H58 Antibiotic Resistant Typhoid: Facts & Information
Author: Disabled World : Contact: Disabled World
Synopsis and Key Points:
A strain of antibiotic-resistant bacteria that causes typhoid fever has spread to several countries and reached epidemic levels in Africa.
The strain, 'H58,' emerged from South Asia around 25-30 years ago and has grown to become one of the predominant forms of the bacteria, 'Salmonella Typhi,' according to the author of the study, Vanessa Wong, who is a microbiologist at the University of Cambridge in England. Ms. Wong stated, "This multi-drug-resistant strain, H58, is resistant to a number of first-line antibiotics used to treat the disease and is continuing to evolve and acquire new mutations to newer drugs."
Salmonella enterica subsp. enterica - A subspecies of Salmonella enterica, the rod-shaped, flagellated, aerobic, Gram-negative bacterium. It is a member of the genus Salmonella. Many of the pathogenic serovars of the S. enterica species are in this subspecies, including that responsible for typhoid.
Typhoid Fever - Also known simply as typhoid, is a symptomatic bacterial infection due to Salmonella Typhi. Symptoms may vary from mild to severe and usually begin six to thirty days after exposure. Often there is a gradual onset of a high fever over several days. Weakness, abdominal pain, constipation, and headaches also commonly occur.
Typhoid itself does not present a direct threat to people who are living in America, where clean water supplies and good sanitation prevent exposure of people to the bacteria, according to Dr. Henry Chambers who is Chief of Infectious Diseases at San Francisco General Hospital, as well as a Professor at the University of California. Yet travelers going to typhoid-ridden parts of Asia and Africa need to make sure they have received a vaccination prior to traveling. President-elect of the American Academy of Family Physicians, Dr. Wanda Filer, agrees.
Dr. Filer stated, "We recommend that people who are traveling to parts of the world where typhoid is endemic get the typhoid vaccine." Dr. Filer added that the vaccine is 50-80% effective against all strains of typhoid, even those that have become antibiotic-resistant. Typhoid fever affects approximately 20-30 million people around the world every year, according to researchers. The symptoms of typhoid include:
- Stomach pains
- Loss of appetite
- High and sustained fever
Up to 20% of people with typhoid may die from complications related to a typhoid infection, which may last for weeks or even months without appropriate treatment, according to the U.S. Centers for Disease Control and Prevention (CDC). People contract typhoid when they consume beverage or food that has been contaminated with the bacteria says the CDC. A person who is infected with S. Typhi may pass it on by handling drinks or food. Water used for washing food or drinking could become contaminated with sewage containing the bacteria.
In the new study, a multinational team of researchers used genetic sequencing to track the spread of antibiotic-resistant typhoid. The researchers discovered that the H58 strain has displaced other typhoid fever strains that have endured for decades or even centuries. H58 was identified in almost half of greater than 1,800 bacteria samples collected from 63 countries between the years of 1992-2013.
Once the H58 strain emerged in South Asia more than twenty years ago, it spread to Western Asia, Southeast Asia, Fiji, as well as both East and South Africa, according to the researchers. They also discovered evidence of a recent and unreported wave of H58 transmission in several countries in Africa - something that might represent an ongoing epidemic. The tactics used to fight typhoid in these countries seems to have led to an increase in antibiotic resistance. Ms. Wong said:
"Vaccinations are not currently in widespread use in typhoid-endemic countries. Instead, antibiotics are commonly used as a preventive measure. As a consequence, there is a rise in antibiotic resistance to many pathogens and in particular a resurgence of multi-drug-resistant typhoid has been observed in some areas, including parts of Africa."
Americans who travel to a country that has typhoid should get vaccinated and then monitor their temperature in the weeks after they return home. If they do develop a fever, they should inform their doctor about their travels. It is important to tell your doctor that you have been to one of these areas of the world because certain antibiotics that might be administered would have no effect. There are guidelines to use antibiotics that work against the more drug-resistant strains of typhoid.
What to do if You Think You Have Typhoid
If you are experiencing a high fever and feel very sick, visit your doctor promptly. If you are traveling in a foreign country you can usually call the U.S. Consulate for a list of recommended doctors. Typhoid fever is treated with antibiotics.
Resistance to multiple antibiotics is increasing among Salmonella that cause typhoid fever. Reduced susceptibility to, 'fluoroquinolones,' such as ciprofloxacin and the emergence of multi-drug-resistance has complicated treatment of infections, particularly those acquired in South Asia. Antibiotic susceptibility testing might help guide appropriate treatment. Choices for antibiotic therapy include fluoroquinolones, azithromycin, and ceftriaxone. People who do not receive treatment might continue to experience a fever for weeks or months; as many as 20% could die from complications of the infection.
The Danger Does Not End when Symptoms Disappear
Even if a person's symptoms seem to disappear, they might still be carrying Salmonella Typhi. If this is the case the illness could return, or the person could pass the disease along to others. If you work at a job where you hand food or provide care for small children, you might be legally barred from returning to work until a doctor has determined that you no longer carry any typhoid bacteria.
If you are treated for typhoid fever it is important to continue taking the antibiotics prescribed for you for as long as your doctor asks you to take them. Wash your hands carefully with soap and water after using the bathroom and do not prepare or serve food or beverages for other people. Doing so will decrease the chance that you will pass the infection along to someone else. Have your doctor perform a series of stool cultures to make sure that no Salmonella Typhi bacteria remain in your body.
Even if your symptoms seem to go away, you may still be carrying Salmonella Typhi. If so, the illness could return, or you could pass the disease to other people. In fact, if you work at a job where you handle food or care for small children, you may be barred legally from going back to work until a doctor has determined that you no longer carry any typhoid bacteria.
- In 2000, typhoid fever caused an estimated 21.7 million illnesses and 217,000 deaths.
- In 2013 it resulted in about 161,000 deaths - down from 181,000 in 1990.
- Historically, in the pre-antibiotic era, the case fatality rate of typhoid fever was 10 to 20%. Today, with prompt treatment, it is less than 1%. However, about 3 to 5% of individuals who are infected will develop a chronic infection in the gall bladder.
- Lately, the study of Typhi associated with a large outbreak and a carrier at the genome level provides new insights into the pathogenesis of the pathogen.
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