Showing posts with label antivenom. Show all posts
Showing posts with label antivenom. Show all posts

Friday, November 4, 2011

Camels as a Source of Antivenom

The following story is from The National, a UAE media outlet. The article was written by Caline Malek.

DUBAI // An innovative plan to use camels as four-legged factories for snakebite treatment has been put on hold despite promising early results. 
The problem: a lack of funding.
"It's a shame," says the virologist Renate Wernery, "because the principle is magnificent." 
The antivenins were developed last year using camel antibodies in the hope they could be used in Africa as early as next year to treat snakebites. They were being developed by researchers in the United Kingdom, and at Dubai's Central Veterinary Research Laboratory, among them Mrs Wernery. 
She said testing of the antivenins - each is specific to a species of snake - had cleared its first two phases. 
The first phase had found that camel antibodies were as effective as existing sheep and horse antivenins but were smaller, cheaper and could be stored unrefrigerated - making them an appealing substitute. 
"You can carry this vaccine in your pocket, it's that easy," Mrs Wernery said. Not having to be stored cold would make any treatment far more useful in developing countries where refrigeration might be unavailable or unreliable. 
Current treatments have a short shelf life, so hard-up hospitals in the developing world are often reluctant to order them. With few customers, big pharmaceutical companies largely stopped production a decade ago. 
Another advantage of camel-derived antivenins over those extracted from sheep and horses is that camel antibodies are smaller - about a tenth the size. One of the problems with horse and sheep antibodies is that their large size hinders their movement through the human tissue wall, making them less able to stop the death of living tissue as toxins from venom spread.

The more compact camel antibodies are better able to get to where they are needed. They are also less dangerous than existing antibodies, which cause severe side effects in 15 to 30 per cent of patients, according to Dr Rob Harrison, the head of the Alistair Reid Venom Research Unit at the Liverpool School of Tropical Medicine. His lab milked snakes of their venom, which was then sent to Dubai to be injected into the camels, thereby provoking their system into producing antibodies. 
Camel antibodies are "more tolerated by the human system, whereas the horse's isn't so good because it causes reactions in humans called anaphylactic shocks, which can then cause the same problems as the venom", Mrs Wernery said. 
Anaphylactic shocks are allergic reactions that can cause loss of consciousness, laboured breathing, blueness of skin, low blood pressure, heart failure and death. 
"Those are the effects that we were interested in reducing," Dr Harrison said 
The researchers successfully completed the second phase of the research, creating antivenins specific to individual snake species - such as the puff adder, the saw-scaled viper and the black spitting cobra - and testing them, safely and effectively, in mice. 
Forty camels in Dubai were injected with tiny amounts of the toxins from snakes commonly found in Africa, using venom from Dr Harrison's lab. Over six months, the Dubai scientists extracted around 70 litres of antivenin serum, which was refined to seven litres of antivenin - enough to treat 1,000 snakebites. 
The team was ready to go to the next stage of producing antivenins in quantity, having fitted out two laboratories with equipment worth Dh3 million to produce the antibodies needed for the treatment. 
At that point, costs ground the project to a halt. "It became too expensive," Mrs Wernery said. "There was more than Dh1 million that still needed to be invested in it." 
Since then the project has remained on hold, despite hopes of using the same technique to make vaccines for diseases such as polio, tuberculosis, malaria and HIV. "We haven't touched phase three yet and that involves clinical trials on humans in Africa." 
Dr Harrison is among those left in limbo. "We haven't been able to secure the funds to do a clinical trial with the antivenins and we need that to move forward," he said. "The great shame about this research project is that we came up with what is potentially a very promising therapeutic lead but were not able to pursue it."

Friday, October 28, 2011

The Non-Production of Antivenom, A Sign of the Times

The commentary below is from Mike Leggett at the Austin Statesman's website.
I’m a capitalist in a capitalist society and so I have to support business decisions made for profit/loss reasons. Right? Therefore I must support the decision by drug manufacturers NOT to produce any more coral snake antivenom products in this country. The current supply, which was stockpiled in 2003, has been declared expired already but tests showed it still potent enough to use on humans. But it’s supposed to go away again Oct. 31. The odd truth is that not enough people are getting bitten by coral snakes and therefore there’s no money to be made in restocking the supply.Therefore, North America’s only neurotoxic poisonous snake — the Eastern diamondback and a couple of others have some neurotoxic properties — will have free rein to bite, poison and possibly kill a couple of people each year. Red and yellow, kill a fellow. Those are the cold hard facts. Here are some others: There is a Mexican version of the antivenom but it hasn’t been approved for use in this country as far as I can tell.There are only about 20 bites per year by coral snakes in this country and 60 percent of those — because of the snake’s primitive poison delivery system — involve no venom at all. Before the development of the antivenom, only 10 percent of coral snake bites were fatal, so we’re talking two per year, far less than from rattlesnakes (which do have antivenom), dog bites, bees and falling in the bathtub.With such a low incidence of harm or fatal bites, we have to wonder why we went to the trouble to acquire the amounts of venom needed to develop the serum and then grow it for sale. Maybe it’s because of the way a coral snake kills. There’s a Poe-like quality to a serious coral snake bite. The respiratory system slowly begins to shut down and victims, untreated victims, tend to die from a lack of oxygen as their lungs slowly cease functioning. Fortunately, coral snakes are really shy little creatures. I’ve only seen four or five of them in my entire life. And I’m looking. And, they have fixed fangs in a tiny mouth and requires them to sort of grind their teeth to break the skin and eventually inject any venom at all. Get them off quickly and you’re unlikely to receive any dose of venom from the bite. Of course, if I’m ever in that group of 20 bites, I want my antivenom. And I want it now.
This commentary clearly reflects the problem with big pharmaceutical companies and the profit motive. Being a capitalist should not be the reason to allow human deaths from snakebites or any other disease. It is at the heart of the twisted view that if you can't make money from human suffering, we should just let humans suffer. Antivenom is not the only disappearing pharmaceutical product, there are hundreds of them. It seems to be time to re-think the way medical care is delivered - do we really want big, greedy corporations practicing medicine - they are doing so right now.

Sunday, September 11, 2011

The African Snakebite Problem

© IRD / JF Trape
The following press eelease and some interesting photos can be found here.

A million and a half: the number of victims of poisoning after a snake bite each year in sub-Saharan Africa. An IRD researcher has analyzed hundreds of studies and medical reports published over the last forty years. So far, no large-scale review of the situation had been made and the health authorities underestimated the extent of the problem. Thus, today, only 10% of victims are treated because of lack of antivenoms and a non-medical staff awareness. However, clinical complications can be very serious or fatal. A bite of cobra or mamba can lead to death by asphyxiation - due to respiratory paralysis - in 6 hours following the accident. That of échide ocellated, a viper widespread in African savannahs, may in turn cause bleeding resulting in death within days. This new study provides the authorities with figures more accurate and reliable, allowing them to adjust their systems of care as close as needed

The best defense of snakes is a good offense. Some prove to be ruthless when they feel threatened. Each of his method. The Gabon viper, for example, injecting its venom deep into the muscles with its hooks than 5 cm long. The spitting cobra for his blind its victims of his venom. If only one bite of venomous snakes out of two, these reptiles are nonetheless a real danger to humans. The number of accidents is significant, particularly in sub-Saharan Africa where they constitute an important public health issue, neglected by health authorities.

Indeed, as recently shown in an IRD researcher, more than 300,000 people south of the Sahara are being treated each year as a result of a bite. But given the lack of access to health centers and the frequent use of traditional medicine, many cases go unreported. This figure does not reflect all of envenomation. Experts believe that it reflects that between one third and one fifth of reality. According to this new study, so there would be up to one and a half million victims a year. The death from a bite - probably also underestimated - reach for their number of 7000 and amputations in 6000 to over 14,000 per year.

While various specific studies have advanced estimates, no major review has been made so far. To fill this gap, the specialist conducted a meta-analysis, that is to say a critical review of existing scientific studies, taking into account the representation and heterogeneity of their results. To do this, he sifted through hundreds of scientific articles, conference proceedings, and clinical reports published from 1970 to 2010. This detailed study allows to announce much more reliable figures on the number of patients who had a snake.

This work has also helped point the finger at the conditions most conducive to accidents: 95% of bites occur in rural areas, especially in plantations. The people who run the greatest risk are farm workers. Yet in Africa, agriculture is the main economic activity.

Cities are not spared, even though the incidence of bites is about ten to twenty times lower than in rural areas. Thus, in some areas during the rainy season, the envenomation more than 10% of hospitalizations.

Among the most dangerous African species, two types of venom may be opposed, that of cobras and mambas, which is neurotoxic, and the snakes - which échide Frog Eye, the most common in savanna - which is bleeding and necrosis. In other words, the first cause respiratory paralysis, which can lead to death by asphyxiation between 1 and 6am. The second leads to edema and necrosis of the members and a hemorrhage can be fatal within days. The only effective treatment remains the injection of antivenin * intravenously as soon as possible after the bite to neutralize the toxic substance.

But the availability of these products is now small: only 10% of envenomations are treated. Given the lack of data so far, the problem remained underestimated by health authorities. Moreover, the high cost of these remedies and their short life span - 3-5 years - has discouraged supplies. Under these conditions, difficult to set budgets and allocate funds for the management of envenomation, the installation of equipment necessary for sensitization of medical personnel. In the absence of formation of the latter to the use of antivenoms, these treatments can produce disappointing results, discouraging reuse later. These chain reactions reduce claims. Manufacturers are reluctant to produce anti-venom so they are not safe to sell. Hence a reduction in terms of accessibility: the number of doses sold was divided by ten in Africa since the 1980s, from about 200,000 per year to less than 20,000 in the early 2000s.

This study suggests realistic figures needs antivenoms. Given the results, the specialist believes that 500 000 doses would be needed each year. The health authorities of these countries can now use these data to improve the quality of care for victims and deploy a system for identifying and monitoring.

Thursday, March 17, 2011

Unfortunately Poor Advice and a Bad Situation

The following article was published by the Philippine Information Agency, March 11, 2011. It is unfortunate that there is an antivenom shortages, and it is even more unfortunate that the idea that antivenom can only be administered within a narrow window is still accepted in some parts of the world.

No snake anti-venom stockpile in hospitals
TAGBILARAN CITY, Mar. 11(PIA)--- FOR snake bites, immediately wash the bite wound with soap and water and rush the victim to the nearest hospital for proper administration.

This sums up Dr, Reymoses Cabagnot’s advice to patients in snake bite cases after admitting that snake anti-venom are not included in the stocked drugs at government hospitals.

Venomous snake bites may be treated with an anti-venom, Dr. Cabagnot said.

Snake antivenins are a man-made biological product called anti-ophidic serum, which can be extracted by milking a snake to extract its venom.

Collected snake anti-venom is then administered into the test animals with natural immune response to allow them to develop antibodies. These are then harvested and stored for medicinal use.

But, the presence of different poisonous snakes in the country also requires different kinds of effective anti-venom, usually obtained from the same kind of snake that bit.

“This makes stockpiling anti-venom for all kinds of snake difficult,” added another medical professional who refuses to be identified.

“While there are polyvalent antivenom-antivenins that are effective on a broad range of poisonous snakes, it would be hard to stockpile them with cases of snake bites rarely occurring,” she said.

Dr. Cabagnot, provincial health officer also added that the government hospitals have no stocks of these antivenins.

The doctor was interviewed after radio reported of a 9-year-old girl who died without treatment.

The child from barangay Napo, Alicia town was believed to be a victim of poisonous snake bite.

Neighbors and relatives brought the nine-year old victim to an alternative healer but the patient was not ushered in as the alternative medicine man had a lot of patients.

Relatives then brought the victim to Dr. Bienvenido Molina, around 6:00 but, sources said the child was dead for 30 minutes before the doctor saw her.

But even if antivenins are effective on most snake bite victims, they may be only if administered within an extremely narrow window of opportunity, the medical practitioner said.

Antivenins are normally administered to the victim as soon as possible that is 4-5 hours after a snake bite attack.

But, “doctors may also have some reservations in antivenins as these may have adverse reactions to some people, so these must be administered in extreme caution,” she warned. (rac)

Monday, February 21, 2011

African Viper Envenomation Needs to be Treated with Antivenom - Despite Delay Time to Treatment

Recently this blog reported on a forthcoming article by  P. Chippaux that suggests snake bite mortality in sub-Sahara Africa is much lower than previously thought - about 7000 deaths per annum. Now, a new study by Sebastien Larreche and colleagues examined 12-years of viper bite data from the Republic of Djibouti, and compared the impact of an early administration of antivenin versus a delayed administration on restoring the victims’ normal blood chemistry. The study looked at 73 cases (from 1994-2006), where patients presented with symptoms of viper bites in the intensive care unit of the French military Hospital, in Djibouti. Snakes involved in the bites were Echis pyramidum and Bitis arietans, and patients treated prior to 2001 received Echis-Bitis-Naja serum (Pasteur-Mérieux, Lyon, France), those treated after 2001 received FAV-Africa (Aventis-Pasteur), which is useful against Echis, Bitis, Naja, and Dendroaspis venoms. The research team examined antivenin efficiency in correcting blood chemistry to the time of treatment - before or after the 24th hour after the bite. Forty-two patients (58%) presented with bleeding - blood in their urine, coughing blood, or bleeding gums. Larreche and colleagues found antivenin was effective in improving hemostasis, and the time to normalization of blood chemistry was similar, whether the treatment was started before or after the 24th hour after the bite. They authors report that antivenin should ideally be administered as early as possible. In Africa, time to treatment often exceeds 24 hours because of the distances and transportation available. However, the results suggest that antivenom should be used despite the delay in getting treatment, and that the fact that time has elapsed between the envenomation and treatment should in no way prevent the use of antivenin immunotherapy for treatment of  African viper bites.
Larréché, S., G. Mion,  A. Mayet, C. Verret, M. Puidupin, A. Benois, F. Petitjeans, N. Libert, and M. Goyffon. 2011. Antivenin remains effective against African Viperidae bites despite a delayed treatment. The American Journal of Emergency Medicine, 29(2):155-161.