Thoughts on the New Bird Flu H7N9 & It’s Animal Connection

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Much of the United States is mesmerized by the belligerent squawks from North Korea’s Kim Jong-un and the volatile tension straddling the Korean peninsula, but I’m more concerned about what is happening in China right now and the troubling trickle of news on a new bird flu strain H7N9.

At least 16 people have been infected, patients who were widely distributed through the geographic enormity that is China, and already six have died. But what makes this small cluster of flu cases unusual is its timing – we usually see flu outbreaks emerging in the fall and winter months and we are just now breaking into the month of April – and that this type of flu strain is not known to infect humans.

H7N9 seems to be following a well established pattern of other emerging viruses: originating in east Asia, the infection appears to have a tentative association with wet markets and butchering, and is of zoonotic or animal origin. We’ve seen this situation previously with Nipah virus in Malaysia infected pigs and slaughterhouse employees and with SARS and its birth in the wet markets of Guangdong Province in China.

Laurie Garret masterfully crafts an unnerving story, of unknown unknowns regarding these human flu cases and the potential linkage between the thousands of pigs and fowl carcasses that clogged Chinese waterways in March.

Here’s how it would happen. Children playing along an urban river bank would spot hundreds of grotesque, bloated pig carcasses bobbing downstream. Hundreds of miles away, angry citizens would protest the rising stench from piles of dead ducks and swans, their rotting bodies collecting by the thousands along river banks. And three unrelated individuals would stagger into three different hospitals, gasping for air. Two would quickly die of severe pneumonia and the third would lay in critical condition in an intensive care unit for many days. Government officials would announce that a previously unknown virus had sickened three people, at least, and killed two of them. And while the world was left to wonder how the pigs, ducks, swans, and people might be connected, the World Health Organization would release deliberately terse statements, offering little insight.

By the end of March, at least 20,000 pig carcasses and tens of thousands of ducks and swans had washed upon riverbanks that stretch from the Lake Qinghai area all the way to the East China Sea — a distance roughly equivalent to the span between Miami and Boston. Nobody knows how many more thousands of birds and pigs have died, but gone uncounted as farmers buried or burned the carcasses to avoid reprimands from authorities.

We are very early into this developing scenario and this spate of cases could fizzle into just a blip in the news cycle and on the infectious disease radar. You should read Maryn McKenna’s reasoned and calm analysis here and to devour a slew of delicious infectious disease geek resources at the tail end of her article.

The point I want to make here is a reminder of how closely intertwined the lives of humans are with the lives of the animals we breed and eat. Not many of us raise pigs in the backyard or hear the cock’s crow in the morning and it’s easy to forget that for thousands of years we have lived in close proximity to our poultry and livestock.

But this is still the case in developing nations and particularly those with industries reliant on raising and butchering animals for the global market as well as people supporting a family with their hens and chicks. It is these people and places that are at most risk of emerging zoonotic infections like H7N9 and they require careful surveillance and monitoring of the health and well-being of both people and animals. Remember: catching a novel disease from an animal is the rule not the exception.

Resources

The most important link I can give you: “The New Bird Flu, And How To Read The News About It” from Maryn McKenna.

A timeline of events from Laurie Garret’s article “Is This a Pandemic?” in the short news cycle of H7N9. Her article can be accessed here.

Shanghai will be temporarily closing its live poultry markets on Saturday due to fears of a spreading H7N9 .

A Mess in Texas: What Happened in Dallas with West Nile Virus?

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That insistent buzzing drone you hear? It’s the sound of our burgeoning mosquito problem and the nasty diseases that they carry wreaking havoc throughout the world. 2012 was a prodigious year for mosquito-borne arboviral diseases, with West Nile virus, Japanese encephalitis, malaria, dengue and yellow fever outbreaks and epidemics raging in the United States, the Sudan, Puerto Rico, Malaysia,  IndonesiaIndiaPeruBrazil and many other nations besides.

“Don’t Mess With Texas,” the road sign warning drivers throughout the State to not litter Texan roadways. This year, Texas had a more insidious mess on their hands. Image: Anne Ward. Click for source.

If you live in the US, you might know that this year the country suffered the largest outbreak of West Nile virus (WNV) since 2003. As of December 11th, infections with the virus have been reported in humans, birds and mosquitos in all of the lower 48 states. In humans, there have been a reported  5,387 cases of WNV disease with 2,734 or 51% of these cases classified as West Nile neuroinvasive disease (WNND), a severe manifestation of the infection resulting in encephalitis, chronic mental sequelae and occasionally death, and there have been 243 deaths; 80% of these cases have occurred in 13 states with a third of all cases reported in Texas (1).

Though it’s unknown why 2012 proved to be a particularly noxious and geographically expansive year for WNV in the States, there were several environmental factors that precipitated the outbreak’s emergence in Texas that may have influenced its severity. A short, mild winter at the tail end of 2011 may have allowed for greater numbers of mosquitos to survive the winter, an occurrence known as “overwintering”. In the spring and summer that followed, bouts of rain provided standing water for mosquito breeding and egg laying while droughts and higher than average temperatures may have also accelerated the replication of the WNV in birds and increased its transmissibility to mosquitoes, thereby augmenting its spread across the country (2)(3)(4)(5).

Dallas county in Texas has disproportionately suffered the majority of WNV cases and fatalities – 405 total cases of WNV disease and 18 deaths (6). Aside from auspicious environmental conditions for the mosquito population and the virus, the scale and severity of the outbreak can partly be attributed to the county’s inadequate dedication to mosquito surveillance and control, which led to several challenges to WNV disease prevention within the local population.

http://www.cdc.gov/ncidod/dvbid/westnile/Mapsactivity/surv&control12MapsAnybyCounty.htm

West Nile virus (WNV) activity reported to the CDC’s arbovirus surveillance system ArboNET as of December 11, 2012, by county in the United States. Source: ArbnoNET. Click for more in-depth data and info.

Dallas county did not follow their own established protocols for mosquito surveillance or the recommendations of mosquito experts, and decided to test mosquitoes for arboviruses in May rather  than April despite the aforementioned environmental conditions. In doing so, the county failed to adequately evaluate the extent of WNV infection in the mosquito population (7)(8). As the outbreak crescendoed over the early summer, the county had only a scant four employees dedicated to mosquito surveillance and control for an area 871 square miles wide and with a population of 1.2 million residing in Dallas city alone (7).The county administered a woefully low number of mosquito traps – one trap for every 19 square miles and only 20 traps per week – once more failing to either assess the magnitude of the mosquito population or properly identify the cities most at risk for transmission of mosquito-borne diseases (7). Furthermore, Dallas county did not track and test deceased birds for the virus, a well-established and commonly used sentinel surveillance strategy for monitoring arboviral diseases in susceptible populations of wild and domestic animals (4)(8). Larvicide to treat egg-laden mosquito pools wasn’t purchased until July 30th, well into the beginning of the epidemic, “days after the CDC told the city’s health department that Dallas was already at the highest-possible risk level for West Nile virus.” (8)

Simply put, there were inadequate resources available for vector and viral monitoring in Dallas County and throughout the state oF Texas as a whole and, as a result, the mosquito population and the levels of WNV infection present in the population skyrocketed, all the while unbeknownst to local health officials. The outbreak only became apparent as escalating numbers of human infections were reported by local and state health officials to ArboNET, the CDC’s national database for monitoring arboviral infections in the populace, and the CDC  in turn notified Texan public health officials. In the end, extreme and expensive measures had to be taken in the form of aerial and land pesticide spraying to staunch the numbers of increasing WNV infections and infection-related deaths.

http://www.dallasnews.com/news/community-news/dallas/headlines/20120713-dallas-area-cities-working-to-curb-west-nile-virus-after-outbreak-this-year.ece

North Dallas neighborhoods sprayed in mid-July to kill mosquitoes carrying the West Nile virus. Image: Tom Fox at Dallas News. Click for source.

The WNV outbreak in Dallas county is a grim yet instructional example of the importance of active disease surveillance and institutionalized vector control programs. Surveillance – whether through monitoring the levels of tick populations or tracking the numbers of people reporting with flulike symptoms in emergency rooms – is the foundation of preventative public health. Without some truly simple and basic methods of tracking mosquitos and testing them for life-threatening diseases, we will again have outbreaks that can only be controlled by expensive, draconian measures that include using planes to shower urban cities with pesticide. Just a few short months after the outbreak that claimed 18 lives, Dallas county is now conducting year-round surveillance and testing of mosquitos to prevent another costly and deadly outbreak (10). Hopefully, the lessons learned in the 2012 outbreak will influence future public health efforts regarding mosquito and arbovirus surveillance in Texas in the years to come.

Full disclosure: This article is adapted and modified from an essay on the investigation of the WNV outbreak in 2012 from a class I took last semester on outbreak epidemiology.

Note: The information in this article is heavily reliant on the excellent investigational reporting by Scott Friedman at NBC 5. You can see an archive of his work for NBC, including his WNV investigative work, here.

Resources

A brief article in Emerging Infectious Diseases, “West Nile Virus Infection among Humans, Texas, USA, 2002–2011,” found that WNV has become endemic in the state and the number of reported cases of infection increased every three years though that doubtlessly has changed following this year.

An incredible close-up and personal view of the eyes of a mosquito.

“Over one million people worldwide die from mosquito-borne diseases every year.” Curious about what those are? Check out mosquito.org for their list of the nasty infections that mosquitos spread to humans, horses, birds and dogs.

The strange weather we’ve had this year – from droughts to monsoonal rainstorms to shocking heat waves – certainly played a role in the WNV outbreak in Dallas. The NYT talks about the new climatological reality in this superb article.

References

(1) CDC (December 11, 2012) “2012 West Nile virus update: November 20” CDC West Nile Virus Homepage. Accessed January 11, 2013 here.

(2) JE Soverow (2009) Infectious Disease in a Warming World: How Weather Influenced West Nile Virus in the United States (2001–2005). Environ Health Perspect. 117(7): 1049–1052

(3) RM Kinney (2006) Avian virulence and thermostable replication of the North American strain of West Nile virus. J Gen Virol. 87(12): 3611-3622

(4) R Jaslow (August 24, 2012) “What’s making the 2012 West Nile virus outbreak the worst ever?” CBS News [Online]. Accessed November 23, 2012 here.

(5) CDC (August 22, 2012) CDC Telebriefing on West Nile Virus Update. CDC Newsroom. Accessed November 23, 2012 here.

(6) Texas Department of State Health Services. (December 17, 2012) News Updates Webpage. Accessed January 11, 2013 here.

(7) S Friedman. (September 17, 2012) “Missed Opportunities in Fight Against West Nile Virus.” NBC Dallas-Forth Worth. Accessed November 22, 2012 here.

(8) S Friedman (September 13, 2012) “Dallas Revisits West Nile Virus Attack Plan.” NBC Dallas-Forth Worth [Online]. Accessed November 22, 2012 here.

(9) M Fernandez (August 16, 2012) “West Nile Hits Hard Around Dallas, With Fear of Its Spread.” The New York Times [Online]. Accessed November 22, 2012 here.

(10) J Stengle (December 26, 2012) “Health experts turn attention to learning lessons from historic West Nile outbreak.” The Republic [Online]. Accessed January 11, 2013 here.

ResearchBlogging.orgSoverow, J., Wellenius, G., Fisman, D., & Mittleman, M. (2009). Infectious Disease in a Warming World: How Weather Influenced West Nile Virus in the United States (2001-2005) Environmental Health Perspectives DOI: 10.1289/ehp.0800487

A Season of Hemorrhagic Fevers

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Uganda and the Democratic Republic of Congo have been bedeviled by viral hemorrhagic fever outbreaks this year. Since the summer, Ebola and Marburg have appeared throughout the two verdant countries killing dozens of people.

An Ebola outbreak in western Uganda began in early July, another Ebola outbreak materialized in eastern DR Congo in August, and then Marburg made an appearance in south-western Uganda as well as in the capital Kampala in October. Last month, Uganda finally declared the country free of hemorrhagic fevers after three months of battling these seemingly omnipresent sanguinary viruses. And then Ebola appeared yet again in Luweero, a village located just 47 miles from the capital. It has been an incredibly psychologically and financially taxing period for the two countries.

(Confused on the timeline of events? I certainly was! But the WHO is here to help with a chronology of Ebola outbreaks here and Marburg outbreaks here.)

Ebola and Marburg hemorrhagic fevers outbreaks in Uganda and the Democratic Republic of Congo in 2012. Red crosses represent reported cases and the green amorphous shapes represent parks, forests and reserves as identified by Google Maps. Click to visit the map, zoom in and get additional info. © Google.

The thing to remember with viral hemorrhagic fevers is that they’re not toxic miasmas, diffusing through households and indiscriminately infecting innocents. They’re viruses. They spread through contact with infected bodily fluids, resulting in the transmission of viral particles and like any other infectious disease, there’s a method to the madness. True, they’re frightful illnesses and quite deadly, but there are clear epidemiological patterns and even cultural contexts to their arrival and spread in communities.

Take these viral hemorrhagic fever outbreaks, for example. Uganda and the DR Congo are incredibly rich and diverse in their ecology – the Congo Basin is one of the largest and densely forested regions in the world – and much of their economy depends upon safari tourism and gorilla trekking (1). The livelihood of their peoples is also greatly reliant on poaching and bushmeat; for many in the DR Congo, primates, ungulates, primates and rodents are often their only form of animal protein considering the prohibitive cost of raising or purchasing domesticated animals for food (1). It can be easier and kinder on limited finances just to go into the forests to get your dinner. Coincident with the diverse wildlife and the lush wilderness that flourishes in these countries are also viruses simmering away, undisturbed for the most part.

The recent outbreaks in Uganda and the DR Congo have some local officials pinpointing the origin of the these most recent outbreaks on infected bushmeat and contaminated fruit. The Ebola outbreak in August in the Dungu district in northern DR Congo began with a hunter who found and consumed the remains of an antelope, quickly fell ill and died (2). October’s Marburg outbreak in Kabale, Uganda is speculated to have occurred when villagers ventured into the wild to collect fruits that were contaminated by fruitbats, a known reservoir of the virus (3).

An isolation camp for infected patients and suspected cases during Uganda’s Ebola hemorrhagic fever outbreak this year. Image: The Lancet. Click for source.

There’s an unexpected upside to these grim epidemics as public fears of these deadly viral hemorrhagic fevers are keeping wildlife poachers and bushmeat hunters from venturing into the forests for profit and food. Park rangers in the DR Congo report that there has been demand for bushmeat has crashed with a concomitant rise in fear of contracting a fatal disease. Media Congo, an online newspaper covering the Congo, notes, “the fight against poaching of rare species that was once the sole preserve of NGOs and officials of the Congolese Institute for the Conservation of Nature (ICCN) has become the business of everyone” (4). Giant primates have been threatened for years by poachers and bushmeat hunters and though our closest ancestors are also at great risk of contracting and dying of Ebola and Marburg, for now they’re safe from those hunting them (5).

To figure out just where the outbreaks were occurring, I began playing around with a few maps to pinpoint the locations of reported villages in relation to nearby protected park, forests and game reserves. There’s limited information on the outbreaks – even from the WHO and Medecins Sans Frontiéres/Doctors Without Borders – on the exact origins of the many victims who have traveled to hospitals seeking care and then have died and these maps are the best I could do with the limited information available. The maps give a good idea of how geographically disparate the epidemics were, the proximity of the legion parks and reserves to reported outbreaks and how the two countries are just entirely covered in lush, green forest.

Resources

Ebola may be transmitted by respiratory means; the possibility of airborne transmission of this virus would go far in explaining how transmissible the virus is within households and hospitals.

“Protein from forest wildlife is crucial to rural food security and livelihoods across the tropics.” A great read on bushmeat in the two most densely forested and least populated places in the world.

The WHO’s Global Alert & Response monitors all global epidemics and public health emergencies. This is the current list of 2012 epidemics.

The gorilla population was devastated in 2002 and 2003 as outbreaks of the Zaire strain of Ebola killed nearly 5000 gorillas in northwestern DR Congo.

References

(1) R Nasi et al. (2011) Empty forests, empty stomachs? Bushmeat and livelihoods in the Congo and Amazon Basins. International Forestry Review 13(3):355-368

(2) Irin News Africa (August 23, 2012) DRC: Bushmeat blamed for Ebola outbreak. Irin News. Accessed here on November 20, 2012.

(3) E Biryabarema (October 23, 2012) Killer disease reaches Uganda capital, five dead. Reuters. Accessed here on November 20, 2012.

(4) J. Kikumi (October 26, 2012) Le virus d’Ebola chasse les braconniers. Media Congo [mediacongo.net]. Accessed here on November 20, 2012.

(5) M Bermejo et al. (2006) Ebola outbreak killed 5000 gorillas. Science. 314(5805):1564

ResearchBlogging.orgNasi, R., Taber, A., & Van Vliet, N. (2011). Empty forests, empty stomachs? Bushmeat and livelihoods in the Congo and Amazon Basins International Forestry Review, 13 (3), 355-368 DOI: 10.1505/146554811798293872