HPV Vaccine and Tweeners

30 04 2012

(Welcome to CDC! Read along as they talk about tweeners and HPV.)

When it comes to their kids, parents are always planning. Healthy dinners. Safe activities.

One plan that’s easy to make could have a tremendous benefit, even saving a life. That’s planning to have preteens vaccinated against HPV, the leading cause of cervical and anal cancers.

“There are about 12,000 new cervical cancer cases each year in the United States,” says Dr. Melinda Wharton, deputy director of the National Center for Immunization and Respiratory Diseases at the Centers for Disease Control and Prevention (CDC). “Cervical cancer causes about 4,000 deaths in U.S. women each year. But vaccinating boys and girls against HPV greatly reduces the chances that today’s girls will ever have to face this devastating disease.”

CDC recommends HPV vaccination for 11- and 12-year-old girls and boys, as well as for young women ages 13 through 26 and young men ages 13 through 21 who have not yet been vaccinated.

Two HPV vaccines—Cervarix and Gardasil—are available for girls to protect against the HPV types that cause most cervical and anal cancers. Gardasil also protects against the HPV types that cause most genital warts. Gardasil is the only vaccine approved for boys.

Both brands of HPV vaccine are given in three doses (shots) over six months, and protection requires all three doses. “Completing the three-dose HPV vaccine series is very important to ensure protection against HPV-related disease,” adds Dr. Wharton.

While vaccinating against a sexually transmitted virus at age 11 or 12 might seem unnecessary, the preteen years are the best time to vaccinate. “The HPV vaccine only provides protection if it is given before exposure to HPV,” says Dr. Wharton. “Someone can be infected with HPV the very first time they have sexual contact with another person.”

To get the most benefit from HPV vaccination, all three doses must be received before any kind of sexual activity with another person begins.

Atlanta mom Amber Zirkle recognizes the importance of vaccinating her children now for protection they’ll need in the future. Her 11-year-old daughter will get an HPV vaccine this year at her regular check-up. As for getting HPV vaccine for her 16-year-old son, Amber says, “I didn’t know it was available for boys. I’ll talk with the pediatrician about it.” She adds, “Genital warts aren’t something I want my son to deal with.”

Other vaccines recommended specifically for preteens include meningococcal conjugate, which protects against bacterial meningitis, and Tdap, which boosts immunity against pertussis (whooping cough). Everyone age six months and older should get an annual flu vaccine.

To learn more, visit CDC’s teen website or call 800-CDC-INFO.

Ask Emily

26 04 2012

What’s the deadliest infectious disease ever and what currently is the most deadly infectious disease?

The answer to this question is more complex than simply counting up numbers of people who die from infection. For example, diseases like measles and smallpox have proved to be far deadlier in some populations—such as Native Americans—than in others, because of population differences in disease resistance.

Another variable is intensity of the illness a pathogen causes. Influenza comes in many forms of virulence, and as the Spanish flu pandemic of the early 20th century made clear, even that virulence can vary depending on specific population features; the Spanish flu, which took an estimated 50 million lives, killed the young most relentlessly.

Even an individual disease vector can wax and wane in terms of how virulent it is or which tissues it invades. For example, Yersinia pestis, the bacterium responsible for the infamous Black Death that swept through Europe in the 14th century, may vary over time in its virulence and is far more deadly when transmitted as an aerosol to lung tissues than when it invades the lymph and causes the bubos that characterize it.

Another issue is, how do we calculate “deadliest?” Is it in terms of sheer overall numbers, or do we calculate it in terms of how many people it kills among the number infected? For the sake of addressing this question, let’s talk about both.

Historically, in terms of sheer numbers, the deadliest diseases were smallpox, measles, tuberculosis, plague (e.g., the Black Plague), and malaria. According to a handy Website, the Book of Odds, which calculates odds for us, measles has killed about 200 million people worldwide in the last 150 years and still kills hundreds of thousands in the developing world. Thanks to vaccines, the odds of contracting measles in the United States today are very low unless you are an unvaccinated person living in areas where vaccine uptake is low.

The story on smallpox is similar—it may have killed more people by percent or sheer numbers than any other infectious disease in history, including 300 million in the 20th century alone by some estimates. Yet smallpox as an infectious disease no longer exists thanks to its total elimination through vaccine campaigns.

Thus, along with the plague, smallpox and measles have, for millennia, been the historical killers of humans and would still be among the deadliest infectious diseases today were it not for vaccines. What we have left are some old killers on the list—tuberculosis and malaria—and a newer entity, HIV, the virus that causes AIDS.

We have yet to develop efficient vaccines against any of them. According to USAID, in terms of absolute numbers of deaths, AIDS kills the most people each year, with 2.8 million AIDS-related deaths in 2004, followed by tuberculosis and malaria.

Indeed, AIDS and tuberculosis are often co-conspirators in death, as infection with the HIV virus makes people 20 to 30 times more likely to develop active TB with TB infection. Research for vaccines against HIV and malaria has been feverish but as-yet incompletely successful, one reason these diseases remain the top global killers.

But what about the deadliest disease in terms of how many of infected people die? In the absence of effective treatment, HIV might be one candidate. But the ones that come first to mind are the viruses that cause fast-moving hemorrhagic fevers, such as the Marburg or Ebola viruses.

The Marburg virus, named for the location of the first outbreak and a virus that may reside without symptoms in fruit bats, has caused death rates as high as 90% in some areas, although the average is 23–25%. It is a filovirus, in the same viral family as the five Ebola viruses. One of the Ebola viruses, Ebola-Reston, is perhaps the most notorious of the hemorrhagic fever viruses, having led to death rates as high as 89% in outbreaks.

A near-100% mortality rate is about as deadly as an infectious agent can be if that’s the measure of “deadly” we’re using.

By Emily Willingham

Image courtesy of Wikimedia Commons

Shot at Life

23 04 2012

Remember SARS? That virus popped up in China in 2003 and quickly coughed and sneezed its way to dozens of other countries. And the 2009 H1N1 virus made its introductory appearance in Mexico, when a pig infected a human. It then traveled the globe with a speed that shocked us.

The world is enormous, but nowadays it’s also quite small.

Long ago, when people were mostly nomadic in nature, diseases were not easily spread, at least not outside of one’s group or tribe.

Then we formed societies, lived closer together, traded wheat and pelts, and passed germs like nobody’s business. But it still took months and sometimes years for diseases to become widespread.

Today, with air travel, diseases can spread from country to country in a matter of days, and sometimes, within a few hours.

These diseases are not all new; many are vaccine-preventable. But, when the immunity in a community is low due to reluctance to vaccinate or lack of access to vaccines, these diseases which science has bested scatter anew, bringing illness and sometimes death.

The United Nations Foundation’s Shot@Life campaign targets Americans with the hope that we will be inspired to advocate for those with little or no access to vaccines.

That inspiration isn’t too hard to find, if you’re a mom or dad. Once you’re a parent, you acquire a faint and nagging voice that compels you to “parent” all kids, anyone’s kids, every kid.

There are numerous self-serving reasons to ensure everyone is vaccinated, and that’s OK. Who wants to get sick? There are some of us for whom this or that vaccine simply doesn’t work, or we can’t use a vaccine due to allergies or for other reasons. We’re unprotected and we depend on those around us to not get sick and, so, not infect us.

There are also simple, human reasons for wanting everyone vaccinated. There are boys and girls in need who should grow up laughing and being naughty sometimes, who should go to school and raise families. This one will clean toilets for 30 years and then retire to enjoy his grandchildren. That one will discover life on another planet. Another will be the teacher who changes the lives of hundreds of students, who in turn go on to do wondrous deeds.

It’s a really small world, when you think about it. Protecting other children will protect our own children. And, it’s what we do for neighbors.

Check out Shot@Life. Do something this week to help your neighbors in Nigeria, Laos, Bangladesh, and elsewhere.

By Trish Parnell

Image courtesy of Shot@Life

The Laboratory Diagnosis of Pertussis in the United States

19 04 2012

(Pertussis outbreaks are occurring in the U.S. and elsewhere, yet many healthcare professionals seem reluctant to test for it. We asked Dr. James D. Cherry to explain when testing should be done and we extend our thanks to him for this post on diagnosing whooping cough. Dr. Cherry is a member of the Global Pertussis Initiative (GPI) and author of previous papers on pertussis Dx. Please feel free to share this post with your healthcare provider.)


In pertussis the site of infections is on ciliated epithelial cells in the nasopharynx (NP).  In primary infections (infants and young child not previously vaccinated) the bacterial load is high and is present in the nasopharynx from the onset of illness (coryza) the second week of the paroxysmal stage and often longer.  In children who are vaccine failures the bacterial load in the NP is less than in primary infections and the bacteria are present for a shorter period of time (ie onset of coryza through the second week of cough).

In adults (all of whom have had previous infections unknown to them) the bacterial load is less than in previously vaccinated children and the duration of presence of bacteria is also less.  Also, adolescents and adults rarely seek care for their pertussis cough illness until the third or fourth week from illness onset.  Nevertheless adults with unrecognized pertussis are the most common source of infection in infants who are unimmunized or only partially immunized.



Culture is 100% specific whereas all other tests are not.  Culture in children is a much more sensitive test than generally believed.  However, today in the U.S., for the most part, culture is a lost art in most diagnostic laboratories because of lack of fresh media and technicians with little experience.  With a good laboratory the main reason for failure to isolate Bordetella pertussis is that the specimen was not collected properly or that it was collected too late in the illness.

To obtain an adequate sample the ciliated cells in the NP must be touched by the dacron tip of the NP swab or the catheter used in a NP aspirate must touch the ciliated cells.  Nasal wash is frequently done but this is much less sensitive than either NP swab or NP aspirate.  For PCR the same facts apply regarding specimen collection.


For children (during the first 3 weeks of illness) and adults (during the first week of illness) PCR is the method of choice because it is much more sensitive than culture.  Unfortunately, there has been much misinformation disseminated about PCR results.  PCR is readily available in the U.S. in hospital labs and several commercial labs.

The test that is universally available in the U.S. uses primers that identify insertion sequence (IS) 481 for B. pertussis and IS1001 for B. parapertussis.  Because B. pertussis contains ~238 copies of IS481 this test is exceedingly sensitive.  It is so sensitive that it can pick up examination room contamination because of a previous patient with pertussis or the immunization with DTaP of a previous patient in the room.  Therefore NP specimens should not be collected in rooms where DTaP immunization is being carried out or in rooms that have been occupied by previous patients with pertussis.

Today in the U.S. real time PCR is the method most often used and the number of cycles necessary to obtain a positive result reflects the concentration of B. pertussis in the sample.  The lower the cycle the greater the number of bacteria.  With high cycle detection the possibility of contamination at the collection site is a likely possibility.  However positives are positives regardless of the cycle.  It has been suggested that labs not report high cycle positives as positive results.  This is wrong; these results represent infections or contamination and the physician who obtained the specimen must decide if the findings are consistent with the patient’s illness.  The lab should not call high cycle positives as negative or indeterminate because this relays false information to the physician.

In situations in which both IS481 and IS1001 are positive this may be due to infection with B. holmesii (also a cause of clinical pertussis) or a mixed infection with B. pertussis and B. parapertussis.

PCR should only be performed on patients with cough illnesses.  During pertussis outbreaks asymptomatic infections are very common in previous vaccinees so that you will get positive PCR results from people who are well and these results just confuse the picture (except in planned surveillance studies).


All persons who have been previously vaccinated or who have had previous infection will have a rapid rise in antibody to various B. pertussis antigens so that pertussis illness can be diagnosed by single serum serology.  The most useful antibody to determine if a cough illness is pertussis is that to pertussis toxin (PT) because this antigen is exclusive of B. pertussis.  Some tests also determine antibody to filamentous hemagglutinin (FHA) but since this antigen is not exclusive to B. pertussis high titers could be due to B. pertussis infection, other Bordetella spp and M. pneumoniae and perhaps other microorganisms.

Single serum serologic Dx has been used successfully in Massachusetts for over 20 years.  Commercial laboratories also perform single serum serology but unfortunately many of these tests are poor.  Specifically any test that uses the whole B. pertussis bacterium is virtually useless as are tests that don’t express results in units.  Tests that say they are measuring IgM antibody are also useless.  To my knowledge the only commercial test available in the U.S. that is acceptable is that offered by Focus Laboratories.  This test has specificity of ~95%.

Serologic diagnosis will be affected by recent immunization with either DTaP and Tdap so it should not be attempted if the patient has been vaccinated within the previous year.  In general single serum serology should be used for the diagnosis of pertussis in adolescents and adults who have not been recently vaccinated.

White Blood Cell (WBC) Count

Primary infections of pertussis universally have high WBC counts with absolute lymphocytosis.  This is seen in all infants who have not been immunized and who have not received antibody to PT from the mother transplacentally.  Therefore in young infants with afebrile cough illnesses the WBC count with differential can be diagnostic.  Because the WBC count has prognostic implications it should be performed on all infants who might have pertussis at the time of first physician encounter.  A WBC count of  > 20,000 cells/mm3 with a lymphocyte count of  > 10,000 cells/mm3 should be diagnosed as pertussis and immediately treated with azithromycin.


  • The onset of cough illnesses in afebrile or minimal febrile persons of all ages should be suspected of having pertussis.
  • Lab confirmation tests should be performed and specific tests employed relate to patient age, vaccine history and duration of cough.
  • For infants and children PCR is the most sensitive and specific test.
  • Whenever possible cultures should also be performed so that epidemic trends can be followed (ie antibiotic resistance, genetic changes in the organism)
  • For adolescents and adults single serum serology to determine antibody to PT is the most sensitive and specific test (unless the patient is seen during the first week of cough).
  • For young infants the WBC count with differential is often diagnostic.

James D. Cherry, MD, MSc

Distinguished Professor of Pediatrics

David Geffen School of Medicine at UCLA

Attending Physician

Pediatric Infectious Diseases

Mattel Children’s Hospital UCLA

Brady’s Life

16 04 2012

Kathryn shares the story of her son Brady’s life, and his ferocious battle with pertussis.

Listen now!

Right-click here to download podcast (14 mins/7mb)

Hey Mom and Dad. Get Vaccinated!

12 04 2012

When I was 32 I got married, had braces put on my teeth, acquired my first pair of reading glasses, and erupted in pimples the size of which I’d not seen on any adolescent.

I was something to look at.

The pimples turned out to be chickenpox. On hearing the news, my shiny new husband smirked, explaining he’d been infected as a child; as if I was somehow lame to get such a disease at my age.

The source of my infection turned out to be my sweet, sick young nephew.

The varicella vaccine was not yet routinely recommended for kids at that time, so I couldn’t blame anyone for not vaccinating the boy. I did try, though.

All this is to say that adults get sick, and sometimes their infections are preventable. It’s now recommended that adults get vaccinated against chickenpox if they have never been infected. And there are a host of other vaccines available to us, although if you are like me, you rarely think about getting immunized against anything other than influenza. We think about the kids, and we worry about our parents, but for ourselves, no.

It’s time to think about us. The National Foundation for Infectious Diseases (NFID) revamped their adult vaccination website and it’s worth a look. On the site you’ll find specifics about the vaccines you may need and details about the diseases those vaccines prevent.

Healthcare professionals weren’t forgotten. There’s a toolkit of ready-to-use resources and listings of more such items, should they be needed.

Bonus: much of the site’s information is presented in English and Spanish.

Take a few minutes this week to email or call your healthcare provider. Find out which vaccines you need and then go in, get vaccinated. Vaccines don’t work 100% of the time on 100% of those who are vaccinated. If we as adults get vaccinated, we will stop many of the incidents of parent-to-child infection. So, if you don’t want to take time for yourselves, take time to get vaccinated for your family.

By Trish Parnell

Image courtesy of sheknows.com

Why Nurses Should Get Vaccinated

9 04 2012

(Welcome to guest blogger Dr. Mary Beth Koslap-Petraco. She is a nurse practitioner in New York and a frequent guest speaker around the country on the topic of vaccines.)

Nursing organizations are opposed to mandatory immunization for nurses. I wonder why? We mandate vaccines for children to attend school to protect not only the children who are immunized, but those children who cannot be immunized for medical reasons. 

We nurses have a moral responsibility to protect our patients and our families, as well as ourselves. There would be much less chatter about mandatory vaccination for health care workers (i.e. nurses) if nurses ALL stepped up to the plate and were vaccinated themselves.

All of the arguments to encourage nurses to be immunized against not just influenza but pertussis (whooping cough) have fallen on deaf ears in one community hospital. Seems the nurses see no need to be immunized themselves. These same nurses do not have a very good track record for encouraging new mothers to be immunized against pertussis before discharge. 

The Advisory Committee on Immunization Practices (ACIP) recommends that all new mothers be immunized against pertussis with a Tdap shot before they are discharged, if they have not been immunized during pregnancy. 

Some of the mothers who delivered at this hospital said they either did not remember being asked if they wanted a Tdap shot, or it was presented to them with little or no explanation, which made them refuse the vaccine.

And I know of another community hospital which has a policy to offer Tdap to its postpartum moms but does not seem to be following its own recommendation. Two moms on two different occasions were asked if they were offered Tdap before they went home with their babies. The answer from the moms was that the vaccine was never offered. 

Meanwhile, the discharge paperwork from the hospital noted the moms ‘refused’ the vaccine, and a nurse had signed both notes. Seems it was the same nurse who had treated both of these moms. Was this nurse too busy to take a few minutes to explain the need for the vaccine to these moms, or was the nurse not ‘a nurse who vaccinates?’

If this occurred with these two moms, you can be sure it happened with other moms. Moms went home with their newborn babies without the protection they need to prevent their babies from contracting pertussis. Their babies were too young to be immunized themselves.

Recently, an incident occurred at one of these community hospitals that houses a very large mother/baby unit. There can be extremely serious consequences when nurses do not accept vaccination for themselves. A nurse working on a mother/baby unit in the hospital developed pertussis. Thankfully, no infants were infected, nor were any moms or other staff members. I think this hospital was VERY lucky. One would think that following such a scare the hospital would become pro-active about getting their staff immunized against pertussis, but it didn’t happen.

Educational programs have been aimed at this hospital, but there is still no organized program to get the nursing staff immunized. But, there is hope!  At least one of the nurses is actively encouraging her colleagues to be immunized. Kudos to this nurse ‘who vaccinates!’ The nurses need to be advocates for the vaccine for themselves . . . because it is the right thing to do.

There are lessons to be learned here. Will nurses heed these lessons?

By Dr. Mary Beth Koslap-Petraco


The end in sight – eliminating seven diseases plaguing half a billion kids

5 04 2012

(Welcome to End7. Thank you for sharing information about your work through this guest post!)

Moms and Dads from every country want one thing; healthy kids.  That’s why groups like PKIDs form—to help educate parents and the general public about specific diseases and to provide families with the support they need.

While the languages, food and clothes may be quite different for some of the kids we work with, we have a lot in common with PKIDs. Unfortunately, for families living in the poorest communities in the world, there is little in the way of support networks or treatment programs for children and adults who have neglected tropical diseases—or NTDs.

NTDs are a group of parasitic and bacterial diseases that infect half a billion kids around the world, most coming from families living on less than a $1.25 a day. These kids don’t always have shoes or clean water, which is a problem since they can get NTDs just by doing the things that kids love to do—playing, swimming and other daily activities.

When kids get sick with NTDs like hookworm, whipworm and roundworm, parasitic worms grow in their stomachs, robbing them of food and energy and making them too weak to pay attention in school. For those who live near water sources, flies may carry a disease called River Blindness, which causes rashes and severe itching and can eventually lead to blindness. These NTDs disable and debilitate their victims, keeping children out of school and preventing parents from working. They take away any chance that families have of lifting themselves out of poverty.

But this is a major global health issue that actually has a simple, cost-effective solution.  It costs just 50 cents for a packet of pills that treats and protects a child for a year. Since the drugs are donated by major pharmaceutical companies, we just need the funds to get them to the people that need them most and set up treatment and education programs that communities can run themselves.  Even better, the medicine is so easy to administer that communities don’t even need medical professionals—who are often in very short supply in developing countries—to administer them to sick kids.  The medicine can be dispensed right in schools or community centers.

The END7 campaign is working to raise awareness and donations in order to actually eliminate seven of these NTDs by 2020—the WHO said it could be done and we accepted the challenge.

To learn more about NTDs and to join the movement to eliminate them, visit our campaign on  Facebook and tell your friends to do the same. We need help in taking the “neglected” out of NTDs and that starts with you.

Together we can see the end.

By Mara Veraar, Social Media Officer at Sabin

Image courtesy of Esther Havens

The Parasitic Implications of Raccoons in Your Backyard

2 04 2012

The re-wilding or “greening” of urban and suburban spaces has been an indefatigable trend in urban planning for the past two decades. We like accessible parks and community gardens and food forests and stately trees to go along with our car-filled cities.

One of the charming/troubling manifestations of this trend can be rodents, coyotes, foxes, opossums, and raccoons joining the ‘hood.

Let’s talk raccoons. The bandit-style masking covering their faces, their insatiable curiosity, and nimble human-like hands have popularized them as mischievous varmints. Though their nocturnal habits tend to keep them out of the sights of most of us, they can be unseemly guests with their destructive tendencies. All that these small mammals need is a permanent water source, an enclosed setting for their den, and access to food. Luckily, they can find all these things and more when living in suburbia and cities. Human dwellings and activities serve as both a den reservoir and food source; we are nothing but extraordinarily generous, unwitting hosts.

They can eviscerate lawns in their search for earthworms and grubs, steal your invaluable rubbish from trash bins, suck dry bird feeders, and shred the ventilation ducts, sheetrock and insulation in attics. So cute! In addition, they are hosts to diseases that can kill you. Like rabies. And baylisascariasis.

Baylisascariasis describes the human infection with the raccoon roundworm Baylisascaris procyonis. The parasite is endemic in raccoons, with infection rates ranging from 72% to 100% (1)(2).

If you live in a place with sidewalks, there are most certainly infected raccoons living in close proximity to you; B. procyonis is the pathogen hiding in your backyard (3). One of the larger parasitic worms out there, this big guy inhabits the intestinal tracts of raccoons and produces thousands of eggs that are shed in the feces.

Like humans, raccoons can be fastidious about their pooping habits. They make communal latrines that can be found on natural or artificially flat surfaces—at the bases of trees and in branch crotches, on woodpiles, along and on the top of fences, on roofs, attics, and sandboxes (2).

This results in a condensing and localizing of the eggs in one specific spot, attracting foraging birds and small rodents to undigested seeds and the like, and successfully ensuring the continuation of the parasite’s life cycle as it infects and kills the intermediate host.

The raccoon scavenges the dead, becomes infected with the larva, and the parasite keeps marching on into life cycle infinity.

Raccoons sharing your living space, whether in the attic above you or in a nearby tree or under the porch, means that there’s a raccoon latrine near you; thankfully, they’ve kindly kept all their crap in one place, unlike some roommates I’ve had the pleasure of co-habiting with.

A 2009 survey checking out an area of suburban Chicago close to a marsh and forest preserve found that 51% of lawns had a raccoon latrine (4). This kind of work suggests that there’s a good chance of fecal contamination in many of our backyards, spaces that typically serve as children’s play areas. The uniqueness of the latrine itself—piles of feces with undigested seeds, berries and bones—can also attract curious toddlers. Alternatively, if raccoons occupy chimneys, infective feces can settle within and around fireplaces, contaminating the home.

How is it that this random raccoon parasite can make it onto a child’s fingertips, aside from the obvious hand-to-mouth behavioral sequence most parents are familiar with? There are three major ways this happens. One is that the raccoon can defecate prodigious amounts of B. procyonis eggs, on the order of a million a day. The other is that the parasite’s egg is unbelievably hardy and damn near resistant to all of our arsenals against eradicating grime, schmutz and filth. The egg has four shell layers and is resistant to high temperatures, strong acids and bases, oxidants and reductants, and protein-disrupting agents (2). Guys, that’s pretty much all we got in terms of dealing with dirty surfaces and buggies, and it’s resistant to all of them except for applying direct flames to the egg. And how often do you find yourself planning to incinerate your backyard, aside from Fourth of July celebrations? Lastly, the eggs are remarkably sticky, gluing themselves to available surfaces, which may include toys littered in the backyard.

Once hatched from the egg, the larva has a cruel propensity for the cranial region of their intermediate hosts and, as such, its carousing in the head and thoracic region has grim neurological implications. In fact, the parasite is the most common cause of larva migrans—larval worm migration in bodily tissues—in animals and can produce severe neurological larva migrans (NLM) in over 100 species of birds and animals (1).

That these alarmingly large adult worms produce sizable larva also bodes poorly for us humans. The immensity of these worms can cause significant tissue trauma, especially in young children. The most common diagnosis from infection is eosinophilic meningoencephalitis, in which the brain and spinal cord and the meninges membranes surrounding the two become enormously inflamed due to the larva activating a type of white blood cell known as an eosinophil.

Clinical symptoms can develop two to four weeks after initial infection (5). Usually children have been lethargic, feverish and a little “off” for a few weeks before being rushed to the emergency room with seizures, unsteady gait, or abnormally regressive behavior. There is no commercial test to confirm antibodies to the infection, making it difficult to have an accurate diagnosis (6).

Meningoencephalitis is an affliction whose originating cause can be tough to track down; there are numerous other larval worms to cross off the list before making a diagnosis (including Toxocara canis, Ascaris lumbricoides, as well as species of Angiostrongylus, Ancylostoma, Taenia and Echinococcus).

The infection is not well known to many clinicians outside of the infectious disease field, which can complicate proper treatment of the symptoms (6). In the emergency room, the most pressing need is to control the damaging inflammation, not figure out which worm is the culprit.

Children are more likely to suffer devastating effects of this infection than adults due to their relatively smaller brains (2). Infection outcomes have been statistically grim—many of these young patients either suffer permanent neurological and ocular defects or death. A microbiology paper from 2005 puts it bluntly, “To date, all survivors have been left in a persistent vegetative state or with severe residual deficits”(1).

And the victims are mostly very young children, typically boys. Infants and toddlers are predisposed to learn about their world by oral contact and commonly engage in pica and geophagia (eating of dirt). These types of behaviors can also be demonstrated by older children with developmental disabilities, another important subset of patients that have become infected with the parasite (3). Overall, important risk factors for baylisascariasis infection include exposure to raccoon feces, pica or geophagia, age under 4 years, male gender, and intellectual development delay.

Thankfully, the number of cases is low, but it’s hard to discern whether that’s attributable to an actual low incidence of disease or a lack of reporting. Many parents decline autopsies, the only true way to identify a case of baylisascarisasis.

I tracked down 22 cases that have been reported in the literature (1)(3)(6)(7)(8)(9). Subclinical infection may also occur—a Chicago study found that 8% of children showed antibodies to the parasite though none had ever shown symptoms of disease (10); baylisascariasis may be much more prevalent than we think.

The number of reportable cases has been steadily rising in the past decade for unknown reasons, though I suspect that the greening of our surroundings and the increase in diagnosed autism cases, a medical situation that can predispose children to pica habits, may have something to do with it.  Most recently, adult B. procyonis worms have been detected in pet dogs (2). This worrisome finding suggests that cases could continue to rise.

There are few wild animals that live so freely alongside humans that are cable of transmitting such a ferociously nasty and fatal disease. Parents and communities should be made aware of the dangers of having such animals close by and should go to efforts to locate and remove any raccoon latrines within or near the home.

Bringing nature to the neighborhood isn’t always a deliberate process, like revitalizing our neighborhoods by putting in a park or planting some trees. Industrial decay, environmental catastrophes and housing foreclosures can transform our urban landscape into a more inviting setting for nature to recolonize our space. Bobcats have been found living in foreclosed homes, neighborhoods in New Orleans are literally turning into marshland, and feral animals prowl through Detroit. One of the benefits of living in a city, away from nature, is that the only animals we have to deal with are ourselves.

(1) Gavin PJ, Kazacos KR, and Shulman ST. (2005) Baylisascariasis. Clin Micro Rev. 18(4): 703-18
(2) Gilbert CE (Date unknown) Concern with Communicable (Infectious) Diseases of Raccoons. Epidemiology and Toxicology Institute, LLC.  Accessed online March 27, 2012.
(3) Hajek J et al. (2009) A child with raccoon roundworm meningoencephalitis: A pathogen emerging in your own backyard? Can J Infect Dis Med Microbiol. 20(4): e177 – e180
(4) Page K et al (2009) Letter: Backyard Raccoon Latrines and Risk for Baylisascaris procyonis Transmission to Humans.  Emerg Infect Dis. 15(9): 1530-1
(5) Park SY et al (2000) Raccoon Roundworm (Baylisascaris procyonis) Encephalitis: Case Report and Field Investigation Pediatrics. 106(4): E56
(6) Frank Sorvillo et al. (2002) Baylisascaris procyonis: An Emerging Helminthic Zoonosis. Emerg Infect Dis. 8(4): 355-9.
(7) Moertel CL et al. (2001) Eosinophil-Associated Inflammation and Elaboration of Eosinophil-Derived Proteins in 2 Children With Raccoon Roundworm (Baylisascaris procyonis) Encephalitis. Pediatrics. 108(5): E93.
(8) Haider S et al. (2012) Possible pet-associated baylisascariasis in child, Canada [letter]. Emerg Infect Dis. 18(2): 347-9. Accessible online.
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By Rebecca Kreston

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