Preclinical efficacy testing of three antivenoms against Naja ashei venom-induced lethality.

This study aimed to determine the efficacy of Inoserp, Vins bioproducts, and South African Institute of Medical Research (SAIMR) polyvalent antivenoms in neutralizing Naja ashei venom-induced lethality in mice. The neutralization efficacy of the antivenoms were expressed as effective dose, median effective ratio, potency, normalized potency, volume, and the number of vials of antivenom required to neutralize 100 mg of Naja ashei venom (NAV).

Artemia salina as an animal model for the preliminary evaluation of snake venom-induced toxicity.

Lethality and cytotoxicity assays of snake venoms and their neutralization by antivenom require many mice for the experiments. Recent developments have prompted researchers to seek alternative strategies that minimize the use of mice in line with Russel and Burch's 3Rs philosophy (Replacement, Reduction, and Refinement). Artemia salina is an animal model widely used for toxicity screening. However, its use in snake venom toxinology is limited by a lack of data. The present study compared the toxicity of venoms from Bitis arietans, Naja ashei, and Naja subfulva using mice and Artemia salina. In the Artemia salina test at 24 h and the dermonecrotic test in mice, the toxicity of the venoms was in the order Naja ashei ~ Naja subfulva > Bitis arietans. In the lethality test in mice, the toxicity of the venoms was in the order Naja subfulva > Naja ashei > Bitis arietans. These findings suggest that the toxicity of the venoms in Artemia salina and the dermonecrotic bioassay in mice have a similar trend but differ from the lethality test in mice. Therefore, it may be relevant to further explore the Artemia salina bioassay as a potential surrogate test of dermonecrosis in mice. Studies with more venoms may be needed to establish the correlation between the Artemia salina bioassay and the dermonecrotic assay in mice.

Co-Occurrence and Levels of Mycotoxins in Fish Feeds in Kenya.

This study determined the presence, levels and co-occurrence of mycotoxins in fish feeds in Kenya. Seventy-eight fish feeds and ingredients were sampled from fish farms and fish feed manufacturing plants and analysed for 40 mycotoxins using high-performance liquid chromatography-high resolution mass spectrometry. Twenty-nine (73%) mycotoxins were identified with 76 (97%) samples testing positive for mycotoxins presence. Mycotoxins with the highest prevalences were enniatin B (91%), deoxynivalenol (76%) and fumonisin B1 (54%) while those with the highest maximum levels were sterigmatocystin (<30.5-3517.1 µg/kg); moniliformin (<218.9-2583.4 µg/kg) and ergotamine (<29.3-1895.6 µg/kg). Mycotoxin co-occurrence was observed in 68 (87%) samples. Correlations were observed between the fumonisins; enniatins B and zearalenone and its metabolites. Fish dietary exposure estimates ranged between <0.16 and 43.38 µg/kg body weight per day. This study shows evidence of mycotoxin presence and co-occurrence in fish feeds and feed ingredients in Kenya. Fish exposure to these levels of mycotoxins over a long period of time may lead to adverse health effects due to their possible additive, synergistic or antagonist toxic effects. Measures to reduce fish feed mycotoxin contamination should be taken to avoid mycotoxicosis in fish and subsequently in humans and animals through residues.

Enzymatic activity and brine shrimp lethality of venom from the large brown spitting cobra (Naja ashei) and its neutralization by antivenom.

OBJECTIVE: Naja ashei is a snake of medical importance in Kenya, Ethiopia, Somalia, Uganda, and Tanzania. Little is known about the enzymatic (snake venom phospholipases A2; svPLA2's) and toxic (lethal) activities of N. ashei venom and crucially, the safety and capacity of available antivenom to neutralize these effects. This study aimed to determine the enzymatic and toxic activities of N. ashei venom and the capacity of Indian and Mexican manufactured antivenoms to neutralize these effects. The protein content of the venom and the test antivenoms were also evaluated. A 12-point log concentration-response curve (0.5-22.5 µg/mL) was generated on an agarose-egg yolk model to predict the svPLA2 activity of the venom. The toxicity profiles of the venom and antivenoms were evaluated in the brine shrimp lethality assay. Lowry's method was used for protein estimation. RESULTS: Low and intermediate concentrations of the venom exhibited similar svPLA2 activities. The same was true for concentrations > 15 µg/mL. Intermediate and high doses of the venom exhibited similar mortalities in brine shrimp and test antivenoms were generally non-toxic but poorly neutralized svPLA2 activity. Mexican manufactured antivenom had lower protein content but neutralized venom-induced brine shrimp lethality much more effectively than Indian manufactured antivenom.

Occurrence and Levels of Aflatoxins in Fish Feeds and Their Potential Effects on Fish in Nyeri, Kenya.

Aflatoxins are fungal metabolites that contaminate foods and feeds, causing adverse health effects in humans and animals. This study determined the occurrence of aflatoxins in fish feeds and their potential effects on fish. Eighty-one fish feeds were sampled from 70 farms and 8 feed manufacturing plants in Nyeri, Kenya for aflatoxin analysis using competitive enzyme-linked immunosorbent assay. Fish were sampled from 12 farms for gross and microscopic pathological examination. Eighty-four percent of feeds sampled tested positive for aflatoxins, ranging from 1.8 to 39.7 µg/kg with a mean of 7.0 ± 8.3 µg/kg and the median of 3.6 µg/kg. Fifteen feeds (18.5%) had aflatoxins above the maximum allowable level in Kenya of 10 µg/kg. Homemade and tilapia feeds had significantly higher aflatoxin levels than commercial and trout feeds. Feeds containing maize bran and fish meal had significantly higher aflatoxin levels than those without these ingredients. Five trout farms (41.7%) had fish with swollen abdomens, and enlarged livers with white or yellow nodules, which microscopically had large dark basophilic hepatic cells with hyperchromatic nuclei in irregular cords. In conclusion, aflatoxin contamination of fish feeds is prevalent in Nyeri, and may be the cause of adverse health effects in fish in this region.

Prevalence of gastrointestinal helminths and management practices for dogs in the Greater Accra region of Ghana.

Toxocariosis and ancylostomosis remain the most important parasitic infections affecting companion animals worldwide and pose a risk to animal and human health. Information on these infections in dogs in Ghana is inadequate. A cross sectional study was undertaken to determine the occurrence of gastrointestinal helminths infections and management practices of dogs in the Greater Accra Region (GAR) of Ghana. Faecal samples were obtained from 380 dogs from communities in 11 out of 16 districts in the GAR. Coprological examination of the samples was performed using the modified McMaster technique. Management practices for control of helminths in dogs were assessed through questionnaire interviews of the dog owners. Most dogs (70.7%) were kept for security reasons and were not housed (61.8%). Prevalence of gastrointestinal helminths was 62.6%. Hookworm eggs were found in 178 (46.8%) dogs, Toxocara canis eggs in 22 (5.8%) and mixed infections of hookworms and T. canis in 38 (10.0%). Dipylidium caninum was found in 51 (13.4%) dogs, while Isospora species was in 33 (8.5%) dogs. Most households (68%; 133/194) of the sampled dogs had at least a child below the age of 5 years. Hookworm, T. canis and D. caninum were the zoonotic gastrointestinal helminths prevalent in dogs in the study area. Lack of housing for dogs creates ideal conditions for infection and spread of the zoonotic parasites.

Risk factors associated with infectious bursal disease vaccination failures in broiler farms in Kenya.

Immunization together with application of biosecurity measures are the principal methods of preventing infectious bursal disease outbreaks in high-risk areas. However, outbreaks in vaccinated chicken flocks have been reported in many parts of the world as a result of factors of vaccine virus, animal, or vaccine handler. In Kenya, such outbreaks have been reported, but the causes have not been studied. This study aimed at determining the risk factors associated with vaccine handling leading to vaccine failure in broiler flocks in Kwale County, Kenya. Structured questionnaires and visual observations were used to collect data from 83 broiler farms, 6 breeding farms, and 17 vaccine outlets. Relative risk (RR) analysis was used to determine the association between identified potential risk factors and vaccination failure. Results show that vaccines were properly handled in all vaccine outlet shops. Breeding farms maintained high levels of biosecurity and employed standard vaccine handling practices. Basic biosecurity practices were poor in broiler farms. Broiler farms failed to meet all the recommended standard procedures for vaccine storage, reconstitution, and administration. Risk factors included poor vaccine storage (RR = 8.7) and use of few drinkers to administer vaccine (RR = 5.8); traces of disinfectants in drinkers used to administer live vaccine (RR = 2.8); use of wrong vaccine-infectious bronchitis instead of infectious bursal disease vaccine (RR = 2.1); and use of improper diluents (RR = 1.6). Broiler farmers need training on basic farm biosecurity measures and standard vaccine handling practices.

Viral nucleoprotein localization and lesions of Newcastle disease in tissues of indigenous ducks.

Localization of Newcastle disease viral nucleoprotein and pathological lesions was evaluated in tissues of 55 indigenous ducks (45 experimentally infected and 10 sentinel ones). In addition, ten Newcastle disease infected chickens were used to ensure that the virus inoculum administered to the ducks produced the disease in chickens, the susceptible hosts. Ducks were killed on day 1, 4, 8 and 14 post-infection. Post-mortem examination was done with six tissues (liver, spleen, lung, caecal tonsils, kidneys and brain) being collected from each bird. The tissues were preserved in 10% neutral formalin for 24 h. They were then transferred to 70% ethanol for histology and immunohistochemical staining. Airsacculitis, necrotic splenic foci, congested intestines, lymphoid depleted caecal tonsils and focal infiltrations by mononuclear cells were the main pathological lesions in infected ducks. Over 28.9% of the infected ducks had Newcastle disease viral nucleoprotein in macrophage-like large mononuclear cells in the caecal tonsils and kidney tubular epithelium. The viral antigens were located in the cytoplasm and nucleolus of the cells. The other organs had no detectable viral antigens. This study shows that the kidneys and caecal tonsils are the likely predilection sites for the virus in ducks. They thus need to be considered as diagnostic indicators for the viral carriage in ducks.