Evaluation of Anti-venoms Serum in Africa

Globally, the number of annual envenomings is estimated to be between 420,000 and 1,800,000. In sub-Saharan Africa, the annual number of envenomings is estimated at 315,000, leading to more than 9,000 amputations and about 7,000 deaths.

Snake bites are recognized by many authors as a neglected disease, whose incidence is underestimated or even unknown in several countries of sub-Saharan Africa. Few data are currently available on the morbidity, mortality and economic impact of snake bites.

In Cameroon and particularly in the northern part of the country, where the density of snakes is high, a few studies have been carried out. In 2002, the annual incidence of envenomings was estimated at 200/100 000 inhabitants, of which 85% was due to Echis ocellatus, and the lethality was 23.9% in some centers. The Ministry of Public Health introduced snake bites in 2015 as a priority health problem in the list of diseases being monitored. Thus, a national epidemiological surveillance system, with a weekly count of snake bites, has been implemented. In the first year, the incidence of annual snake bites was 11.4/100,000 inhabitants, representing more than 2,500 bites per year, including 43 deaths and a case fatality rate of up to 6% in some areas. The northern region (Adamaoua, North and Far North regions) (savanna and mixed zone) accounts for 40% of the country's burden and 77% of the deadly burden, while the forest zone accounts for 32% of the burden Morbid disease and 16% of the fatal burden (ministerial source). The monitoring is based on paper registers for bite reporting, supplemented by the sending of pharmacovigilance data by text messages, but this is very little used in current practice. The data collection system in Cameroon could therefore be improved in terms of both completeness and speed of centralizing data.

These estimates are likely to be well below the reality given the non-exhaustive nature of the data collection and the frequent use of traditional practitioners without referral in a hospital structure.

In recent years, FAV-Afrique® produced by Sanofi-Pasteur was the treatment of reference for venomous snake bites in West and Central Africa. It was the most evaluated and the most effective, reducing by a factor 5 to 10 the mortality. This anti-venom serum was polyspecific, containing an antivenom against ten species of snakes: Naja melanoleuca, nigricollis \& haje; Dendroaspis polylepis, viridis \& jamesoni, Bitis gabonica \& arietans; Echis leucogaster \& ocellatus.

However, Sanofi-Pasteur stopped production (last batch produced in January 2014 and expired in June 2016), making it necessary to use other snake antivenoms. Since the end of 2015, two new antivenoms are available in Cameroon where they are granted a provisional marketing authorization. Few clinical trials have evaluated the antivenoms currently available in Africa.

Some clinical efficacy and safety data have been published for Inoserp Pan-Africa®. However, the number of subjects was limited and assessment was limited to the period of hospitalization.

The lack of sufficient data on incidence and mortality associated with snake bites, the current weakness of the epidemiological data collection system and the presence on the market of antivenoms that are very little evaluated in terms of tolerance, effectiveness make action necessary.

The main objective of the study is therefore to assess the tolerance and the efficacy of the antivenom Inoserp Pan-Africa® from Inosan laboratory currently available in Cameroon.This study will be conducted under routine conditions in order to avoid bias in the results through the implementation of dedicated logistics which would not be representative of the usual conditions.