Typhoid fever and paratyphoid fever
What are Typhoid and Paratyphoid fevers?
Typhoid and paratyphoid fevers are systemic infections that can affect many organs and are caused by the bacteria Salmonella Typhi and Salmonella Paratyphi respectively. The incubation period for typhoid fever is 3-60 days and is usually 7-14 days while it is usually 1-10 days for paratyphoid fever.
Common symptoms of typhoid fever include prolonged fever, headache, malaise, nausea, abdominal pain, loss of appetite, and constipation or diarrhoea (constipation occurs more often than diarrhea in adults). In some cases, rose-coloured spots appear on the trunk and enlarged spleen and liver can be detected. In severe cases, there may be life-threatening intestinal bleeding and perforation. The majority of patients can fully recover after treatment.
Apart from symptomatic patients, some asymptomatic infected individuals are able to shed bacteria in their faeces or urine. About 2–5% of patients will become carriers and continue to shed the bacteria in their faeces after recovery from the disease who may require long-term follow-up.
Paratyphoid fever presents a similar clinical picture but the illness tends to be milder.
How does it spread?
Typhoid and paratyphoid fevers are mainly transmitted via the faecal-oral route. The causative bacteria are passed in the faeces and urine of infected people, which may contaminate food, water or beverages and cause infection in those who have consumed the contaminated items. Types of food which are susceptible to contamination include shellfish (particularly oysters), raw fruits and vegetables, and unpasteurised milk and dairy products. Transmission through sexual contact, especially among men who have sex with men, has rarely been documented.
How can you prevent it?
Travellers should observe good personal hygiene and food hygiene. They should always wash their hands thoroughly with liquid soap and water before eating or handling food, and after going to the toilet. They should avoid drinking contaminated water or beverages with ice of doubtful origin, eating uncooked or undercooked food, particularly shellfish, and eating cut or peeled fruits.
Typhoid vaccination is not routinely recommended. Even vaccinated individuals should take care to avoid consumption of potentially contaminated food and water as the vaccine does not provide full protection from infection.
Vaccination should be considered for those going to endemic areas, in particular long-stay travellers and those visiting rural areas where food and beverage choices may be limited. More information on typhoid vaccine can be found here: https://www.travelhealth.gov.hk/english/vaccine_prophylaxis/typhoid.html.
How is it treated?
Infected individuals should seek medical attention for management. The infection can be effectively treated by antibiotics. Symptomatic treatment such as fluid replacement and adequate rest is also important.