Typhoid fever, also known simply as typhoid,[1] is a common worldwide bacterial disease transmitted by the ingestion of food or water contaminated with the feces of an infected person, which contain the bacterium Salmonella enterica enterica, serovar Typhi.[2]
The disease has received various names, such as gastric fever, abdominal typhus, infantile remittant fever, slow fever, nervous fever and pythogenic fever. The name typhoid means "resembling typhus" and comes from the neuropsychiatric symptoms common to typhoid and typhus.[3] Despite this similarity of their names, typhoid fever and typhus are distinct diseases and are caused by different species of bacteria.[4]
The impact of this disease fell sharply in the developed world with the application of 20th-century sanitation techniques.[citation needed]
In the first week, the temperature rises slowly, and fever fluctuations are seen with relative bradycardia, malaise, headache, and cough. A bloody nose (epistaxis) is seen in a quarter of cases, and abdominal pain is also possible. There is a decrease in the number of circulating white blood cells (leukopenia) with eosinopenia and relative lymphocytosis; blood cultures are positive for Salmonella typhi or paratyphi. The Widal test is negative in the first week.[citation needed]
In the second week of the infection, the patient lies prostrate with high fever in plateau around 40 °C (104 °F) and bradycardia (sphygmothermic dissociation or Faget sign), classically with a dicrotic pulse wave. Delirium is frequent, frequently calm, but sometimes agitated. This delirium gives to typhoid the nickname of "nervous fever". Rose spots appear on the lower chest and abdomen in around a third of patients. There are rhonchi in lung bases. The abdomen is distended and painful in the right lower quadrant, where borborygmi can be heard. Diarrhea can occur in this stage: six to eight stools in a day, green, comparable to pea soup, with a characteristic smell. However, constipation is also frequent. The spleen and liver are enlarged (hepatosplenomegaly) and tender, and there is elevation of liver transaminases. The Widal test is strongly positive, with antiO and antiH antibodies. Blood cultures are sometimes still positive at this stage. (The major symptom of this fever is that the fever usually rises in the afternoon up to the first and second week.)
In the third week of typhoid fever, a number of complications can occur:
By the end of third week, the fever starts subsiding (defervescence). This carries on into the fourth and final week.
The Widal test is time-consuming, and often, when a diagnosis is reached, it is too late to start an antibiotic regimen.
The term enteric fever is a collective term that refers to typhoid and paratyphoid.[8]
There are two vaccines licensed for use for the prevention of typhoid:[9] 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 50% to 80% protective and are recommended for travellers to areas where typhoid is endemic. Boosters are recommended every five years for the oral vaccine and every two years for the injectable 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 (mainly pain and inflammation at the site of the injection).[9]
Where resistance is uncommon, the treatment of choice is a fluoroquinolone such as ciprofloxacin.[8][10] Otherwise, a third-generation cephalosporin such as ceftriaxone or cefotaxime is the first choice.[11][12][13] Cefixime is a suitable oral alternative.[14][15]
Typhoid fever, when properly treated, is not fatal in most cases. Antibiotics, such as ampicillin, chloramphenicol, trimethoprim-sulfamethoxazole, amoxicillin and ciprofloxacin, have been commonly used to treat typhoid fever in microbiology (Baron S et al.). Treatment of the disease with antibiotics reduces the case-fatality rate to approximately 1%.[16]
When untreated, typhoid fever persists for three weeks to a month. Death occurs in between 10% and 30% of untreated cases.[17] In some communities, however, case-fatality rates may reach as high as 47%.[citation needed]
If antibiotic treatment fails to eradicate the hepatobiliary carriage, the gallbladder should be resected. Cholecystectomy is not always successful in eradicating the carrier state because of persisting hepatic infection.
Ciprofloxacin resistance is an increasing problem, especially in the Indian subcontinent and Southeast Asia. Many centres are therefore moving away from using ciprofloxacin as the 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 that azithromycin is better at treating typhoid in resistant populations than both fluoroquinolone drugs and ceftriaxone.[10] 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.[18] 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.
The disease has received various names, such as gastric fever, abdominal typhus, infantile remittant fever, slow fever, nervous fever and pythogenic fever. The name typhoid means "resembling typhus" and comes from the neuropsychiatric symptoms common to typhoid and typhus.[3] Despite this similarity of their names, typhoid fever and typhus are distinct diseases and are caused by different species of bacteria.[4]
The impact of this disease fell sharply in the developed world with the application of 20th-century sanitation techniques.[citation needed]
Signs and symptoms
Classically, the course of untreated typhoid fever is divided into four individual stages, each lasting approximately one week. Over the course of these stages, the patient becomes exhausted and emaciated.[5]In the first week, the temperature rises slowly, and fever fluctuations are seen with relative bradycardia, malaise, headache, and cough. A bloody nose (epistaxis) is seen in a quarter of cases, and abdominal pain is also possible. There is a decrease in the number of circulating white blood cells (leukopenia) with eosinopenia and relative lymphocytosis; blood cultures are positive for Salmonella typhi or paratyphi. The Widal test is negative in the first week.[citation needed]
In the second week of the infection, the patient lies prostrate with high fever in plateau around 40 °C (104 °F) and bradycardia (sphygmothermic dissociation or Faget sign), classically with a dicrotic pulse wave. Delirium is frequent, frequently calm, but sometimes agitated. This delirium gives to typhoid the nickname of "nervous fever". Rose spots appear on the lower chest and abdomen in around a third of patients. There are rhonchi in lung bases. The abdomen is distended and painful in the right lower quadrant, where borborygmi can be heard. Diarrhea can occur in this stage: six to eight stools in a day, green, comparable to pea soup, with a characteristic smell. However, constipation is also frequent. The spleen and liver are enlarged (hepatosplenomegaly) and tender, and there is elevation of liver transaminases. The Widal test is strongly positive, with antiO and antiH antibodies. Blood cultures are sometimes still positive at this stage. (The major symptom of this fever is that the fever usually rises in the afternoon up to the first and second week.)
In the third week of typhoid fever, a number of complications can occur:
- Intestinal hemorrhage due to bleeding in congested Peyer's patches; this can be very serious but is usually not fatal.
- Intestinal perforation in the distal ileum: this is a very serious complication and is frequently fatal. It may occur without alarming symptoms until septicaemia or diffuse peritonitis sets in.
- Encephalitis
- Neuropsychiatric symptoms (described as "muttering delirium" or "coma vigil"), with picking at bedclothes or imaginary objects.
- Metastatic abscesses, cholecystitis, endocarditis and osteitis
By the end of third week, the fever starts subsiding (defervescence). This carries on into the fourth and final week.
Transmission
The bacterium that causes typhoid fever may be spread through poor
hygiene habits and public sanitation conditions, and sometimes also by
flying insects feeding on feces. Public education campaigns encouraging
people to wash their hands after defecating and before handling food are
an important component in controlling spread of the disease. According
to statistics from the United States Centers for Disease Control and Prevention (CDC), the chlorination of drinking water has led to dramatic decreases in the transmission of typhoid fever in the U.S.A.
Cystic fibrosis
It has been hypothesized that cystic fibrosis may have risen to its present levels (1 in 2,500 in the UK) due to the heterozygous advantage that it confers against typhoid fever.[6] The CFTR protein
is present in both the lungs and the intestinal epithelium, and the
mutant cystic fibrosis form of the CFTR protein prevents entry of the
typhoid bacterium into the body through the intestinal epithelium.
However, the heterozygous advantage hypothesis was proposed in one
review in which the author himself writes, "Although cellular/molecular
evidence presently is not available for this hypothesis, the CF mutation
may be one of several mutations that have spread in European
populations because they increased resistance to infectious diseases."
Since no molecular experimental evidence has been presented in support
of this theory, this theory is not accepted by the majority of the
scientific community.
Diagnosis
Diagnosis is made by any blood, bone marrow or stool cultures and with the Widal test (demonstration of salmonella antibodies against antigens O-somatic and H-flagellar). In epidemics and less wealthy countries, after excluding malaria, dysentery or pneumonia, a therapeutic trial time with chloramphenicol is generally undertaken while awaiting the results of the Widal test and cultures of the blood and stool.[7]The Widal test is time-consuming, and often, when a diagnosis is reached, it is too late to start an antibiotic regimen.
The term enteric fever is a collective term that refers to typhoid and paratyphoid.[8]
Prevention
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 prevent typhoid.There are two vaccines licensed for use for the prevention of typhoid:[9] 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 50% to 80% protective and are recommended for travellers to areas where typhoid is endemic. Boosters are recommended every five years for the oral vaccine and every two years for the injectable 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 (mainly pain and inflammation at the site of the injection).[9]
Treatment
The rediscovery of oral rehydration therapy in the 1960s provided a simple way to prevent many of the deaths of diarrheal diseases in general.Where resistance is uncommon, the treatment of choice is a fluoroquinolone such as ciprofloxacin.[8][10] Otherwise, a third-generation cephalosporin such as ceftriaxone or cefotaxime is the first choice.[11][12][13] Cefixime is a suitable oral alternative.[14][15]
Typhoid fever, when properly treated, is not fatal in most cases. Antibiotics, such as ampicillin, chloramphenicol, trimethoprim-sulfamethoxazole, amoxicillin and ciprofloxacin, have been commonly used to treat typhoid fever in microbiology (Baron S et al.). Treatment of the disease with antibiotics reduces the case-fatality rate to approximately 1%.[16]
When untreated, typhoid fever persists for three weeks to a month. Death occurs in between 10% and 30% of untreated cases.[17] In some communities, however, case-fatality rates may reach as high as 47%.[citation needed]
Surgery
Surgery is usually indicated in cases of intestinal perforation. Most surgeons prefer simple closure of the perforation with drainage of the peritoneum. Small-bowel resection is indicated for patients with multiple perforations.If antibiotic treatment fails to eradicate the hepatobiliary carriage, the gallbladder should be resected. Cholecystectomy is not always successful in eradicating the carrier state because of persisting hepatic infection.
Resistance
Resistance to ampicillin, chloramphenicol, trimethoprim-sulfamethoxazole, and streptomycin is now common, and these agents have not been used as first–line treatment for almost twenty years.[citation needed] Typhoid that is resistant to these agents is known as multidrug-resistant typhoid (MDR typhoid).Ciprofloxacin resistance is an increasing problem, especially in the Indian subcontinent and Southeast Asia. Many centres are therefore moving away from using ciprofloxacin as the 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 that azithromycin is better at treating typhoid in resistant populations than both fluoroquinolone drugs and ceftriaxone.[10] 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.[18] 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.
No comments:
Post a Comment