Dengue

Dengue has become a health problem for tropical areas of Latin America over the last several decades. But this disease, cause by four types of virus transmitted by a mosquito, has been known for centuries.

The viruses -- with the scientific labels DEN-1, DEN-2, DEN-3 and DEN-4 -- can cause different manifestations of dengue, the most serious form being hemorrhagic dengue, which can be mortal.

The Pan-American Health Organization (PAHO) has deployed intense operations to aid countries in their battles against the epidemic. On the Internet is a website that serves as the PAHO's center of operations, providing information about the traits of the disease and its presence in the region.

According to the history of dengue in the Americas included on the PAHO site, the disease is believed to have first appeared in 1635 on Martinique and Guadalupe. In the 18th century, dengue epidemics were recorded in the United States, Asia and Africa, and later in Peru.

The resurgence of dengue in recent times, which has hit Venezuela, Colombia and Brazil, and more recently El Salvador and Honduras, is directly related to the proliferation of the virus's vector of transmission, the Aedes aegypti mosquito.

This mosquito species is at home in the urban environment and its presence is reinforced by phenomena like the growth of metropolitan areas and the deterioration of sanitary conditions. The campaigns against dengue are focused on eradication of the Aedes aegypti.

According to figures from the World Health Organization (WHO), the scope of dengue infection has risen dramatically in recent decades and is now an endemic disease in more than 100 countries, endangering some 2.5 billion people.

The Internet holds abundant information about dengue, such as websites with frequently asked questions, explanations about symptoms and treatment, and even lists of health experts dedicated to combating the disease.

Pan-American Health Organization (PAHO): Dengue
PAHO: History of Dengue in the Americas
World Health Organization: Dengue
WHO: DengueNet
U.S. Centers for Disease Control
Microscope view of dengue virus

A Cup of Tea

Tea is a plant of Chinese origin which gave rise to the most widely consumed beverage in the world, from the far East to Latin America. It was first consumed by human beings nearly 5,000 years ago.

Descriptions of the history of tea found on the Internet cite the legend of Chinese Emperor Shen Nung, an herbalist who discovered tea by chance one day as he sat under a wild tea tree, leaves from the tree fell into a pot of boiling water, and he decided to try the brew.

China is considered the birthplace origin of tea or "cha", which was spread throughout Asia, and later the world, by merchants and monks.

According to a website that provides answers to frequently asked questions about tea, there are 3,000 varieties today, although true tea is always brewed from the leaves of Camellia sinensis, the scientific name for the plant.

There are three basic types of tea, depending on the degree of fermentation of the leaves: green, black and oolong. Most of the tea consumed in the West is black.

Many varieties of tea are known by their place of origin, and tea-lovers are familiar with their specific flavors, aromas and characteristics.

The widespread consumption of tea has led to the cultivation of the plants across the world. More than 35 nations in Asia, Africa, the Americas and Oceania are listed as tea producers on a website that reports their share of the competitive global market, which has given rise to institutions like the tea council that links a number of the main exporters.

Tea - home page
Origin of tea
Tea in the world
The Tea Council
The world of tea
Frequently asked questions about tea
Tea producing nations

Mangroves

Mangroves populate the coasts of many tropical and subtropical areas of the world, serving as the backbone of an ecosystem that sustains a great wealth of biodiversity. However, their future is threatened by deforestation and the degradation of their habitat.

Mangrove forests grow in areas where there is abundant water, a mix of fresh and sea water, an ecosystem of marshes or swamps.

According to one Internet site explaining the taxonomy of this unique tree, there are some 100 species within the mangrove family, all of which are vascular plants.

Resistant to salinity, mangroves grow in coastal areas, such as estuaries, and their wood is highly prized. They normally have extensive roots, some of which extend from the trunk and are partially exposed to the air and partially submerged in its watery environs.

These trees produce nutrients that allow a great variety of air, land and aquatic life forms to flourish. The loss of the ecosystem they create means a reduction in biodiversity, coastal erosion, and poor water quality, according to organizations that promote mangrove conservation and sustainable use.

Some of these groups are leading intensive campaigns to save the mangrove, such as the Mangrove Action Plan, which reports that there was a time when three-quarters of the world's tropical and subtropical coasts were populated by these trees. Today, just a portion of that area remains, and at least half is threatened with destruction.

According to the United Nations Food and Agriculture Organization (FAO), mangrove forests cover a total of 181,000 square km in different parts of the world.

Mangrove Action Plan
Mangrove Art by Kids
Wetlands and rainforests: Mangroves
FAO: Information on Mangroves
Taxonomy of Mangroves