In the late eighteenth century the Scottish Highlands were attractive to travellers eager to test themselves against climatic, dietetic and other deprivations. From the early nineteenth century, the Scots themselves became more adventurous and Scottish medical men, notably Mungo Park and David Livingstone, played a prominent part in the exploration of Africa. In the 1860s Livingstone's prolonged travels through the Dark Continent and his belief that he had conquered malarial fever led to the dispatch of the first Christian Mission to the Zambesi region, a venture which failed largely as a result of the missionaries' ignorance of hygiene and medicine.

The establishment of the European presence in British Central Africa (now Malawi) was accomplished by representatives of the Scottish Presbyterian Churches in the 1870s. This paper examines some of the problems encountered during the ensuing half century. Specific themes include the impact of developments in transport systems; housing and sanitation; hints on suitable clothing; the presence of trained medical personnel in both Mission and Government and their role in the study of tropical disease; use and abuse of alcohol.

The speed and frequency of modern travel has brought problems to the traveller that were less obvious in more leisurely days; these are both of an infectious and non-infectious nature and especially relevant to travel in tropical and subtropical areas.

Not everyone is at ease with air travel and travel sickness, anxiety, fatigue, and jet lag are experienced by many; sudden arrival in a new environment means adjustment to differences in heat, humidity and diet.

Infectious diseases are more prevalent in many hot countries and fall into three broad groups: (a) those where fever predominates, (b) where diarrhoea is the main feature, and (c) a miscellaneous group.

(a) Malaria, enteric fever, trypanosomiasis, leishmaniasis, typhus fever, brucellosis and a wide range of viral infections.

(b) Diarrhoea may vary from relatively mild travellers' diarrhoea to more serious dysentery. Other infections include cholera, salmonellosis, schistosomiasis and infections due to vibrios, protozoa and helminths.

(c) Miscellaneous infections include rabies, poliomyelitis, hepatitis and the sexually transmitted diseases.

To fully appreciate overseas travel the traveller must adopt sensible precautions before, during and after his journey. Practitioners must become familiar with the possibility of exotic illness and both under-graduate and post-graduate training take them into account.

The occurrence of an outbreak of Legionnaires' Disease among members of a package tour who had stayed in Benidorm, Spain, in 1973 gave an insight into some of the hazards encountered by tourists abroad.

Subsequent surveys of travellers returning to Scotland have been carried out and of 2,211 persons questioned 43% had been ill during their stay abroad or shortly after return. Package holidaymakers reported most symptoms and university personnel least. Alimentary disorders accounted for the majority of illnesses but respiratory difficulties were recorded by 16% of those who were ill. Tourists to North Africa were particularly affected. Most attributed their illnesses to problems associated with food, drink or excessive sunbathing.

All travellers have recourse to food and drink either while journeying or having arrived. Either way they represent problems of quality control to caterers as any deterioration in standards can have serious effects on travellers' physical and mental well-being, albeit in the short term. The rapid expansion of travel in the last few years, which is unlikely to diminish, has probably improved standards of hygiene and nutrition as a whole but not without some curious side effects. Despite all the years of study and effort put into food hygiene in many countries, most travellers to a foreign state can still expect an upset stomach within a few days of arrival. The main problem for caterer and customer alike is the provision of safe food so this paper deals with the problems encountered in ensuring that travellers have ready and universal access to wholesome meals. In many cases satisfactory sources of supply, methods of preparation and staff training have been evolved so the problem is not of establishing standards but of ensuring continuity and development, especially in times of economic recession or after the first flush of enthusiasm has evaporated. Also considered is the problem of matching strangers demands for ‘native’ food with what they will actually eat, plus the problem of producing safe food which retains some of the original flavours, aroma and effects.

Diarrhoea caused by intestinal infections is the commonest symptom affecting travellers particularly those from developed countries with temperate climates who are visiting less advanced countries in tropical and subtropical parts of the world. It can be troublesome, embarrassing and sometimes incapacitating and has spoiled many holidays.

The infections are almost invariably contracted from food or water although the primary source is usually man, frequently a food handler who is a faecal carrier of one or more pathogenic organisms and whose personal hygiene is inadequate. In many tropical countries human faeces (‘night soil’) is used to fertilise crops especially vegetables such as lettuce and if these are eaten uncooked or unwashed intestinal infection may result.

Infective diarrhoea in travellers may be caused by bacteria, viruses or certain protozoal organisms. Bacterial aetiological agents include Salmonellae, Shigellae, Vibrio cholerae and also certain strains of Escherichia coli which are capable of producing enterotoxins. These enterotoxins are potent causes of diarrhoea in travellers. Recently recognised as a bacterial cause of intestinal infection in travellers are campylobacter species. The protozoa which cause travellers' diarrhoea are Entamoeba histolytica and Giardia lamblia, the latter organisms being a common cause of chronic diarrhoea in recent travellers. A number of recently recognised viruses have been associated with diarrhoea in travellers, the most notable being rotaviruses.

The above micro-organism;, cause disease in the intestinal tract by different pathogenic mechanisms which are described in this paper.

The prevention of travellers' diarrhoea, especially the use of chemoprophylaxis, is a controversial topic which is discussed.

It has been estimated that approaching one thousand million people will travel annually on commercial airlines by the end of the present decade. Many will be transported to tropical and subtropical countries and it is, therefore, an opportune time to consider the present topic.

The traveller requires an easy guide to the important preventive measures for the common ailments that may be acquired on journeys. The card described is useful for this purpose.

The most important disease for the traveller to avoid and for physicians to suspect in travellers is malaria. All tropical Africa and most tropical areas in the East and Far East are now malarious. The infection has returned in recent years to India and several other parts of the East and Far East from which it had been almost eradicated. Travellers to those regions should, therefore, take appropriate malarial prophylactics and malaria should be the cause first suspected among those with fever who have recently visited malarious areas. The emergence of malarial strains resistant to chloroquine poses problems both for prophylaxis and treatment of the established disease.

The recognition in 1969 of Lassa fever has introduced a new problem in managing those with fever who have been to West Africa within the preceding three weeks.

Travellers to game parks in Africa have greatly increased in number within the last decade and are exposed to trypanosomiasis. Several cases resulting from such exposure are known. They cause special diagnostic problems.

Hepatic amoebiasis may be unsuspected until a considerable amount of pus has collected and the risk of complications developed. Its clinical features need to be borne in mind.

Helminthic infections are ubiquitous in the tropics. Schistosomiasis, ascariasis and strongyloidiasis are of special importance and practitioners in developed countries need to be familiar with their characteristics.

Awareness of the possible presence of tropical infections is the keynote to success both in avoiding them and in managing them among those whose precautions have been deficient.

The pleasure of a holiday in warmer and sunnier climates can be increased by ensuring graduated exposure to the sun. Suitable measures can avoid the inflammatory reaction of sunburn in the short term and also be of benefit to the individual in the long term.

This paper considers the hazards of getting to and from one's destination; the subject of accidents occurring as part of a holiday is too broad for present consideration.

The symposium is mainh concerned with travel abroad but, since one has to reach the definitive means of travel, the epidemiology of road traffic accidents is first considered. An unusually optimistic view is taken of the current position as regards fatalities. Emphasis is placed on the importance of recent legislation in the prevention of injury. Overall, the chances of being killed on the roads are now not much greater than those of suffering an accidental death in the home. The effect of alcohol and common drugs on the holiday motorist are discussed and mention is made of the hazards of carbon monoxide poisoning.

Death and injury due to travel by boat or train is so unusual as to eliminate them from useful discussion and most interest probably centres on the accidental hazards of air travel.

The major anomaly here is that, on a passenger-mile basis, the worldwide chances of being killed in an accident involving a scheduled air carrier are about the same as for travelling on British Rail. The relationship of aircraft accidents to fatalities is discussed and reasons advanced for the remarkable improvement in both. Potentially survivable accidents are commonest at take off and landing. It is in such accidents that the hazard of fire is of maximal importance though adequate restraint is also highly significant. Suggestions are made for increased safety.

The wholly fatal accident is commonly associated with a catastrope in flight and some of the dangers of exposure to high altitude are considered. There is considerable public interest in sabotage as a cause of aircraft accident and its incidence is briefly considered. The overall message is that air travel is quite remarkably safe and that the unduly widespread fear of flying is related, in the main, to the publicity which inevitably surrounds the occasional disaster.

A number of factors increase the stress on both driver and vehicle when going on holiday or unaccustomed journeys. Greater distances than normal are attempted in short periods of time without rest and the economics of motoring often mean that small family cars are expected to carry heavy loads for long distances. Drivers become easily exhausted under these conditions and due care should be taken in preparation for long journeys to reduce the strain on both car and driver to a minimum.

Environmental hazards present themselves in different parts of the world. Hurricanes plague the Caribbean, typhoons sweep the China Seas and cyclones rage in the Bay of Bengal. Volcanoes erupt and the earth quivers in a circumpacific belt, in northern India, Soviet Central Asia, Turkey, Italy, etc. Extremes of heat and cold promote adverse reactions in the skin. Diseases of insanitation (enteric fevers, dysentery, cholera, etc.) are prevalent in tropical countries with low standards of hygiene; insect-borne diseases (malaria, yellow fever, filariasis, etc.) are common in certain warm countries. Prior warning of these dangers and appropriate health safeguards (vaccination, inoculation) should be obligatory.

During the 7 year period between 1975–81, a total of 2081 cases of infection were reported to the Communicable Diseases (Scotland) Unit, concerning persons with a history of recent overseas travel. The most frequently reported diseases were salmonellosis (829 cases), bacillary dysentery (345), malaria (236), campylobacter enteritis (219), giardiasis (125), enteric fever (82) and viral hepatitis (74).

Holidaymakers, particularly those who had visited the Mediterranean area, were most frequently affected, comprising more than two-thirds (67·8%) of the total, followed by business travellers and immigrants. Nearly three-quarters (72·7%) of infections were reported between June and November. Young adults, particularly males between 15 and 34 years, were responsible for almost one-half (48·l%) of cases.

Secondary spread of infection after arrival in Scotland was uncommon, occurring in less than 3% of cases. One unusual episode occurred in the North of Scotland when an imported rare salmonella serotype (S. zanzibar) subsequently contaminated milk at a dairy farm and later caused disease among young calves on another farm with seagulls being the apparent vehicle of secondary infection.

Being a healthy traveller involves communication in more than one sense of the word.

Health administrations have a responsibility to prevent illness associated with international travel and trade without undue interference to these inevitable activities. Past experience of travel-associated disease transmission should determine epidemiologically justified and cost-effective preventive measures.

The aeroplane transmits disease faster but should not become the scapegoat for travel-associated ill health. Viral influenza can spread rapidly because of air travel but the latter's role in transmission of diseases such as cholera and smallpox in the past or viral haemorrhagic fevers in the future may not be clear cut.

Surveillance activities are essential to enable the earliest possible detection of disease because measures taken with the intention of keeping a disease out of a country cannot be foolproof. Frank and rapid exchange of information between national epidemiological services is essential for effective control of international spread of diseases.

National health administrations have an obligation to provide travellers with reliable information. A specific programme co-opting the medical profession, travel agencies of every form and the media is necessary.

The World Health Organisation should collaborate with national health administrations in the prevention of disease associated with travel.

Member airlines of the International Air Transport Association in general accept very seriously the responsibilities regarding health problems due to travel. They lay down standards in a practical manner which they try and maintain, the principle being to combine maximum safety regulations with minimum restrictive practices to fit in with a successful commercial operation. These standards cover the prevention of spread by not carrying contact passengers who are in a stage of incubation; the prevention of food- and water-borne disease which covers satisfactory food preparation and food handling and also satisfactory water supplies on the aircraft; the prevention of insect-borne disease by adequate aircraft spraying; the prevention of animal-borne disease and the avoidance of, and, if necessary, the adequate treatment of, any animal vermin on the aircraft, and the avoidance of zoonoses carried by animals transported as air freight. In addition to these standards, British Airways run an immunisation centre which provides various pamphlets and booklets which give medical advice. Finally, they make an announcement of the need to take an antimalarial when entering a malarious area.

From the organisations other than the airlines the situation is mainly advisory —the World Health Organisation, the Department of Health and Social Security, the Health Educational Council; all issue booklets and pamphlets to a greater or lesser extent. The medical profession and the pharmacists regrettably tend, on the whole, to be ill-informed and uninterested. The media are often inaccurate and tend to put the stress on less important issues. The travel agents and the inclusive tour operators vary greatly in their attitudes. Some are responsible and some are irresponsible.

All of these points are covered in the article and it is suggested that more post-graduate centres should encourage lectures on the subject of the prevention of imported disease and it should be included in the medical school curriculum along with the lectures on tropical diseases.

The intending traveller should plan a detailed itinerary well in advance of his departure from the United Kingdom if he is to take full advantage of the health precautions and advice that are available. The present mechanism of delivering health care advice is inefficient and many travellers remain ignorant of how they should protect themselves against illness acquired overseas. Passport offices, travel agents, shipping and airline authorities and health insurance firms are in a unique position to share the responsibility with the community health services and general practitioners of ensuring that intending travellers are appropriately briefed and visit their family doctor and dentist in plenty of time. Chemoprophylaxis against malaria and inoculation against many tropical diseases are available and sensible advice can be given about how to keep healthy abroad. Adults and children should also be immune to infections such as poliomyelitis, diphtheria, tetanus and, if visiting the developing world, tuberculosis as well. Sensible clothing, equipment and adequate supplies of any regular medicaments must be taken. Some form of health insurance and, in addition for E.E.C. countries, a certificate of entitlement to free health care are wise additional precautions to take.

World-wide travel leads to disturbances of the sleep and circadian rhythmicity of man, and after transmeridian flights ability to carry out work may be impaired. The initial approach to the problem is to avoid overnight flights, arrive in the new country during the early evening and to rest for an appropriate period of time. However, this is often difficult to achieve, and in this context the use of hypnotics during the flight and the adaptation phase is discussed.

Distress often reveals itself as physical symptoms. The relationship between disease and symptomatology is a complicated interaction where the influence of psychological and social factors in the aetiology of distress should always be considered.

Travel can bring frustration whether it be in the air or on the ground. Disabled people are entitled to equality of opportunity but their opportunity for travel is often very restricted. The needs of psychotic patients and those in the rehabilitative phase of illness also need to be considered.

Many factors contribute to fatigue and insomnia in travel. Some of these are discussed including psychological and social factors, state of mood, fear and circadian rhythms. It is suggested that the solution to some of the problems of hazards of travel will come more from knowledge already acquired than from highly technical consideration.