The Black Plague and COVID

What the Plague Foretold about COVID

Photo by Peter Kvetny on Unsplash

 

Published September 2021 on Maeflowers on Medium - free link to source below

I picked a book out of a random bookcase in my house the other day, wanting to just get out of my head and read a bit. Ended up being an interesting read with more than a few parallels to recent events.

So much for trying to get away from current events

In the Wake of the Plague: The Black Death & the World it Made by Norman F. Cantor, the late professor emeritus of history, sociology, and comparative literature at NYU and celebrated medievalist, was published in 2001 — well before any of the recent nonsense. His questionable plague origin commentary aside, I found parts of the book to eerily echo the last nearly 2 years of the modern age.

As Cantor noted, historians of disease find commonality in pandemics — people tend to flee to supposedly safe areas and conspiracy theories blame the disease on “strangers and unpopular minorities.” We have yet to break the cycle.

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Why is it the "Common" Cold?

 

Photo by Brittany Colette on Unsplash

We’ve all wondered it while trying so very hard to breathe through our mouths and not cough until we’re light-headed as we suffer through the annual scourge — why are colds so common? And why do we get them every winter? 

First, I have to address the misconception — colds don’t happen only in the winter. You can catch a cold-causing virus any time of the year. It’s just that winter is when everyone is stuck indoors with each other. Because the viruses that cause the common cold are spread by human-to-human contact and highly contagious, winter provides ample opportunity for transmission. There has also been some research to indicate that certain respiratory viruses are more infectious in drier air. So running the humidifier does more than moisten your sinuses — it may also help stop the spread to family members. 

Now, onto the culprits...

Finish reading in Maeflowers on Medium

HIV, genetic disease, and psilocybin E. Coli - Quora roundup

There have been some very interesting questions on the Maeflowers Quora in the last few weeks - the current trend is concerns about HIV and monkeypox, as well as the normal questions about inheriting diseases such as cancer and Alzheimer's. The most interesting questions though have been about a breakthrough in the production of psilocybin for mental health research.

 pPsilo16 E. coli

What are the effects of oral administration?

Could a human contract the bacteria?

Genetics and Alzheimer's

APOE4 and reducing the chances of developing Azheimer's

Loss of sense of smell in Alzheimer's? Isn't that like COVID?

What kind of diseases do gene therapy treat?

 

HIV testing

What's the testing protocol after PEP? 

How accurate is testing after PEP?

Meningitis vaccine guidelines

Two types of meningococcal vaccines are currently used to prevent the infection that causes meningitis: meningococcal polysaccharide vaccine (MPSV4) and meningococcal conjugate vaccine (MCV4). Particular high-risk groups should be immunized according to CDC guidelines.

Read an overview of meningococcal vaccination and booster guidelines

Colds are just common symptomatology

The common cold - the bane of the winter season.

The common cold is so common because it's actually a set of symptoms derived from infection of the upper respiratory tract. It can be any one of hundreds of viruses that cause the infection. And because it's a virus, there's no treatment for it. You can only treat the symptoms - and since they're the same, you end up with common treatments for the common cold.

 

Causes of the common cold

 

Colds can be caused by more than 200 different viruses. Approximately one-third of all colds are caused by rhinoviruses, of which there are more than 100 types, and they tend to get the fame for causing the illness. Other cold viruses include adenovirus, parainfluenzae, coronavirus, and respiratory syncitial virus (RSV), which is common in young children. This variety is why a vaccine is not available and why people often suffer through multiple colds in a season.

What is common about colds is how they manifest-infecting the upper respiratory tract. When a virus infects the cells of the respiratory tract it produces an immune response, resulting in inflammation of the infected tissue. Because the various cold viruses infect a similar part of the body, they result in a similar inflammatory pattern.

Symptoms of a cold

A cold is characterized by nasal congestion and sneezing, sometimes with sore throat, coughing, headache and other uncomfortable respiratory symptoms. You may also feel fatigued and sore depending on how severe the infection is.

The inflamed cells in the respiratory system produce chemicals (such as histamine) that alter vascular permeability and induce a runny nose and congestion in efforts to thwart other invaders in the sinuses and nasal cavity. The inflammation can also result in soreness of the infected respiratory tract (i.e. the throat or nasal cavity/sinuses), irritation of the area (i.e. sneezing and coughing), and general fatigue due to nonspecific immune responses throughout the body.

Some research has shown that it goes even beyond the normal immune response, though – rhinovirus has been shown to hijack the cell’s genetic mechanisms, over-stimulating the immune response. Other cold viruses may also be associated with more severe infections of the lower respiratory system and other complications. Colds usually are not discerned by the type of viral infection unless other symptoms are present.

 

Coughing and sneezing are both reflexes to clear the throat and nose, respectively, of an irritant. The Centers for Disease Control and Prevention (CDC) recommend sneezing into the crook of your elbow into the clothing to prevent spreading the viruses.

As most people who have been ill know, other symptoms of a cold are body aches and headaches, that general sense of not feeling well. This is the body’s immune response fighting the virus and why the feeling starts to edge in before the respiratory symptoms appear-the body knows there is an invader before it has taken hold as an infection. 

Treating a cold

For the most part, viruses simply have to run their course-they are what is known as self-limiting. a number of home remedies and over the counter solutions to the symptoms have become part of the winter repertoire, including chicken soup, cough syrup, and boxes of tissues on the bedside stand.

 

Antibiotics do not treat viral infections, but they may be used to fight off secondary bacterial infections, such as pneumonia and ear infections, that may occur when the body is down with a severe cold. Children with a fever over 100 degrees Fahrenheit or symptoms lasting more than 10 days should be seen by a doctor.

Over-the-counter pain relievers should dissipate some of the symptoms, including aches and pains. The CDC recommends seeking medical attention for children who do not respond to over-the-counter medications, and the labels should be read well to ensure acetaminophen and antihistamines are not given in too high of a dose. Children should not receive more than one medication at a time to avoid an accidental overdose.

 

Preventing colds

The viruses that cause the common cold are spread by human-to-human contact. The time of year when everyone is stuck indoors with each other (i.e. winter or cold weather) provides ample territory for transmission. Colds happen other times of the year, too, they just tend to become more rampant when humans are in closer quarters.

 

To help prevent a cold, wash your hands regularly with warm water and mild soap, use hand sanitizers with a minimum 60% alcohol concentration, avoid touching your eyes, nose, and mouth, and avoid contact with people who have respiratory infections. Although these things may work towards preventing a cold, there are hundreds of common viruses capable of causing the misery, and it is not entirely preventable.

World AIDS Day

December 1 - it's World AIDS Day and this year it's been 30 years...30 years of fear, death, and a struggle to fight against a virus that uses our own bodies against us.

Looking for information on HIV/AIDS?

Want to read the latest UNAIDS report on the status of the epidemic (released November 2011)




Or maybe you just want to talk to someone...here are some Twitter accounts to follow:

@CDC_HIVAIDS - by the CDC
@talkHIV - by the CDC
@HIVReport - news aggregate
@AIDSinfo - by the NIH
@AIDSgov - U.S. Dept of Health and Human Services
@pozmagazine - lifestyle magazine about being HIV-positive
@UNAIDS - the United Nations joint program on AIDS
@hivlawproject - The HIV Law Project
@IndianaSHINE - Indiana University School of Medicine project for prevention, treatment, and management
@napwaus - National Association of People with AIDS
@MNAIDSProject - the Minnesota AIDS Project
@ProjectInform - HIV/AIDS support line
@AIDSConnect - Chicago area community group
@iasociety - International AIDS Society in Geneva
@HIVthisweek - blog from the director of UNAIDS
@ActionAIDS - so you don't have to face AIDS alone
@AIDSHealthcare - AIDS Healthcare Foundation, San Francisco
@AIDSmeds - info on meds
@cressycat - Cressy the AIDS cat
@joinRED - fighting AIDS in Africa (and holding an event with President Obama)
@HIVAlliance - the HIV Alliance of Oregon

These are just a sampling - a number of other state, local, and country-based organizations are out there. They're all "facing AIDS" for World AIDS Day.

Types of pneumonia

Pneumonia in the lungs. BruceBlaus, CC4.0 license

Pneumonia is a breathing disorder caused by infection and subsequent abscess formation in the lungs. The condition affects millions of people in the U.S. each year and can be caused by various pathogens. The type of pneumonia a patient has is based on the cause of the infection. According to the National Heart Lung and Blood Institute (NHLBI), community-acquired pneumonia is the most common type of pneumonia.

Community-acquired pneumonia (CAP)

Community-acquired diseases occur outside of hospitals or health care centers, i.e. in the community. CAP is transmitted by breathing in the pathogens expelled by infected individuals from their respiratory system. CAP is most common during the winter, and approximately 20 percent of infected individuals end up being treated in the hospital according to NHLBI. The condition is sometimes referred to as bronchopneumonia and is most often caused by a bacterium called pneumococcus (Streptococcus pneumoniae). Viral forms of CAP also occur, sometimes in children as a complication of respiratory syncytial virus (RSV).

Walking pneumonia

Also known as atypical pneumonia, this type of lung infection is a CAP caused by non-pneumococcus bacteria. Bacterial strains include Legionella pneumophila, Mycoplasma pneumoniae, and Chlamydophila pneumoniae. It is transmitted from person to person like pneumococus pneumonia.

Hospital-acquired pneumonia (HAP)

Hospital-acquired, or nosocomial, diseases occur when a patient in a hospital is exposed to and infected by an infectious agent during their treatment for an unrelated illness. Health care-acquired pneumonia is similar, but it occurs in other health care facilities, such as nursing homes. HAP tends to be related to ventilator use (ventilator-associated pneumonia) and is a more serious infection than community-acquired infection, often due to the already weak health of the patient prior to infection. HAP is caused by hospital-associated bacterial strains, including Streptococcus aureus and Gram-negative bacteria.

Aspiration pneumonia

Aspiration occurs when food, drink, or digestive secretions (i.e. vomit or saliva) are inhaled into the lungs. Disruption of the swallow and gag reflex (for example, due to excessive alcohol use, brain injury, medication use, or anatomical dysfunction in the throat) can allow particles to enter the airway and form a cavity in the lung tissue. The immune system reacts to the presence of the foreign particles and causes inflammation, leading to abscess formation and pneumonia.

Fungal pneumonia

Fungal infections that occur in humans tend to be either endemic or opportunistic. Endemic fungal strains that cause pneumonia include Coccidioides and Histoplasma. Opportunistic fungal strains that cause pneumonia include Candida, Aspergillis, Mucor, and Cryptococcus neoformans. However, Cryptococcus gattii is a new strain in the Pacific Northwest of the U.S. and Canada in the past decade (endemic strain). Individuals with a suppressed immune system, such as AIDS patients, sometimes have pneumonia caused by Pneumocystis jiroveci (formerly known as Pneumocystis carinii pneumonia, PCP), a type of CAP.

Thus, pneumonia type can be based on infectious agent or mode of transmission. For example, viral pneumonia vs. bacterial pneumonia is important for determining treatment, but CAP vs. HAP can aid in preventing further cases. However, all types of pneumonia are based on breathing difficulties that stem from inflammation of the lungs, which requires treatment.

Bacteria can be used to fight dengue fever-causing viruses

Wolbachia infected insect cell, by Scott O'Neill

 

Dengue fever is caused by four viruses that are spread by mosquitoes. Some infections are severe, leading to a hemorrhagic fever. The common fever is generally not fatal, but infection causes uncomfortable and unpleasant symptoms for a week or longer without any available treatment. Dengue hemorrhagic fever, on the other hand, has a higher mortality rate due to blood loss and shock. Dengue fever affects 100 million people each year and kills more than 12,000. Because the mosquitoes that transmit the virus are active during the day, the preventative measures used to curb other mosquito-borne diseases, like bed nets for malaria, are not helpful in preventing its spread. Infective agents and the introduction of anti-dengue genetic strains into the mosquito populations have been pursued as alternatives.

Aedes aegypti mosquitoes are the primary vector of dengue virus. Wolbachia is an intracellular bacterium that tends to be endosymbiotic with the host mosquito and passed to its offspring. This bacterium has been found to inhibit viral replication within the mosquitoes that harbor it and prevent its transmission without the need for genetic engineering. In the journal PLoS Pathogens in 2010, researchers at Michigan State University showed that Wolbachia bacteria completely block the transmission of dengue from more than one-third of the infected Aedes aegypti mosquitoes they evaluated.

As noted in the journal Nature in August 2011 by Walker et al., several Wolbachia strains have been identified, each with their own effects on the mosquitoes. The strain wMelPop-CLA was shown to reduce the lifespan of the Aedes aegypti mosquitoes, which in turn reduces the transmission of dengue. Another strain causes cytoplasmic incompatibility, which reduces the reproductive activity of the mosquitoes. Female mosquitoes infected with Wolbachia pipentis had half the reproductive lifespan as female mosquitoes that were not infected. Reducing the number of mosquitoes that a mosquito can have aids in controlling the dengue-spreading populations. This feature of Wolbachia infection has been known since at least the 1990s (as noted in PNAS in 2004).

This strategy against dengue transmission has been shown to be possible based on the natural infection of two mosquito populations in Australia, as described by Hoffmann et al. in Nature in August 2011. Though the exact mechanism underlying the bacterium’s effect on the virus is not certain, researchers find the current results promising as the bacteria are naturally occurring endosymbiotes, spread quickly in the mosquito population, and appear effective at controlling both the mosquito populations and viral transmission.

Eastern equine encephalitis risk

EEEV in a mosquito saliva gland

Eastern equine encephalitis (EEE) is caused by the eastern equine encephalitis virus (EEEV), which is transmitted by infected mosquitoes. As implied by its name, the virus primarily affects horses, but human cases sometimes occur. The Centers for Disease Control and Prevention (CDC) in the United States considers EEE one of the most severe mosquito-borne illnesses because its mortality rate is approximately one-third of all individuals who develop EEE. The disease has a sudden onset with swelling and inflammation of the brain (encephalitis), causing headache, fever, chills, and vomiting. However, only 4 to 5 percent of human infections with EEEV are thought to actually develop into EEE.

The transmission cycle of the virus tends to occur in and around swampy areas, including the freshwater hardwood swamps of the Unites States - the Atlantic and Gulf Coast states of the United States have endemic areas of virus transmission, and the endemic areas also now include around the Great Lakes. Wetland birds are infected with EEEV, which then infects the mosquitoes that bite them. When the virus is present in high enough quantity in the bird population, mosquitoes that bite humans may also become infected, allowing them to spread the virus to humans. Horse epidemics of the disease tend to occur in Summer and Fall. The CDC has received reports of only an average of 6 human cases of EEE per year in the United States. Since 1964, the most number of cases in a given year was earlier this past decade with nearly 25, and the average reported per year appears to be increasing.

Florida, Georgia, Massachusetts, and New Jersey have reported the most cases of EEE (neuroinvasive EEEV infection) since 1964, and were some of the earliest areas of the country affected by the disease. However, between 1964 and 2010 cases of EEE have also been reported in individuals living in Wisconsin, Michigan, Indiana, Pennsylvania, New York, New Hampshire, Rhode Island, Delaware, Maryland, Virginia, North Carolina, South Carolina, Alabama, Mississippi, Louisiana, and Texas (see a distribution map). The breakdown of number of cases per year per state available from the CDC indicates that the areas of viral transmission have been spreading since 1964.

Massachusetts is considered particularly vulnerable to the chance of an EEE outbreak. The density of residents, coastal area, history of EEE cases, and confirmed presence of EEEV in mosquitoes in a number of counties in the state create a situation that requires preventative measures to avoid human transmission. Outbreaks occur in the state every 10 to 20 years. The last outbreak in Massachusetts was 2004 to 2006.

States that have not previously had experience with EEE may be even more at risk because they do not have the surveillance system in place to monitor the viral load in mosquito populations. The economic conditions of some areas may also hamper proper preventative measures. As horse outbreaks occur (as in Michigan in 2010), the risk of human infection increases in any area of the country.

 

Cryptococcus gattii: Emerging fungal infection

Source: CDC

 

Cryptococcus gattii is a fungus that infects the respiratory tract of animals, including humans. C. gattii has been isolated from soil, trees, air, and water and is usually found in the eucalyptus trees of the tropics and subtropics. However, an outbreak of C. gattii in British Columbia, Canada, in 1999 resulted in the identification of the species on native trees of Vancouver Island, as well as surrounding soil and air, and spread to the mainland has been indicated. Recently, since 2004, outbreaks of infection in Oregon have prompted concern over this pathogen.

How infection occurs

Infection is caused when the spores of the fungus are inhaled. After taking up residence in the respiratory tract, illness can take 2-12 months to appear, but usually symptoms appear at 6-7 months after exposure. The lungs develop cavities and infiltrates from the fungus growing and taking up residence. It is also estimated that 20% of those who are infected develop meningitis because the infections spreads to the central nervous system. However, some infections are asymptomatic, in that the individuals do not develop symptoms.

 

Symptoms of Cryptococcus infection

The symptoms that occur with C. gattii infection vary greatly, but include: 

• fever and chills
• night sweats
• weight loss
• cough and shortness of breath
• headache
• chest pain
• neck pain and stiffness
• light sensitivity
• decreased alertness (neurological symptom). 

Death is estimated to occur in less than 5% of human cases. However, the recent strain in Oregon (VGIIc) has an initial 25% mortality rate and the previous strain (VGIIa/major) had a 9% mortality rate.

 

Similar infections

A close relative to C. gattii is Cryptococcus neoformans, a more common human pathogen that acts as an opportunistic fungus that infects individuals with a depressed immune system (e.g., transplant patients, HIV/AIDS patients, the chronically ill). The two infections can be differentiated by lab workups on suspected cases. Cryptococcosis is infection with Cryptococcus fungus, and mainly considered to be the neoformans variety. However, the U.S. Centers for Disease Control and Prevention (CDC) consider C. gattii an emerging infectious disease. Lethal hybrids of the two strains have also been seen in recent years.

How to avoid Cryptococcus

Infection does not spread from person to person or from animal to animal, or even between humans and animals. The risk of infection is considered to be low, even for people living in endemic areas (only a couple hundred known North American cases over the last decade), but it is an environmental pathogen with no known risk factors for infection. Thus, no known way to prevent it. Most cases respond to anti-fungal medications, so early diagnosis and treatment is important.

 

The fungus grows on trees and can be found in the surrounding soil, air, and water. It is an environmental pathogen with no known risk factors for exposure and infection. The U.S. Centers for Disease Control and Prevention (CDC) do consider C. gattii an emerging infectious disease.

 

MRSE: The other Staph

 

Staph biofilm, Source: CDC

Drug-resistant Staphylococcal infections usually bring to mind MRSA (methicillin-resistant Staphylococcus aureus), but another bacterial strain is also resistant to methicillin treatment, Staphylococcus epidermidis. The infection is known as MRSE (methicillin-resistant Staphylococcus epidermidis). This strain was the original methicillin-resistant hospital strain of Staph.

S. epidermidis are Gram-positive, coagulase-negative cocci that can survive on dry surfaces for long periods of time. This bacterium is a leading cause of hospital-based (nosocomial) infections, particularly when a foreign body is introduced into the body, such as catheters and implants, due to its ability to form biofilm. The bacterial strain exists normally on human skin and mucous membranes, but a breach in the body’s defenses can open the door to infection. MRSE is commonly resistant to multiple antibiotics, including the penicillins as well as methicillin.

Urinary catheter use

Urinary catheter use is the primary source of nosocomial infections. In the 1980s, S. epidermidis was the most common bacteria isolated from catheters, but in recent years S. aureus (MRSA) has become the more common Staph strain associated with this route of infection (the same can be said for central lines and subsequent infection). Preventative measures have included antimicrobial ointments and new catheter materials to prevent biofilm formation, but the bacteria can contaminate the catheter from the skin of the patient or health care worker, and even from tap water used to clean the catheter or body. Catheter coatings, such as bacteriophages, have been investigated as another method of active prevention.

Symptoms of catheter-associated urinary tract infections include: cloudy urine, bloody urine, foul-smelling urine, leakage around the catheter, pelvic pressure or pain, and common symptoms of infection, including fever, fatigue, chills, and vomiting. Like any other bacterial infection, antibiotics are used for treatment. Since at least the early 1990s, vancomycin has been the only antibiotic to which methicillin-resistant Staph strains are still sensitive for treatment. However, new antibiotics like ciprofloxacin may be effective against MRSE.

Endophthalmitis

Inflammation of the inside of the eye, known as endophthalmitis, can also be caused by Staph infection. Generally, the bacteria enter the ocular cavity from the blood and it may appear as secondary to infection elsewhere in the body. The eye may appear simply to have white nodules, or it can appear cloudy and red, with vision greatly affected. Infection can spread to the surrounding tissues. The condition is treated with aspiration of the infected fluid and antibiotics, generally vancomycin in the case of MRSE, local (via drops or intravitreal) or systemic depending on the extent of infection. Topical steroids, particularly dexamethasone, are also considered helpful.

Cardiac symptoms and treatment

Endocarditis is inflammation of the lining of the heart chambers and valves, known as the endocardium, and is most often caused by bacterial infection. Symptoms are weakness, swelling of the limbs and extremities, paleness, fever, fatigue, chills, night sweats, abnormal urine color, and muscle aches among others. The bacteria may enter due to cardiac catheters, dialysis, or other medical devices.

Vancomycin treatment is, again, the standard antibiotic treatment. However, research published in The Journal of Infectious Diseases in 1993 found that amoxicillin plus clavulanate was just as effective in treating experimental MRSE endocarditis. Researchers at Johns Hopkins in 2007 found that linezolid can also be used to treat endocarditis caused by MRSE.

Meningitis

Meningitis is inflammation of the lining of the spinal cord and brain (known as the meninges). If MRSE infects the central nervous system, it can cause acute infective meningitis (known as Staphylococcal meningitis). When the condition does occur, it is usually with prosthetic use. Symptoms may escalate quickly over 12 to 24 hours and include confusion, fever, rash, nausea or vomiting, severe headache, stiff neck, and light sensitivity.

Treatment is chosen after confirming the infectious agent behind the meningitis via spinal tap, gram stains, and antigen tests. For MRSE, dexamethasone is sometimes used to decrease inflammation, and antibiotic treatment normally consists of vancomycin, but this drug does not penetrate well into the cerebrospinal fluid unless the disease has progressed to severe inflammation. A 2003 study found that linezolid may also be an option for treating this condition when low-level inflammation is present. Removal of the device responsible for infection is also an option to remove the source.

 

Hepatitis C phenotypes

Cancer caused by HCV

Hepatitis C virus (HCV) is the most common bloodborne infectious agent in the United States. It causes hepatitis - inflammation of the liver. Approximately three-quarters or more of infected individuals go on to develop chronic disease after infection (currently 3 million people), many of whom originally appeared asymptomatic, but some may experience other phenotypes with or without treatment, including spontaneous viral clearance and sustained virological response. HCV is most commonly spread through contaminated blood, including intravenous drug use. Sexual transmission is also possible.

Read more about the three phenotypes of HCV infection below the jump.

Bzzzz mosquito season

In the developed world, mosquitoes are best known as annoying buzzing insects that invade picnics and barbecues, but in the developing parts of the world they kill tens of millions of people a year. The most well known mosquito-borne disease is probably malaria, but there are dozens more, from parasites that infect pets with heartworm to viruses that cause fatal disease in humans.

Mosquito facts

Mosquitoes belong to the same insect class as flies (Diptera, meaning “two wings”), but they have a proboscis – a long needle-like mouth. This physical adaptation allows the female mosquitoes to feed on blood for nourishment when preparing to lay eggs for the next generation of mosquito. Different species of mosquito like different species of blood. Culex, Aedes, and Anopheles are a few genus’ of mosquitoes that bite humans.

How mosquitoes spread disease

Because the female mosquito drinks blood, it can also take up infectious agents that live in the blood. Some of these pathogens have a life cycle that includes using the mosquito stomach as an incubator and then are transferred to another bite victim (such as Plasmodium), or they are capable of surviving in progeny to be transmitted later (such as arboviruses). Mosquitoes that spread disease are known as vectors.

Malaria

According to health agencies, malaria kills 2 to 3 million people a year in developing countries. The Anopheles gambiae mosquito transmits the sporozoites of the Plasmodium falciparum parasite to humans after incubating the parasite in its gut. The Centers for Disease Control (CDC) offer a diagram of the Plasmodium life cycle involving two hosts – an infected human and a mosquito, which then infects a second human. Malaria can occur in the United States, though mosquito control over the decades has removed much of the threat.

Malaria appears 10 days to 2 weeks after the infecting mosquito bite, causing fever, headache and vomiting. The World Health Organization (WHO) and other groups work to prevent disease with mosquito netting, insecticide control, and immediate treatment. Prophylactic treatment, including chloroquin and other similar drugs, is used for travelers from developed countries.

Arbovirus-based encephalitis

Arthropod-borne viruses, or arboviruses, are viruses that live in mosquitoes and other insects for transmission to vertebrate hosts, such as humans. These include a number of different types of viruses that cause swelling of the central nervous system and meningitis, including West Nile, eastern equine encephalitis, west equine encephalitis, St Louis encephalitis, Powassan encephalitis, Venezuelan equine encephalitis, Japanese encephalitis, and La Crosse encephalitis. Arboviruses have a global distribution, with more cases being seen in the United States in past years, particularly of West Nile Virus. Transmission risk can be minimized by using insecticide containing 30 percent DEET (10 percent for children) and taking other basic precautions to avoid mosquito bites (long sleeves, not going outside at dusk, and prevent standing water, where mosquitoes lay eggs and hatch).

Fevers

Mosquitoes also spread viruses that cause Yellow fever and Dengue fever, which are endemic to underdeveloped parts of the world. However, these diseases have been seen in the United States and Dengue has spread to the Caribbean and become a global issue according to the CDC. Dengue hemorrhagic fever, a specific course of Dengue virus infection, is transmitted by Aedes aegypti and Aedes albopictus mosquitoes. In addition to having a fever for several days to a week, the infected individual also suffers from bleeding and pain. No specific treatment exists for either course of infection with Dengue virus. Aedes aegypti also spread yellow fever. Yellow fever causes jaundice, with a 15 to 50 percent fatality rate. Yellow fever can be prevented by vaccine, which is recommended for travelers to parts of the world with endemic mosquito-borne diseases.

 

Herpes simplex - not as simple as you think

Herpes labialis

Cold sores are the commonly known form of oral herpes, though herpes is best known as its genital form. Both are caused by the herpes simplex virus. No cure is available for herpes simplex infection because it hibernates in the nerve cells. A weakened immune system puts an individual at greater risk for infection.

HSV-1 and HSV-2 can both cause oral or genital lesions, and can be spread by symptomatic or asymptomatic individuals via body fluids. When spread by an individual who lacks sores or symptoms, the transmission is called asymptomatic viral shedding. After initial infection, outbreaks can be triggered by stress, menstruation, sun exposure, fever, and illness.

Read more about types of herpes simplex virus below the jump, and then protect yourself.

Preventing meningitis

Meningitis is inflammation of the lining of the central nervous system, often by infection. It can be transmitted as viruses, bacteria, fungi, or parasites. The most common form of the disorder is viral meningitis, which tends to resolve on its own. On the other hand, bacterial meningitis can be severe and lead to brain damage, hearing loss, or learning disabilities if not properly treated. Good hygiene is the general practice for preventing the transmission of meningitis. Vaccines are available against the common bacterial causes, including Hib and meningococcus and recommended for college students due to the close quarters they live in.

Read more about how meningitis is transmitted below the jump.

Should I delay pneumococcal conjugate vaccine?

The pneumococcal conjugate vaccine is used in infants and young children to prevent infections by the bacteria Streptococcus pneumoniae. The vaccine contains inactivated or killed bacteria to stimulate the immune system against it. In 2000, the US Food and Drug Administration (FDA) licensed a 7-valent (protects against 7 serotypes of the bacteria) vaccine (PCV7), but this was replaced in 2010 with a 13-valent vaccine (PCV13), allowing greater protection. PCV13 is administered to children from 6 weeks up to 71 months according to the Centers for Disease Control (CDC). 

Traditionally, the pneumococcal conjugate vaccine was outlined for use by the National Institutes of Health (NIH) in children aged between 2 and 15 months, though the last booster could be up to 59 months. A different vaccine, pneumococcal polysaccharide vaccine (PPV23), is given to older children and adults because children under the age of 2 cannot mount the T cell response required. However, vaccination with PCV13 may be delayed for a number of different reasons.

Why vaccinate against pneumococcus?

In 2006, the World Health Organization (WHO) published a detailed review on pneumococcal infections and vaccination. According to the WHO review, 10 serotypes of pneumococcus are responsible for invasive pediatric infections, though 20 serotypes are responsible for infections in all age groups worldwide. Streptococcus pneumoniae usually colonizes the nasopharynx (the cavity behind the nose and above the throat). It typically does not cause infection or symptoms. However, when the bacteria spread to the ear or sinuses, or are aspirated into the lungs, it can cause an infection.

After the introduction of PCV7, the number of invasive infections decreased 80 percent, decreasing complications and death along with it. However, in 2006, the WHO pointed out that more than 1.5 million people, half of them under the age of 5 years, still die each year due to pneumococcal infection. Invasive S. pneumoniae causes pneumonia, meningitis, and blood infection, which are all serious diseases. Young age is a specific risk factor for pneumococcal infection, and one-quarter to one-half of pneumococcal meningitis survivors have long-term neurological disease. In addition, the antibiotics used to treat infection are becoming less and less useful due to bacterial resistance to treatment. Approximately 10 percent of infected children die according to the CDC.

Vaccination against the bacteria reduces the risk of invasive disease. It prevents pneumococcus-associated ear infections, pneumococcus-associated meningitis and long-term neurological damage and, most importantly, pneumococcus-related death. Young children are vaccinated because they are the population most at risk, though the elderly and HIV patients are also at-risk populations. The 2006 WHO review indicated that vaccinating children benefitted all age groups in the form of decreased disease.

Reasons for not vaccinating

Though most children can go into a pediatrician’s office or health department and get a vaccine without additional considerations, there are times when a vaccine should not be given. Pneumococcal conjugate vaccine may be delayed if the child has a current infection or illness more serious than a cold. Once they have recovered, they may be vaccinated. Some healthcare providers may choose to administer PCV13 separately from Hib vaccine due to potentially decreased efficacy, though the WHO does not find support for the practice.

Pneumococcal conjugate vaccine may be withheld (not given at all) when the child simply cannot tolerate it, such as in the case of a previous allergic reaction to any component of PCV7 or PCV13 or any vaccine containing diphtheria toxoid (DTaP). In addition, the WHO recommends that anyone who has already received PPV23 not receive PCV7 (and by equivalence PCV13).

Standard practice

Most children can and should be vaccinated with pneumococcal conjugate vaccine. Any exceptions can be discussed with your pediatrician.

The benefits of acidophilus probiotics

Supplements Image by Ragesoss

Probiotics are bacterial supplements taken to increase the colonization of commensal bacteria in the gut. Acidophilus is one such probiotic, although individuals with intestinal damage, a weakened immune system, or overgrowth of intestinal bacteria should avoid supplementation (safety in pregnant women is also not yet known). A number of health issues are purported to benefit from supplementation with acidophilus, though there are multiple strains of lactobacilli, each with its own effect in particular conditions.

Medical studies have shown general benefits of supplementation for:

• Preventing C. difficile infection after antibiotic use
• Treating rotavirus associated diarrhea
• Treating vaginal infections
• Preventing necrotizing enterocolitis in premature infants
• Treating thrush and other yeast infections

Read more about health issues that can be treated with acidophilus probiotics and recommendations for use.

Coming to a town near you: Whooping cough

Australia is seeing a surge in whooping cough cases. So much so that they've released the vaccine for free! California is also requiring teen vaccinations in light of recent whooping cough deaths.

Whooping cough is a respiratory infection caused by a Gram-negative bacterium called Bordetella pertussis. Pertussis is endemic to the United States, with epidemics occurring every 3-5 years and with an average 5000-7000 cases per year. However, since the 1980s, the incidence of whooping cough has increased, with more than 10,450 cases reported in 2007. The last major outbreak occurred in 2005, with more than 25,000 cases. Health officials are hoping to prevent another such outbreak.

Since the 1990s, cases have disproportionately increased in older children and young adults, likely because of anti-vaccine momentum among their parents and possibly evolution of the bacterium itself.

Infants and young children are particularly prone to respiratory and neurological complications from the infection, and deaths are more common among unvaccinated children or those who are too young to be vaccinated. The disease is highly contagious, with 90% of contacts with an infected individual becoming infected themselves. Since the 1990s, cases have disproportionately increased in older children and young adults, likely because of anti-vaccine momentum among their parents and possibly evolution of the bacterium itself.

One challenge to decreasing the incidence of whooping cough in the U.S. is to increase vaccine (DTaP) and booster (Tdap) coverage among both children and adults. The vaccine for pertussis is given in conjunction with the vaccines for diphtheria and tetanus. There are also variations and lower strength doses (such as the booster) for children who cannot tolerate the pertussis vaccine. Children generally get five doses of DTaP (containing full strength dose of pertussis toxin protein): 2, 4, 6, and 15-18 months old and again at 4-6 years of age. A booster (low dose, Tdap) is recommended for adolescents around the age of 11-12 years. The pertussis component can be given in conjunction with a regular tetanus booster (Td) in a single injection. The anti-vaccine movement has raised parents’ fears about a number of disorders being associated with pediatric vaccines, from autism to SIDS, but no medical evidence exists to substantiate these fears.

From 1990-1993, the coverage of the third DTaP dose decreased in the United States to below 90%, even below 85% in 1992. Though it increased back to the mid 90 percent range, it has remained lower than the coverage in the 1980s. A child’s immune system does not develop until roughly 9 months of age, making the third and later doses critical to their long-term immunity against whooping cough. The bacterium can be transmitted to others even before the distinctive cough sets in, making transmission among adults and adolescents who did not receive all of their doses as children highly likely.

Other factors that have led to increased incidence of whooping cough in the U.S. is an adaptation of the pertussis bacteria to survive in vaccinated individuals. The exact mechanism of this adaptation is not clear, possibly linked to the decreased vaccination coverage or adaptation to the immune response, or possibly genetic drift and decreased vaccine efficacy. The vaccine is being updated from a whole cell formulation to an acellular formulation to avoid side effects among some children, but further improvements in the components of the vaccine may be necessary to have an effect on new strains of the pathogen.

Anti-HIV treatment may reduce transmission to partners

AZT - antiretrovirals

Individuals diagnosed with HIV are presented with a life-shattering possibility – transmission of the eventually lethal virus to their spouse/partner. Condom use and abstinence have been the recommended prevention methods, but on May 12, 2011, researchers announced startling findings that may aid in preventing transmission further. The antiretroviral drugs HIV-positive patients take to stave off AIDS may actually prevent them from infecting their partners.

The 73 million dollar study was funded by the National Institutes of Health and conducted in nine countries, mainly in Africa, where the majority of AIDS cases are found (only two American couples took part, presumably due to the possibility of not receiving treatment until later in the study). As summarized by the LATimes, the current results on transmission to partners among more than 1700 couples were released four years before the study is even supposed to end due to their outstanding nature. The researchers found that antiretroviral treatment reduced the transmission of the virus 96%. Twenty-seven of 28 new infections occurred among couples who were not treated until their CD4 T cell count reached 350 compared to one case of infection among couples treated when the count fell below 500. The results indicate that new guidelines to treat HIV infection earlier, when the CD4 count drops below 500 rather than 350 as previously recommended, are beneficial.

The Wall Street Journal estimates that the study results may add fuel to the treatment versus prevention debate for funding in AIDS research, as the two aspects now clearly overlap. Increasing the number of individuals who are treated decreases the overall community viral load, resulting in decreased transmission overall in addition to reduced transmission among partners of HIV-positive patients. In addition, it should put pressure on companies to make the drugs less of a financial burden, ensuring that those who need treatment can seek it, especially amid current under-treatment – according to the Journal, only a third of those who required treatment in 2009 received it. As noted in the LATimes, the drugs used in the study were provided free of charge by the pharmaceutical companies that made them. The cost would normally be in the hundreds of dollars per year in developing countries, and they have not traditionally been affordable according to the AIDS charity AVERT.

The researchers also found that the earlier treatment benefitted the HIV patients by reducing the incidence of disseminated tuberculosis. Tuberculosis is one of the primary causes of death among HIV-infected individuals.

The study began in 2005 and researchers will continue following the couples for another year to ensure the results hold up over time. Experts quoted in news reports remind people that more than one prevention method increases the chances of actually preventing transmission, so condom use should still be emphasized if receiving antiretroviral treatment.

 

Broadly neutralizing HIV antibodies and the hope for a vaccine

Antibody binding HIV. Peter Kwong, NIH

Yesterday I posted about how HIV antibodies are made. But why are they important? More specifically - why is the recent work on broadly neutralizing antibodies important?

Antibodies are produced against cell surface proteins, the portions of the infecting agent visible to immune cells. The problem thus far with HIV is the broad range of cell surface proteins expressed by the various strains currently infecting the human population, as well as the potential mutations to come. However, broadly neutralizing antibodies, though rare, have been identified in the blood of HIV-infected patients. They bind and affect portions of the cell surface that remain relatively constant among HIV strains.

Read more about the challenges and promise of broadly neutralizing antibodies in HIV vaccine development below the break.