Travellers' risk behaviors and health problems: Post-travel follow up in two travel medicine centers in Italy

Health problems and exposure to infectious risks in returning humanitarian aid workers

BACKGROUND

Humanitarian aid workers are exposed to deployment-related health threats. Identifying subgroups at a higher risk of infection in this diverse population could help optimize prevention.

METHODS

We carried out a retrospective study based on anonymized data of humanitarian aid workers that visited our clinic for a post-deployment visit between 1 January 2018 and 31 December 2021. We conducted a descriptive analysis of basic demographic data, self-reported risk exposure and health problems encountered during deployment extracted from a standard questionnaire.

RESULTS

The questionnaire was administered to 1238 aid workers during 1529 post-deployment medical consultations. The median age was 37.2 years (IQR 31.7-44.3), and 718/1529 (47.0%) were female aid workers. The median duration of deployment was 6 months (IQR 3-12 months). Most deployments (1321/1529 (86.4%)) were for a medical organization and in Sub-Saharan Africa (73.2%). The most common risk exposures were contact with freshwater in schistosomiasis endemic regions (187/1308 (14.3%)), unprotected sexual contact with a person other than a regular partner (138/1529 (9.0%)), suspected rabies exposure (56/1529 (3.7%)) and accidental exposure to blood (44/1529 (2.9%)). Gastrointestinal problems (487/1529 (31.9%)), malaria (237/1529 (15.5%)) and respiratory tract infections (94/1529 (6,2%)) were the most encountered health problems. Fifteen volunteers (1%) were hospitalized during deployment and 19 (1.2%) repatriated due to health problems. Adherence to malaria chemoprophylaxis was poor, only taken according to the prescription in 355 out of 1225 (29.0%) of aid workers for whom prophylaxis was indicated.

CONCLUSION

Humanitarian aid workers deployed abroad encounter significant rates of health problems and report a high level of risk exposure during their deployment, with the risks being greatest among younger people, those deployed to rural areas, and those working for non-medical organizations. These findings help guide future pre-deployment consultations, to increase awareness and reduce risk behaviour during deployment, as well as focus on adherence to medical advice such as malaria chemoprophylaxis.

cGMP-dependent kinase 2, Na+/H+ exchanger NHE3, and PDZ-adaptor NHERF2 co-assemble in apical membrane microdomains

AIM

Trafficking, membrane retention, and signal-specific regulation of the Na+/H+ exchanger 3 (NHE3) are modulated by the Na+/H+ Exchanger Regulatory Factor (NHERF) family of PDZ-adapter proteins. This study explored the assembly of NHE3 and NHERF2 with the cGMP-dependent kinase II (cGKII) within detergent-resistant membrane microdomains (DRMs, "lipid rafts") during in vivo guanylate cycle C receptor (Gucy2c) activation in murine small intestine.

METHODS

Small intestinal brush border membranes (siBBMs) were isolated from wild type, NHE3-deficient, cGMP-kinase II-deficient, and NHERF2-deficient mice, after oral application of the heat-stable Escherichia coli toxin (STa) analog linaclotide. Lipid raft and non-raft fractions were separated by Optiprep density gradient centrifugation of Triton X-solubilized siBBMs. Confocal microscopy was performed to study NHE3 redistribution after linaclotide application in vivo.

RESULTS

In the WT siBBM, NHE3, NHERF2, and cGKII were strongly raft associated. The raft association of NHE3, but not of cGKII, was NHERF2 dependent. After linaclotide application to WT mice, lipid raft association of NHE3 decreased, that of cGKII increased, while that of NHERF2 did not change. NHE3 expression in the BBM shifted from a microvillar to a terminal web region. The linaclotide-induced decrease in NHE3 raft association and in microvillar abundance was abolished in cGKII-deficient mice, and strongly reduced in NHERF2-deficient mice.

CONCLUSION

NHE3, cGKII, and NHERF2 form a lipid raft-associated signal complex in the siBBM, which mediates the inhibition of salt and water absorption by Gucy2c activation. NHERF2 enhances the raft association of NHE3, which is essential for its close interaction with the exclusively raft-associated activated cGKII.