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Selected Category: mosquito-borne disease

CDC Scientist Fights Chikungunya

Categories: chikungunya, mosquito-borne disease

investigation in Comoros in 2005.

Investigation in Comoros in 2005.

Ann Powers, Ph.D., Research Microbiologist and Chief of the Alphavirus Laboratory in CDC’s Division of Vector-Borne Diseases

Ann Powers, Ph.D., Research Microbiologist and Chief of the Alphavirus Laboratory in CDC’s Division of Vector-Borne Diseases

One of the most telling signs of the complexity surrounding chikungunya is that educating people on pronouncing the name correctly is perhaps the easiest challenge.

I’m exposed to that truth more than most.  And for the record, it’s pronounced chick-un-goon-ya.

As a research microbiologist for CDC’s National Center for Emerging Zoonotic and Infectious Diseases, my job is to better understand and occasionally chase (literally) an often overlooked, mosquito-borne, threat to public health; one that holds the potential to spread sickness and misery in the United States.

Chikungunya is viral disease that is transmitted to people by two species of mosquitoes that are present in the United States. Aedes aegypti and Aedes albopictus, often called the Asian tiger mosquito, can be found in about a third of the U.S.  They are the same mosquito species that transmit dengue in much of the tropics.  And while chikungunya does not kill people, the toll it inflicts ranks high on the misery index; it hits fast and hard and with almost no subtlety. People infected with chikungunya typically experience high fever and severe joint pain soon after they are exposed. Sometimes those problems are long-lasting.

Chikungunya’s reach has been rapidly expanding for eight years. From its origins in Africa, it’s been detected throughout tropical Asia, in Italy and France, and since December, 2013, in the Caribbean, including in the U.S. territories of Puerto Rico and the U.S. Virgin Islands. Today, the Pan American Health Organization (PAHO) reports more than 300,000 suspected cases of chikungunya have been identified across the Caribbean, Central, and South America.

Investigation in Comoros in 2005

Investigation in Comoros in 2005.

And while it hasn’t taken root yet in the United State yet there are cases in travelers. On average, several dozen cases have been introduced each of the last five years into the U.S., all from people coming from countries with active transmission.

More than one-third of the United States has the warm to moderate climate necessary for the mosquito vectors, which are known to be “aggressive daytime biters.” Since the virus has largely been absent from the United States, there’s a huge population with little to no immunity. But a large-scale outbreak in the mainland U.S. will not be easy to achieve. There has to be a perfect convergence of enough mosquitoes and infected people as well as timing. Mosquitoes become infected when they feed on a person recently infected (within the first few days of illness onset) with the virus.  That infected mosquito can bite another person who may then become infected with the virus.  Outbreaks occur when multiple mosquitoes and humans get infected.

The potential, however, for limited transmission is real and it’s the reason CDC has been actively working to curb the virus and the threat it poses to humans.  There is no vaccine and in most cases the best medical response is using over-the-counter medication such as acetaminophen or ibuprofen to treat fever and aches.

Much of CDC’s work is with regional partners. Since 2010 for example, CDC has joined with the Pan American Health Organization to craft a regional surveillance and response plan for the Americas. CDC has also developed, evaluated, and published diagnostic testing protocols, produced and distributed diagnostic test reagents and positive controls and developed notices with specific information for health departments, health care providers, and travelers, among other acts.

Other work is with state and local health departments, including in Puerto Rico and the U.S. Virgin Islands. My colleagues and I are educating public health officials and physicians about the disease and the need to consider using laboratory testing to confirm the virus, particularly with samples from areas not previously affected. Getting accurate chikungunya surveillance data is challenging because the disease is not a “nationally notifiable disease” in the United States.

Even harder are the demands of the groundwork which often requires labor-intensive efforts to trap and count mosquitoes; getting an accurate census of the distribution and type of mosquitoes is critical to predicting chikungunya’s threat. Even in places like Florida and Texas where the mosquito vectors thrive and where the threat is real, tight budgets in local and state public health agencies can make it difficult to find partners.

The science is just as challenging. The virus, like all viruses is ever changing, subject to mutations that can affect its potency and how it’s treated.  And yet, progress has been realized. In the 15 years public awareness of the virus has grown. People understand that preventing mosquito bites by covering as much skin as possible, using insect repellent and convincing local governments to more aggressively combat mosquitoes remain the best defense.

Refining surveillance data along with a deeper understanding of the biology and clinical aspects of chikungunya has also prompted pharmaceutical companies to work on a potential vaccine. Several show promise and the pace will accelerate as comprehensive data better defines CDC’s capability to  predict chikungunya’ s reach, where it may be heading, and what populations are most at risk. All of it means that a reasonable goal is that 10 years from now chikungunya will be on the decline because we will better understand the virus and have more effective control options widely available.

April 7 is World Health Day

Categories: child health, infectious disease, malaria, mosquito-borne disease, neglected tropical diseases (NTDs), parasitic diseases


April 7 marks World Health Day. This year World Health Day focuses on vector-borne diseases. More than half the world is at risk from vector-borne diseases. What exactly is a vector? A vector is a small organism, like a tick or mosquito, that transmits disease. Malaria, dengue, Chagas Disease and lymphatic filariasis are just four examples of vector-borne infectious diseases.   

Come learn about some of these vector-borne diseases and the work that CDC does to prevent, treat, and control these diseases around the world.    

Number of U.S. Malaria Cases Highest in 40 Years. Have We Forgotten What It Takes To Prevent It?

Categories: infectious disease, malaria, mosquito-borne disease, parasitic diseases


This blog was originally posted in the Huffington Post on October 31, 2013.


CDC Director Dr. Tom Frieden

CDC Director Dr. Tom Frieden

Progress can be dangerous.

Thanks to malaria elimination efforts in United States in the 1940s, most people in the U. S. today have never had any direct contact with the disease and most doctors have never seen a case. That success means it’s easy to have a relaxed attitude about protecting ourselves.

We’re now seeing the result of that relaxed attitude – the highest number of malaria cases in the United States in the past 40 years.

That’s the conclusion of our recent analysis that finds there were 1,925 malaria cases reported in the United States in 2011. Sadly, the number also includes five deaths.

Uganda Makes Impressive Progress on Health

Categories: HIV/AIDS, global disease detection, global health security, health systems strengthening, mosquito-borne disease, women's/maternal health


This blog was originally posted in the Huffington Post on August 8, 2013.


CDC Director Dr. Tom Frieden peers into Python Cave.

CDC Director Dr. Tom Frieden peers into Python Cave.

Last month I was in Uganda. As I planned for this trip, I wasn’t sure what to expect. Uganda is the only country served by the president’s Emergency Plan for AIDS Relief (PEPFAR) with a rising HIV incidence; I anticipated that there might be problems.

CDC Director Dr. Tom Frieden

CDC Director Dr. Tom Frieden

What I saw instead was impressive progress.

Although Uganda will have challenges for many years as a result of increased HIV infections over the past decade, and has much more to do, I was struck by how much headway they’ve made in the past couple of years. The country has scaled up lifesaving anti-HIV treatment as well as voluntary medical male circumcisions, which sharply reduce the chance of becoming infected.

While in Uganda, I got to peer into a cave — the same cave where two tourists got Marburg virus in 2007. This deadly virus, similar to Ebola, was unknown in this location until identified by CDC staff.

This is Python Cave — and I was awed to see the python, which is at least 12 feet long and 24

CDC Malaria Hotline—When the Caller is Ill Abroad

Categories: malaria, mosquito-borne disease, parasitic diseases

Photo by Solomon Eshetu, UN driver

Photo by Solomon Eshetu, UN driver

Since 2007, managing the CDC Malaria Hotline has been a large part of my job as a health educator in the Division of Parasitic Diseases and Malaria at CDC. It’s wonderfully fulfilling because it gives me the opportunity to talk directly with the public to share information that can help them avoid malaria infection when they travel. I can hear the public’s concerns and misconceptions about malaria and work to address them in our educational materials.   

Stefanie Steele, RN, MPH, CPH, CDC Division of Parasitic Diseases and Malaria

Stefanie Steele, RN, MPH, CPH, CDC Division of Parasitic Diseases and Malaria

On average the Hotline handles 6,000 calls a year from mostly the public and healthcare providers—the vast majority are from within the United States. 

The public’s primary concern is whether malaria occurs in the area they plan to visit and if so, what they can do to protect themselves. Sometimes people who have returned ill from their travel call to ask if their symptoms might be malaria. Fortunately, in the U.S. there are well-qualified healthcare providers, clinics, hospitals, and labs available most everywhere, as well as CDC prevention information I can direct them to. 

Dengue in Haiti

Categories: mosquito-borne disease


Dengue in Haiti

There is arguably one place that was more affected by the January 2010 earthquake than Port-au-Prince, and that is Léogâne. A low-lying coastal town about a two-hour drive from the capital, Léogâne was the epicenter of the earthquake that devastated Haiti. As part of my Epidemic Intelligence Service (EIS) fieldwork, I have been investigating a possible outbreak of dengue among aid workers in Léogâne.

Stephanie Salyer, DVM, MPH - Epidemic Intelligence Officer in the CDC Division of Global Health Protection (proposed)

Stephanie Salyer, DVM, MPH - Epidemic Intelligence Officer in the CDC Division of Global Health Protection (proposed)

Since the earthquake, Léogâne has become a site of ongoing infrastructure development, with visible construction of new roads, and water and sanitation projects. The town has also become a hub for non-governmental organizations (NGOs); within this small town one can see Médecins Sans Frontières (MSF, or Doctors Without Borders) working next door to International Federation of Red Cross and Red Crescent Societies (IFRC), Red-Cross Germany, Red-Cross Spain, and Red-Cross Swiss. Each organization has its own site within Léogâne. Some NGOs are housed within temporary buildings and others are housed in small compounds that contain office buildings, clinics, and residences for workers. The NGO workers in Léogâne include Haitians and expatriates from all over the world. All of these NGO workers, regardless of their origin, face the threat of mosquito-borne diseases, including malaria, lymphatic filariasis, and dengue.

Haiti is Saying Goodbye to Lymphatic Filariasis, In Spite of Earthquake

Categories: child health, mosquito-borne disease, neglected tropical diseases (NTDs), parasitic diseases


Valery E. Madsen Beau De Rochars, MD, MPH

Our teams gave a two-medicine dose to Haitians in our capital city, Port-au-Prince—but most people had no water to swallow the pills. How would we overcome the ongoing cholera outbreak and displacement from the 2010 earthquake to finally rid Haiti of the horribly disfiguring and painful disease called lymphatic filariasis

Lymphatic filariasis, sometimes known as elephantiasis, is delivered by mosquitoes infected by young, blood-born parasites. The worms lodge in a person’s lymph nodes, causing fluid to pool in their legs and testicles, forcing them to swell dramatically. 

Humans are the only known host for the parasite in Haiti, which means it’s an ideal infectious disease to eliminate. Once we eliminate it from people, it can’t be brought back by animals carrying the parasite, which is the case for many infectious diseases. 

Investing in the Future

Categories: malaria, mosquito-borne disease, parasitic diseases

Dr. Patrick Kachur

Dr. Patrick Kachur, Chief, CDC Malaria Branch

Last month I took a few days of vacation and traveled to Basel, Switzerland. The sky was grey and a cold drizzle was steadily falling, melting the remaining layer of snow and ice that winter’s last storm had blasted onto the sides of trees and buildings. Many of the staff and students at the Swiss Tropical and Public Health Institute (Swiss TPH) had already begun traveling to warmer places. I had come to take part in a viva voce: the oral examination of a PhD candidate at the Institute. The candidate was M. Irene Masanja, a Tanzanian colleague with whom I had worked for some time. She presented her thesis: “Influence of health systems in malaria case management as part of malaria control in Tanzania,” to three examiners and a lecture room surprisingly packed with her fellow students and supporters (including her mother). She confidently answered all of our questions, including some from an examiner who attended by video link from the UK. Following that, the examiners met privately while Irene and the rest of the crowd waited anxiously outside the door. When they were permitted back into the room, the Department Chair asked her to swear an oath to maintain a high standard of scientific integrity in all her work, and conferred upon her the degree of Doctor of Philosophy, magna cum laude.

Fresh Voices From the Field—Reaching for Zero Malaria Deaths: a Story From Uganda

Categories: child health, malaria, mosquito-borne disease, parasitic diseases


This is the second in our ongoing “Fresh Voices From the Field” series, where we hear from ASPPH (Association of School and Programs of Public Health) Global Health Fellows working throughout the world. Global Health Fellows are recent Master of Public Health or Doctoral graduates placed in CDC global health offices in Atlanta and abroad. They work on a range of priority public health issues and bring a fresh perspective to CDC’s efforts in the field. (See other “Fresh Voices” blogs.)



Melody Miles, President’s Malaria Initiative team at CDC

As a member of the President’s Malaria Initiative team at CDC, I support malaria efforts in Uganda, where 42% of children are infected with the malaria parasite. Since 2007, Uganda has operated one of the best malaria surveillance systems in the world, providing accurate, timely malaria data from 12 “sentinel” health facilities throughout the country. Despite high demands and limited staffing, these sites perform a laboratory test on every patient suspected of having malaria and ensure all malaria deaths are reported.

To better understand the dramatic burden of the disease on the community, I recently crossed Uganda’s Nile River and made the long, tumultuous drive to a hospital in the northern part of the country. I knew malaria-related mortality was high in this area, but what I found when I arrived brought tears to my eyes.

Accelerating Up the Hill: Maintaining Malaria Progress

Categories: child health, malaria, mosquito-borne disease, parasitic diseases

Twenty-five years ago, I went to western Kenya as a Centers for Disease Control and Prevention (CDC) Epidemic Intelligence Service (EIS) officer to study an outbreak of severe anemia. No one was sure of the cause. Was it parvovirus, or exposure to an environmental toxin, perhaps? In the hospital there were five or six sick children to a bed, and they were so anemic that their blood looked more like a pinkish fluid than the rich red to which we are accustomed. As it turned out, there was no exotic cause. I was seeing the ravages of drug-resistant malaria at a time when chloroquine, the routinely used antimalarial drug, was failing globally.“In the hospital there were five or six sick children to a bed, and they were so anemic that their blood looked more like a pinkish fluid than the rich red to which we were accustomed.”

That kind of grim hospital scene is much rarer these days, thanks to the enormous investment in malaria programs in Africa over the past decade and the improvements these investments have made possible. Programs that provide proven interventions—artemisinin-based combination therapies (ACTs), insecticide-treated bed nets (ITNs), and indoor residual spraying (IRS)—have achieved a 33% reduction in malaria deaths in the African region and 1.1 million lives saved globally. We have much more to do, but this is a reason to celebrate. As we celebrate, however, we must realize that we are also in the midst of a very fragile situation for three major reasons.

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