What is a virus?

A virus is basically a nucleic acid (RNA or DNA) wrapped by a protein coat or capsid. Most biologists do not consider them to be alive. Here is a typical definition from Suite 101.com: "Viruses are acellular non-living particles...incapable of carrying out all life processes."

There is some disagreement, however, and it begins with the definition of life itself. The University of Cape Town (South Africa), in its on-line course on the Introduction to Virology, defines an organism as "the unit element of a continuous lineage with an individual evolutionary history." By this definition, viruses can be considered organisms because they do replicate and have a traceable evolutionary history.

Whether considered living or non-living, viruses are efficient parasites of plants and animals. The diagram above, taken from Wikipedia, shows a typical virus replication cycle. It begins with the virus attaching itself to a suitable cell, followed by the injection of the viral genetic material into the cell. Once inside, the virus comandeers the cell's machinery to assemble the building blocks needed to produce new virus particles.

The encoded hereditary information, or genome, inside a virus particle is incredibly diverse, a greater variety of structures than those found in plants, animals or bacteria. In addition, viruses may change their genetic code through mutation, or simple errors in copying the RNA or DNA that make up the virus. They may also "reassort" or swap genetic information with another virus strain to create a new, drug-resistant one. This is what scientists believe happened with the current flu bug affecting Mexico. It is actually a mixture of genetic information from swine, avian and human inluenza viruses.

Given this genetic complexity, the identity of a virus is diffiucult to nail down. Health authorities in Mexico have had to send samples from flu victims to Winnipeg, Manitoba or to the Center for Disease Control and Prevention in Atlanta, Georgia for confirmation. This is one of the reasons that it has been so difficult to get clear data about the number of people infected with the new virus or the mortality rate it has caused.

In today's press conference, Health Secretary José Angel Córdova announced that Mexico is in the process of establishing six new laboratories that will be able to speed up the identification process. Hopefully, these new resources will be able to give us a clearer picture of the status of the outbreak and the possiblities of resuming a more normal routine next week.

Factory Pig Farms: Culture Media for Viruses

Two articles in today's La Jornada point to one of the possible reasons for the current world public health alert: the way we raise livestock for food. Mike Davis, in "Los cerdos peligrosos usan traje," Dangerous Pigs Wear Suits, points out the problems created by the "transnational industrialization of livestock production." Raised in cramped pens, fed antibiotics and hormones to keep them alive long enough to go to market, pigs have become the perfect culture medium for new strains of drug-resistant virus. According to Davis, in 1965 the US raised 55 million pigs on a million farms. Today it raises 65 million swine in only 65,000 farms, more than half of which contain more than at least 5,000 animals each.

The current crisis was predicted years ago. Davis cites a 2003 Science article by Bernice Wuerthrich that states that "after years of stability, the North American swine flu virus has jumped towards a fast track evolution." In 1998 a North Carolina pig farm was decimated by an outbreak of a particularly virulent strain of the swine flu. For some scientists this event marked the genetic change towards ever more lethal viral strains.

The second La Jornada article of interest today was "Cuna de la influenza patógena," written by Alejandro Nadal. The article traces the viral outbreak in Mexico to a young boy who contracted the disease in the town of La Gloria, near Perote, Veracruz. The boy came down with the disease in March along with 400 others in that mountain village. By April 6 state government authorities had recognized a strange "respiratory disease" and cordoned off the area.

So why might the disease appear in a small village in Mexico's Sierra Madre Oriental? Well, it turns out that the Granjas Carroll, a subsidiary of the transnational Smithfield Foods, has a pig farm in the area. In last night's news conference, Health Secretary José Angel Córdova avoided answering a journalist's question about whether the Perote outbreak was the origin of the disease in Mexico.

A crisis such as the one we are living, is an opportunity for reflection about the way we live. One element that deserves thought is our diet. We tend to take the food on our table for granted without questioning its origin, or the form in which it was produced. An increasing number of authors have suggested that the way we raise our livestock is a danger to our health.

The above photo was taken from Marlerblog, http://www.marlerblog.com/tags/campylobacter/, written by Bill Marler who writes about health issues related to our farming techniques.

For further information, check out this article from El Universal http://www.eluniversal.com.mx/notas/594485.html

Science in the Time of Influenza

April 28, 2009--It has been three days since the World Health Organization declared a worldwide health alert due to the appearance of a new virus in Mexico. While some are calling it "swine flu," others point out that it has genetic information from avian and human flu virsues as well. What makes this outbreak important is that the disease is able to be transmitted from human to human and a vaccine has not yet been devoloped against it.

Schools have been shut down, first in Mexico City and the State of Mexico, now nationwide. Public meetings for entertainment have been canceled. Yesterday the mayor ordered all restaurants and bars to close their doors. Discussions have been held to decide on shutting down the capital city's vast transportation system which transports millions daily. In the absence of a vaccine it is hoped that keeping people at home will shut the virus down.

While this blogspot was designed to comment on natural history in Mexico from a Humboldtonian perspective, this public health emergency is something that would have attracted the Prussian scientist's attention. For what distinguished Humboldt was his awareness of the impact of the environment on people and the need to use science to improve people's lives.

In the next days, I invite my students to offer their opinions, to share information they find important to understanding what is happening. Why are there more mortalities in Mexico than in other countries where the disease has appeared? What is the link with pigs? Why did they become a jumping off point for this new viral strain? How do viruses operate? If they're not alive, how can they evolve?

There are many scientific questions to be asked. Newspapers, television and the interent are now offering a variety of reports that try to help us understand what is going on. If you find an important piece of information, share it here. If you have an opinion about the response to the crisis, post it here. The aim is to provide a forum in which we can learn together about what is happening and try to understand it better.