According to news reports, ten people in Auckland have been hospitalised with typhoid, and health officials say we can expect more cases. So what is typhoid and why is this news?
Typhoid is an infection caused by the bacterium Salmonella enterica subspecies enterica serovar Typhi, usually abbreviated to Salmonella Typhi or S. Typhi. Humans are this bacteria’s only known host. The bacteria can be passed from person to person through the faecal-oral route. That’s why it’s so important for everyone to wash their hands properly after they’ve been to the toilet, or changed any nappies. Typhoid can also be caught be eating contaminated food or drinking contaminated water. The symptoms of disease are a high fever which can last for weeks, as well as nausea, tiredness, headaches, and loss of appetite. Some people might have diarrhoea, constipation, or a rash.
While the symptoms might not sound much different from other types of food poisoning, typhoid can be very serious. If not treated, between one to three in ten infected people can die. The good news is that the majority of infected people can be treated with antibiotics.
In New Zealand, most people with typhoid have caught the infection overseas – we get 20 to 30 cases a year. The disease is widespread in Southeast Asia, the Western Pacific, Africa and Central and South America. There are a couple of vaccines available, which is why people going on holiday are usually advised to get vaccinated.
The reason this outbreak is news is because we only ever usually see one or two cases at a time. This outbreak involves at least ten people from different parts of Auckland. Public health officials will be working very hard to try to find a link between the cases so they can work out how the disease is spreading. So what might the options be?
Contaminated imported food or drink
In 2010, an outbreak of typhoid in the USA was traced back to the importation of a ready-to-eat frozen fruit drink imported from Guatemala (1), an area where typhoid is prevalent. There were no more cases once authorities recalled the frozen drink. The same manufacturer was implicated in another outbreak in Florida in 1998. It would surprise me if something like this was the source of our outbreak as New Zealand has strict rules around the importation of fruit and vegetables.
People with typhoid are infectious before they show any symptoms and while they have symptoms. Some people can also carry on shedding the bacteria for months after they have recovered. And a small number of people become chronic carriers of S. Typhi, spreading the bacteria while showing no signs of infection. Ever heard of Typhoid Mary? She was a cook in New York in the early 1900’s who ended up living out her days in quarantine after spreading S. Typhi to many of the families she worked for.
Since Typhoid Mary, there have been plenty of documented cases of S. Typhi shedders working in restaurants who have managed to contaminate the food they are preparing and make diners ill (2,3). Has someone in Auckland with a job involving food preparation recently returned from a trip overseas with S. Typhi?
But what a difference a century makes. Now typhoid is treatable with antibiotics. If this outbreak does turn out to be caused by our own S. Typhi ‘super-shedder’ at least they won’t have to be imprisoned on an offshore island for the rest of their life.
- Loharikar A, et al (2012). Typhoid fever outbreak associated with frozen mamey pulp imported from Guatemala to the western United States, 2010. Clin Infect Dis. 55(1):61-6. doi: 10.1093/cid/cis296.
- Am JKobayashi T, et al (2016). Case report: An outbreak of food-borne typhoid fever due to Salmonella enterica serotype Typhi in Japan reported for the first time in 16 years. Trop Med Hyg. 94(2):289-91. doi: 10.4269/ajtmh.15-0484.
- Yoon J, et al (2004). An outbreak of domestically acquired typhoid fever in Queens, NY. Arch Intern Med. 164(5):565-7.