Tag: epidemiology

What to Know About the Acute Flaccid Myelitis Investigations

Although you may just now be hearing about acute flaccid myelitis, it is important to understand that it isn’t new.

The rise in AFM cases began in 2014 and seem to occur every other year.
The rise in AFM cases began in 2014 and seem to occur every other year.

It wasn’t even new when we started to see an increased number of cases a few years ago.

What is new, is that we are seeing an increased number of cases.

Acute Flaccid Myelitis Timeline

AFM refers to acute (sudden onset) flaccid (droopy or loose muscles) myelitis (inflammation of the spinal cord) and it is a subtype of acute flaccid paralysis.

If that explanation doesn’t really help you, it might help to understand that paralytic polio, like AFM, is another subtype of acute flaccid paralysis.

“In August 2012, the California Department of Public Health (CDPH) was contacted by a San Francisco Bay area clinician who requested poliovirus testing for an unvaccinated man aged 29 years with acute flaccid paralysis (AFP) associated with anterior myelitis (i.e., evidence of inflammation of the spinal cord involving the grey matter including anterior horn cell bodies) and no history of international travel during the month before symptom onset. Within 2 weeks, CDPH had received reports of two additional cases of AFP with anterior myelitis of unknown etiology.”

Acute Flaccid Paralysis with Anterior Myelitis — California, June 2012–June 2014

That seems to be about when this started, in 2012.

Unfortunately, they didn’t figure out what was causing the paralysis in these three patients, despite extensive testing and more cases followed.

“To identify other cases of AFP with anterior myelitis and elucidate possible common etiologies, CDPH posted alerts in official communications for California local health departments during December 2012, July 2013, and February 2014.”

Among 23 cases, California health officials found that the median age of the patients was 10 years old, only two tested positive for EV-D68, although most did have a recent “an upper respiratory or gastrointestinal prodrome.”

“Acute flaccid paralysis (AFP) with anterior myelitis is not a reportable condition, and baseline rates of disease are unknown but are likely quite low. Data from 1992–1998 on children aged <15 years in California indicated an incidence of 1.4 AFP cases per 100,000 children per year and did not identify a single case of AFP with anterior myelitis.”

California wasn’t the only state with cases.

In 2014, there were at least 12 cases in Colorado and 11 in Utah.

“In response to the CDPH and CHCO reports, the CDC established a case definition for enhanced nationwide surveillance of AFM, which included individuals less than 21 years of age with acute flaccid limb weakness and MRI involvement of predominantly the gray matter of the spinal cord without identified etiology presenting after August 1, 2014.”

Messacar et al on Acute Flaccid Myelitis: A Clinical Review of US Cases 2012–2015

All together though, in 2014, once  the CDC began actively investigating cases, at least 120 cases were discovered in 34 states. The cases were associated with a large outbreak of EV-D68-associated respiratory illness, although they weren’t able to conclusively link those respiratory illnesses to the AFM cases.

Is there any evidence that there were a lot of cases before 2012?

Or that the CDC has dropped the ball and hasn’t been doing enough to investigate cases?

Not if you look at the timeline.

The CDC was involved very early, called for all cases to be reported, and is actively investigating those cases.

CDC activities include… using multiple research methods to further explore the potential association of AFM with possible causes as well as risk factors for AFM. This includes collaborating with experts to review MRI scans of people from the past 10 years to determine how many AFM cases occurred before 2014, updating treatment and management protocols, and engaging with several academic centers to conduct active surveillance simultaneously for both AFM and respiratory viruses.

CDC on the AFM Investigation

And if the first cases in California and Colorado triggered so much attention, isn’t it likely that any cases anywhere else would have done the same thing?

That makes it very unlikely that many cases were missed in earlier years.

  • EV-D68 first identified as a cause of respiratory tract infections – 1962
  • the first reports that EV-D68 could cause severe, even fatal respiratory disease – 2008
  • first AFM cases are discovered in California – August 2012
  • the Colorado Department of Public Health and Environment notifies the CDC about a cluster of AFM cases at Children’s Hospital Colorado and a joint investigation begins between the CDPH, CDC, and the physicians caring for the patients  – September 2014
  • the CDC issues a health advisory on Acute Neurologic Illness with Focal Limb Weakness of Unknown Etiology in Children and calls on local and state health departments to report patients to the CDC – September 2014
  • the CDC conducts a conference call on Neurologic Illness with Limb Weakness in Children, so that clinicians could learn about the latest situation, surveillance, and CDC clinical guidance for AFM testing, patient evaluation and case reporting – October 2014
  • the CDC posts Interim Considerations for Clinical Management – November 2014
  • 120 AFM cases in 34 states – 2014
  • Council of State and Territorial Epidemiologists AFM case definition adopted – June 2015
  • 22 AFM cases in 17 states – 2015
  • 149 AFM cases in 39 states – 2016
  • Council of State and Territorial Epidemiologists AFM case definition updated, which once again, recommends against adding AFM to the Nationally Notifiable Disease List – June 2017
  • 33 AFM cases in 16 states, including one death – 2017
  • CDC Telebriefing on Acute Flaccid Myelitis in the US with Dr. Nancy Messonnier, director of CDC’s National Center for Immunization and Respiratory Diseases – August 2018
  • 90 AFM cases confirmed in 27 states among 252 reported cases that are being investigated – 2018

The other issue that concerns many parents is why a definitive cause hasn’t yet been identified. And why don’t we have treatments or a cure yet?

“To date, no pathogen (germ) has been consistently detected in the patients’ spinal fluid; a pathogen detected in the spinal fluid would be good evidence to indicate the cause of AFM since this condition affects the spinal cord.”

CDC on AFM Investigation

Although enteroviruses can be difficult to detect in spinal fluid, it is important to keep in mind that isn’t the only thing that is keeping experts from declaring the investigation over and naming a cause, such as EV-D68.

“Among 41 patients whose upper respiratory tract samples were available for enterovirus/rhinovirus testing at CDC, 17 (41%) tested positive: eight (20%) for EV-D68 and nine (22%) for eight other enterovirus/rhinovirus types.”

Eyal Leshem on Notes from the Field: Acute Flaccid Myelitis Among Persons Aged ≤21 Years — United States, August 1–November 13, 2014

Another big issue is that EV-D68 has not been detected in every, or even most AMF patients, and many others have been found to have other enteroviral infections, including EV-A71.

Could it be a coincidence that investigators are finding these enteroviruses simply because it is the season for them to appear? That would mean something else is causing these kids to have AFM.

“During September–November 2016, 10 confirmed cases of AFM were reported in Washington. No common etiology or source of exposure was identified. Enterovirus-A71 was detected in one patient and EV-D68 in two patients, one of whom also tested positive for adenovirus.”

Acute Flaccid Myelitis Among Children — Washington, September–November 2016

While the focus is on EV-D68 as a cause and everyone wants an answer, no one wants the CDC or other investigators to be wrong.

That doesn’t mean that they should be overly cautious and waste time or resources once an answer is evident, but just that they should follow sound epidemiological principles, get the right answer, and help stop kids from getting AFM.

What’s Next for AFM?

There are still a lot of unknowns about AFM, but this is likely what we can expect in the coming months:

  • the CDC will continue to investigate all unconfirmed cases that have occurred this year, which can take about four weeks after a case is reported and all necessary information is sent in. Keep in mind that since we don’t know if the CDC has already received all of the information on the cases they are investigating, we don’t know when they will finish investigating any pending cases.
  • local or state health departments will likely reach out to treating physicians to get followup about AFM patients about two months after they developed limb weakness and then report this short-term follow-up data to the CDC. In general, the CDC does not seem to contact patients directly.

From the current investigation, information from outbreaks and cases over the previous years, and cases in other countries, we will hopefully get the answers we need soon to prevent and treat AFM.

During the COCA Call, the AFM Surveillance Team will discuss the activities CDC is conducting as part of its AFM investigation.
The AFM Surveillance Team will participate in a COCA Call in mid-November.

Maybe some of those answers will come during a Clinician Outreach and Communication Activity (COCA) Call on November 13, when members from the CDC Acute Flaccid Myelitis Surveillance Team discuss the “activities the CDC is conducting as part of its investigation into AFM.”

The fact that the CDC has an Acute Flaccid Myelitis Surveillance Team will be news and is hopefully reassuring to some folks…

This is also probably a good time to remind folks that funding for public health has been declining in recent years, even as we expect our public health officials to respond to more things and react more quickly to keep us all safe and healthy. Let’s make sure we fund our public health programs, including the CDC and NIH, so that they have all of the resources they need to address all of today’s public health challenges.

More on the Acute Flaccid Myelitis Timeline

Updated on November 13, 2018

The Case for Making AFM Reporting Mandatory

There have been 90 cases of acute flaccid myelitis (AFM) so far this year, with another 162 cases under investigation by the CDC and state and local health departments.

“Acute flaccid myelitis (AFM) is not nationally notifiable; CDC relies on clinician recognition and health department reporting of patients under investigation (PUIs) for AFM to learn more about AFM and what causes it.”

But could there be more cases?

The Case for Making AFM Reporting Mandatory

Although AFM isn’t yet a nationally notifiable disease,  120 other diseases are, from Anthrax and Botulism to Vibriosis and Zika virus disease.

The Nationally Reportable Disease List depends on state laws for any mandate to report.
The Nationally Notifiable Condition List depends on state laws for any mandate to report.

Who picks them?

The Council of State and Territorial Epidemiologists.

“Although AFP surveillance is commonly conducted in many countries currently still at risk for ongoing transmission of poliovirus, AFP is not a reportable condition in any U.S. state and routine surveillance and assessment for AFP is not performed. Therefore, understanding the baseline incidence and epidemiology of AFM and its public health impact in the United States is significantly limited.”

Revision to the Standardized Surveillance and Case Definition for Acute Flaccid Myelitis

Acute flaccid paralysis (AFP) isn’t a reportable disease in the United States either.

While many people would like AFM to be added to the the Nationally Notifiable Condition List, the CSTE has instead recommended that we:

  1. Utilize standard sources (e.g. reporting to a local or state public health department) for case ascertainment for acute flaccid myelitis (AFM), including clinician and laboratory reporting, reporting by hospitals, hospital discharge notes, neurology or infectious disease consult notes, MRI reports and images, outpatient records, and extracts from electronic medical records, etc.
  2. Utilize standardized criteria for case identification and classification for acute flaccid myelitis (AFM) but do not add AFM to the Nationally Notifiable Condition List . If requested by CDC, jurisdictions (e.g. States and Territories) conducting surveillance according to these methods may submit case information to CDC.
  3. Report cases as soon as possible and continue surveillance.
  4. Share data to “measure the burden of acute flaccid myelitis (AFM).”

And the CDC has agreed.

“CDC concurs with this position statement. We look forward to continuing to work with our jurisdictional partners to address this important public health issue. This standardized case definition provides an opportunity to better define the spectrum of illness seen with AFM and to determine baseline rates of AFM in the United States. During review of the position statement, a few minor edits were identified as necessary for clarification, and we are working with the author to make these changes.”

What would be the difference if AFM was added to the Nationally Notifiable Condition List?

For one thing, because the list of reportable conditions varies from state to state, it would provide a uniform case surveillance and case definition.

But we already have that in the CSTE Position Statement on Acute Flaccid Myelitis.

The big issue is that there is no federal law that actually mandates reporting for the diseases on the list! Or even to report them to the CDC.

“Each state has laws requiring certain diseases be reported at the state level, but it is voluntary for states to provide information or notifications to CDC at the federal level.”

CDC on Data Collection and Reporting

It is up to state laws – in each and every state.

“The legal basis for disease reporting is found at the state level, where inconsistent laws may differ in terms of which conditions are reportable and their reporting process.”

Brian Labus on Differences In Disease Reporting: An Analysis Of State Reportable Conditions And Their Relationship To The Nationally Notifiable Conditions List

So even if the Council of State and Territorial Epidemiologists added AFM to the Nationally Notifiable Condition List, you would then need each state to pass a law adding AFM to their lists of notifiable diseases.

“Currently AFM is not a reportable condition in Texas.”

TxDSHS on Acute Flaccid Myelitis

How long would that take?

Zika is on the Nationally Notifiable Condition List, but guess what, like AFM, it isn’t on the reportable condition list in many states…

Utah has already added AFM to its list of notifiable conditions. Has your state?
Utah, Washington and Colorado have already added AFM to their list of notifiable conditions. Has your state?

Want to get more cases of AFM reported to the CDC?

Let’s raise awareness about AFM and educate parents and health professionals to get all cases diagnosed, as they can then get reported to local and state health departments, who will then report them to the CDC.

Making AFM reporting mandatory might sound like a big deal, but will it really make any difference in getting kids diagnosed and treated?

“Ultimately, we would have to decide what the purpose of making something nationally notifiable is. We can investigate it just as well without that designation, and keeping things at the state level (for now) allows a lot more flexibility in how we define and investigate it. It might seem frustrating because it isn’t on the nationally-notifiable list, but that honestly doesn’t matter in terms of how we investigate things.”

Brian Labus, PhD, MPH

Cases still get investigated without being on the Nationally Notifiable Condition List.

Cases still get reported without being on the Nationally Notifiable Condition List.

And that’s good, because adding AFM to the Nationally Notifiable Condition List is not something that would happen overnight.

CP-CRE was added to the National Notifiable Disease List in 2018 at the 2017 CSTE annual meeting.
CP-CRE was added to the National Notifiable Condition List in 2018 at the 2017 CSTE annual meeting.

The CSTE would probably discuss it at their next meeting (next summer), and if approved, it would take effect at the beginning of the new year – January 2020. But then, then CDC has to get approval from the Office of Management and Budget (OMB) to actually get permission to start collecting the data on AFM for the Nationally Notifiable Condition List. All of that likely means that the earliest we would see “national” reporting for AFM would be sometime in 2022.

Does that mean we should jump on it now if it is going to take so long, or should we wait to figure out a definitive cause, and then put that on the Nationally Notifiable Condition List?

Whatever we do, remember that it still wouldn’t be mandated reporting unless each and every state actually passes a law mandating reporting of AFM cases to the CDC. Again, being on the Nationally Notifiable Condition List simply means that states are strongly encouraged to report their cases, as they do now. There are several diseases on the Nationally Notifiable Condition List that states never add to their own notifiable conditions list.

“It is voluntary that notifiable disease cases be reported to CDC by state and territorial jurisdictions (without direct personal identifiers) for nationwide aggregation and monitoring of disease data. Regular, frequent, timely information on individual cases is considered necessary to monitor disease trends, identify populations or geographic areas at high risk, formulate and assess prevention and control strategies, and formulate public health policies. The list of notifiable diseases varies over time and by state. The list of national notifiable diseases is reviewed and modified annually by the CSTE and CDC. Every national notifiable disease is not necessarily reportable in each state. In addition, not every state reportable condition is national notifiable.”

CDC on Data Collection and Reporting

Mostly, folks should understand that simply being on the Nationally Notifiable Condition List may not mean as much as they think it does.

“Although disease and condition reporting is mandated at the state, territory, and local levels by legislation or regulation, state and territory notification to CDC is voluntary. All U.S. state health departments, five territorial health departments, and two local health departments (New York City and District of Columbia) voluntarily notify CDC about national notifiable diseases and conditions that are reportable in their jurisdictions; the data in the case notifications that CDC receives are collected by staff working on reportable disease and condition surveillance systems in local, state, and territorial health departments.”

CDC on Data Collection and Reporting

And that epidemiologists at the local, state, and national level are working hard to identify all cases of AFM, which will hopefully help them figure out what is causing these cases, how to treat kids who are already affected, and how to prevent new cases.

They are identifying more and more cases of AFM even though few states have mandatory reporting, AFM isn’t on the Nationally Notifiable Condition List, and reporting of cases to the CDC is voluntary.

More on Making AFM Reporting Mandatory

Updated on November 13, 2018

Incubation Periods of Childhood Diseases

The incubation period or latency period is the amount of time between being exposed to a contagious disease and when you begin developing symptoms.

This is not the same as the contagious period or the time during which your child can get others sick.

Incubation Period

Depending on the disease, the incubation period can be just a few hours or can last for several months. Knowing the incubation period for a disease can help you understand if your child is still at risk of getting sick or if he is in the clear — whether he is exposed to someone with strep throat, measles, or the flu.

“The incubation period is the time from exposure to the causative agent until the first symptoms develop and is characteristic for each disease agent.”

CDC

It can also help you figure out where and when your child got sick. For example, if your infant develops chickenpox, a vaccine-preventable disease, you can’t blame it on your cousin who doesn’t vaccinate her kids and who was visiting just three days ago. The incubation period for chickenpox is at least 10 to 21 days. So your child who is too young to be vaccinated likely caught chicken pox from someone he was exposed to a few weeks ago.

As we saw in recent outbreaks of Ebola and measles, a diseases incubation period can also help you figure out how long an exposed person needs to stay in quarantine. After all, if they don’t get sick once the incubation period is over, then they likely won’t get sick and can be released from quarantine.

Incubation Periods of Childhood Diseases

The incubation period for some common diseases includes:

  • Adenovirus – 2 to 14 days, leading to a sore throat, fever, and pink eye
  • vomiting after exposure to Bacillus cereus, a type of food poisoning – 30 minutes to 6 hours (short incubation period
  • Clostridium tetani (Tetanus) – 3 to 21 days
  • Chickenpox – 10 to 21 days
  • Epstein-Barr Virus Infections (Infectious Mononucleosis) – 30 to 50 days (long incubation period)
  • E. coli – 10 hours to 6 days (short incubation period)
  • E. coli O157:H7 – 1 to 8 days
  • Fifth disease – 4 to 21 days, with the classic ‘slapped cheek’ rash
  • Group A streptococcal (GAS) infection (strep throat) – 2 to 5 days
  • Group A streptococcal (GAS) infection (impetigo) – 7 to 10 days
  • Head lice (time for eggs to hatch) – 7 to 12 days
  • Herpes (cold sores) – 2 to 14 days
  • HIV – less than 1 year to over 15 years
  • Influenza (flu) – 1 to 4 days
  • Listeria monocytogenes (Listeriosis) – 1 day to 3 weeks, but can be as long as 2 months (long incubation period)
  • Measles – 7 to 18 days
  • Molluscum contagiosum – 2 weeks to 6 months (long incubation period)
  • Mycobacterium tuberculosis (TB) – 2 to 10 weeks (long incubation period)
  • Mycoplasma penumoniae (walking pneumonia) – 1 to 4 weeks
  • Norovirus ( the ‘cruise ship’ diarrhea virus) – 12 to 48 hours
  • Pinworms – 1 to 2 months
  • Rabies – 4 to 6 weeks, but can last years (very long incubation period)
  • Respiratory Syncytial Virus (RSV) – 2 to 8 days
  • Rhinovirus (common cold) – 2 to 3 days, but may be up to 7 days
  • Roseola – about 9 to 10 days, leading to a few days of fever and then the classic rash once the fever breaks
  • Rotavirus – 1 to 3 days
  • gastrointestinal symptoms (diarrhea and vomiting) after exposure to Salmonella – 6 to 72 hours
  • Scabies – 4 to 6 weeks
  • Staphylococcus aureus – varies
  • Streptococcus pneumoniae (can cause pneumonia, meningitis, ear infections, and sinus infection, setc.) – 1 to 3 days
  • Whooping cough (pertussis) – 5 to 21 days

Knowing the incubation period of an illness isn’t always as helpful as it seems, though, as kids often have multiple exposures when kids around them are sick, especially if they are in school or daycare.

Conditions with long incubation periods can also fool you, as you might suspect a recent exposure, but it was really someone your child was around months ago.

More About Incubation Periods