Ebola Outbreak Update: July 31-August 1

cdc.gov

The World Health Organization has posted updated information on the Ebola outbreak in West Africa.

Between July 31 and August 1 there were 163 new (presumptive) cases with 61 deaths; cases are being reported from Guinea, Liberia, Sierra Leone and Nigeria.

The total number of presumptive cases is now 1,603 with 887 deaths; at this point the outbreak is nowhere near contained and current infection control efforts appear inadequate. Unfortunately there are no Ebola-specific therapies available; treatment is supportive in nature and the disease carries a very high mortality rate (71-86% based on a recent report in the New England Journal of Medicine).

Total Ebola Cases/ Deaths Per Country to Date

As noted recently by CDC director Dr. Thomas Frieden "Ebola poses little risk to the U.S. general population." From an infection control standpoint preventing disease transmission is relatively easy, at least on paper and in resource-rich environments. The disease can be prevented by preventing contact with potentially infected blood and body fluids in people with suspected infection, coupled with aggressive contact tracing, monitoring and isolation of people who may have been exposed. This said, there are many barriers to effectively controlling the current epidemic, not the least of which is access to critical infection control resources and personnel.

One of the factors that promoted the expansion of the current outbreak was the long time it took for the outbreak to be recognized. Cases of people with a disease characterized by vomiting and diarrhea with a high mortality rate were first identified in clusters in Guinea in December 2013; the outbreak was not reported to international authorities until March 2014. As a global community we need to promote access to resources and technology that support the rapid detection and diagnosis of key infectious diseases; this is in all of our best interests. This current outbreak is yet another reminder that new (and old) diseases will continue to emerge and that something that emerges in a 'remote' part of the world can rapidly become a global issue.

Dengue: Over Three Times More Common Than Previously Thought

Aedes aegypti mosquito
(cdc.gov) 

Here is a new article on the worldwide incidence of dengue viral infections that was just published by Bhatt and colleagues in Nature.

Dengue is a viral infection transmitted by Aedes aegypti (and Aedes albopictus) mosquitoes; it is the most common mosquito-borne viral infection. It causes an acute febrile illness characterized by severe pain (which gives the disease its colloquial name: "breakbone" fever). Although not associated with high mortality, the disease is nonetheless associated with significant morbidity.

Using worldwide data on dengue incidence as well as statistical modeling, these authors estimate that there are upwards of 390 million dengue infections per year, with approximately one third of people actually having symptomatic disease. Three-hunded and ninety million is a pretty staggering figure (just around 5% of the world's population), and is over three times the estimated annual incidence per the WHO.

Here in the United States, this is definitely an issue "right in our backyards." In recent years we have seen dengue expand into previously unaffected areas, including the southern United States.

The study by Bhatt and colleagues will hopefully further raise awareness about dengue and the need for a coordinated global strategy to combat it.

Update on Human H7N9 Avian Influenza Cases in China

VCU Global Health & Health Disparities Program (GH2DP)
group entering Honduras during the H1N1 pandemic, 2009

Here is the latest update from the WHO on human H7N9 avian influenza cases in China; as of April 5 16 patients have laboratory-confirmed infection (up from just 3 a few days ago) and 6 have died. Contacts of the people who are infected are being closely watched for signs and symptoms of respiratory infection; to date no clear evidence of person to person transmission has been found.

Although it not clear yet where people acquired H7N9, the virus has been detected in pigeons in a major Chinese agricultural market, leading to the mass execution of 20,000 birds.

Here is an April 4th health advisory on H7N9 from the CDC and an April 5 'telebriefing' with the CDC's director Dr. Tom Frieden. Here is detailed, specific travel advice from the CDC for people going to China (emphasizing such things as avoiding live bird and poultry markets, practicing good hand hygiene, et cetera).

Much is unknown about the epidemiology and transmissibility of the H7N9 virus; to date it does not look efficient in terms of person to person transmission, which is the public health community's greatest concern. One thing is certain: these new human cases of "bird flu" illustrate how quickly novel infectious disease threats can emerge, and we must be vigilant and act quickly as a global community to identify, contain and development treatments for these diseases when they appear.

New Article on Zombies Published in Emerging Infectious Diseases

cdc.gov

Here is an interesting article that was just published in Emerging Infectious Diseases on the use of the public's general fascination with zombies for public health education.

The article refers to back to an earlier CDC blog post that used a "zombie apocalypse" as a vehicle for educating about disaster preparedness. I definitely remember when this clever 2011 CDC blog post was published, and the general content of the message. I have to admit that I can not recall any other general disaster preparedness messages delivered by the CDC or any other group... perhaps there really is something to tying health messages to fictional, highly memorable content?

The current Emerging Infectious Diseases article provides both historical background information on zombies as well as information on their popularity across a variety of media/ entertainment platforms (books, films, video games, et cetera).

The article discuss how public health messages that pull from fictional depictions of zombies could be used to educate about such real-world issues as infection control, risk for bioterrorism, disaster preparedness, provide a framework for ethical discussions, et cetera.

The authors provide a real-world example of the mass killing of 50,000 or so dogs in Bali in 2008 in an effort to control a rabies outbreak; this led to a discussion about the most optimal, ethical, control of rabies in a given area (e.g., mass killing versus vaccination). The authors of the Emerging Infectious Diseases article posit that ethical dilemmas depicted in fictional dramas (such as those involving zombies) can help provide a relatable framework for real-life infection control and infectious diseases issues.

Anyway, I am going to stop blogging now so I can go work on my emergency kit/ plan; you never know.

Rainfall, Temperature and Dengue Risk: New Insights from Rio

Aedes aegypti mosquito (cdc.gov)

Here is a study by researchers from Brazil that looked at the relationship between dengue activity and climate in Rio de Janeiro from 2001 to 2009. Using statistical modeling, they found that a 10-millimeter rise in rainfall led to a 6% increase in dengue cases in the subsequent month, and a 1 degree celsius rise in temperature led to a 45% increase.

Dengue is a viral infection transmitted by Aedes aegypti (and Aedes albopictus) mosquitoes; it is the most common mosquito-borne viral infection. It causes an acute febrile illness characterized by severe pain (giving it its colloquial name: "breakbone" fever). The disease is associated with significant morbidity.

The findings in the above study are not surprising: increased temperature allows the mosquitoes that carry dengue to breed and feed more efficiently. Increased rainfall can increase potential breeding sites for these mosquitoes (which breed in freestanding water). This study adds to the growing body of literature linking climate and infectious disease activity.

A warmer world is one in which the various vectors for tropical infections (especially mosquitoes) will enjoy a broader environment in which to breed and feed. More research into the relationship between climate change and emerging infectious diseases is warranted.

Hottest Year on Record for the Contiguous US: Implications for Emerging Infectious Diseases?

http://climate.ncdc.noaa.gov

Here is an article from the Huffington Post discussing National Oceanic and Atmospheric Administration (NOAA) data from 2012, noting that 2012 was the "hottest year on record for [the] lower 48 [United] states." The article is compelling and contains some nice images that outline how the average temperature has increased in the contiguous United States over the past century; it is believed that climate change has played a role in this mean temperature increase.

A byproduct of increasing global temperatures is the expansion of insect habitats that can harbor viral infections (such as dengue, chikungunya and yellow fever).  As I have previously noted, this phenomenon may have contributed to a dengue outbreak in southern Florida, and may lead to other viral infections (such as chikungunya) emerging in other parts of the United States, as well. A recent study from Mexico found the mosquitoes that can carry dengue (as well as the chikungunya and yellow fever viruses) at higher elevations than previously identified; this may represent expansion of the mosquitoes' habitat due to global warming.

If the world continues to grow warmer, the medical and public health communities need to be aware (and vigilant in surveillance) of the potential for traditionally "tropical" infectious diseases to emerge in (what were once) more temperate climates.

New Study Explores Relationship Between Biodiversity, Vector-borne Diseases and Economics

Aedes aegypti mosquito (one
of the mosquitoes that carries
the dengue virus; cdc.gov)

Here is an interesting article by Bonds and colleagues in PLOS Biology. Via creative statistical modeling techniques, these authors examined the relationship between the 'latitudinal gradient in income' (the fact that there are more poor people living in the tropics) and vector-borne and parasitic diseases (diseases like malaria that are carried by mosquitoes).

The authors found that vector-borne diseases (VBDs) have significantly affected economic development, and that VBDs are affected by underlying ecologic conditions, especially biodiversity. Interestingly, their model predicts that the burden of VBDs will rise (and local economies will suffer) if biodiversity falls.

Dengue risk map (for past 3 months); tropical areas are
disproportionately affected by many tropical infections;
www.healthmap.org/dengue/index.php

An example of a VBD is dengue, a viral disease carried by mosquitoes (the disease 'vectors'). Both the dengue virus and its mosquito vectors are influenced by local ecosystems. One example of how influencing an ecosystem can affect a VBD is the release of genetically altered mosquitoes into an area to help control the spread of dengue disease. This practice has been used in multiple locations to control dengue spread via limiting the local mosquito population's ability to reproduce.

An example of a VBD that has potentially emerged due to relatively poor biodiversity is Lyme disease; this is a bacterial infection carried by ticks; there were over 24,000 cases in the US in 2011.

The authors note that diverse, well-functioning ecosystems may have a positive effect on the health of a given population via decreasing the burden of vector-borne diseases. This, in turn, will positively affect a given area's economy. This research is intriguing and more research into the relationship between the burden of VBDs and ecology is warranted.

Importance of "Super-spreaders" in Infectious Disease Outbreaks

Entering Honduras during the H1N1 influenza
pandemic, June 2009

Here is an interesting article from Slate looking at the role of "super-spreaders" in infectious disease outbreaks. This refers to a sub-population of individuals who are more likely to spread an infectious disease than others; it is believed such "super-spreaders" played a role in the SARS pandemic. Identifying these individuals may have a role in managing global infectious disease outbreaks.

At the hospital level, Polgreen and colleagues have studied this phenomenon as it applies to hand hygiene and disease spread. Their work supports the idea that certain healthcare workers are more likely to spread an infectious disease, and has implications for targeting these individuals to prevent disease spread (via such things as optimizing hand hygiene, et cetera).  

Dengue: Already Entrenched in Southern Florida?

Dengue activity over the past 3 months (blue areas = areas of ongoing
transmission risk); www.healthmap.org/dengue

Here is a nice article on the potential for dengue virus to re-emerge in the United States. The article links to a poster presentation by Shin and colleagues from the University of Florida that was presented at last month's American Society of Tropical Medicine and Hygiene annual meeting. These authors isolated a distinct strain of dengue virus from an outbreak of dengue fever in Key West in 2010 and note that this strain may circulate in the region. Only their abstract is available for review so it is not possible to comment on their research further at this time.

Dengue is a viral infection transmitted by Aedes aegypti (and Aedes albopictus) mosquitoes; it is the most common mosquito-borne viral infection. It causes an acute febrile illness characterized by severe pain (which gives the disease its colloquial name: "breakbone" fever). Although not associated with high mortality, the disease is nonetheless associated with significant morbidity.

Aedes albopictus mosquito (one of the mosquitoes
that carries dengue in the United States); cdc.gov

It is worth taking a second to orient yourself to the map that appears at the beginning of this post; this map shows areas of dengue activity over the past three months, and areas of sustained transmission appear in blue. The research by Shin and colleagues begs the question: should southern Florida also appear in blue on this map?

In recent years we have seen outbreaks of dengue in multiple areas of the United States, including Hawaii, Texas and Florida (as noted above). It is possible that climate change, with global increases in mean temperatures, is playing a role in expanding the disease by increasing the geographic range of the mosquitoes that carry the dengue virus.

Anything that can capture rainwater can become a breeding
ground for the mosquitoes that carry dengue (cdc.gov)

Here is an abc news story on dengue in Florida that provides a lot of nice background information on this problem. The article also discusses the use of genetically modified mosquitoes to help control the disease; see here for a previous discussion of this practice.

More examples of potential breeding grounds
for mosquitoes (cdc.gov)

The environment in southern Florida (and many other areas of the United States) can support endemic dengue transmission. To boot, we already have the mosquito vectors that carry this disease (as well as other diseases such as chikungunya). As both of these mosquito-borne viral illnesses have seen geographic expansion in recent years, the medical and public health communities in the US need to be especially vigilant in looking for cases of these diseases and controlling the mosquitoes that transmit them.

Chikungunya: Coming to the United States?

cdc.gov

Could we see chikungunya outbreaks in the United States? According to a modeling study by Ruiz-Moreno and colleagues the answer is yes.

Chikungunya is a viral illness carried by mosquitoes that was first isolated in Tanzania in the 1950s. The name derives from the Kimakonde language and means "to become contorted." Profound joint pain leads to a 'stooped over' appearance, thus the name.

Symptoms of acute infection are nonspecific and are similar to dengue, with fever, headache, nausea, muscle and joint pains and fatigue. Peculiar to this virus, some people can have longstanding joint pain that can last for months, even years. There is no vaccine to prevent this illness and no treatment (other than supportive care).

Global spread of chikungunya virus, 2005-2009 (cdc.gov)

Chikungunya is endemic in Southeast Asia and Africa. In recent years the disease has "emerged" from these areas; in 2005 we saw outbreaks on islands in the Indian Ocean (following an outbreak in Kenya in 2004), with subsequent spread across India. A related outbreak occurred in Italy in 2007, as well.

The mosquitoes that transmit chikungunya (Aedes albopictus, or the "Asian tiger" mosquito and Aedes aegypti) are both present in the United States. If a returning traveler has chikungunya virus in their blood and are bitten by one of these mosquitoes, conceivably that mosquito could transmit the virus on to other people.

The study by Ruiz-Moreno et al, published in PLOS Neglected Tropical Diseases in November, utilized computer modeling to assess if a single returning traveler infected with chikungunya could cause sustained transmission in the United States.

Aedes albopictus (the "Asian tiger") mosquito, one of the
vectors for chikungunya (cdc.gov)

This study revealed that cities with marked seasonal temperature variation (such as New York and Atlanta) have potential for periodic chikungunya outbreaks. In these areas epidemics could occur during the periods in time the mosquitoes are most likely to breed (warmer times of the year). Cities with less seasonal temperature variations (such as Miami) with higher mean temperatures have the potential for sustained epidemics.

Chikungunya is a serious viral illness with the potential for significant morbidity. Since it was first discovered in the 1950s it has "emerged" dramatically, with considerable additional expansion over this past decade. The study by Ruiz-Moreno and colleagues confirms that epidemic potential exists in the United States. The medical and public health communities need to be aware of this potential and vigilant in monitoring for chikungunya cases.

Update on Yellow Fever Outbreak in Darfur

Yellow fever risk area in Africa (cdc.gov)

Here is an update from the WHO on the yellow fever outbreak in Darfur.

"Yellow fever" refers to the disease caused by the yellow fever virus that is transmitted by mosquitoes in areas of Africa and South America. This a hemorrhagic fever virus associated with substantial mortality and high morbidity. Worldwide there are approximately 200,000 cases yearly with 30,000 deaths. Although a safe and effective vaccine is available for this disease, there is no treatment (other than supportive care) for people who contract it. 

Yellow fever virus (cdc.gov)

As of December 4th in the Darfur outbreak there have been 732 suspected cases of yellow fever with 165 deaths.

A multi-disciplinary team is investigating the outbreak to better understand its scope and epidemic potential. War and social upheaval have traditionally been linked to infectious disease outbreaks. Recent conflict and mass population displacement in Sudan likely has contributed to this current outbreak. 

An emergency mass vaccination campaign has been occurring in the region since late November; the goal is to vaccinate over 3 million people at risk for acquiring the disease. This vaccination effort will be critical in curbing this outbreak and preventing a full-blown epidemic. 

Aedes aegypti mosquito (the mosquito that transmits
the yellow fever virus); cdc.gov

Update on Novel Coronavirus in the Middle East

Arabian peninsula (wikipedia.org)

Here is the WHO update on the new coronavirus that was recently discovered in the Arabian peninsula. What is concerning is that this novel coronavirus, known for now as "hCoV-EMC," is (distantly) related to the Severe Acute Respiratory Syndrome (SARS) coronavirus that caused a worldwide outbreak in 2003 with 8,098 cases and 774 deaths. With the hCoV-EMC virus all patients have been severely ill with acute respiratory disease; there have been 9 confirmed cases with 5 deaths as of November 30th.

The earliest reports of hCoV-EMC infection came from 2 retrospectively identified cases in Jordan in April of 2012. Cases have also been identified in Qatar and Saudi Arabia. Across the 9 confirmed cases there have been two "clusters" of infections, raising concern about human-to-human transmission or a common source of exposure.

SARS coronavirus (cdc.gov)

At this point we do not know how this virus is transmitted or what its natural reservoir is. Unlike the SARS virus, it does not appear to easily transmit between people.

We do know that patients with hCoV-EMC present with severe respiratory disease and the virus has been associated with high mortality. Vigilant surveillance of patients presenting with acute respiratory disease and unexplained pneumonias is needed, especially patients in (and with recent travel to) the Middle East.

SARS coronavirus (cdc.gov)

This infection is another reminder that new infectious diseases will continue to "emerge," and the medical community needs to be ever vigilant in identifying these early.

HIV: Learning From Stigmatization

wikipedia.org

Here is a thoughtful piece from over at PLoS on the stigma associated with various infectious diseases, especially HIV. Despite decades of research and education, discrimination still exists for people living with HIV; Gorman cites examples of people denied employment, of HIV positive inmates being isolated from other inmates and the ban on people with HIV entering the United States that was only lifted in 2009.

She poignantly notes that discrimination leads to false beliefs about disease transmission that in turn drive the stigma associated with disease. She also notes that stigmatization is a not a phenomenon isolated to HIV, but rather has been associated with many infectious diseases throughout history. Stigmas alienate people and undermine disease detection, prevention and treatment efforts.

Gorman calls for research into what drives stigmatization, with a special focus on what we can learn from history. As the emergence of new infectious diseases is a reality of human existence, learning from the stigma associated with HIV and other infectious diseases is critical.

Global Warming: Promoting Mosquito Expansion?

Aedes aegypti mosquito; cdc.gov

Here is an interesting study by Lozano-Fuentes and colleagues that was just published in this month's American Journal of Tropical Medicine and Hygiene. They looked at the presence of Aedes aegypti mosquitoes across a number of communities at different elevations in Mexico and found that the mosquitoes were present at elevations as high as 2,130 meters, over 300 meters higher than previously described in Mexico. The authors posit that global warming may increase the geographic range of Aedes aegypti mosquitoes, thereby putting previously protected populations at risk of mosquito-borne illnesses. Their results are intriguing (although by no means conclusive) and contribute to the growing body of literature examining the effects of climate change on emerging infectious diseases.

Aedes aegypti mosquitoes are an important vector for a number of viruses, including dengue, chikungunya and yellow fever. Conceivably, if the geographic range of Aedes aegypti mosquitoes expands more people will be at risk for these serious infections. The ongoing dengue outbreak in Madeira and recent reports of infections in the United States illustrate the need for further research into the relationship between climate change and emerging infectious diseases, and underscores the need for robust surveillance for all emerging mosquito-borne infections.

Update on Ebola Outbreak in Uganda




wikipedia.org

 
Here is an update from the WHO on the Ebola outbreak in Uganda; as of November 23rd there have been 10 cases with 5 deaths in Luweero and Kampala. What is worrisome about this outbreak is that the disease made it as far as the capitol city. Although this current outbreak appears to be contained, this is a good reminder that a disease that emerges in a remote jungle today can spread to anywhere in the world in a very short period of time.

European Dengue Outbreak: Etiology & Implications

Here is a link to a Reuters story reporting on the large outbreak of dengue ("breakbone") fever in Madeira (a Portuguese-controlled series of islands in the Atlantic just west of Morocco).  Over 1,300 cases have been reported since the outbreak was first recognized in October; significantly, this is the first sustained European dengue outbreak since the 1920s.

Dengue fever is a viral infection transmitted by Aedes aegypti (and Aedes albopictus) mosquitoes; it is the most common mosquito-borne viral infection. This is a febrile illness associated with high morbidity and low mortality; the disease can be deadly, however, as it can cause shock and an illness characterized by widespread hemorrhaging.

It is believed that the virus crossed species from monkeys to humans in Southeast Asia or Africa sometime in the past 1,000 years, with rapid dissemination of the disease around the world in the 20th century. Per WHO estimates 50-100 million infections occur each year with 22,000 deaths; see the CDC's site for great information about the disease.

Dengue fever is an excellent example of a disease that has emerged and expanded due to globalization; it is believed that rural-urban migration, explosive population growth, increased international trade and poor urban infrastructure all have played roles in the rapid expansion of this disease.

Dengue infections have made a resurgence in the United States as well, with cases reported in Key West in 2009 and recent cases being reported in Hawaii and in Texas, also. There is concern that climate change and global warming are playing a role in the re-emergence of dengue in the US: see a thoughtful commentary on this in the Lancet.

http://www.who.int/csr/disease/dengue/impact/en/; Areas in red
represent areas where dengue has emerged since 1960

What are the implications of the outbreak of dengue in Madeira and the sporadic cases being seen in the United States? It is clear that "tropical" infections can emerge and expand rapidly, and that infectious diseases are affected by globalization and do not respect traditional borders. Any solution to the dengue problem must involve a trans-national approach that emphasizes collaboration and brings together professionals across disciplines.

cdc.gov; Aedes aegypti mosquito

It is also clear that this is not a static issue: the public health community must be vigilant with dengue surveillance and early intervention (such as improved mosquito control) when disease expansion is detected.

Finally, here is a nice CBS News piece with a general discussion of the scope of the dengue problem, as well as an interview with Dr. Anthony Faucci, director of the National Institutes of Allergy and Infectious Diseases.