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.