Aerosolized Fungal Infection from Bats

By Jonathon Marioneaux

As promised, we will be continue our coverage of bats and their diseases this week.  Over the last several postings we have covered different diseases bats can carry and their place in folklore.  In many horror stories and movies the main antagonist resides in a cave which makes you wonder, what else is in that cave? One of the main diseases that can be contracted in caves is histoplasmosis, which as it turns out is a relatively common disease.  Researchers from Heliopolis Hospital in Brazil documented a case of oral manifestation in a patient in 2013 that provided clinical details to the history and progression of the disease.

Histoplasmosis is a fungal infection caused by Histoplasma capsulatum and has two variants—capsulatum and duboisii. The fungus is found in caves worldwide, however most clinical cases occur on the American continent.  H. capsulatum requires moderate temperatures and constant humidity to grow and does best in bird or bat guano.  The fungus is found in its hyphae form primarily in caves and reverts to its yeast form in human lungs due to the higher temperature.  The fungus is primarily transferred to humans in its aerosolized form during cave diving, giving it the nickname “Caver’s disease” and “Spelunker’s disease.” However, it can also be transferred any time soil aerosolizes, for example, during digging.

The disease has a relatively low mortality rate in immunocompetent people and may go undetected as mild flu symptoms. Yet in people with compromised immune systems, such as AIDS patients, it can reach mortality rates as high as 80% and can be a tool for AIDS diagnosis.  In some cases the disease can become chronic in the presence of underlying disease and become severe to life threatening.  Diagnosis of H. capsulatum can be difficult due to its mimicking of other diseases, such as tuberculosis, and limitations of diagnostic exams.  The gold standard for diagnosis is culturing of the fungi on dextrose slats which will show white or brown filamentous colonies.

The Brazil patient was initially admitted on complaints of oral lesions and shortness of breath to the Heliopolis hospital.  The initial diagnosis was tuberculosis, however radiography diffuse infiltrate of both lungs and negative acid-fast staining discounted this.  Subsequent tests showed CD4/CD8 lymphocyte count was normal, discounting HIV, and culture tests indicated fungi presence.  A biopsy of lung tissue showed Langhas-type multinucleated giant cells with variable amounts of lymphocytes consistent with histoplasmosis. The patient was treated with Itraconazol for six months and showed marked improvement.

The above example explains why the conversation between patient-doctor and doctor-doctor is very important.  Without knowledge of the patient’s history and the referral by the dentist it is possible that a positive diagnosis could never have been made. This is especially true with organisms which are hard to grow or mimic symptoms of other disease.  In addition, knowing the immunocompetent state of a patient can give clues to what type of pathogen might be present.

So, when going spelunking or anywhere near animal feces wear a mask or other protective covering to prevent infection from various diseases including H. cacsulatum. Bats are our friends and serve a much needed role in pollenating plants and keeping insects under control during the warm parts of the year.  Let’s not forget their contributions when discussing their role in disease transmission and the Hollywood spin put on them for Halloween. It is always advisable to take caution when handling bats of any species or geographic location to prevent the spread of numerous viral, bacterial, and fungal agents that they carry.

With Halloween upon us, this concludes our series on bats and their diseases. Next week, we will pick up coverage of birds (if you have a specific bird you would like me to cover send me an email) to get into the Thanksgiving spirit.

As always remember to wave at the next bat and thank them for their invaluable service to our ecosystem!

New Bat Flu Found

By Jonathon Marioneaux

Halloween is right around the corner, so we continue our coverage of one of the most notable creatures of the season: bats. Previously we covered vampire bats and their role in spreading rabies to humans and livestock in South America.  Considering how bats appear to be vectors for both Ebola and rabies this made left me wondering what other viruses bats carry.

Many animals carry some sort of virus that belong to the Orthomyxoviridae family which is broken into three classes A, B, and C.  Classes B and C primarily infect humans while class A infects a range of hosts including birds, mammals, and reptiles. However, no Orthomyxoviridae virus has been found in bats, or so we thought.  In October researchers from Maryland and Kanas discovered a new flu virus that can be transmitted between bats and in doing so discovered a new lineage of the Orthomyxoviridae family and a potential new pandemic flu.

Influenza is a negative sense RNA virus consisting of 7-8 segments allowing it to recombine during infection and create new combinations of RNA segments.  Multiple types of influenza can infect a host cell simultaneously allowing strains of flu from different hosts to recombine in novel ways.  This ability to be infected with different types of influenza viruses is why there are new outbreaks of the flu every year and why the virus has the potential to become a global pandemic if the correct reassortment happens.

Bats carry many diseases such as Coronaviruses, Filoviruses, and Henipaviruses, but as stated earlier, no Orthomyxoviridae have been previously found.  While trying to sequence genomes the researchers found influenza-like RNA sequences in tissue cultures.  However, when these sequences were introduced into cell cultures they did not replicate efficiently.  The researchers then synthetically altered the surface protein structure and re-infected cell and animal models.  The virus reproduced efficiently in the cell and mice models with high mortality among the mice; thus showing that the virus can reproduce in traditional flu hosts. The researchers indicated that the bat virus does not have the same surface proteins that influenza A and B contain.  This lack of ability to infect the same cells shows high cell specificity that results in a limitation of the cell types that influenza A and bat influenza can infect.  Finally, the genetic differences that are seen in the bat influenza virus indicate that they are a distant relative of the current influenza types, thus potentially making them a new branch of the Orthomyxoviridae family tree.

The difficulty in growing the bat viruses in traditional cells without modification indicates that the virus does not have the necessary surface proteins to enter cells.  However, after synthetic modification the bat virus was very lethal in host cells and animal models.  This indicates that the bat virus is only distantly related to the influenza A and B types that circulate currently.  Therefore, the risk of reassortment between flu viruses is small and there is a smaller risk of a global pandemic.

In conclusion,  bats harbor many viruses and make great Halloween decorations but they pose little risk for a global pandemic of zombie apocalyptic proportions and are great for the environment.  So, make sure you thank the next bat that you see and we will continue our coverage of our winged friends next week.

Transmission of Rabies by Bats in South America

By Jonathon Marioneaux

Halloween is still weeks away but it is never too early to get into the spirit of ghosts, goblins, and vampires.

Two common Halloween characters are the vampire and the bat so it is fitting to review vampire bats and their real impact on modern society.  In addition, another favorite of Hollywood is the zombie, depicted as a flesh eating undead corpse infected by a rapidly progressing virus.  The closest virus that causes these symptoms is the rabies virus which makes its host bite other animals in order to spread the virus by contaminated saliva. In my research of these two organisms (vampire bats and rabies), I discovered an interesting mini-literature review published in 2003 on the spread of rabies by vampire bats in South America.

Vampire bats are the principle spreader of rabies in South America. The virus infecting humans and livestock causes millions of dollars’ worth of damage to local economies. These bats are known as haematophagous bats belonging to the order Chiroptera with the most well-known species being the hairy-legged vampire bat (Diphyella ecaudata) and the rarer Desmodus rotundus. These bats feed on animals ranging from snakes to amphibians and cattle to humans and drink between 15 and 25 milliliters of blood per meal.  During their blood meal the bats spread the rabies virus through their saliva resulting in paralytic rabies.  Rabies has an incubation period of 21-150 days and causes muscular tremors, excessive salivation, spasms, and erratic activity.  If left untreated rabies is almost 100% fatal with only three known causes of survival without prophylactic treatment at the time of publication. Rabies can be prevented by the rabies vaccine however it is only given irregularly in South American livestock thus leaving many animals susceptible to paralytic rabies.

In South America, rabies has been blamed for expanding bat populations. Different population control methods have included lethal gas and/or dynamiting bat caves and coumarin paste. These methods led to the death of enormous quantities of bats but only a slight reduction in the numbers of rabies cases.  The rabies virus is spread by saliva and asymptomatic bats do not excrete infectious virions therefore the majority of the bats killed probably did not have rabies.  The spread of rabies in humans is mainly in areas that were previously covered by rain forests that were cleared to make build ranches and urban areas.  The main site of transmission is usually in the toes of individuals living in hazardous housing.

Therefore, urban sprawl and deforestation have led to the spread of rabies from bat populations to humans and livestock.  The current methods of controlling rabies, such as dynamiting caves and gassing known populations, may have the unintended effect of killing beneficial bats such as insectivorous (those that feed on insects) and nectarivorous (those that feed on nectar).  A more effective way of reducing the damage to livestock is more consistent animal vaccination practice which is effectively makes the animals vampire bat repellent.  In addition, educational campaigns should be introduced to reduce the “Dracula” image that many bats have.  It is widely known that bats are beneficial to the ecosystem and must be protected. Indiscriminate killing of bats might make a good Hollywood thriller but it is not good for the environmen

Pandora Report 4.4.14

It’s been a busy week in the biodefense world, between the continuing outbreak of Ebola in Western Africa and the realization that the Black Death may actually have been pneumonic plague rather than bubonic plague, so let’s take a moment this Friday to slow things down.

Highlights include Ebola travel restrictions, a possible source for the Ebola outbreak, and how to protect yourself during the most serious pandemic of all—the zombie pandemic. Have a great weekend!

When planning your vacation to Guinea, keep this in mind…

As of April 1, the number of suspect Ebola cases in Guinea has risen to 127 with 83 deaths (for a case fatality rate of 65%) according to the WHO. Liberia now has eight suspected cases with five deaths. Sierra Leone has had only two deaths after two bodies were repatriated after dying from Ebola. In neighboring Mali, the government has instituted thermal scans for those travelling to Mali as well as restricting movement within the capital city of Bamako. Meanwhile, Senegal has closed their border with Guinea and Saudi Arabia has suspended visas for Muslim pilgrims coming from Guinea and Liberia. Despite all of this, the WHO does not recommend travel restrictions.

Philippine Daily Inquirer—“The international health agency said there was not enough reason to push for the imposition of travel restrictions in response to the Ebola outbreak. “WHO does not recommend that any travel or trade restrictions be applied with respect to this event,” it said in a statement.”

And while on vacation, here are some foods to avoid…

In another response to the Ebola outbreak in Guinea, officials have taken an unusual step of banning the consumption of bats as food—including grilled bat, bat soup and “other local delicacies.” It has long been suspected that bats are somehow instrumental in the spread of Ebola either as a vector or a reservoir for the disease.

CBS News—“‘We discovered the vector [infectious] agent of the Ebola virus is the bat,” Remy Lamah, the country’s [Guinea] health minister, told Bloomberg News. “We sent messages everywhere to announce the ban. People must even avoid consumption of rats and monkeys. They are very dangerous animals.’”

The good news is, in the event of a serious pandemic, you may have new protection!

Just in time for the Walking Dead finale last weekend, the American Chemical Society released new research related to the chemistry of death, and how that chemistry can shield us from the flesh and brain eating horde of zombies.

Science is a serious subject and pandemic possibilities are crises in the making…but that doesn’t mean science can’t be fun for a general audience!

Zombie Apocalypse Survival Chemistry: Death Cologne

What virologists’ dreams are made of: A total viral catalog

Believe it or not, we have a tremendous deal to learn about viruses. A lot of huge, fundamental questions about viruses remain unanswered –  are they alive or dead? Where did they originate? How many are there? This last question is in some ways the most feasible to answer, and scientists have begun to do so by examining Indian Flying Fox bats. In a new study, scientists at Columbia university took over a thousand samples from the bat species and scoured them for viruses. They turned up 55 viruses, of which a staggering 50 were hitherto undiscovered. Ten of them are in the same family as Nipah. The scientists now hope to take the viruses found from the Indian Flying Foxes and begin a catalog of viruses which infect the remaining 5,484 known species of mammals. Such a resource, while expensive to produce, would be a huge aid in preparing us for future zoonotic outbreaks.

New York Times – “We might be able to take away this element of surprise if we had a catalog of all the viruses lurking in mammals. As soon as a mysterious epidemic broke out, scientists could turn to the catalog to figure out where the virus came from, potentially gaining some crucial clues to the virus’s biology. But few scientists have ventured to build such a catalog, perhaps because there seemed to be such a vast number of viruses to contend with.’No one’s really been addressing this question, even though it seems like such a fundamental one,’ said Simon J. Anthony, an associate research scientist at Columbia University and a researcher at EcoHealth Alliance, a New York-based scientific research organization.”

Read the full article here.

(image: Fritz Geller-Grimm)