Final blog post

Thanks everyone for reading my blog I had fun putting the posts together. The semester has ended and so has the class that these blog posts were for. I will not be updating the blog any longer. Thanks for visiting the blog for infectious disease. I hope you enjoyed the posts.

Coccidioides

Coccidioides has been in the news lately. It is causing havoc in the California DOC causing them to have to relocate many prisoners and the rates of diagnosis is increasing as primary care providers are educated on the characteristics of the infection. Annually as many as 150000 people are infected in the US. Most of these people are in the southwest. Rep Kevin McCarthy of California is asking the FDA to add Coccidioides to the list of qualifying pathogens so that it will e more attractive for medical research and better treatments are cures can be found. Currently the standard for diagnosis is fungal culture. This culture can take up to 28 days and is difficult to perform. A recent study,¹ evaluated the ability of PCR detection. In this study the sensitivity and positive predicative value and determined that though they have improved in the last few years they are at 75 and 60% similar with the standard culture methods. Though the positive rates are low the negative predictive value and specificity are each 99%. As these tests are developed they will become cheaper and doctors will become more comfortable is can be used as a test to exclude the diagnosis of Coccidioides.

1  http://link.springer.com/article/10.1007/s11046-010-9327-0#page-1

Toxins make HIV worse

When you think of immunosuppression you think of a few things. First is AIDS or HIV but that is not the only thing that can cause immune suppression. Next is cancer another is other viruses and there are also many chemicals that are known to suppress the immune system. Many have been adapted for therapy weather it is for organ transplants or to treat cancers their use has saved many lives. Rarely thought of is that a fungus can suppress a person’s immune system.  Some very common fungi, members of Aspergillus, produce an aflatoxin which is one of the most carcinogenic substances known. A recent study of 314 Ghanaians showed a correlation between the aflatoxins and severity of HIV. It was shown when the levels of these aflatoxins were higher that the viral load of HIV increased. How can these toxins be avoided. Avoiding them is hard because the fungi that produce them are everywhere and they like to grow in

aflatoxin

grains and beans that are waiting for processing after harvest. In the US we are safe because federal law limits concentrations to 20 in 1 billion but in other areas of the world where much of the processing is not regulated and done by hand concentrations in moldy grain can get as high as 8000 per billion.

http://www.nytimes.com/2013/07/23/health/mold-toxins-tied-to-aids-epidemic.html?_r=1&

Blastomycosis rare CNS complications

Blastomycosis normally is an acute disease that usually presents in people that spent much time near rivers. It is endemic in areas near the Great Lakes and the Mississippi river valleys. It is very low in prevalence less than 2 in 100,000. Because it usually presents as a non-specific flu-like illness it is not usually identified unless there is an outbreak. If it becomes more serious it usually presents as a chronic pulmonary disease. In rare cases it may have central nervous involvement. This involvement is very serious and involves death at higher rates.  CSF evaluation will present with elevated protein, normal to decreased glucose, and a pleocytosis that is either lymphocytic or neutrophilic. Blastomycosis with only CNS involvement without other evidence of infections is rare.  Because CSF culture is insensitive it is useful to assay for antigen to detect blastomycosis in the CSF. It is important to be aware that the assay has crossreactions with H. capsulatum. Because of the mortality associated with blastomycosis when there is CNS involvement it is necessary that one be careful when identifying suspected blastomycosis. As laboratory scientists we can do much to identify blastomycosis and the faster it is identified the sooner the proper treatment can be engaged.

The attack of the killer squirrels

The plague has been found in a squirrel in Southern California. The plague infected squirrel was found July 16 by the California Plague Surveillance and Control Program. The positive tests prompted the closure of three campgrounds in the Angeles National Forrest. Warning signs were also posted in the area. It is now the duty of the health officials to find the squirrel’s homes and dust them for the fleas that spread Yersinia pestis. Once the testing indicates the area is plague free it will reopen.

This shows that plague is still a concern to worry about. Though plague is easily cured by antibiotics up to 10% of those infected may still die from it. This is much lower than before antibiotics where as many as 60% died. Though the plague is rare in humans now this shows that it persists in animals and that it can easily be found. Even with low death rates it is still a serious infection and because it can be found in animals it is something that we need to always be watchful for. Someone with the proper equipment and training could get many people sick and overwhelm the health system in an area which is the main concern for plague. 

Bacteria “talk”

Pathogenic bacteria have many selective pressures but one of the most important is antibiotics. Since the discovery of antibiotic compounds the seriousness of a bacterial infection has decreased to the point that most people recover from what is making them sick. We have heard of people getting one infection or another and having to have amputations because it destroys the tissue or dying from the infection but these are extraordinary circumstances. The use of antibiotics has made bacteria that have resistance to the drug better able to survive and the resistance has been spreading for years. We now have MRSA and VRE among the resistant infections we can acquire. Usually we think that resistance spreads by the spread of the bacteria or bacteria sharing genetic material.  Omar M. El-Halfawy, and Miguel A. Valvano showed another way that bacteria can share resistance in Chemical Communication of Antibiotic Resistance by a Highly Resistant Subpopulation of Bacterial Cells. In the article they show that when there is a mix of highly resistant bacteria and bacteria with less or no resistance that the resistance can be communicated to the entire population. The way that the resistance is communicated is the resistant bacteria excrete a chemical that inactivates the antibiotic and in doing so makes the entire colony resistant to the drug.

Chagas disease in the United States

As we learned in class, Chagas disease can be found in the United States and the CDC lists Trypanosoma cruzi as a neglected parasitic infection along with neurocysticercosis, toxocariasis, toxoplasmosis, and trichomoniasis. The CDC also estimates that there are at least 300,000 people in the United States with Chagas disease.

How does Chagas disease affect so many people? The triatomine bugs can be found from the east to west coasts and as far north as Pennsylvania. There are eleven species of triatomine in the US. Not only are triatomines found in much of the US but mammalian hosts with Trypanosoma cruzi have been found almost everywhere the triatomines live.

What can we do to prevent the spread of Chagas disease? The first thing is that living in a well-made dwelling prevents contact with triatomines. Because we do not contact the bugs there are only 7 known cases of autochthonous transmission to humans on the US. But currently it is estimated that 300 cases of congenital Chagas transmission happen each year. The biggest barrier to control is knowledge. Doctors don’t know that it is and that there are treatments once it is detected. Detection is also hampered because of the lack of any rapid point of care detection methods.

Bern, Caryn, et al. "Trypanosoma cruzi and Chagas' disease in the United States." Clinical microbiology reviews 24.4 (2011): 655-681.

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.

Better protection by saliva as we age

Better protection by saliva as we age

from UCLA 

Recently studies discovered that important changes in saliva happen as we age. But first what is saliva. Saliva is a secretion found in the oral cavity. It is required for many things. It initiates digestion, helps maintain teeth, is necessary for oral homeostasis, and has antimicrobial properties. Saliva is approximately 94% water the rest is an interesting mix of molecules. Many of the minor constituents have biologic activity required for the roles that saliva plays.

One of the major changes recently discovered is that as we age the glycoproteins that are expressed change. One change is that older people express glycoproteins with more terminal alpha 2-3/6-linked sialic acid residues¹. These sialic acid residues bind the hemagglutinin(HA) on the surface of viral particles. This provides protection against influenza. Qin et. al.¹ showed that the binding of the virus particles to the glycoprotein increases  and that the composition of glycoproteins changes to a mixture that has more binding sites as we age. This shows that even though as we age our immune system declines in effectiveness we have other protective mechanisms that continue to protect and even improve in their effectiveness as we age. 

1. Yannan Qin, Yaogang Zhong, Minzhi Zhu, Liuyi Dang, Hanjie Yu, Zhuo Chen, Wentian Chen, Xiurong Wang, Hua Zhang, and Zheng Li Age- and Sex-Associated Differences in the Glycopatterns of Human Salivary Glycoproteins and Their Roles against Influenza A Virus
   Journal of Proteome Research 2013 12 (6), 2742-2754

MERS- CoV an emerging virus

from presstv

Coronaviruses are of emerging concern. From the SARS outbreak to the current threat of MERS coronaviruses are definitely pathogens of concern.  What are coronaviruses and specifically MERS-CoV?  Coronaviruses are positive sense RNA viruses that have bulbous projections that appear like the solar corona. Coronaviruses have the largest genome of the RNA viruses. Upper respiratory and gastrointestinal tracts can be infected by coronaviruses. MERS-CoV was identified in 2012 as the cause of a respiratory illness in people. Discovery of this virus makes it the sixth coronavirus known to infect humans.  MERS-CoV is like the SARS-CoV in that it also involves the lower respiratory tract and is a cause of severe acute respiratory disease.

from abc news

Current reports are that the MERS-CoV has out of 55 cases 31 patients died. Whether this is from underreporting of mild cases or increased virulence is unknown. Symptoms start with cold or flu like respiratory symptoms. Like SARS-CoV, the MERS-CoV progresses to severe acute respiratory disease. Currently all cases are like to four Middle East countries: Saudi Arabia, Jordan, Qatar, and UAE. Travelers to these countries have also shown MERS-CoV. Close contacts have also presented with MERS-CoV indicating that it is transferable from person to person. Ease of transmission is currently unknown. In France, at least one case of nosocomial infection was reported. It is important to remember that though this is a rare it has the potential to become an important pathogen with high mortality rates and unknown transmission rates.

Blood volume effects recovery in bacteremia in automated blood culture systems

Automated blood culture systems have made bacteremia much easier to detect. The current systems use a prepared bottle that has responds to the growth of bacteria to induce an observable change. These systems use color, pressure change, or chemical change to detect the growth of bacteria in the inoculated bottle. These automated systems require a ratio of blood to medium between 1:10 and 1:5. If the volume of blood is too low there may not be enough colony forming units for detection. And if the ratio goes below 1:5 blood components may not be diluted enough and may inhibit bacterial growth. A study performed at China Medical University Hospital in Taichung, Taiwan1 showed the effects that blood volume can have on detection of bacteremia. Hsiu-Hsien et. al. performed this study were they retrained the ER department where 97% of blood cultures were done with less than 5mL of blood  and after training greater than 70% of blood cultures were done with at least 5mL of blood. In this study, it is evident that the amount of blood used has great impact on the recovery of organisms. They showed that with blood volumes of 5-10 ml that recovery increased by 17% over low volumes. Volumes greater than 10mL showed lower recovery rates than smaller volumes.

blood culture bottles

http://www.medicalobserver.com.au/assets/images/07-09-12-germgems.jpg

1 Hsiu-Hsien Lin et.al.  Evaluation of the blood volume effect on the diagnosis of bacteremia in automated blood culture systems  Journal of Microbiology, Immunology and Infection (2013) 46, 48-52 Http://www.sciencedirect.com/science/article/pii/S1684118212000503

post for the week of June 2

Welcome to my first blog post.

This is my blog for the infectious disease course, CLS538 at UAB. The purpose of this is to discuss the class and current developments in clinical microbiology.

I am a student in the Clinical Laboratory Science masters program at the University of Alabama at Birmingham. After all the other experiences I have had in school I am really enjoying the experiences and course work in this masters program. One thing that I think drew me to this program is the fact that as a medical technologist what I do in the laboratory has a direct effect on the health of a patient. What I do is helping others.

hCMV infected cells

http://www.meddean.luc.edu/lumen/MedEd/orfpath/images/fig131x.jpg