New and speedy methods for detecting Candidemia

In class we learned that Candida species can cause disease in humans. They can cause thrush or genitourinary, yeast, infections. In healthy individuals these diseases are easily treated and usually mild. If the Candida is found intravenously or in immunocompromised patients it can become systemic causing various symptoms. In these situations it is imperative that the cause of the systemic infection be diagnosed quickly. Currently because of the difficulty in diagnosing systemic Candida it has a mortality rate of 40 – 50%. This leads to 36 – 45000 deaths in the US each year.  This is a serious risk for many patients and it is important that they are diagnosed as rapidly as possible and Neely et al demonstrates such a rapid detection in T2 Magnetic Resonance Enables Nanoparticle-Mediated Rapid Detection of Candidemia in Whole Blood. In short, the method that Neely developed starts with standard PCR method to selectively amplify DNA that was released from the Candida. From here the amplified DNA is captured by probes that have specific spectra that allows the species to be identified by T2MR, magnetic resonance. This allows for detection at levels, much lower than conventional methods, down to 1 to 3 CFU/ml depending on the species. Though the sample sizes was small if this can be proven to work well it may improve the outcome of patients and lower the mortality rates. There is also the potential that this can be used on diseases caused by organisms other than Candida when time is critical and there are no rapid tests currently.

Travelers' diarrhea traveled to Iowa

Cyclospora is a parasite that is known to cause disease in humans. It was first found in the United States when fecally contaminated raspberries were imported around 1990. When Cyclospora causes disease it is usually acquired when a person travels to an endemic area. The symptoms of Cyclospora infection are gastroenteritis which includes watery diarrhea for which it has gotten the name travelers’ diarrhea. Humans are the only host and it is transmitted by the fecal oral route. Though this can be quite unpleasant it is a rare and self-limiting infection. Though unlikely if left untreated it averages 2 month of diarrhea.

Recently dozens have gotten sick in Iowa with this parasite. In the last 20 years only ten cases of Cyclospora were reported and in the last few weeks 45 have gotten sick in Iowa and another 35 in Nebraska. Currently the source is still under investigation but it is believed to be a shipment of vegetables from a single farm outside of Iowa.  Because it can take two weeks for symptoms to appear it has been hard to find the shipment responsible for the contamination. Fresh vegetables don’t usually last two weeks and the new cases are slowing. Remember the benefits of vegetable are much more than the risks of contaminated food. 

Expanding vector the Asian tiger mosquito

So far this year there have been reports of West Nile Virus in 21 states and 10 cases of West Nile disease in the United States. West Nile is a mild disease that only causes symptoms in 20% of people infected and less than 1% of the infected progress to the sometimes fatal neurologic illness.

Most people know that West Nile virus is spread by mosquitoes and mosquitoes are active at dusk and early evening. In many parts of the country that is changing, 30 years ago the Asian tiger mosquito came to Texas on a tire shipment and is now found on 27 states. It is an interesting looking mosquito with a black body that has white stripes. This mosquito is particularly adept at spreading disease including West Nile virus because it is active at all times of the day and very aggressive and will not let go once it bites.

To best control the Asian tiger mosquito it is important to remove all sources of standing water and experts recommend that individuals use a repellant with DEET cover up with long sleeves and pants. The Asian tiger mosquito likes to bite ankles and knees.

This is an invasive species that may be impossible to control because it is aggressive and spreading and has an advantage over the native mosquitoes in that its eggs are much more resilient and can survive winter freezes.

So if you see a mosquito it is time to cover up. 

Viral hemorrhagic fevers

In class we talked about viral hemorrhagic fevers caused by Marburg virus and Ebola virus. The diseases caused by these viruses are very scary but rare. There are no known vaccines or cures and the disease progresses quickly and can lead to death. Human to human transmission has been shown death rates approach 90%. The rapidly progressing disease is unpleasant to say the least, vomiting, diarrhea, and hemorrhaging.

A little more on the Marburg virus, it was first isolated in 1967 in Germany. Since 1967 most outbreaks have occurred in sub-Saharan Africa. It is a zoonotic disease that has been shown to have at least bats as one reservoir it is unknown if other hosts exist. The structure of Marburg is a filamentous viral structure.

Currently work is progressing on vaccine development because it is such a deadly virus that can be used for bioterrorism. The first vaccine attempts which failed were using inactivated virus. Recombinant glycoprotein vaccine attempts were protective in some animal models but protection was incomplete in NHP. Current approaches that are showing progress are the use of viral vectors using either replication-defective adenoviral vectors or recombinant VSV expressing MARV GP.  Because of the lack of treatment and ability to spread from human to human this is a dangerous virus to work and requires BSL-4 safety precautions. But because it is a rare disease it is not one that most should worry about.

Forty-Five Years of Marburg Virus Research

Kristina Brauburger,† Adam J. Hume,† Elke Mühlberger,†* and Judith Olejnik†

Viruses. 2012 October; 4(10): 1878–1927. 

Differing views on the HPV vaccine

In the United States, the rates of vaccination for HPV are currently about 1/3 of females 13 – 17 have completed the vaccination schedule with another 16% have had at least one of the three doses for the vaccination.  With vaccination rates approaching 49%, infection by the strains included in the vaccine have dropped by 56% in girls 14 – 19 in the four years that the vaccine has been available. With such results the CDC is asking healthcare professionals to help them reach rates of 80% or greater as quickly as they can.

CDC Director Tom Frieden described the potential of HPV vaccination in terms of the impact on cancer prevention.

"Our low vaccination rates represent 50,000 preventable tragedies -- 50,000 girls alive today will develop cervical cancer over their lifetime that would have been prevented if we reach 80% vaccination rates,” Frieden said in a statement. “For every year we delay in doing so, another 4,400 girls will develop cervical cancer in their lifetimes."

In contrast to the reports from the US, Japan’s Ministry of Health, Labor and Welfare on June 14 withdrew its recommendation of the vaccine. Japan currently covers the cost of the vaccine for anyone that receives it but the Ministry has concerns of side effects. There are nearly 2000 possible cases of side effects from 3.28 million vaccinations some are severe. Because of this the Ministry is investigating the vaccine and currently allows the vaccination to continue while support is withdrawn but has not made a final decision.

A link between latency and oncogenic viruses

This is a hepatocellular carcinoma in a woodchuck caused by hepadanvirus.

Viral latency is a stage in the lifecycle of some pathogenic viruses that may help a virus hide from the host. In latency viruses become dormant, also called latent, in infected cells. These infections are considered persistent but not chronic because viral replication is not occurring. During this time the viral genome is still present.  The viral genome may be in one of two forms; genetic episomes, distinct objects that may be in the nucleus or cytoplasm in lariat or linear structures, or as a provirus which is the genome of the virus integrated into the host cell’s genome.  Once the virus has entered latency it may need maintenance by the expression of some viral genes. As the cell replicates the daughter cells are already infected and any of the latently infected cells can be stimulated to proceed to lytic infection.

transformation

Though a latent virus may at times be reactivated a more serious complication is the transformation of the cell and forcing it into uncontrolled division.  Many of the known oncogenic viruses including herpesviradae and HPV are shown to have latent periods. The transformation of the infected cell can be from the effects of the maintenance proteins activating growth receptors. When the viral genes insert into the host DNA it may change the expression of host genes and cause transformation of the cell. Either of these effects increases the replication of infected cells and are beneficial for the virus but may increase the harm done to the host.

rapid ID testing

an array of rapid id kits

Much of the testing in the microbiology laboratory uses technology and techniques that haven't

changed much since the 1800’s. Many of the tests used to identify organisms require special reagents or advanced training. Many of the test procedures require extended time from days to weeks depending on what organism is causing one’s disease. Another disadvantage of these testing methods is that many organisms isolated are so similar that it can be difficult to determine what is causing a person to be sick. Because of the limitations of the test available in the microbiology laboratory and advances in our understanding of pathogens rapid testing kits that can identify the causative agent during the course of a doctor’s office visit have been developed and many more will be developed.

prototype of mobile test
LCN

Currently there are rapid identification kits for many common or very serious pathogens such as strep, Malaria, and HIV. Though new tests are being developed at incredible speeds the list of potential pathogens is long and is growing. In class we were shown examples of cassette type rapid tests. With the penetration of the smartphone throughout the world many new types of test are being developed that can take advantage of the always connected nature to not only diagnose but to track the spread in effort to prevent the spread. Because these rapid tests require less specialized training they are beginning to appear on store shelves so that you can know the results of the test and inform the doctor so that he can start the treatment much quicker.