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.