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Travel to the developing world by Swiss citizens has been increasing. Vaccine-preventable diseases challenges the physician to provide pre-travel advice. Each traveler's itinerary, duration of stay and medical history, including previous immunization, should be reviewed. Vaccinations are required or recommended according to the requirements and the epidemiology of countries being visited. This article summarizes updated recommendations to individual vaccines and immunoglobulins.

In a retrospective study, 113 bites which occurred in Switzerland within a 16-year period by either of the two indigenous adders (Vipera berus and Vipera aspis) were analyzed. 13 patients showed no signs of envenomation. Out of the other 100, 62 patients had merely minor (local edema only) and 24 moderate envenomation (vomiting, diarrhea, cramps, hypotension), while 24 had severe envenomation (shock and angioneurotic edema of the tongue and lips). No fatalities were recorded. In residents of the endemic area the bites occurred accidentally in 86% of the cases, while tourists were bitten after manipulating the snake in 42%. Specific antivenin was given to 49 of 95 hospitalized patients. In cases of severe envenomation (n = 14) a reduction of the median duration of hospitalization from 10 days in patients without antivenin therapy (n = 4) to 5 days in patients with antivenin therapy (n = 10) was obtained. In cases of moderate (n = 21) or minor envenomation (n = 49), antivenin therapy did not influence the hospital stay of 4 and 2 days respectively. In the 11 patients with bites not followed by envenomation the antivenin treatment increased the duration of hospitalization from 1 day (in 6 patients without antivenin) to 2 days (in 5 patients with antivenin). Side effects of the antivenin treatment, such as urticaria, angioneurotic edema, respiratory distress, fever and lymphadenopathy were noted in 4 out of 49 patients.

The lancet fluke is a common parasite in Swiss sheep and cattle. From 1976 to 1980, 77 patients were found to have eggs of D. dendriticum in the stool. No genuine human infection could be diagnosed, and in all patients the coprologic finding of D. dendriticum eggs had to be considered the result of spurious infections due to the consumption of infected livers. The annual incidence of stool specimens positive for D. dendriticum eggs was between 0.20 and 0.38%.

In recent years there has been an increase in imported tropical diseases in Switzerland. Travellers to the tropics are often inadequately or not at all informed about the dangers and possible prophylaxis of infection. This is true for malaria, of which 207 cases covering the years 1974 to 1976 are studied. Most involved were people between 21 and 30 years old. The main infections (71%) come from African countries. Plasmodium falciparum was found somewhat more frequently than P. vivax. Only a seventh of those infected took chemoprophylaxis regularly. Very many took irregular prophylaxis, while scarcely a third ever took an antimalarial drug. All the severe cases were in this group. A review is conducted of aspects of malaria in Switzerland, a country where the disease is not endemic. However, as it can be brought in at any time from tropical areas, it must be considered in the diagnosis of various clinical pictures. As the characteristic course of the fever is rare and onset of the disease often follows later than a month after the return from the infection area, malaria is only recognized late. The diagnosis is nevertheless relatively easy if the possibility of malaria is borne in mind.

In a prospective study 20 P. falciparum isolates imported from Africa by non-immune tourists were investigated for chloroquine sensitivity using the in vitro microtest and the results were compared with the plasma chloroquine concentration. All 6 patients taking correct chloroquine prophylaxis (chloroquine plasma levels between 0.1-0.5 nmol/ml) harboured highly resistant P. falciparum strains (schizont maturation at 3.2 and 6.4 nmol/ml blood in 3 patients each). In the 4 patients with inadequate prophylaxis (plasma levels between 0.02-0.1 nmol/ml) the degree of resistance was lower (at 1.6 and 6.4 nmol/ml blood in 2 patients each). Chloroquine-sensitive strains were found only in patients with chloroquine plasma levels below 0.02 nmol/ml and in 4 of 5 patients who did not show chloroquine in the plasma. Selection of chloroquine-resistant P. falciparum strains under short term chloroquine chemoprophylaxis appears to be highly probable.