Sunday, January 31, 2010

Digestive enzymes

"Malaria causes more than two million deaths each year, but an expert multinational team battling the global spread of drug-resistant parasites has made a breakthrough in the search for better treatment" (McGill). Examining the way malaria parasites reproduce, a team led by John Dalton, has identified "a plan of attack" to develop new and urgently needed treatments, which combat malaria.

The secret lies in how the parasites propagate. "Malaria parasites live inside our red blood cells and feed on proteins". They break down the proteins to "use the proceeds (amino acids) as building blocks for their own proteins". Once they "a sufficient size they divide and burst out of the red cell, entering another and repeating the process until severe disease or death occurs."

Specialized digestive enzymes of the parasites "enable them to undertake this process." Researchers have now developed three-dimensional structures of these two enzymes and "demonstrated how drugs can be designed to disable the enzymes."

"By blocking the action of these critical parasite enzymes, we have shown that the parasites can no longer survive within the human red blood cell," Dalton explains. "The team is putting their findings into action immediately and is already pursuing anti-malarial drug development."

Publications: The discovery will be published in the Proceedings of the National Academy of Sciences, and is the result of collaboration including Australia’s Queensland Institute of Medical Research, Monash University and the University of Western Sydney, Wroclaw University of Technology in Poland and the University of Virginia in the U.S.

Read more about digestive enzymes and malaria

McGill University (2010, January 29). Breakthrough could lead to new treatment for malaria. ScienceDaily. Retrieved January 31, 2010, from¬ /releases/2010/01/100128165850.htm

Saturday, January 16, 2010

Haiti in the wake of disaster

"Tuesday's earthquake could decimate what fragile medical care exists" in Haiti "and spawn a 'perfect storm' in a country already struggling to fight rare tropical and infectious diseases, health experts" warn. The Red Cross has estimated that "3 million people -- one-third of Haiti's population -- were affected by the quake", which was measured at a magnitude of 7.0 and "ripped apart buildings, shearing huge slabs of concrete off structures in the poorest country in the Western Hemisphere" (Park). The homeless are "clustering in public places without food, clean water or sanitation. It's the perfect environment for the spread of communicable disease." Photo by Pinheiro.

The earthquake has thwarted medical efforts in a place that already struggles to stave off infectious diseases. "Even before the earthquake, the country has been the subject of intense public health efforts, as nearly half the causes of deaths have been attributed to HIV/AIDS, respiratory infections, meningitis and diarrheal diseases, according to the World Health Organization." "Hundreds of thousands of people are sleeping in tents, or filling public squares waiting for some kind of help. There is no water, food or sanitation. Many of the survivors have broken arms and legs" (Kenny). "The earthquake decimated Haiti's capital just days ago[, but] it's an eternity in terms of getting medical care to the injured" (Pearson). Now, "if left untreated, minor injuries or fractures can become life-threatening because they're left open to bacterial infections such as tetanus".

Even the uninjured face severe medical risks.

"The disaster cut power, electricity and other utilities." Without clean drinking water, endemic diseases are hard to resist. "What you have is the perfect storm of infection. What you have is a breakdown. It is already a fragile infrastructure with high rates of infectious and neglected tropical disease. Now there are potential breakdowns in sanitation, clean water, housing and subsequent crowding. That's a terrible mix," says Dr Peter Hotez, head of the department of microbiology at George Washington University. "The potential new mass of displaced persons could create crowded, unsanitary conditions that facilitate the spread of contagious respiratory infections."

Cholera, typhoid fever, and other diarrheal diseases threaten the people. "Bacterial and mosquito-borne diseases such as dengue and malaria" are also major risk factors to the injured and uninjured alike.

Dirty water, broken drainage, and a tattered terrain create natural reservoirs where disease can breed. Malaria, an infectious disease that kills approximate one million people each year and is carried by mosquitoes, is expected to intensify in the aftermath of the quake. Malaria is already endemic in this region, and in the midst of this chaos, it will be difficult to avoid.

Doctors "worry that the major, long-term health initiatives to treat preventable diseases" like malaria and dengue "could be upended" by this disaster. "Any interruptions in fighting these preventable diseases has disastrous consequences", claims Hotez. "This is going to a big setback for public health control measures, and you will see the impact of this earthquake at least for months and possibly for years." Kaplan, who formed the Cap Haitien Health Network to tackle preventable diseases such as diarrhea, malaria and malnutrition agrees, "That's another tragedy of the earthquake."

"When the rubble is cleared and the bodies are buried," Haiti will still face the threat of devastating disease as it always has. But by that time, medical supplies and money will be expended on the newly injured, clinics and hospitals will need to rebuild, and the landscape will need to be reshaped in order to prevent water buildup, which fuels the spread of infectious diseases.

Despite it all, Kaplan has hope. He hopes that "this situation may lead to improvements, because it's bringing lots of attention and help to the area." "There's that silver lining," he said.

Want to help the relief & malaria prevention effort in Haiti? Support the Red Cross.
Send a $10 Donation by Texting 'Haiti' to 90999
You may also call 1-800-REDCROSS to make a donation over the phone.

Please DO NOT send donations for Haiti relief efforts to Infectious Bite. Donations to support the Infectious Bite malaria awareness campaign are always welcome.

Kenny, Sean. Common Dreams. "Haiti's earthquake survivors face massive risk."
Park, Madison. "Haiti's earthquake could trigger 'Perfect Storm'." 13 January 2010.
Pearson, Carol. VOA News. "In Haiti, Wounds, Infectious Diseases are top concern." 15 January 2010.
Pinheiro, Roosewelt. AgĂȘncia Brasil. [PHOTO]

Wednesday, January 13, 2010

Who ya gonna call?

Blood-drinkers be warned: Slayers are on the prowl. Taking a note from a cheesy '80s movie, these hunters have equipped themselves with a backpack-carried weapon and are crawling the sewers collecting the flying fiends who annoy the living.

Mosquito hunters from Emory University have developed an efficient way to monitor adult mosquitoes and the deadly diseases they carry, and they have done it cheaply. "Emory has filed a provisional patent on the Prokopack mosquito aspirator, but the inventors have provided simple instructions for how to make it in the Journal of Medical Entomology."

"This device has broad potential, not only for getting more accurate counts of mosquito populations, but for better understanding mosquito ecology," according to Gonzalo Vazquez-Prokopec. "There is a great need for effective and affordable mosquito sampling methods. Use of the Prokopack can increase the coverage area, and the quality of the data received, especially for blood-fed mosquitoes. Ultimately, it can help us develop better health intervention strategies."

This new invention outperformed standards for resting mosquito surveillance in lab and field tests. The Prokopack has a longer reach than the Center For Disease Control and Prevention Backpack Aspirator (CDC-BP), which enables "it to collect more mosquitoes than the CDC-BP". The Prokopack is also "significantly smaller, lighter, cheaper, and easier to build" than its predecessor.

"Anyone with access to a hardware store, and about $45 to $70, can make the Prokopack, which uses a battery-powered motor to suck up live mosquitoes for analysis."

"The CDC-BP can quickly vacuum up samples of live specimens, which can be analyzed in a lab to determine the source of blood they recently consumed. The drawbacks to the CDC-BP, however, include its heavy weight (26 pounds), its bulk and its price -- about $450 to $750 in the United States."

"With a bit of ingenuity and a few trips to the hardware store," the Emory research team "put together a solution: a plastic container, a wire screen, a plumbing pipe coupler, a battery-powered blower motor and painter extension poles. After some experimentation with these components, the Prokopack was born.

"Collecting more mosquitoes in higher locations can give researchers more insights into their behaviors. Upper foliage, for instance, can yield more mosquitoes resting after feeding on birds. And upper walls and ceilings of homes may harbor more mosquitoes resting after a meal on humans."

Emory University (2010, January 13). Mosquito hunters invent better, cheaper, DIY disease weapon. ScienceDaily. Retrieved January 13, 2010, from¬ /releases/2010/01/100112152402.htm

Friday, January 8, 2010

Alarm amid medicine shortage

Kenya's rainy season is the most dangerous for contracting malaria, a deadly disease carried by mosquitoes, and children are the most susceptible. "A shortage of malaria drugs for children has hit hospitals as fears of an outbreak of the disease loom following heavy rains in various parts of the country."

"The Kenya Medical Supplies Agency said stocks of the drugs were running low, but were in the process of being procured and could be delivered by the beginning of February." The Chief executive, John Munyu, is hopeful that the crisis will be avoided because deliveries are continuing. He indicated that "adult malarial drugs are already being supplied after a reported shortage in parts of the country."

The minister of medical services, Anyang' Nyong'o, claims that "the shortage of drugs was caused by inadequate funding by the Treasury." The "budget for Health ministries was laughable when compared to that for the Ministry of Education", he says. This is not the first shortage that Kenya has suffered in recent years. Antibiotics used to treat cholera "were nearly exhausted due to last year's outbreak".

Still, Nyong'o is confident that disaster will be avoided. He says, "I do not envisage any crisis because the government is already adding stocks to what is already there in the health facilities. That is mere replenishment."

Ogo, Kenneth. "Children's malaria drugs run out." Daily Nation. 7 January 2010.

Sunday, January 3, 2010

Critically weakened

What happens when a vampire does not feed on human blood?

If you believe the tales spun in Vampire Diaries, then the once-deadly creature becomes significantly weakened, looses the ability to affect the human brain, and is generally much less threatening than his human blood consuming counterpart. The same is true for the variety of parasite that Dr Andrea Crisanti is studying in an attempt to find a malaria vaccine.

Malaria, a mosquito-borne disease that affects 300-500 million people each year, is caused by infection with Plasmodium parasites. The deadly disease kills approximately one million people every year, most of whom are children and pregnant women, is treatable and preventable. The search for a malaria vaccine is well under way, but the "number of life cycle changes" that the parasites undergo increase "the challenges of malarial vaccine development." In other words, because the malaria parasites change and adapt rapidly, a workable vaccine is difficult to develop.

However, recent research by Crisanti and her colleagues "have found that weakened Plasmodium elicits a protective immune response." This means that clinically and genetically weakened parasites may be used for vaccine development. Crisanti's team targeted Plasmepsin 4, "a digestive enzyme that is critical for Plasmodium growth and survival within the host red blood cells." Research showed that parasites without the critical digestive enzyme "were significantly less virulent than their wild-type [define: normal] counterparts."

Furthermore, "infection with plasmepsin 4-deficient parasites, in contrast to infection with wild-type Plasmodium, did not induce cerebral complications", which means that infection with the weaker parasite produces a less severe illness than an ordinary malaria infection. Also, parasites without the digestive enzyme "induced strong protective immune responses against secondary immunization with wild-type Plasmodium." This weakened parasite may provide a model for comparing genetically-weakened malarial vaccines.

Dr. Crisanti and colleagues conclude that "it is possible, by engineered inactivation of parasite proteins, to generate attenuated blood stage parasites that are capable of inducing protective immunity against blood-stage infection. Such parasites should be powerful tools in elucidating parasite-derived factors that cause severe disease and should provide additional insight into factors that are required to induce protective immunity."

American Journal of Pathology (2009, December 31). Weakened Plasmodium generates protective immunity. ScienceDaily. Retrieved January 3, 2010, from¬ /releases/2009/12/091230193211.htm