US health officials have warned that the global warming and inadequate control of mosquito populations could see dengue fever spread from the tropics to the continental US, Reuters reports.

According to Dr Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, and his senior scientific adviser, Dr David Morens, cases of dengue have already been reported in Texas, which "may be the beginning of a new trend".

Dengue fever is transmitted by Aedes albopictus (Asian tiger mosquito, first seen in the US in 1985), or more commonly by the ubiquitous Aedes aegypti.

The disease is caused by one of four members of the dengue viral family, DEN-1 to DEN-4. Although the four are "immunologically related", they don't provide "cross-protective immunity" against each other, meaning if you've been been infected by one of the viruses, you can still be infected by the other three.

It's symptomised by fever, rash, severe headache, pain behind the eyes, and muscle and joint pain, and although most attacks result in a "relatively mild" illness, it can develop into potentially-fatal dengue hemorrhagic fever which provokes bleeding both internally and from the nose, mouth, and gums.

Fauci and Moren compared the threat from dengue to fever to that of West Nile virus, another mosquito-borne disease which was first identified in the US in New York in 1999, has since spread across the entire country, and last year killed at least 98 Americans.

They concluded: "The combined effects of global urbanization and increasing air travel are expected to make dengue a growing international health problem for the foreseeable future." ®

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