PARIS, April 2, 2023 (BSS/AFP) - A typhoid outbreak on an old cruise ship housing asylum seekers in the Netherlands last year was caused by sewage leaking into the drinking water supplies, an investigation said on Sunday.

The Dutch government's use of ships for asylum seeker accomodation has been widely criticised by rights groups -- and the results of the investigation come just days after the UK said it was considering using ferries and barges in a similar manner.

Cases of fever and stomach pain were first reported on April 6, 2022 on the Liberty Ann cruise ship docked in the Dutch city of Haarlem, west of the capital Amsterdam.

Health authorities identified that it was typhoid fever, which is caused by an infection with the bacteria Salmonella Typhi, and is deadly in around one percent of cases.

Nearly 350 people were exposed to the bacteria, with 52 asylum seekers and 20 staff contracting typhoid fever, the investigation found.

All recovered from the illness, though 25 were hospitalised. All asylum seekers and staff were moved to other accommodation.

Local health authorities then launched an investigation to find the source of the typhoid outbreak, which normally occur due to contaminated water.

The results were presented at the European Congress of Clinical Microbiology and Infectious Diseases in Copenhagen on the weekend.

- 'Not easy to find' -

Anne de Vries, a disease control expert at the Municipal Health Service Kennemerland-Haarlem who helped lead the probe, told AFP that the source of the contamination "was not easy to find".

Lacking a blueprint of the ship, it took numerous visits to locate the freshwater tank containing the drinking water.

The freshwater tank shared a wall with the wastewater tank holding sewage, which is against existing guidelines for such accommodation, de Vries said.

The common wall was severely corroded, with numerous small holes peeking through.

While the holes were quite high, de Vries speculated that bad weather -- such as Storm Eunice which pummelled the Netherlands in February 2022 -- could have led to "a lot of wastewater coming in".

The Dutch government announced last year that it would house asylum seekers on ships, a plan that rights group slammed as "absurd".

On Wednesday, the UK immigration minister Robert Jenrick said the British government was exploring the "possibility of accommodating migrants in vessels" such as ferries and barges in a bid to reduce hotel bills.