Tropical infections as occupational diseases among young volunteers in social projects.

PURPOSE: The trend of volunteering overseas has increased tremendously over the last decade. Volunteers often go to regions where they are exposed to the risk of tropical infections like malaria, dengue, typhoid fever and schistosomiasis. Health assessments have shown a high occurrence of tropical infections among young volunteers. Such tropical infections are notifiable in Germany, as they are covered by a separate branch of the social insurance system. However, there is still limited data on systematical improvement of medical prevention and health care for volunteers. METHODS: This retrospective study included 457 cases with a diagnosis for a tropical infection or typhoid fever from January 2016 to December 2019. Data sets were anonymised and then analysed with descriptive statistics first. Cases of volunteers sent abroad by "Weltwärts" were compared to cases of aid workers sent to non-industrial countries. RESULTS: A high occurrence of tropical infections as occupational diseases has been shown for volunteers compared to other (mostly older) aid workers being sent to tropical regions. The risk of acquiring a tropical infection was significantly higher in Africa compared to other tropical regions. Cases of malaria were reported significantly more often among the group of volunteers than among aid workers during the period under review. Medical check-ups after travel were rare among volunteers. CONCLUSIONS: Data imply a disproportionate risk for malaria in Africa with a higher risk of acquiring malaria tropica in Sub-Saharan regions. Region-specific risks need to be addressed in training seminars in order to raise awareness among young volunteers before travel. Medical examinations after travel should be mandatory and specific to a particular region.

Assessing the generation of tissue resident memory T cells by vaccines.

Vaccines have been a hugely successful public health intervention, virtually eliminating many once common diseases of childhood. However, they have had less success in controlling endemic pathogens including Mycobacterium tuberculosis, herpesviruses and HIV. A focus on vaccine-mediated generation of neutralizing antibodies, which has been a successful approach for some pathogens, has been complicated by the emergence of escape variants, which has been seen for pathogens such as influenza viruses and SARS-CoV-2, as well as for HIV-1. We discuss how vaccination strategies aimed at generating a broad and robust T cell response may offer superior protection against pathogens, particularly those that have been observed to mutate rapidly. In particular, we consider here how a focus on generating resident memory T cells may be uniquely effective for providing immunity to pathogens that typically infect (or become reactivated in) the skin, respiratory mucosa or other barrier tissues.

Epicutaneous immunization with modified vaccinia Ankara viral vectors generates superior T cell immunity against a respiratory viral challenge.

Modified Vaccinia Ankara (MVA) was recently approved as a smallpox vaccine. Variola is transmitted by respiratory droplets and MVA immunization by skin scarification (s.s.) protected mice far more effectively against lethal respiratory challenge with vaccinia virus (VACV) than any other route of delivery, and at lower doses. Comparisons of s.s. with intradermal, subcutaneous, or intramuscular routes showed that MVAOVA s.s.-generated T cells were both more abundant and transcriptionally unique. MVAOVA s.s. produced greater numbers of lung Ova-specific CD8+ TRM and was superior in protecting mice against lethal VACVOVA respiratory challenge. Nearly as many lung TRM were generated with MVAOVA s.s. immunization compared to intra-tracheal immunization with MVAOVA and both routes vaccination protected mice against lethal pulmonary challenge with VACVOVA. Strikingly, MVAOVA s.s.-generated effector T cells exhibited overlapping gene transcriptional profiles to those generated via intra-tracheal immunization. Overall, our data suggest that heterologous MVA vectors immunized via s.s. are uniquely well-suited as vaccine vectors for respiratory pathogens, which may be relevant to COVID-19. In addition, MVA delivered via s.s. could represent a more effective dose-sparing smallpox vaccine.