Nairobi — It's official: British visitors, including some well-meaning medical students, brought swine flu to Kenya -- and probably the East African region as a whole.

According to an evaluation done by Kenya's flu surveillance programme in collaboration with the US Centres for Diseases Control (CDC), all four initial outbreaks of H1N1 in the country had a British connection.

"Since the introduction of the four cases, pandemic H1N1 has spread throughout all of Kenya's provinces," says the report by the surveillance programme. "As of October 9, Kenya had identified 359 cases of pandemic H1N1, 28 or 7.8 per cent of which were patients who were subsequently hospitalised. None died."

According to the epidemiological data, the Kenyans who contracted the British-linked H1N1 transmitted the virus to a third of those people they came into close contact with.

Britain is one of the countries hardest-hit by H1N1 with 78,000 new cases reported just last week.

By Thursday, it had 750 patients hospitalised because of the flu, of whom 157 were in intensive care.

The country has reported 137 deaths as result of swine flu.

The prevalence of swine flu in the UK continues to be particularly significant for Kenya because the former is its single largest source of tourists.

Between January and September this year, a total of 122,327 visitors from the UK landed in Kenya, accounting for about 18 per cent of all arrivals.

According to the surveillance report, the first case of pandemic H1N1 was definitively confirmed in Kenya on June 29.

At that time, only four other countries in sub-Saharan Africa had reported outbreaks, and secondary transmission had not been documented in the region.

That index case was significant because from the beginning of May through June 28, a total of 28 samples from suspected cases were tested, all of which were negative for pandemic H1N1.

The report states that Kenya's first confirmed case occurred in a British male medical student from Nottingham, UK who flew into the country on June 21 accompanied by 33 colleagues.

During the flight to Kenya, the student had developed a headache and fever, but somehow was not detected at the Jomo Kenyatta International Airport, where Kenyan authorities were screening arriving visitors.

After entering Kenya, the Nottingham students subsequently made a five-hour journey to the western city of Kisumu, where the still mildly ill student participated in group activities for three days, including working at a school and at a centre for homeless children.

After his symptoms worsened, swabs were taken from him on June 27.

Laboratory analysis on June 29 confirmed that he was suffering from swine flu.

Of the 33 other students in the group, who were all staying on the same floor in a Kisumu hotel, 23 subsequently developed fever or upper respiratory symptoms between June 24 and 30, and 11 were eventually confirmed to have contracted H1N1.

The surveillance report does not indicate whether any of the local people the students interacted with contracted H1N1, which is highly likely since Nyanza Province subsequently became one of Kenya's swine flu hotspots.

Kenya's second batch of H1N1 cases also occurred in a group of four British public health students, who again flew into the country on June 26 and proceeded to Kisumu.

A 22-year old woman in this group subsequently went down with flu symptoms, and was confirmed to be suffering from H1N1 on July 1.

A colleague of hers was also diagnosed with the infection on July 3.

The third batch of infections occurred when a 5-year old boy travelled by plane, accompanied by two members of his family, from London to Nairobi on vacation.

On June 29, he developed a fever, cough, and started vomiting. His guardians sought treatment at a Nairobi clinic, where swine flu was suspected.

Those suspicions were soon confirmed, but not before the boy and his relatives had travelled 500 kilometres from Nairobi to Northeastern Province, where he subsequently infected his 8-year-old brother.

The brother's infection was diagnosed on July 7.

The fourth outbreak occurred when a Kenyan man aged 21 years who was studying in the UK travelled by plane to Nairobi on vacation on July 2.

Two days later, the man was confirmed to be infected with H1N1, and was isolated at a private residence in Nairobi for seven days where he infected a 51-year old woman with the virus.

According to the surveillance report, although no person has died of H1N1 in Kenya yet, there is still cause for concern.

Globally, nearly 400,000 cases and 4,700 swine flu-related deaths have been confirmed.

"Despite the mild nature of the initial infections in Kenya, the H1N1 pandemic ultimately might have severe outcomes," says the report. "Relatively high rates of malnutrition and human immunodeficiency virus, malaria, and other infectious diseases, combined with limited health-care infrastructure and reduced healthcare utilisation, create the possibility that the H1N1 pandemic could cause more severe disease and deaths (than elsewhere)."

Kenya currently has one of the most elaborate flu surveillance programmes on the continent.

Since 2006, the country's Ministry of Public Health and Sanitation has maintained 26 influenza-sentinel surveillance hospitals and clinics that identify patients with severe acute respiratory illness and influenza-like illnesses.