Monday, June 15, 2015

Where are the pediatric cases of MERS Infections?

Prior to the report of the Middle East Respiratory Syndrome (MERS) outbreak in the Republic of Korea (South Korea) in mid-May, more than 1000 cases of MERS had been reported from around the world since 2012. Most of these cases, about 87%, have been reported from the Kingdom of Saudi Arabia (Saudi Arabia). Only about 3% of the MERS cases reported through mid-May from Saudi Arabia can be can be classified as pediatric cases (cases less than 18 years old). There has been speculation that Saudi Arabia has had pediatric cases of MERS that were unreported (link).

Through June 14, 2015, South Korea has reported 150 MERS cases. The number MERS cases reported from South Korea is second only to Saudi Arabia. Since the beginning of the outbreak in South Korea only a single pediatric MERS case has been reported, a hospitalized, 16-year-old male.

As unfortunate as the outbreak in South Korea is, it provides an important data set for analyzing the nature of MERS infections. The South Korea outbreak was caused by a single individual (index case) who was infected on the Arabian Peninsula and returned to South Korea. Unlike the Arabian Peninsula, there is no evidence that any animal species on the Korean Peninsula is infected with or could transmit the MERS coronavirus to humans. The infection of all 150 cases in South Korea is a direct result of human-to-human transmission that can be traced back to the initial index case.

A risk assessment from the European Centre for Disease Prevention and Control (ECDC) (link) provides a graph showing the relationship of age groups of MERS cases distinguished by gender for about 200 cases from Saudi Arabia since the beginning of 2015 and the 107 cases from South Korea since the MERS outbreak began. The graphs seem to show a comparable age distribution of infected individuals from South Korea and Saudi Arabia in 2015. A more rigorous statistical comparison can be developed by comparing the age distribution of the currently confirmed 150 cases from South Korea with the most recent 150 MERS cases reported by the Saudi Arabia Ministry of Health (150 cases since February 15, 2015).

The table and graph below present the count and percentages of MERS cases by10-year age groups for these two countries. The table and graph demonstrate that there is a high correspondence in MERS cases by age category between South Korea and Saudi Arabia. In fact, these two age-category distributions of infected individuals, separated geographically by almost 7500 km, are highly correlated with an R value of .95. But, what can we learn from this table and what does this correlation tell us?

First, it tells us that pediatric cases are rare in South Korea, and by extension, they are also rare in Saudi Arabia. Second, the high correlation coefficient, along with few pediatric cases in both countries, indicates that Saudi Arabia is not hiding or covering up pediatric cases of MERS. Third, its tells us that MERS seems to be differentially infecting adults compared to children or adolescents. Why this is the case is not clear.

It is important to reiterate that all of the MERS cases in  South Korea are a result of human-to-human transmission. None of the MERS cases in South Korea are a result of the coronavirus jumping from an animal host to humans. The outbreak in South Korea is shedding light on the nature of the MERS coronavirus and how it affects and transmits among humans.

Thursday, June 11, 2015

38 Hospitals in South Korea with MERS Exposure

Currently, at least 122 people have been infected with MERS in South Korea, all from a single index case who became sick in mid-May. The index case had visited several health care facilities before being diagnosed and hospitalized. Several health care workers became infected while examining this individual prior to hospitalization. The index case exposed a number of people to the MERS coronavirus during his hospitalization. Several of these exposed individuals were released from the hospital and later became symptomatic and were later diagnosed with MERS. By that time, some these individuals had infected others and the chain of transmission began.

An important component of breaking the transmission chain and containing an infectious disease outbreak is restricting its geographic spread. As of June, 11, 2015, South Korean health authorities have identified 38 hospitals where MERS patients are currently being treated or where MERS patients apparently visited prior to being diagnosed. The map below shows the wide geographic distribution of these hospitals across South Korea. We will have to wait for the MERS incubation period to pass to see whether or not MERS cases start to occur in these outlying areas.

Data from:

Saturday, June 6, 2015

Preliminary Timeline of the Initial MERS Outbreak in the Republic of Korea

The MERS outbreak in the Republic of Korea began when a 68-year-old man returned from visiting countries on the Arabian Peninsula in early May. He was symptomatic after returning to Korea and visited several hospitals.  He infected a few health care workers before being diagnosed with MERS and hospitalized.  Since then at least 50 people have been infected.  Some of these cases represent third generation infection; hundreds of people are currently being monitored. This outbreak is far from over.

Below is a preliminary timeline of the first 35 cases reported by the Korea Ministry of Health.

The data and information used here have been derived from numerous publicly available sources including WHO, various ministries of health, internet bloggers, internet forums, and other media reports available online. For some individual cases, specific details are lacking or conflicting information is presented in online reports. However, the information and graphics presented here are based on data which is believed to be reasonably accurate and current through June 3, 2015.

Sunday, May 10, 2015

H5 HPAI outbreaks in poultry flocks in the USA

Since December 2014, the United States Department of Agriculture (USDA) has confirmed H5 Highly Pathogenic Avian Influenza (HPAI) in commercial and backyard poultry flocks in the United States. At least 142 separate incidents have been detected through May 7, 2015; most are the H5N2 virus.[1] According to USDA, more than 29 million birds have been infected including chickens, ducks, pheasants, and turkeys mostly in commercial poultry flocks. Chickens represent about 81% of all infected poultry followed by turkeys with 18% of the total.

In addition to the poultry flock infections in the United States, at least 60 incidents of detection of H5 HPAI in wild birds have also been reported since early December 2014 from the 13 states [2] shown in the map below.

H5 HPAI has been detected in poultry flocks in 13 states as well. However, there is no on-to-one correspondence between the states reporting wild bird infections and those with poultry flock infections as show on the map below.

Based on the number of infected birds, the geographic distribution of the H5 HPAI poultry outbreaks is concentrated in the Upper Midwest. There is no sign that the poultry flock infections are declining. The good news is that no human cases of these H5 subtypes have been reported from the United States. And according the Center for Disease Control, the risk of human infection from these H5 avian influenza subtypes is low.[3]

Wednesday, March 25, 2015

Confusion surrounds the number of H5N1 cases in Egypt

The most recent, cumulative World Health Organization (WHO) table of human H5N1 cases was published on March 3, 2015.[1] This table notes a total of 88 human H5N1 cases in Egypt through March 3, 2015. As I noted previously [2] the tabulation of counts based on the line list of cases published in the monthly risk summaries only totals 82 cases for Egypt in 2015 based on onset dates in reports of 2015.

To understand the confusion in the Egyptian case counts in the WHO table, it is necessary to consider the 2014 totals provided by WHO. The current WHO cumulative table reports 46 cases of H5N1 in 2014 with 31 cases from Egypt.[1] However, individual enumeration of WHO-confirmed H5N1 cases based on line lists in the monthly risk assessments shows a total of 52 H5N1 cases in 2014 (based on onset dates), with 37 of these reported from Egypt.[3] The table below identifies the distribution of WHO-confirmed H5N1 from Egypt by each of the monthly summaries for 2014 through the most recent assessment posted on March 3.[4]

Further complicating the confusion is the Regional Office Eastern Mediterranean (EMRO) of WHO. On March 21, 2015 EMRO published a table that only identifies 29 H5N1 cases from Egypt in 2014.[5] The EMRO data has a 8-case discrepancies with the line list of confirmed cases published by WHO.

In summary, Egypt experienced a total of 37 confirmed H5N1 in 2014 based on onset dates. In 2015, 82 WHO-confirmed cases with onsets dates before February 20 have occurred in Egypt. Since February 20, there have been at least 22 additional official cases from Egypt with onset dates on or after 20 February. Another 3 H5N1 cases have been also reported from Egypt but are not yet corroborated.

Until we get the numbers right for H5N1 in Egypt from 2014, we can’t correct the numbers for 2015. Based on the above discussion, through March 25, 2015 there have been 107 H5N1 cases in Egypt with symptom onset since January 1, 2015.  

Friday, March 13, 2015

Egypt leads the world in the number of human H5N1 cases

In late December 2014, Egypt surpassed Indonesia in the number of reported A(H5N1) cases.[1] As of March 3, 2015, the World Health Organization (WHO) has confirmed a worldwide cumulative total of 784 human H5N1 cases, about 37% or 292 of these cases have been reported from Egypt (Table 1). Eighty-two of those cases from Egypt occurred in the first two months of 2015.[2] In addition, media reports suggests that another four cases have occurred since late February in Egypt and may be included in future monthly updates by WHO.[3]

The recent WHO report from 3 March 2015 notes “ The number of laboratory-confirmed human cases of avian influenza A(H5N1) virus infection in Egypt with onsets of illness in the months of December 2014, January and February 2015 are the highest numbers reported by any country in a single month.” To put these statistics in perspective, about 36% of all H5N1 cases reported from Egypt have occurred in the last 3 months. The graph below shows the distribution of WHO confirmed cases by ISO week number in Egypt since December 2014.

 Based on onset dates, since December 2014 there have been 105 H5N1 cases reported from Egypt. According to WHO at least 28 of these individuals have died. The fatality rate among this group is 27% to date, although only 17 of these cases have been reported in media reports to have recovered.

Besides the 82 cases from Egypt since the beginning of 2015, only one other case of H5N1 has been confirmed by WHO in 2015, a 37-year-old woman from Suzhou, Jiangsu Province in the People’s Republic of China. With 83 cases so far this year, the H5N1 case count for 2015 already exceeds the annual case count of H5N1 for the preceding seven years.[4]

While the spot light is on human H5N1 infections in Egypt, the single case from Suzhou, China is a reminder that the H5N1 influenza virus is endemic in many parts of the world and that human outbreaks of H5N1 in the size and the scope now occurring in Egypt could quickly develop elsewhere in the world.

Saturday, January 31, 2015

The CDC is Watching for Human Avian Influenza Infections

So far, North America has been lucky. Community acquired infections of avian  influenza have not yet occurred, although an imported case of H5N1 was identified in Alberta Canada in 2013 and two imported cases of H7N9, a husband and wife, were reported from British Columbia in just this past week.

Because of recent outbreak of highly pathogenic avian influenza (H5 subtypes) in wild birds and domestic flocks in North America, the Center for Disease Control has issues guidance for health care workers for identifying and testing patients with potential avian influenza infections. As of January 31, 2015, no H5 subtype human avian influenza infections have been recorded from these outbreaks which have been reported from six western states along the Pacific Flyway (Washington, Oregon, Idaho, Nevada, Utah, and California ). (link)

The CDC guidance will help health care workers to assess patients with influenza symptoms that might be at infected with an H5 subtype of avian influenza.   The CDC identifies the following  items as risk factors for potential avian influenza infections. Individuals
who have had recent contact (<10 days prior to illness onset) with sick or dead birds in any of the following categories:
Domestic poultry (e.g., chickens, turkeys, ducks)
Wild aquatic birds (e.g., ducks, geese, swans)
Captive birds of prey (e.g., falcons) that have had contact with wild aquatic bird
Contact may include: direct contact with birds (e.g., handling, slaughtering, defeathering, butchering, preparation for consumption); or direct contact with surfaces contaminated with feces or bird parts (carcasses, internal organs, etc.); or prolonged exposure to birds in a confined space.

The CDC also states that exposures that occur in geographic regions in the United States where newly detected avian influenza A H5 viruses have been identified are of most concern ( e.g. Washington, Oregon, Idaho, Nevada, Utah, and California).

Health care workers need to be familiar with this CDC guidance in order to adequately assess patients who might be infected with avian influenza. Last year a suspected Ebola patient was not correctly diagnosed and was sent home causing an Ebola scare in Texas. The patient later died.  Human infections from H5 subtypes are virulent often resulting death. There is some evidence that H5 subtypes can be transmitted from human-to-human, so early detection is important.

If you experience influenza symptoms and meet any of the risk factors for avian influenza be sure to mention it to your doctor or health care professional at the time of your visit.