Natural disasters and sexual risk taking behaviour: correlation or causation? And what is the relevance for global public health?

Background, aim - Natural hazards have intensified as a result of climate change. Their impact has a negative effect on people’s health, including mental health. Increased risk-taking behaviour such as alcohol (ab)use, excessive smoking and illicit drug use have been observed. High-risk sexual behaviour has poorly been investigated, to date. The aim of this ecological study is to investigate the association of exposure to natural disasters and sexual risk-taking behaviour as measured by increased HIV incidence, at country level, worldwide. Methods - All data was extracted from publicly available sources. Crude and adjusted linear regression models were built to explore the association between the proportion of people affected by natural hazards and HIV incidence. Models were adjusted for socio-demographic variables (literacy, income and age), and then further adjusted for antiretroviral therapy coverage and the healthcare access and quality index. Results - In the crude regression, the total number of people affected by disaster over a 5-year period was positively associated with HIV incidence: for every 10 new people per 100,000/year affected by natural hazards, the HIV incidence in the country was 1.5 per 1,000 uninfected higher. After adjusting for socio-demographic variables, the association was lost. When further adjusted, only antiretroviral therapy coverage and health care access and quality were positively and negatively associated with HIV incidence, respectively. No interaction was found with income groups, world regions or categories of high and low HIV prevalence. Conclusion – No association between exposure to natural hazards and increased sexual risk-taking behaviour at country level worldwide was found, after accounting for socio-demographic variables. Nonetheless, countries with a higher proportion of population affected by natural disasters were those whose health system quality and accessibility was poorer, and this in turn was associated with higher incidence of HIV potentially highlighting different mechanisms explaining the crude association.