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Air Pollution Leaves Traces In The Brain

by Zadie Neufville

The following was published in Spanish by SciDev.com
Researchers at UK’s University of Lancaster have found toxic nanoparticles similar to that associated with Alzheimer’s disease could come from industrial air pollution which may enter the brain by the nasal passage, suggesting a new environmental risk factor in neurodegenerative diseases.

Traces of magnetite, a magnetic iron oxide compound and a very common air pollutant, are known to be present naturally in human brain and derived from the iron used in normal brain function.

According to the study published in the Proceedings of the National Academy of Sciences (PNAS) on Sept 5, researchers measured magnetic samples and examined their sizes and shape to determine the source of the particles.

In analysing brain tissues from 37 people in Manchester, England, and Mexico City, aged between 3 years old and 92, the researchers observed that most of the magnetite particles were rounded small nonosphere (ranged from less than 5 nanometers to more than 100 nanometers), while biological magnetite are angular crystals and with a diameter from 50 to 150 nanometers.

The shape responds to the origin of the particles, “because they were formed as molten droplets of material from combustion sources, such as car exhausts, industrial processes, open fires,” Barbara Maher, lead author of the study, told SciDev.Net.

In the study, researchers also detected other metal particles like platinum, cobalt and nickel, and since none of them occurs naturally in the brain, their findings suggest that those particles could come from motor vehicle exhaust.

“Scientists have always believed the metal was formed in the body. The surprise is finding that they can enter the brain via inhalation,” Maher said.

Earlier studies suggested possible links between high levels of toxic magnetite in the brains of people who lived in highly polluted areas and Alzheimers disease and dementia. She noted: “These findings do not particularly prove that air pollution will cause brain diseases”.

“We need to do more work to see if this is a cause of brain disease,” Maher added.

According to the World Health Organisation (WHO) air pollution kills 1.3 million people globally each year.

Denise Eldemire-Shearer, a professor at the University of the West Indies, said the study raised the need for critical research given the “ageing populations and the increased importance of dementia research, the cost and the possible associated social costs”.

“We look forward to the wider study”, she said noting that the numbers of the individuals involved in the study were small.

Link to PNAS study

More than two billion people at Zika risk

Mapping Zika

Mapping the “environmentally suitable” areas where the Zika Virus could take a foothold.

 

More than two billion people who live in “environmentally suitable” areas around the world are at risk at of being infected by the Zika Virus, a study  from Oxford University in England suggests.

The team of researchers including Oxford’s Moritz Kraemer and Jane Messina concluded that the likelihood of the disease getting a foothold in vulnerable areas from the United States to China, is extremely high. The researchers combined climate data, mosquito prevalence and the socio-economic makeup of each region in the study: Mapping global environmental suitability for Zika virus.

With the state of Florida already caught up in its own mosquito eradication programme after several infections, researchers have also identified the states of Texas, sections of Louisiana, Georgia, Alabama and the Carolinas as vulnerable.

‘Environmental suitability’ also extends to large areas of sub-Saharan Africa, to more than two million square miles of India “from its northwest regions through to Bangladesh and Myanmar”; the Indochina region, southeast China and Indonesia. The study which was  published April 19 this year noted: that roughly 250,000 square miles of Australia are also at risk.

According to the researcher: “Globally, we predict that over 2.17 billion people live in areas that are environmentally suitable for ZIKV transmission”.

The researchers mapped data on the virus from its emergency in 1947 to the present and into the future. The findings indicate that a global area inhabited by 2.17 billion people is ‘highly suitable’ for the transmission of the Zika virus.

2006 Prof. Frank Hadley Collins, Dir., Cntr. for Global Health and Infectious Diseases, Univ. of Notre Dame This 2006 photograph depicted a female Aedes aegypti mosquito while she was in the process of acquiring a blood meal from her human host, who in this instance, was actually the biomedical photographer, James Gathany, here at the Centers for Disease Control. You’ll note the feeding apparatus consisting of a sharp, orange-colored “fascicle”, which while not feeding, is covered in a soft, pliant sheath called the "labellum”, which retracts as the sharp stylets contained within pierce the host's skin surface, as the insect obtains its blood meal. The orange color of the fascicle is due to the red color of the blood as it migrates up the thin, sharp translucent tube. The first reported epidemics of Dengue (DF) and dengue hemorrhagic fever (DHF) occurred in 1779-1780 in Asia, Africa, and North America. The near simultaneous occurrence of outbreaks on three continents indicates that these viruses and their mosquito vector have had a worldwide distribution in the tropics for more than 200 years. During most of this time, DF was considered a mild, nonfatal disease of visitors to the tropics. Generally, there were long intervals (10-40 years) between major epidemics, mainly because the introduction of a new serotype in a susceptible population occurred only if viruses and their mosquito vector, primarily the Aedes aegypti mosquito, could survive the slow transport between population centers by sailing vessels.

This 2006 photograph shows a female Aedes aegypti mosquito getting a blood meal from her human host, who in this instance, was the biomedical photographer, James Gathany, at the Centers for Disease Control.

The efficiency of the mosquitoes at spreading disease in urban areas plus population densities are reportedly the main factors contributing to this estimate. The study pointed out that the Zika Virus has been isolated in 19 different species of the Aedes family, although the virus was most prevalently found in the Aedes aegypti.

Other studies into the distribution of vectors have found that the Asian Tiger Mosquito (Aedes albopictus) – which is also responsible for the spread of the Chikungunya virus -has increased its territory and can now be found in Europe. Other Aedes species have also been found to spread the Zika virus, although to fewer people.

Health authorities are scrambling to produce a vaccine as other recent studies have indicated that ZIKV could lead to more severe complications than those already identified.

The Zika virus was first identified in Uganda and is transmitted by Aedes aegyptai mosquitoes, also the vector insect for the dengue and Chikungunya viruses. Prior to an outbreak in Micronesia in 2007, the virus was only known to cause illness in Africa and parts of Asia. In 2013 it began spreading outside its usual areas until the first outbreaks in Latin America in 2015 with Brazil bearing the burden of infections.

Aedes albopictus, the Asian tiger mosquito

Aedes albopictus also known as the Asian tiger mosquito, one of the most effective vector insects for mosquito diseases

The rapid spread of the virus raises concern that it could quickly impact vulnerable areas around the globe, leading to its declaration as a Public Health Emergency of International Concern by the World Health Organization.

In addition to the UK, researchers also came from several prominent universities in the USA, Canada, Sweden, Australia and Germany.
-Zadie Neufville

The study Mapping global environmental suitability for Zika virus is online

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