Mexico trials world’s first dengue vaccine
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Mexico trials world’s first dengue vaccine

The world’s first vaccine against dengue fever has been approved for use in Mexico.

Also known as ‘breakbone fever’ for its symptoms of excruciating joint and muscle pain, dengue kills 22,000 people annually according to the World Health Organization. It is a leading cause of hospital admissions in Latin America and is estimated to affect 50-400 million people globally each year.

Developed by the French pharmaceutical company Sanofi at a cost of $1.6 billion, the new vaccine is called Dengvaxia. It provides an overall protection rate of 60 percent in four out of five sub-types of the disease, but is less effective in children younger than 9-years-old. Some 40,000 people in Mexico will receive the treatment initially, specifically, those between 9 to 45-year-olds in dengue-prone areas.

“With this decision, Mexico moves ahead of all other countries, including France, to tackle the spread of this virus,” said the health ministry in a statement.

Tackling the virus…

The dengue virus is transmitted via the notorious Aedes aegypti mosquito, also known as the yellow fever mosquito, which originated in Africa but can now be found in tropical and subtropical regions around the world. It is a vector for several unpleasant diseases including zika fever, yellow fever and chikungunya – a dengue-like illness that recently began sweeping across Latin America following decades of inactivity.

The Aedes aegypti mosquito is easily recognizable thanks to the distinctive white stripes on its legs. Its main breeding ground is standing water – such as uncovered catchment barrels or stagnant troughs – meaning that dengue predominantly impacts urban or settled areas. The first cases of dengue were reported in the 1950s in Southeast Asia, but the geographic scope and frequency of outbreaks has increased dramatically since then. The disease has been observed to spread fast and reach epidemic levels very quickly.

Symptoms of dengue include flu-like aches and pains, fever, and a measles-like skin rash. In a small proportion of cases, the disease can develop into the life-threatening ‘hemorrahagic’ form, characterized by internal bleeding and dangerously low blood pressure. For this reason, aspirin and ibuprofen – which both inhibit clotting – should never be given to a dengue patient.

No known cure

A range of anti-viral medicines are currently in development, but as yet there is no known cure for dengue. Rest, rehydration, and simple paracetamol to control the symptoms are the general prescription. Without complications, the worst of the fever is usually over within a week. Mosquito nets and repellent remain the best defense against infection.

Until the efficacy of Dengvaxia has been proven, a number of biotech companies are taking an alternative approach to the problem of mosquito-borne diseases.

The British firm Oxitech has developed swarms of genetically modified male mosquitos which pass on a deadly mutation to their offspring, causing them to die before reaching maturity. In northeast Brazil, a year-long trial by the company saw a reduction of disease-carrying insects by 95 percent, according to a study published in PLOS Neglected Tropical Diseases.

The technology is ingenious and has the potential to impact several diseases simultaneously, but many environmentalists are concerned about unforeseen complications arising from such drastic reordering of local ecosystems. Though mosquitos are universally despised by humans, they are found in all the world’s continents and serve integral functions in nature’s web.

See also:

Latin America prepares for the Zika virus

Brazil releases dengue-resistant mosquitoes