Travel related diseases and optimizing preventive strategies

With the figure of 1 billion annual travellers continuously increasing, travel is becoming more and more common. The binding element of this thesis is the aim to contribute to the improvement of pre-travel healthcare. The diseases studied either carry a high mortality (rabies, malaria, yellow fever) or morbidity (hepatitis A) rate.
At the Academic Medical Center’s travel clinic, pre-travel guidelines were well adhered to. At Schiphol Airport (Amsterdam), we found that just over half of the VFRs travelling to West Africa had started malaria chemoprophylaxis.
Immune-compromised patients showed moderate to good serologic responses to hepatitis A vaccination. TNF-α blockers were associated with better antibody responses than other immunosuppressive drugs. Checking antibody titres is paramount.
The yellow fever vaccination was found to be effective, despite certain immunosuppressive drugs. Protection should be confirmed by measuring yellow fever antibodies, preferably with the plaque reduction neutralization assay, as the sensitivity is higher than the Immune Fluorescence Assay test.
Yellow fever neutralizing antibody titres were detectable up to 35-40 years after vaccination. Memory T-cells become long-lived and capable of proliferation in case of re-infection. In healthy individuals, the time period before revaccination with the 17D-YF vaccination can be prolonged.
Southeast Asia was found to be a risk destination for animal associated injuries. Long-term travel was not associated with a higher risk of rabies exposure, so guidelines advising vaccination because of long-term travel should be changed. Lowering costs of rabies vaccination through more effective low-dose administration could improve vaccination coverage.
These recommendations could complement existing guidelines.