*Perspective Chapter: Diagnostic and Antivenom Immunotherapeutic Approaches… DOI: http://dx.doi.org/10.5772/intechopen.112147*

activated partial thromboplastin times, D-dimer, and products of fibrin degradation. Severe rhabdomyolysis may be indicated by a creatine kinase level greater than 10,000 units per liter. For patients who are in danger of acute kidney damage, serum creatinine and potassium concentrations or blood urea should be measured. Urine tests should be conducted for the presence of myoglobin, hemoglobin, as well as other proteins and blood. Abnormalities from electrocardiograms may include ST-T changes, sinus bradycardia, and signs of myocardial ischemia or different levels of atrioventricular block. The presence of myocardial dysfunction and pericardial effusion can be detected by electrocardiography. Magnetic resonance imaging (MRI) and computed tomography (CT) are increasingly utilized in the assessment of infarcts and intracranial hemorrhages [1]. Wound ultrasonography has also been advocated for use in detecting tissue damage [26].

### **3.4 Snakebite management**

In treating snakebite envenoming, antivenom therapy remains the backbone of therapy. However, the choice of an antivenom is contingent on the species diagnosed. In the absence of the implicated snake being identified or brought in, the species diagnosis is normally based on the conformation of the bite, information on the species frequently recognized for a given geographical location, distinguishing the clinical manifestations, as well as information collected from the victim or witness. In various parts of the world, clinical manifestations form the basis of species differentiation. Nevertheless, this is difficult to the extent that the toxins that constitute venoms of different species are a lot of the time pharmacologically and physiochemically similar and as such may provoke similar clinical effects. For instance, venoms of *Bungarus fasciatus, Naja naja siamensis,* and *Ophiophagus hannah* all comprise postsynaptic neurotoxins that inhibit neuromuscular transmission resulting in the same major clinical features, notably paralysis, respiratory failure, and ultimately death. When the culprit snake is even brought, there is a likelihood of misidentification, and therefore antivenom misadministration resulting in complications as witnessed in the past. Additionally, it is observed that morphologically similar species may exhibit different clinical manifestations due to the difference in venom composition based on differences in geographical locations. Owing to the shortcomings for accurate snake species identification, clinicians may find it problematic to administer suitable antivenoms upon presentation [27]. According to Theakston & Laing [14], the difficulties in identifying the species implicated in a case of envenoming make it even more challenging in the choice of the appropriate antivenom for treatment, particularly in areas where only monospecific antivenoms exist. Accordingly, this dilemma became a key consideration that stimulated the development of sensitive assay methods employing immunodiagnostic, as well as other laboratory-based methods. At the initial stages of investigation, it was demonstrated that immunodiagnosis using enzyme-linked immunosorbent assay (ELISA) or enzyme immunoassay (EIA) was helpful in identifying the species responsible for snakebite envenoming and also in detecting specific venom antibody following the use of radioimmunoassay (RIA) to detect venom in Australia by the Sutherland's group. Subsequently, EIA, a much cheaper technique relative to RIA, was developed in a manner that allowed the diagnostic patterns of envenomation by diverse, occasionally closely related snake species to be accurately detected. Rapid tests for snakebite envenoming are available in Australia, regrettably; however, they are believed to be extremely expensive, coupled with challenges with sensitivity. EIA is, however, valuable in studying both new and existing antivenoms

since it offers a significant objective appraisal of antivenom efficacy and has the potential for application in various aspects of venom research [14, 28, 29].

### *3.4.1 Antivenom treatment and its related problems*

Antivenom immunotherapy remains the only accepted and effective way of treating systemic snakebite envenoming that is yet to confront the regime of rigorous scientific testing. It is also credited as the only therapy that has rescued the lives of snakebite envenoming victims for nearly a century. In spite of this, antivenoms are replete with significant challenges including poor stability of antivenom in its liquid form, adverse side effects/reactions, efficacy issues, and huge production difficulties often resulting in antivenoms that are extremely expensive, especially for those most affected. Antivenoms are produced by immunizing animals, especially large mammals such as horses and in rare instances donkeys and sheep. The large size of these animals allows potentially the collection of large volumes of plasma, and consequently the generation of large volumes of antivenom. The immune system of the animal is, thus, exposed to either a single venom in which case a monospecific/monovalent antivenom is generated or multiple venoms resulting in a polyspecific/polyvalent antivenom. An immune response is elicited by the animal, with antibodies (notably IgGs) been raised to bind specifically to the antigens/immunogens available in the venom (s). Fractionation procedures, such as centrifugation or sedimentation, are then used to separate plasma from the blood and red blood cells reinfused or reinjected into the animal. Subsequently, additional purification activities may be carried out to reduce the non-IgG serum protein content in certain antivenoms. Nonspecific IgGs may sometimes be removed using affinity chromatography. Sometimes, fragment crystallizable regions (Fc) may be removed through enzymatic digestion using pepsin or papain, resulting in F(ab')2 or Fab fragments, respectively, which are used to produce antivenom by most producers in Western countries, albeit intact IgGs are also utilized [1, 2].

#### *3.4.1.1 Challenges in ensuring reproducibility in antivenom production*

The production of conventional antivenoms is a challenging task. The risk involved is not just limited to milking venoms from the species responsible for the potentially deadly bites, but also the fact that an animal has to be immunized with a nonlethal/ safe dose of the venom extracted, or in some instances, the venom is detoxified in a manner that ensures that its immunogenicity is not lost. These issues reflect the inherent problems associated with antivenom production. Aside the fact that the animal can be stressed up, its maintenance is quite expensive and the antivenom yields, which are predicated on the immune responses can be threatened by the stress [30]. Antivenom production processes are not only enormously laborious with low yields but are also confronted with vast batch-to-batch variability [31]. This is, however, expected because when animals are injected with venoms, which vary compositionally, they elicit varied levels of immune responses to the immunogen. Thus, a pool of at least 20–50 venom samples from the same area or region is recommended as a way of mitigating these difficulties [1].

#### *3.4.1.2 Poor stability of antivenoms*

The poor stability of liquid antivenom renders it difficult to make it available for use in remote areas that need it the most and freeze-dried preparations are difficult.
