Typhoid fever
Typhoid fever is also like as typhoid. Its symptoms range from mild to severe and typically start six to 30 days following exposure. Frequent presentation is a slow development of a high fever over the course of several days. This is often associated with weakness abdominal pain constipation headaches and mild nausea. Some individuals have a skin rash with rose-colored spots. People in severe instances may become confused. Symptoms without treatment can last weeks or months. Diarrhea can be severe but is rare. Some individuals can carry it without illness but are still contagious. This is an enteric fever as well as paratyphoid fever. Salmonella enterica Typhi is thought to infect and only grow within humans.
The bacterium Salmonella enterica subsp causes typhoid. enterica serovar Typhi that proliferates in the intestines Peyers patches mesenteric lymph nodes spleen liver gallbladder bone marrow and blood. Risk factors are poor sanitation and lack of access to clean drinking water. Individuals who have not previously been exposed to it and drink tainted drinking water or eat tainted food are most likely to come down with symptoms. Salmonella Typhi which induces typhoid fever is distinct from other Salmonella bacteria that typically induce salmonellosis a common form of food poisoning.
Diagnosis is done by culturing and isolating S. Typhi from patient samples or the presence of an immune response to the disease from blood samples. Recent developments in large scale data acquisition and analysis enabled scientists to come up with improved diagnostics like the detection of altered abundances of small molecules in the blood which could specifically reflect typhoid fever. Diagnostic tests in areas where typhoid is most common are very limited in specificity and accuracy and the time needed for an accurate diagnosis the growing dissemination of antibiotic resistance and the expense of testing are also challenges for under resourced healthcare systems.
This fever continue to be significant public health issues worldwide and leading causes of morbidity in the developing world. They are acute usually life threatening febrile diseases transmitted by systemic infection with the bacterium Salmonella enterica serovar typhi and S. enterica serovar paratyphi respectively. Classical presentation includes onset of long term fever of gradual development chills hepatosplenomegaly and abdominal tenderness. There is rash in some patients along with nausea anorexia diarrhea or constipation headache relative bradycardia and decreased level of consciousness. Although both illnesses have similar clinical presentations paratyphoid fever has a more favorable course of illness. Typhoid fever would otherwise have a case-fatality rate of 10 30%. In properly treated individuals this is lowered to 1 4%.
The latest estimates of global disease burden for paratyphoid and typhoid fever found that in the year 2000 there were 22 million new cases of typhoid fever 210 000 deaths due to typhoid fever, and 5.4 million cases of paratyphoid fever. This research provided better estimates than previous updates and analyses.
There is a pressing need for a revised estimate of the worlds burden of typhoid and paratyphoid fever to facilitate more effective strategies for disease control and prevention. The global epidemiology has shifted with increased population worldwide and availability of clean water and sanitation systems. New data on surveillance, better knowledge of the age distribution of the illness and additional recent studies make possible revised estimates of the global burden of typhoid and paratyphoid fever.
Diagnosis of typhoid
While the gold standard of typhoid fever diagnosis is a blood culture that is positive, only 40-60%17 of cases have a positive test, typically early in the illness. Stool and urine culture tests are positive later than week one of infection, but are far less sensitive. In most of the developing world, access to and indiscriminate use of antibiotics contribute to blood culture low sensitivity. While bone marrow cultures are more sensitive, they are hard to get, somewhat invasive and of limited utility in public health practice.
In spite of these advances typhoid is diagnosed on clinical grounds in much of the developing world. This is problematic as typhoid fever can simulate many of the frequent febrile illnesses without localising signs. In children with multisystem manifestations the initial presentation of enteric fever can be masqueraded as acute gastroenteritis bronchitis and bronchopneumonia. The differential diagnosis would encompass malaria sepsis due to other bacteria such as Haemophilus influenzae.
infections due to intracellular pathogens like tuberculosis brucellosis tularaemia leptospirosis and rickettsial infections and viral infections like dengue fever acute hepatitis and infectious mononucleosis. There is hence an urgent need to design and develop a multipurpose fever stick that can potentially enable the rapid and specific diagnosis of prevalent febrile diseases particularly malaria dengue fever and typhoid.
Treatment of typhoid
Early detection of typhoid fever and immediate use of proper antibiotic therapy are key to optimal treatment, particularly in children. While the majority of cases can be treated at home with oral antibiotics and close follow up severe illness ongoing vomiting extensive diarrhea and abdominal distension necessitate hospitalization and parenteral antibiotic therapy. Supportive therapy and proper nutrition and hydration in addition to antibiotics are also important.
Proper antibiotic therapy the appropriate dose and duration of the right drug is important in the treatment of typhoid with a minimal number of complications.18 Treatment with chloramphenicol or amoxicillin in standard fashion is related to a 5-15% or 4-8% rate of relapse respectively while the new quinolones and third generation cephalosporins have better cure rates. The development of multidrug resistant typhoid during the 1990s prompted extensive use of fluoroquinolones as the preferred treatment for suspected typhoid particularly in South Asia and South East Asia.
Vaccination of typhoid
There are two licensed typhoid vaccines available for use in typhoid prevention and injectable typhoid polysaccharide vaccine. Both are effective and are advisable for visitors to endemic areas for typhoid. Boosters are given every five years for the oral vaccine and every two years for the injected form. An older killed whole cell vaccine is still employed in countries where the new preparations are not accessible but this vaccine is no longer advisable for use since it has more side effects primarily pain and inflammation at the injection site.
In order to assist in reducing typhoid fever rates in developing countries the World Health Organization supported the implementation of a vaccination program from 1999. Vaccination has been effective in preventing outbreaks in high incidence regions and is also extremely cost-effective: costs are typically below US$1 per dose. Due to the low cost poor communities are more likely to avail themselves of the vaccinations. Even though vaccination campaigns against typhoid have been successful, they are not sufficient to eradicate typhoid fever. Only vaccines together with public health interventions are the only proven methods of controlling this disease.
During 1990s the WHO suggested two vaccines for typhoid fever. ViPS is administered through injection and Ty21a through capsules. Only individuals above two years are advised to be immunized with the ViPS vaccine and needs revaccination after 2–3 years with 55–72% effectiveness. Ty21a vaccine is advised in individuals five and above for 5–7 years with 51–67% effectiveness. The two vaccines have been found safe and effective to control epidemic disease in various areas.
A combination with a hepatitis A vaccine is also used. A phase 3 trial of typhoid conjugate vaccine in December 2019 yielded results with 81% fewer cases in children.