Typhoid fever

There are approximately 11—20 million cases of typhoid fever every year (WHO report from 2018), resulting in approximately 128,000 to 161,000 deaths annually. Typhoid fever outbreaks are common worldwide. Primary causes include insufficient access to safe drinking water and inadequate sanitation and hygiene. Countries facing complex emergencies and large population movements (of internally displaced people or refugees) to overcrowded settings are particularly vulnerable to typhoid fever outbreaks. 

The following are standard case definitions to allow national health authorities to interpret data in an international context. However, during an outbreak case definitions may be adapted to the local context and the Red Cross Red Crescent should use those agreed/established by national health authorities. NB: Consider that during community-based surveillance, volunteers should use broad (simplified) case definitions (referred to as community case definitions) to recognize most or all possible cases, provide relevant risk communication and appropriate actions and encourage them to seek care. Other actors such as healthcare workers or investigators studying the cause of a disease, on the other hand, can use more specific case definitions that may require laboratory confirmation.

Outbreak case definitions (similar to routine surveillance case definitions but may have added features):

Suspect case: At least three out of seven consecutive days of fever OR a physician’s suspicion of enteric fever.

Probable case: In line with the suspect case definition plus an epidemiological link to the outbreak.

Confirmed case: Laboratory confirmation by culture or molecular methods of S. Typhi organisms or detection of S. Typhi DNA from a normally sterile site.

WHO case definition source of information: https://www.who.int/immunization/monitoring_surveillance/burden/vpd/WHO_SurveillanceVaccinePreventable_21_Typhoid_BW_R1.pdf?ua=1

• Overcrowded areas where person-to-person spread is easily possible. For instance, peri-urban slums where minimum standards of clean drinking water and sanitation are not met.
• The consequences of a humanitarian crisis – such as disruption of water and sanitation systems, or the displacement of populations to inadequate and overcrowded camps – can increase the risk of typhoid fever transmission, should the bacteria be present or introduced.
• Water contaminated with human faeces, for example from sewage, septic tanks and latrines, is a source of infection. Animal faeces also contain microorganisms that can cause typhoid fever.
• Inadequate access to clean water and sanitation facilities. Water can also be contaminated during transport, storage and handling.
• Food and water when prepared or stored in unhygienic conditions. Raw fruits and vegetables that are not appropriately washed. Seafood taken from contaminated water and eaten raw or not sufficiently cooked.
• Household members and close neighbours of typhoid patients are at increased risk in the days immediately following the person’s illness.
• In developing countries school-age children (aged 5–15 years) are disproportionately affected, but in some endemic areas, children aged under five years of age show incidence rates similar to, or exceeding those of, school-age children.

Attack rates will vary from one outbreak to another. In case of an outbreak, consult the latest information provided by health authorities.

• Serious complications occur in up to 10 per cent of typhoid fever patients, especially in those who have been ill longer than two weeks and who have not received proper treatment.
• Special caution is needed for those experiencing typhoid fever caused by multidrug-resistance (MDR) strains of S. Typhi – that is, resistance to all three of the first-line antibiotics. It is associated with more severe illness and higher rates of complications and death, especially in children aged under two years of age.

Salmonella Typhi (S. Typhi) (bacterium).

Humans.

Faecal oral transmission: Ingestion of contaminated food and water that have been handled by a person who is shedding Salmonella Typhi through the faeces, or if sewage contaminated with Salmonella Typhi bacteria gets into the water used for drinking or washing food. Flies and other insects can mechanically transfer the organism to food, where the bacteria then multiply to achieve an infective dose.

5—60 days, usually 1—3 weeks.

The disease is communicable for as long as the infected person excretes S. Typhi, usually after the first week of illness through convalescence. Approximately 10 per cent of untreated cases will excrete S. Typhi for three months and between two to five per cent of all cases become chronic carriers.

• The disease starts with fatigue, headache, abdominal pain and slow stepwise fever onset. Constipation usually occurs in older children and adults at the beginning of the disease, whereas younger children may suffer from diarrhoea.
• Complications can include continuous fever (temperature always greater than 38°C), rash (called roseola) at the body trunk, relatively slow heart rate.
• Severe forms of typhoid fever may entail cerebral dysfunction, delirium and shock, and occasionally also intestinal perforation and haemorrhages.
• Symptoms are often non-specific and clinically non-distinguishable from other febrile illnesses.
• Clinical severity varies and severe cases may lead to serious complications or even death. Without therapy, the illness may last for three to four weeks and death rates range between 12 and 30 per cent.

Malaria, dengue fever, influenza or other febrile illnesses.

Confirmed diagnosis requires isolating S. Typhi in the laboratory through blood cultures or occasionally through bone marrow culture. After two to three weeks stool cultures can be used as well for diagnosis.

Please refer to the appropriate local or international guidelines for clinical management. All clinical management including the administration of any treatment or vaccine should be conducted by health professionals.

• Typhoid fever is treated with antibiotics.
• The World Health Organization (WHO) recommends the programmatic use of typhoid vaccines for the control of the disease. As of 2021, three types of typhoid vaccines are licensed for use:

1. an injectable polysaccharide vaccine for persons aged two years and above.
2. a live attenuated oral vaccine in capsule formulation for those over five years of age.
3. a typhoid conjugate vaccine (TCV). TCV is the preferred vaccine at all ages due to its improved immunological properties, suitability for use in younger children and expected longer duration of protection.

Typhoid fever reinfections are rare but have been described; this means that immune responses are only partially protective after the initial episode(s) of infection.

The vaccines do not provide long-lasting immunity. The TCV vaccine does provide longer lasting immunity compared to the other ones.