The paratyphoid A is a serotype of Salmonella, a bacterium responsible for producing a condition called "enteric paratyphoid fever". Salmonella is a Gram negative, facultative anaerobic bacillus that does not develop capsules or spores and is part of the Enterobacteria family.
Salmonella make up a genus of more than 2300 serotypes, of which more than 200 are pathogens for man, including "paratypical A". They are mobile, flagellated bacteria that infect man through the ingestion of contaminated food or water.
Global distribution of the endemic areas of typhoid and paratyphoid fever. The red color indicates areas with very high prevalence. Brown indicates high prevalence and white sporadic outbreaks. (Source: Percherie Via Wikimedia Commons)
Infection with Salmonella paratfica A requires a relatively small inoculum. The infection is transmitted to man without an intermediate host. Poor sanitary conditions favor contagion.
There are a number of conditions that increase the susceptibility of people to Salmonella infection, among which can be named: history of surgery and chronic inflammatory problems of the gastrointestinal system, decreased heartburn (the host's first defense barrier) or alteration of the intestinal flora due to recent administration of antibiotics.
Salmonella paratfica A produces an enteric fever similar to typhoid fever, but almost always milder.
characteristics
Worldwide, typhoid and paratyphoid fever or enteric fevers are generally common in areas of the planet where there are poor sanitary measures and water for human consumption is easily contaminated with sewage.
The areas where these diseases occur most frequently are much of Asia, the Middle East, Africa, Central and South America, and parts of southern Europe.
Salmonella paratfica A enters the host orally and lodges in the terminal or distal ileum (small intestine). These microorganisms have “fimbriae” with which they adhere to the epithelium on the lymphoid tissues of the ileum in Peyer's patches.
If the immune system does not stop the infection, the bacteria multiply and enter the bloodstream causing mild septicemia. At this time the fever and general malaise begin. The bacteria then invade the lymphatic tissue and the characteristic symptoms of the disease become manifest.
Sources
Since paratypical salmonellosis A has as a reservoir man, the source of infection is food and water contaminated with feces or urine from healthy or sick carriers.
Among the important sources of infection are raw vegetables, green salads, milk and its derivatives, water or ice, shellfish or any other food that has been contaminated with feces or urine. All those raw foods that are washed with contaminated water are potential sources of infection.
The climatic floods that occur in some poor areas are a major source of wastewater contamination of water for human consumption. These are starting points for many outbreaks.
As Salmonella paratfica A is sensitive to heat, it is recommended to boil water and cook food thoroughly in areas where there is danger or risk of contamination.
Symptoms and diagnosis
Symptoms
The symptoms of paratyphoid enteric fever A or paratyphoid fever are similar to those of typhoid fever, but with a shorter prodrome (1 to 10 days) and less severe symptoms. It is of sudden onset and of shorter duration. Relapses occur in approximately 8% of cases.
The most frequent symptoms are the following:
- Sustained high fever.
- Headache.
- General discomfort.
- Decreased appetite.
- Hepatomegaly and splenomegaly (enlargement of the liver and spleen), which can cause abdominal discomfort.
- Dry cough in the initial stages of the disease.
- Appearance of a "rash" or flat pinkish eruption that may be visible on the trunk.
- Constipation or diarrhea. Constipation occurs much more frequently in adults, while only 20% of sick adults have diarrhea. In children and the elderly, diarrhea is more common.
Lesions in the trunk due to paratyphoid A and typhoid fever. (Source: Photo Credit: Content Providers (s): CDC / Armed Forces Institute of Pathology, Charles N. Farmer Via Wikimedia Commons)
The severity of the disease ranges from moderate to severe with multiple complications. People who do not receive treatment can maintain high temperatures for several weeks and in these cases complications are much more frequent. There are very few healthy carriers for this type of salmonellosis.
The complications associated with the greater number of deaths are fluid and electrolyte disorders in children and bleeding and perforations of the gastrointestinal tract in adults. With proper treatment, mortality is very low, less than 1%.
Diagnosis
The diagnosis is made by blood culture in the early stages of the disease or by culture of urine and / or feces in later stages and then, using different methods, the corresponding serotype is immunologically identified. Currently, many institutions use PCR (Polymerase Chain Reaction) as a diagnostic tool.
Treatment
Treatment requires rest, parenteral rehydration in cases of dehydration due to profuse diarrhea, and antibiotics. Thanks to the use of antibiotics and prescribed vaccines, the disease is not fatal.
The treatment of choice is quinolones, specifically ciprofloxacin. Although this has been the treatment of choice, in the last decade and especially in the Asian continent, many cases of resistance have been reported.
Ceftriaxone or cefotaxime, third-generation, broad-spectrum cephalosporins, can also be used. Another antibiotic that has been shown to be effective is azithromycin, which belongs to the group of broad-spectrum macrolides.
In many endemic areas, the classic treatment with chloramphenicol or trimethoprim / sulfamethoxaxole is still used, but this treatment has ceased to be effective due to the resistance that these microorganisms have developed.
The treatment schedule for paratyphoid fever for adults is ciprofloxacin: 1 gram daily for 10 days (orally or IV); ceftriaxone: 2 to 4 grams daily for 14 days (IM or IV route); cefotaxime: 3 to 6 grams daily for 14 days (IV route) or azithromycin: 1 gram daily for seven days (oral route).
Prevention
Health authorities must monitor and evaluate family contacts and any other close contacts related to cases already diagnosed.
The sick person should not attend kindergarten, schools or work until the health authorities give their approval, in order to avoid the risk of contagion.
People who work handling food, caring for or caring for children, in jobs related to health care or residential care, cannot return to their work activities until the doctor in charge of the case in the health service gives his approval.
Some close contacts of the infected person should also be kept under observation and examined by the health authorities until they are sure that they are not infected.
People with typhoid or paratyphoid fever should not prepare food for other people and should not swim in public or private pools, until they are declared free of the disease by health authorities.
If you are going to travel to areas where these salmonellosis are common or endemic, you should avoid street foods and drinks, as well as raw foods as much as possible. You should drink boiled or bottled water without ice or use water purification (chlorination) tablets. You should consult your doctor about available vaccines.
You should wash fruits with boiled or bottled water and wash your hands before drinking, eating, or smoking.
References
- Barrow, PA (2000). The paratyphoid salmonellae. Revue Scientifique et Technique-Office International des Epizooties, 19 (2), 351-366.
- Bhan, MK, Bahl, R., & Bhatnagar, S. (2005). Typhoid and paratyphoid fever. The Lancet, 366 (9487), 749-762.
- Effa, EE, & Bukirwa, H. (2008). Azithromycin for treating uncomplicated typhoid and paratyphoid fever (enteric fever). Cochrane Database of Systematic Reviews, (4).
- Ochiai, RL, Wang, X., Von Seidlein, L., Yang, J., Bhutta, ZA, Bhattacharya, SK,… & Ali, M. (2005). Salmonella paratyphi A rates, Asia. Emerging infectious diseases, 11 (11), 1764.
- Teh, CSJ, Chua, KH, & Thong, KL (2014). Paratyphoid fever: splicing the global analyzes. International journal of medical sciences, 11 (7), 732.
- Yousif, TAT (2018). Comparison of Widal Test In Diagnosis of Typhoid Fever with Blood Culture and Immuno chromatographic Test among Patients in Wad Medani Teaching Hospital, Gezira State, Sudan (2012-2017) (Doctoral dissertation, University of Gezira).