What is Dengue and why does it concern the USA

The epidemic in Brazil and Argentina is worrying the world

by Lorenzo Ciotti
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What is Dengue and why does it concern the USA
© Chris McGrath / Staff Getty Images

After Covid-19, there is another great fear that scares the world. The Argentine government has declared a health emergency due to the dengue epidemic, after 135,676 cases and 68 deaths.

The disease is transmitted through the bite of the Aedes Aegypti mosquito, and causes high fever, skin rashes and muscle and joint pain. In extreme cases it can cause internal bleeding and thus cause death.

It is a virus widespread in tropical countries, but 93% of infections in Argentina occurred among people who had not been there. The boom in infections could be explained by the change in behavior and reproduction times of the mosquito species vectoring the virus, also due to climate change.

The United States, like the rest of industrialized countries, is worried about the epidemic spread of the disease, so much so that checks and tests are being carried out, as also happens in Italy, for those arriving from Brazil and Argentina.

Dengue
Dengue© Chris McGrath / Staff Getty Images
 

But specifically, what is dengue?

Dengue fever is a tropical infectious disease caused by the Dengue virus. The virus exists in five different serotypes and generally, infection with one type guarantees lifelong immunity to that type, while only resulting in a short and non-lasting immunity towards the others. Further infection with another serotype carries an increased risk of serious complications.

The disease is transmitted by mosquitoes of the Aedes genus, particularly the Aedes aegypti species. It presents with fever, headache, muscle and joint pain, as well as the characteristic rash similar to that of measles. In a small percentage of cases, a life-threatening hemorrhagic fever develops, with thrombocytopenia, hemorrhages and fluid loss, which can progress to circulatory shock and death. Prevention is achieved by eliminating mosquitoes and their habitat, to limit exposure to the risk of transmission.

Therapy is supportive and is based on hydration in the case of a mild-moderate form of disease and, in more severe cases, on intravenous administration of fluids and blood transfusion. The incidence of dengue has grown very rapidly since the 1960s, with approximately 50-100 million people infected each year, and is endemic in 110 countries.

A female mosquito that acquires infected human blood also becomes infected, with the virus localized in the digestive system. About 8-10 days later the virus invades and colonizes the cells of other tissues, especially the salivary glands, from which it is expelled together with the saliva. The infection does not appear to have any effects on the mosquito, which remains a carrier of the disease for the rest of its life.

In serious infections, viral replication is greatly increased, it also occurs in organs such as the liver and bone marrow, and causes the passage of liquids from the bloodstream to the body cavities, through the endothelium of the small blood vessels as a result of its dysfunction.

The severe form of the disease is more common in childhood and, unlike many other infectious diseases, occurs in relatively well-nourished children. Women are more affected than men and the disease can be particularly dangerous in individuals suffering from chronic diseases, such as diabetes mellitus and bronchial asthma.