Infectious Disease Blog

The red, oozing cold sores that come from herpes simplex virus have been a genetic mystery to scientists, at least until now. Researchers from the Utah School of Medicine have located a portion of the chromosome that may be linked to herpes susceptibility, according to the Pharmaceutical Business Review.

The team of researchers has narrowed the search for specific genes to six areas on chromosome 21. The results of the study will be published Friday in The Journal of Infectious Diseases. This is the first whole-genome study of herpes to use linkage analysis.

As John D. Kriesel, one of the study’s authors and a research associate professor in the Utah School of Medicine’s Division of Infectious Diseases, told DailyIndia.com:

“One or more of these genes might make excellent targets for new drugs to reduce the number of herpes outbreaks,” said Kriesel.

Researchers found that herpes outbreaks are about 20 percent heritable. As told to the Deseret Morning News:

“That’s very significant, but it means about 80 percent of the disease is due to other stuff. Do you ski without sunscreen on your lips? Are you prone to febrile illnesses? What strain of virus did you get?” Kriesel said.

The prospect of linking herpes to a gene seems to have excited the online world. Science Blog picked up on the story and got some reader comment already. The Genetics & Health blog discussed the study’s findings and included a helpful 3-D image of the herpes simplex virus.

With global warming there’s more at stake than melting icebergs, dying coral reefs and bizarre changes in weather patterns. As temperatures rise, so will the incidence of disease – and it won’t just hit the nations of the developing world. Britain is at risk, too.

According to a paper published in the British Medical Journal this week, global warming will drive up rates of cardio-respiratory disease, diarrhea and insect-borne diseases in the United Kingdom.

The body has to work harder to cool down when it’s hot outside. A lot of blood is circulated to the skin to keep it cool, which causes strain on the heart. Higher pollution levels from greenhouse gases are expected to increase asthma rates and other respiratory problems.

As mentioned in my post on dengue fever, rising temperatures will likely bring mosquitoes and other insects farther north than they would normally migrate. While it may be hard to believe, malaria could pose a threat to Britain.

Tony McMichael, an author of the study, explained the potential magnitude of the malaria threat to Earthtimes.org:

“While it is unlikely to cause entirely new diseases it will alter the incidence, range and seasonality of many existing health disorders,” he wrote. “So, for example, by 2080 between 20 and 70 million more people could be living in malarial regions due to climate change.”

The UK’s Times Online spoke with an expert who explained the possibility of vector-borne illnesses traveling northward:

“Climate change poses a significant risk of the introduction of vector-borne diseases into Europe and indeed there is evidence that such change has already happened,” says Paul Hunter, a professor of health protection at the University of East Anglia. “Several vector-borne diseases not previously described in Europe have appeared, including chikungunya [a virus carried by Asian tiger mosquito that causes fever, headache and joint pain]. There was an outbreak in Italy last summer.”

McMichael’s study does bring a disclaimer to mind for those who are skeptical about the spread of tropical infectious diseases to northern countries: Watch out Britain, maybe.

A doctor’s worst nightmare is coming true. An even more drug-resistant strain of Methicillin-resistant Staphylococcus aureus, commonly known as MRSA, is emerging in the United States. The strain is an altered version of USA 300, the most common form of community-acquired MRSA in the U.S.

Four treatments formerly effective against USA 300 are now largely unresponsive. These drugs are: clindamycin, ciproflaxcin, tetracycline and mupirocin.

According to the Chicago Tribune, a recent study found the strain of MRSA:

“ … primarily in urban gay communities in San Francisco and Boston, though anecdotal reports indicate it has also been seen in Chicago, New York, Los Angeles and Philadelphia.”

Researchers worry the strain will spread further. Some experts suggest the microbe will adapt and become resistant to more antibiotics.

While the study suggests the more drug-resistant strain of MRSA has been found in gay men, About.com’s Infectious Disease blogger Anna Spector says not to worry:

“But have no fear, all the hype is based on one article published by scientists who studied gay men from two populations. And keep in mind that many previously healthy people get MRSA, so men who have sex with men should not be the only ones targeted in the media.”

A glimmer of hope shined through this week in the battle against malaria. A new malaria vaccine showed promise in a small test trial in Mali.

Researchers said the vaccine was safe and elicited strong immune responses from the 40 adults who participated in the trial.

The vaccine was designed to block the malaria parasite from entering blood cells. This was the first test of the vaccine in a malaria-endemic country. The research team is now conducting the next trial in 400 Malian children ranging in age from 1 to 6.

According to the Malaria Vaccine Initiative, the ideal malaria vaccine would be:

safe

easy to manufacture

easy to administer

when administered in infancy, confer life-long immunity against all forms of the disease

Many vaccine candidates fail during development, making the process an expensive and financially risky venture. With malaria infecting 350 million to 500 million people each year and killing over one million, the need for a malaria vaccine is urgent. Most of the victims are young children in sub-Saharan Africa.

Imagine feeling crawling, biting and stinging sensations on your skin. Colored threads and worms crawling out of eyeballs are also part of the ensuing creepiness.

Can there really be a disease with the symptoms described above? The answer is a disputed yes. Morgellons Disease is the name given to what the CDC calls “unexplained dermopathy.”

The cause of this unexplained skin condition is unknown. Researchers do not have enough information to know if these patients share similar risk factors.

Thanks to a post I read on About.com’s Infectious Disease blog, I found out the CDC announced last week that it is conducting epidemiological studies about the illness.

The goals of the CDC’s investigation is to learn more about:

“… who may be affected with this condition, the symptoms they experience, and to generate hypotheses about factors that may contribute to it.”

If you or someone you know has symptoms like the ones described above, please contact the CDC.

What happens when not just one, but two outbreaks of infectious diseases strike a country? The people of Malta are in the midst of it.

After outbreaks of rubella and scarlet fever were confirmed in Malta this week, the country’s Health Promotion and Disease Prevention Department has told the public there is no reason to be alarmed.

What struck me about these outbreaks is that neither of these diseases is common in Malta. One expert even went as far to call them rare illnesses in Malta. How does an illness rarely found in a part of the world turn up there?

Searching a bit, I also found that there were four confirmed cases of rubella this month in Sydney, Australia.

In this day and age, rubella has become somewhat or a rarity, with most infants receiving the measles, mumps and rubella (MMR) vaccine. Children receive the first shot around the age of one and a booster dose at the age of 4 or 5. In the Australian cases, all four children were infants. Perhaps they had not yet received their MMR vaccines, which would explain their susceptibility to the disease. However, the three people who got rubella in Malta were in their 20s. It was confirmed that none of these three patients had the MMR vaccine.

Following up to my post on low immunization rates in American adults, maybe the U.S.’s National Foundation for Infectious Diseases has a point. Not enough people are getting vaccines. This problem spreads beyond the U.S. and to other countries in the world, such as Malta. Do I hear a global call for vaccination at hand?

A device made to help the environment is likely to be the cause of an outbreak of Legionnaires’ disease in Norway. Industrial air scrubbers, which are air pollution control devices that remove particulates and gases from exhaust streams, may have spread the disease to 56 people.

This is an example of an industrial air scrubber made by Monroe Environmental. Please note that the make and model of the air scrubber were not mentioned in the article. 

Legionnaires’ disease is a form of pneumonia caused by the bacterium Legionella. According to MedlinePlus:  

Legionnaires’ disease is a type of pneumonia caused by bacteria. You usually get it by breathing in mist from water that contains the bacteria. The mist may come from hot tubs, showers or air-conditioning units for large buildings. The bacteria don’t spread from person to person.

Out of the 56 people that were diagnosed with Legionnaires’ in May 2005, 10 of them died. Investigators found matching strains of bacteria in the air scrubbers and the infected patients.

This isn’t the first time the threat of Legionnaires’ has arisen from an air conduit. Less than a month ago in Auckland, New Zealand, high counts of Legionella were found in cooling towers in neighboring buildings. Legionnaires’ was also to blame for three deaths in Christchurch and one in Beachlands, New Zealand, in 2005. 

Last quarter, one of my peers in Methods came down with an illness in the last week of class. We didn’t even get to say goodbye to her after the quarter was over because she was so sick. We later found out that she had fallen prey to shingles, or the adult version of chicken pox. I suppose she had not had the shingles vaccination.

Apparently my peer isn’t the only one who could have avoided an infectious disease if she would have taken its vaccine. New data shows that adults are getting immunized at low rates and that they aren’t very aware of the potential threat of infectious diseases. The National Foundation for Infectious Diseases is sponsoring an event Wednesday talking about the low public awareness of the importance of adult vaccinations.

Here are some quick facts from the data:

• More than 1 million shingles cases per year
• About 6 million HPV cases a year and 10,000 cervical cancer cases
• Significant rise in whopping cough

My friend who had shingles could have taken the vaccine for it, but many of us in our early 20s are not thinking of getting vaccinated for a disease that is most common in people over 50. The FDA-approved shingles vaccine has been out on the market for over a year. Because of the unpredictability of infectious diseases, the National Foundation for Infectious Diseases wants adults to be more aware of the vaccines available to them.

Vaccines could prevent countless cases of the infectious diseases mentioned above and could prevent the deaths of many American adults. Why face the disease if you can prevent it by taking a vaccine?

Some people think diseases from distant lands may not seem like a threat, but they’re wrong. Geographical distance from an affected area is not enough to keep the disease from spreading to other places. Two researchers say this is the case with dengue, a tropical virus that has already struck in the United States. Cases have cropped up in Texas and Hawaii, leading people to fear the spread of the disease.

The researchers suggest global warming is part of the reason to blame for the movement of the disease to non-tropical climates. Dengue is transmitted to humans by Aedes mosquitoes. The mosquitoes are traveling farther north and little is being done to control the mosquito populations.

According to MedicineNet.com, people with dengue fever display the following symptoms:

• chills
• headache
• fever
• pale pink rash
• swollen glands
• pain when moving eyes
• leg and joint pain

The solution to the spread of dengue fever isn’t simple. There is no vaccine. The public will have to wait at least five to 10 years before a vaccine comes out. Instead of vaccines, the CDC recommends mosquito population control and disease prevention. While this may be a good solution in the long run, there needs to be a plan to mitigate the impact of the current spread of dengue fever. Blood screening tests for dengue need to be improved so that doctors can catch cases early and prevent an outbreak in a community. The last thing we need is an epidemic of this potentially deadly virus.

When I think of infectious diseases, I tend to think of the classics: smallpox, AIDS/HIV, Ebola, Tuberculosis, etc. While I have a loose definition of infectious disease, I decided to find out how what it takes to be classified as an infectious disease.

According to the MedlinePlus Medical Dictionary, an infectious disease is:

Main Entry: infectious disease
Function: noun
: a disease caused by the entrance into the body of organisms (as bacteria, protozoans, fungi, or viruses) which grow and multiply there — see COMMUNICABLE DISEASE, CONTAGIOUS DISEASE

An important distinction to note is that an infectious disease is not synonymous with an infection. An infection may not cause clinical symptoms or impair host function.

Infectious diseases can be classified by the type of source they originated from. Viral, bacterial, parasitic, fungal and prion are all types of infectious diseases. Infectious diseases in animals that can be transferred to humans are called zoonotic diseases. Some examples of these are anthrax, plague, Tuberculosis and West Nile Virus.

Symptoms and treatments vary with each disease. Most of the time, infectious diseases are treatable with antibiotics.

Are there any infectious diseases you want to learn about? What infectious diseases have you been following in the news? Please comment so we can discuss it.