Parasitology Blog

by Daniel Gordon

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Scientists from the University of Glasgow have made a major step towards understanding the genetic make-up of a parasite which causes the flesh-eating disease leishmaniasis.

The disease is spread by sand flies and threatens about 350 million people in 88 countries, including Brazil, Iran, Peru, Saudi Arabia, Syria, Afghanistan and parts of China.

There are 21 species of the parasite that cause a variety of forms of leishmaniasis in humans, ranging from disfiguring sores on the skin to potentially fatal infections of the liver and spleen. The parasite, which infects white blood cells, is usually treated with chemotherapy.

Now researchers have been able to analyse the genome of different species which will help them understand how different forms of the disease develop and how they can be better treated.

The research project led by scientists at the Wellcome Trust Centre for Molecular Parasitology at the University of Glasgow with colleagues at the University of York and the Sanger Institute in Cambridge received £1m in funding from the Wellcome Trust and was aimed at furthering understanding what the World Health Organisation (WHO) classifies as a neglected tropical disease.

WHO estimates that up to 12 million people are currently infected, with around one to two million new cases occurring every year.
 
By analysing and sequencing the genome – the complete set of genes within an organism – of four different species of the parasite, as well as different isolates of the same species, scientists discovered they all had a similar genetic content, but were arranged in different ways.

Professor Jeremy Mottram, of the University of Glasgow, said: “There are many species of the parasite that can cause different forms of the disease and require different forms of treatment. This can also cause problems for diagnosis.

“We discovered that different species of the leishmania parasite share a large number of similar genes, but the genomes are structured in different ways and with extensive variation in the numbers of chromosomes – the pieces of DNA that store genetic information about an organism.

Dr Nick Dickens, a genome specialist at the University said “It is largely the different genome structure, including the copy number of genes and as a result, the amount of proteins expressed by these genes that cause differences between the species and hence clinical forms of the disease.

“A combination of many genes within a parasite can be responsible for the disease, so identifying and understanding the genetic and structural differences in the species could help develop improved treatments.”

The leishmania parasite is a form of trypanosomatid protozoa that belongs to the same family of parasites that causes sleeping sickness and Chagas’ disease.

It is a poverty-related disease which affects the poorest people in developing countries, with more than 90 per cent of the severest form of the disease occurring in Bangladesh, Brazil, India, Nepal and Sudan.

A number of British soldiers deployed in Afghanistan have been infected with the parasite and British television presenter and adventurer Ben Fogle was treated for the disease in 2008.

The Leishmania parasite is named after its discoverer William Boog Leishman, the Scottish pathologist and British Army doctor and graduate of the University of Glasgow.

Two research papers ‘Chromosome and gene copy number variation allow major structural change between species and strains of Leishmania’  and ‘Whole genome sequencing of multiple Leishmania donovani clinical isolates provides insights into population structure and mechanisms of drug resistance’ are published in the journal Genome Research.

Source: healthcanal.com

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by Sarah Boseley

A patient being tested for malaria

Malaria is a mass killer, taking just under 800,000 lives a year. Most of them are babies and children under five. A significant number are pregnant women. It is an entirely preventable disease, caused by a parasite transmitted by mosquito bite, but the millions who live under its curse are too poor and have too few options to be able to avoid it.

The malaria vaccine [See: “Malaria vaccine partly effective” — ‘Science & Technology' page, October 20, 2011] that now appears to be within reach, following successful large-scale trials in seven African countries, is a potential game changer for the rural villagers whose children are the main victims of this ancient disease, which was named “mal'aria” for the bad air mediaeval Italians thought caused it.

Early results from 6,000 babies aged 5-17 months show that their risk of malaria was reduced by slightly more than half (56 per cent) and their chance of severe malaria — the kind that affects the brain, kidneys and blood and often kills — by slightly less than half (47 per cent).
Malaria is so common in sub-Saharan Africa that families think any fever in a baby must be the killer disease. Too often it is, and the hospitals are full of listless babies with vacant eyes on drips.

Vast numbers of bed nets impregnated with insecticide have been provided by donors and distributed in malaria-endemic regions. New drugs — compounds involving artemisinin [See: Editorial page, The Hindu, October 5, 2011] — have been developed and widely distributed to replace older antimalarials, which have been failing as the parasite develops resistance to them.

Mortality rate down

Malaria deaths have come down from more than a million to an estimated 780,000 a year, according to the latest report from the Roll Back Malaria partnership of the World Health Organisation (WHO). Three countries were certified malaria-free in the past four years, and nine more are preparing to move towards elimination — but that is out of 108 where the disease is endemic.

Since bed nets are not always effective and drugs can become ineffective, a vaccine could massively improve children's chances.
While researchers started work on a potential Aids vaccine with extraordinary and, as it turned out, misplaced optimism, many in the scientific community thought a malaria vaccine was a non-starter. Nobody had ever made a vaccine against a parasite-borne disease.

Twenty-five years on, a clutch of indomitable scientists — veterans such as Joe Cohen, who has been on the case for the past 23 years — has proved the sceptics wrong. According to Andrew Witty, chief executive of GlaxoSmithKline, the British company that has developed and trialled the vaccine, there were tears among the team when the results of the large-scale trial results came out. “It was the emotion of what they had achieved,” said Witty. “The first vaccine against a parasite-borne infection. They were overwhelmed.” The results show conclusively that it is possible to prevent many cases of malaria in babies aged 5-17 months. Most of these children still got malaria, but less frequently and less severely. There were 750 cases for every 1,000 vaccinated children over a year, compared with 1,500 cases for 1,000 children (as one child can have more than one bout of the disease) among those who were given dummy injections.

That could make a big difference in sub-Saharan Africa. There are 200m cases of malaria every year. Many children are damaged — sometimes brain-damaged — by it. Even stopping half of those cases would save millions of lives over the long term. But there is a way to go yet, with more results from the trial to come, and many uncertainties, including how much this vaccine will cost and who will be persuaded to pay.

Trial in seven countries

The trial is continuing in seven countries: Burkina Faso, Gabon, Ghana, Kenya, Malawi, Mozambique and Tanzania. It is big: there are 15,460 babies and infants involved. The data published so far in the New England Journal of Medicine concerns 6,000 of the older babies, those aged 5 to 17 months. Next year, results are expected for newborns, which are crucial, because the three-dose vaccine, which needs cold storage, must be incorporated into the routine infant vaccination schedule. All the signs are, though, that the response in newborns will be similar.

A bigger question is over the duration of the protection, which appears to have dropped from 47 per cent to 35 per cent for cases of severe malaria after 22 months. Some of the babies will be given a booster, to see whether this helps. While most side-effects were similar in children given the vaccine and given dummy jabs, there were significantly more with meningitis among those given the vaccine. “There seems to be no plausible explanation for this and it may well turn out to be a chance finding, but it cannot be ignored,” wrote malaria expert Prof Nick White in a commentary otherwise warmly welcoming the vaccine.

In three years' time, when the final results are in and the WHO has recommended its use, the scientists may hit the biggest stumbling block of all: money to roll it out. At a press conference to discuss the results, Dr. Regina Rabinovitch, director for infectious diseases at the global health programme of the Bill and Melinda Gates Foundation, was asked whether they would fund it. They would want to look at the data on efficacy, duration and safety in 2014, she said. “Would I prefer to see a 100 per cent vaccine? Certainly,” she added.

Price will be a critical factor. Witty says they will do everything they can to get it down. He is prepared to offer licences to get the vaccine produced cheaply in India or in Africa itself.

“I have got every confidence that we can get this price to a level that makes it very viable for donors to consider,” he said. “I don't want people to think this is an alternative to bed nets. This is about doing all we can to shut the door on malaria.” He recalls the hospital wards he has seen in Africa, full of malaria cases: “If you could take that burden away, imagine what the health capacity would be.”

Source: morungexpress.com

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McALLEN – Chagas disease could be more of a threat in the Rio Grande Valley than previously thought, researchers said.

The kissing bug, also known as a chinche in Spanish, carries a parasite that can cause acute heart and digestive problems and eventually lead to death. The disease is endemic in the Americas, with the majority of infected people living in Central and South America.

Researchers, however, have found the bug in the Rio Grande Valley. They believe about half of them are carrying Trypanosoma Cruzi, the protozoan parasite that causes the disease.

“Hidalgo and Cameron (counties) are at the highest risk here (on) the border,” said Teresa Patricia Feria, a Biology Assistant Professor at the University of Texas – Pan American.

Feria leads efforts in the Rio Grande Valley to collect the bugs found here.  She sends them to Austin to Sahotra Sarkar, a professor of integrative biology and philosophy at The University of Texas at Austin and lead author of a research paper on Chagas disease published in PLoS Neglected Tropical Diseases.

Sarkar has been studying the bug for four years and plans to turn in his final results next month.

According to the New England Journal of Medicine, an estimated 8 to 10 million people living primarily in the Americas are infected. Of those, an estimated 300,000 live in the U.S. — most of them immigrants from areas where the infection is endemic, or widespread.

The disease is transmitted when a kissing bug bites — usually around the eyes and mouth, researchers said.

The insect comes at night, Feria said. It is attracted by the CO2 human exhale, which explains why the bites are normally around the face.

But it’s not the actual mouthful that causes the infection, she said.

The kissing bug is a blood feeder that typically lives near livestock. When it eats, it immediately defecates, and the parasite is found within its feces.

The area around the bite, such as the eyelids, often becomes swollen and can cause an itch, opening the door for a person to scratch and spread the parasite-infested feces into the wound.

DETECTION

There are various reasons Chagas disease goes undetected, researchers said.

One of them is that the disease has two phases with subtle symptoms, with some people often experiencing a fever during the initial phase.

“The symptoms you are getting are kind of non-specific,” said Brian Lund Fredensborg, also a biology assistant professor at UTPA. “Even though you don’t feel well, it could be attributed to a lot of different reasons.”

Acute heart and digestive problems, however, don’t become apparent until 10 or 15 years down the line, he said.

Cardiomyopathy, a chronic disease of the heart muscle that affects the ability to pump blood effectively, is one of the characteristics of Chagas, cardiologist Carlos Morales said.

Morales conducted a study on the disease 35 years ago in El Salvador. The results showed that 25 percent of the insects had the parasite.

“Most of the times, the right (ventricle) is the one that produces more symptoms,” he said.

“And obviously heart attacks can be caused by a lot of other things, so that’s one of the reasons why it’s difficult for physicians to nail this,” Fredensborg said.

Doctors must run blood tests to see if a person infected or not, he added.

The blood sample must be sent to the Centers for Disease Control in Georgia, where results often take weeks to return, cardiologist Luis Padula said.

Padula is “absolutely certain” Chagas disease is under diagnosed. He said doctors in the U.S. are not trained to detect it because it is not as common here as in Central or South America. They don’t have a history of checking for Chagas disease here, he said.

Some doctors don’t think the bug is here and if it they know it is, they don’t think it carries the parasite.

“We have the vector, the thing that bites you, but not the organism,” cardiologist Dr. Terrence Posluszny said. “I’ve never seen a case.”

Padula, Morales and Ofsman Quintana also said they have not seen a case in the Valley, but in their practice in the northern U.S. and in Central America, they saw isolated cases.

“I would say that maybe a couple of times of year, we look for it,” Padula said. “But none of the cases have been positive.”

FUTURE

Sarkar is working to make Chagas a reportable disease and to have mandatory blood screening as the disease also can be transmitted through blood transfusions.

“That is the risk — that we don’t report that as a disease,” Feria said. “Nobody notices that, because it’s something that we don’t monitor here in the area.”

The researcher says that when somebody dies suddenly, without a family history of heart failure, the doctors do not attribute it to Chagas disease.

“The problem is that in Texas, they don’t routinely screen blood samples for the parasite that causes Chagas disease,” Fredensborg said. “They do in other states, but Texas has decided not to routinely screen for that.”

United Blood Services tests its blood regularly, RGV executive director Frank Esparza said.

The agency detected one blood unit that tested positive in 2009 and another in 2010.

“It’s very rare that you get something like that,” he said. But “we have found it. That is why we test.”

United Blood Services estimates one in 2,500 of their cases are infected, while nationwide, the estimate is one in 25,000.

“When we get a positive, we don’t use it,” Esparza said.

Sakra said only 65 percent of the private blood agencies in Texas actually test their blood for Chagas.

The Texas Department of Health and Human Services is waiting for the results of Sarkar’s study to decide if it is going to make the disease reportable, said agency spokeswoman Carrie Williams.

According to Sarkar almost 50 percent of the bugs he’s collected tested positive.

“We don’t want people to panic” he said. “They just need to be aware of the possibility of the existence of this disease in the area.”

Source: themonitor.com

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By PERRY BACKUS Ravalli Republic of missoulian.com

HAMILTON - A potential malaria vaccine that uses an adjuvant manufactured in Hamilton has passed its first large-scale trial.

The New England Journal of Medicine reported last week the GlaxoSmithKline malaria vaccine candidate, RTS,S, provided young African children with significant protection against malaria.

Half the world's population is at risk for the disease. Each year, malaria kills nearly 800,000 people, most of whom are children under age 5 in sub-Saharan Africa.

The malaria vaccine trial was conducted at 11 different sites in seven African countries with 6,000 children aged 5 to 17 months. An analysis showed the vaccine reduced the risk of the children experiencing clinical malaria by 56 percent and severe cases by 47 percent.

Clinical malaria results in high fever and chills, which can rapidly develop into a severe case that can be fatal.

Researchers are now compiling information on the vaccine's effectiveness for 6-to 12-week-old infants. That portion of the trial is expected to be complete by the end of 2012.

The long term effectiveness of the vaccine is also being studied, with results expected by the end of 2014.

If all the trial's components meet requirements established by the World Health Organization, the vaccine could be available for general distribution sometime in 2015.

"These data bring us to the cusp of having the world's first malaria vaccine, which has the potential to significantly improve the outlook for children living in malaria endemic regions across Africa," said GSK CEO Andrew Witty in a news release. "The addition of a malaria vaccine to existing control interventions such as bed nets and insecticide spraying could potentially help millions of cases of this debilitating disease."

The latest trial results were announced at the Malaria Forum hosted by the Bill & Melinda Gates Foundation in Seattle.

"A vaccine is the simplest, most cost-effective way to save lives," said Bill Gates in a news release. "These results demonstrate the power of working with partners to create a malaria vaccine that has the potential to protect millions of children from this devastating disease."

The vaccine triggers the immune system to defend against the malaria parasite when it first enters the human host's blood system. It is designed to prevent the parasite from infecting, maturing and multiplying in the liver and then re-entering the bloodstream, which is when the victim starts to show symptoms.

The vaccine was invented, developed and manufactured at GSK Biological Labs in Belgium in the late 1980s and initially tested on volunteers in the United States.

It uses an adjuvant to increase its effectiveness called MPL, which is manufactured only at GSK Biologicals facility in Hamilton.

Officials at the Hamilton facility have said earlier that if the malaria vaccine is accepted, MPL production at the Hamilton plant could increase by two or three times.

In 2006, the Hamilton plant opened its $137 million, 130,000-square-foot expansion.

Hamilton GSK officials recently announced the production facility would be adding 32 new jobs by 2013.

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The risk of getting infected with Babesios can be reduced if you stay away from tick-infested areas, take precautions when going outdoors, and make sure the tick does not stick to your skin for more than 24 hours.

Babesiosis, or Babesia, is a parasitic infection transmitted to humans through bites of infected ticks. It is caused by Babesia microtie and Babesia divergens protozoa that can bring about harmful complications, especially if you have other health problems. To avoid the risk of being infected with Babesiosis, consider the following tips:

Stay away from tick-infested areas

Ticks, especially deer ticks, are the carriers of Babesiosis, also called Babesia. The first and most practical way to defend yourself from being infected with this disease is to stay away from tick-infested areas. You also need to be aware that ticks are usually found in grassy, wooded areas, especially during late spring, summer, and early fall.

Take precautions when going outdoors

Since Babesiosis infection cases are rare, your fear of being infected with the disease should not stop you from doing outdoor activities, such as hiking and camping. As long as you take the following extra outdoor precautions, you will be safe from tick bites:

* Make sure you cover your body well so the ticks do not get onto your exposed skin. Wear a hat, long-sleeved shirt, long pants, socks, and closed shoes, preferably boots. If you have long hair, tie it back and tuck it in your hat to avoid ticks from crawling through it. For the same reason, it is also advisable that you tuck your pant legs in your socks. Light-colored clothes are also ideal when going outdoors in order to easily find ticks that have stuck on your clothing.

* Put repellents on your skin and on your clothes to ward off ticks. Repellents with DEET can be applied both to your skin and clothes to repel ticks. Permerthrin products can also be used to repel and actually kill ticks that get attached to your clothes and shoes. This treatment should not be used on your skin. Before using these products, make sure you carefully read the application.

*Check for ticks on your clothes from time to time while outdoor to stop them from crawling and getting to your skin.

Make sure the tick does not stay on your skin for more than 24 hours

The parasite causing Babesiosis can only be transmitted if the tick remains attached to your skin for about 24-36 hours. It is very important to carefully check your body after any outdoor activity, preferably using a full-length mirror. Immediately take a shower, washing thoroughly every part, especially at the back of your neck and ears, hair and scalp, underarms, belly button, back, legs, the back of your knees, and in between your toes. Immediately remove any ticks found on your skin to avoid being infected with Babesiosis.

There is really no outbreak of Babesiosis or Babesia, but if you get infected with it, it can be dangerous to your body, especially if it is not detected and treated immediately. It is always best to avoid the infection and take precautions in order to protect yourself.

Source: tempo.com.ph

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