At 8 h into a 13 h flight from Hong Kong to London in December 2009, the patient, a 14-year-old boy from London, started to vomit. The vomiting was not severe and to begin with it seemed possible it could have been related to eating too much chocolate during the flight.
The patient's father, who was sitting next to him on the plane, had himself been ill with violent vomiting 44 h earlier; he had subsequently spent 24 h in bed feeling nauseated, with colicky upper and lower abdominal pains, aching joints and slight diarrhoea. He had described his symptoms over the telephone to a senior clinical pathologist in Hong Kong who felt the most likely diagnosis was a norovirus gastroenteritis.
At 2 days after the onset of the father's illness on the plane journey back to the UK, the patient vomited four times in a controlled manner into a sick bag. On getting home 6 h later he went straight to bed and slept for most of the night and following day, getting up only for drinks and to go to the toilet, on which occasions he had diarrhoea. He was given no medication for these symptoms and experienced no further vomiting after the plane journey. The following evening, the diarrhoea had abated but the patient seemed unusually tired and went to bed at about 20:00. Some 90 min later he awoke and spoke to his mother in an incomprehensible manner, but answered her questions appropriately. On coming downstairs he pointed to a computer screen (which was on) and said ‘what about the papers and medicines?’. On being asked what he meant by this he replied ‘you know, beyond that wing’ pointing to the computer screen. Because the patient was talking grammatically but nonsensically, the patient's father asked him whether he knew he had recently been away from home. Initially, he did not reply. In response to the further questions ‘Where have we been recently, and how did we travel there?’ the patient replied ‘Scotland, came home by bus and train’.
The patient and his parents had been in Hong Kong for 2 weeks, the first week staying in a hotel on Hong Kong Island, the second week staying in a flat on a small island, 30 min by boat from the main part of Hong Kong. During the visit the family had been well until the father began vomiting on day 13 of the stay, which delayed their planned return to the UK by 24 h.
The patient had no previous serious medical or surgical problems, was fully immunised according to the UK's immunisation schedule and has only had a few unremarkable childhood infectious conditions, including chickenpox and tonsillitis, from which he recovered well. On one occasion as a young child when feverish he was noted to be speaking in a confused manner, but this settled as soon as his fever was treated. From 6 to 10 years of age the patient experienced episodes of sleepwalking, where he would arise about 1 h or so after falling asleep and pace about with his eyes open with an ‘unseeing’ facial expression. On occasion during these episodes, he uttered the odd words but not connected speech; during these episodes the patient was generally not anxious or frightened and was responsive to parental reassurance and accepted being put back to bed.
As a baby the patient was a poor sleeper, having ‘settling difficulties’; until 6 years of age he awoke several times a night and subsequently has usually resisted going to sleep at bedtime. Apart from over the counter childhood settlers (which were ineffective) he has not taken medication for this problem. After long distance, international travel the patient's sleep/wake schedule has been slow to adjust to new time zones, and he has sometimes retained the UK pattern for 10 days or so. The patient has no history of mental illness and has not previously vomited when flying.
By the time the patient uttered the apparently nonsensical speech it was 21:30 on 22 December 2009. He was examined by BH, who is a London GP. He found him to be cooperative, sleepy, without slurred speech and neither anxious nor frightened. The patient answered questions, reported no headache and did not appear to be hallucinating. He seemed a little dissociated (for example he showed no insight into his parents’ concern about him); was restless with eyes that looked somewhat glassy but not staring. He showed no automatisms of behaviour, although he twice repeated his question ‘you know, what about the papers and medicines?’. He was oriented in time (initially he stated the month was January but when this was queried he correctly identified it as December) and place. He did not report double vision, moved about normally and all four limbs were active. His pulse was 74 beats/min and regular, he showed no fever (temperature 36C), there was no neck stiffness or rash and he did not appear dehydrated. His pupils were equal, eye movements were normal and was not hyper-reflexive. During the examination, the patient kept lying down and closing his eyes, going off to sleep, but was easily rousable and when roused answered questions appropriately.
The possibility that he may be developing some sort of a brain disorder was considered. When in Hong Kong, his parents had seen posters warning the public about the possibility of developing malaria, dengue and Japanese encephalitis from insect bites, and 1 week before the onset of this behaviour the patient and his father had spent an afternoon hill walking in subtropical woods in the New Territories, where flying insects were present. His parents discussed taking the patient to casualty, but his father felt watchful waiting was probably safe, in view of a complete absence of physical signs, the lack of any fever and the absence of signs of cerebral irritability.
After clinical examination, the patient went to bed but got up again some 90 min later. When he came downstairs he was still noticeably speaking in a similar nonsensical vein. At this later stage, the patient showed no signs of fever and had no headache and went back to bed and immediately fell asleep. During the following night his parents twice woke him, when he responded appropriately and was not found to be hot (temperature not taken). The following day, the patient awoke and spoke quite normally and recalled some of the events of the previous night:
After a long plane journey from Hong Kong, upon which I had been sick, I awoke, feeling nauseous and tired after almost 30 h sleep. The process of waking up was slow, but I remember going downstairs to the kitchen, my intent to ask my father for some paracetamol. However when I got there I found words hard to articulate, and what I actually said remains hazy to me. I remember then going through to the living room after a brief and disorientating chat with my father. I felt dizzy, so I lay down and attempted to go to sleep. My father seemed unduly worried about my condition and insisted upon asking me questions, which I felt at the time to be unnecessary and annoying. I therefore tried to go to sleep on the sofa again, to be awoken once more by him.
He seemed very worried, and asked me what month it was. I found it hard to reply, as though something was blocking my full mental capacity. I eventually replied ‘January’, and after being told that I was mistaken, I answered ‘December’, which was correct. I remember being confused as to why I had got the answer wrong, but my memory of the incident is hazy at best. Next my father asked me where we had been, but I didn't reply and tried to go back to sleep again, to be awoken once more by an increasingly worried Dad. He asked me the question again, and I replied Scotland. He then asked me how we had got there. I replied ‘by train and car’. My father then took my temperature, with a thermometer with mercury in it. I got very worried, as I thought it would poison, me—I obviously did not think about the sealed glass barrier. Once my Dad had recorded my temperature as normal, I went back to bed.
Since the night of these events the patient has been quite well, but on the night of his abnormal speech, his mother also began to feel unwell and started vomiting.