Vectorborne infectious diseases are a significant cause of human and animal mortality and morbidity. Modeling studies predict that changes in climate that accompany global warming will alter the transmission risk of many vector-borne infectious diseases in different parts of the world. Global warming will also raise sea levels, which will lead to an increase in saline and brackish water bodies in coastal areas. Ranjan Ramasamy of the PAPSRB Institute of Health Sciences at the Universiti Brunei Darussalam, and Sinnathamby Surendran, of the Department of Zoology at the University of Jaffna, say that the potential impact of rising sea levels, as opposed to climate change, on the prevalence of vectorborne infectious diseases has hitherto been unrecognized. Their hypothesis was published in BMC Infectious Diseases.
Mosquito species possessing salinity-tolerant larvae and pupae, and capable of transmitting arboviruses and parasites are found in many parts of the world. An expansion of brackish and saline water bodies in coastal areas, associated with rising sea levels, can increase densities of salinity-tolerant vector mosquitoes and lead to the adaptation of freshwater vectors to breed in brackish and saline waters. The breeding of non-mosquito vectors may also be influenced by salinity changes in coastal habitats. Higher vector densities can increase transmission of vectorborne infectious diseases in coastal localities, which can then spread to other areas.
The researchers say the demonstration of increases in vector populations and disease prevalence that is related to an expansion of brackish/saline water bodies in coastal areas will provide the necessary supportive evidence. However the implementation of specific vector and disease control measures to counter the threat will confound the expected findings.
Ramasamy and Surendran add that rising sea levels can act synergistically with climate change and then interact in a complex manner with other environmental and socio-economic factors to generate a greater potential for the transmission of vectorborne infectious diseases. They say that the resulting health impacts are likely to be particularly significant in resource-poor countries in the tropics and semi-tropics.
Reference: Ramasamy R and Surendran SN. Possible impact of rising sea levels on vectorborne infectious diseases. BMC Infectious Diseases 2011, 11:18doi:10.1186/1471-2334-11-18.