asia. Many centers are therefore moving away from using ciprofloxacin as first line for treating suspected typhoid originating in South America, India, Pakistan, Bangladesh, Thailand or Vietnam. For these patients, the recommended first line treatment is ceftriaxone. It has also been suggested azithromycin is better at treating typhoid in resistant populations than both fluoroquinolone drugs and ceftriaxone. Azithromycin significantly reduces relapse rates compared with ceftriaxone.

There is a separate problem with laboratory testing for reduced susceptibility to ciprofloxacin: current recommendations are that isolates should be tested simultaneously against ciprofloxacin (CIP) and against nalidixic acid (NAL), and that isolates that are sensitive to both CIP and NAL should be reported as "sensitive to ciprofloxacin", but that isolates testing sensitive to CIP but not to NAL should be reported as "reduced sensitivity to ciprofloxacin". However, an analysis of 271 isolates showed that around 18% of isolates with a reduced susceptibility to ciprofloxacin (MIC 0.125–1.0 mg/l) would not be picked up by this method. It is not certain how this problem can be solved, because most laboratories around the world (including the West) are dependent on disk testing and cannot test for MICs.