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 ├ęchide 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 ├ęchide 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.

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