Molecular and microscopic detection of natural and experimental infections of Toxocara vitulorum in bovine milk

Synergistic effects of using sodium hypochlorite (bleach) and desiccation in surface inactivation for Toxocara spp

Toxocara cati and T. canis are parasitic nematodes found in the intestines of cats and dogs respectively, with a cosmopolitan distribution, and the potential for anthropozoonotic transmission, resulting in human toxocariasis. Spread of Toxocara spp. is primarily through the ingestion of embryonated eggs contaminating surfaces or uncooked food, or through the ingestion of a paratenic host containing a third-stage larva. The Toxocara spp. eggshell is composed of a lipid layer providing a permeability barrier, a chitinous layer providing structural strength, and thin vitelline and uterine layers, which combined create a biologically resistant structure, making the Toxocara spp. egg very hardy, and capable of surviving for years in the natural environment. The use of sodium hypochlorite, household bleach, as a disinfectant for Toxocara spp. eggs has been reported, with results varying from ineffective to limited effectiveness depending on parameters including contact time, concentration, and temperature. Desiccation or humidity levels have also been reported to have an impact on larval development and/or survival of Toxocara spp. eggs. However, to date, after a thorough search of the literature, no relevant publications have been found that evaluated the use of sodium hypochlorite and desiccation in combination. These experiments aim to assess the effects of using a combination of desiccation and 10% bleach solution (0.6% sodium hypochlorite) on fertilized or embryonated eggs of T. cati, T. canis, and T. vitulorum. Results of these experiments highlight the synergistic effects of desiccation and bleach, and demonstrate a relatively simple method for surface inactivation, resulting in a decrease in viability or destruction of T. cati, T. canis and T. vitulorum eggs. Implications for these findings may apply to larger scale elimination of ascarid eggs from both research, veterinary, and farming facilities to mitigate transmission.

Molecular detection and phylogenetic analysis of Toxocara vitulorum in feces and milk samples from naturally infected water buffaloes

Toxocara vitulorum infects cattle and water buffalo, leading to mild to severe infection in calves and has wide geographic distributions, especially in tropical and subtropical countries. This work aimed to assess the prevalence, distributions, and phylogeny of T.vitulorum in water buffaloes in different parts of Sivas, one of the essential buffalo-breeding areas in Türkiye. T.vitulorum was found in 42 (8.23%) and 54 (10.58%) fecal (n:510) samples using microscopic and molecular techniques, respectively. T.vitulorum was higher in animals aged 0-6 months compared to other groups. Furthermore, when animals aged 0-6 months were grouped within themselves, the prevalence of T.vitulorum in 1-3 month-old-animals was higher than in both younger than one month and older than three months. T.vitulorum was detected in fecal samples obtained from animals older than six months. In colostrum/milk samples (n:100), T.vitulorum-larvae were found in 4% and 10% with microscopic and molecular techniques, respectively. The larvae were detected in colostrum/milk samples in the mother between the 2nd and 28th days postpartum-period. The ITS-1-gene of 11 PCR-positive samples was sequenced. The 98.99-100% nucleotide identity was determined between our T.vitulorum isolates and those present in GenBank. In conclusion, this is the first molecular survey and phylogenetic analysis of T.vitulorum in fecal and colostrum/milk samples from naturally infected water buffaloes. Data obtained in this study will help to understand the life cycle and epidemiology of the nematode. Data also revealed that veterinarians should consider older animals as well as young animals in their control program of nematode infections in farms.

Knowledge and practices on consumption of free-range chickens in selected rural communities of KwaZulu-Natal, South Africa, with focus on zoonotic transmission of Toxoplasma gondii and Toxocara spp

Chickens are a host to a variety of pathogens of zoonotic importance and this depends more on the husbandry system practiced. Toxoplasma gondii and Toxocara spp which are more prevalent in free-range chickens (FRC) can be acquired by humans via the ingestion of raw or undercooked meat (muscle) and/or viscera contaminated with infective stages of T. gondii and Toxocara spp. This study aimed to assess knowledge and practices on the household consumption of FRC meat and viscera by rural communities in KwaZulu-Natal (KZN) province, South Africa, as a risk factor in the transmission of zoonotic pathogens with special emphasis on T. gondii and Toxocara spp. A cross-sectional study was conducted on twenty (20) randomly selected households in four selected communities located on the northern coast (Gingindlovu and Ozwathini) and southern coast (uMzinto and Shongweni) of KZN province using a semi-structured questionnaire. To determine the presence of selected zoonotic pathogens in FRC, birds were purchased from randomly selected households in the study localities for sacrifice. Brain tissues were collected and subjected to molecular detection of T. gondii using TOX4 and TOX5 primers while other tissues and organs that were collected were subjected to molecular detection of Toxocara spp using Nem 18S primers. Questionnaire data were analyzed using the statistical package for social sciences (SPSS) version 25.0. Descriptive and chi-square statistics were used to assess knowledge and practices related to FRC consumption and zoonosis transmission. Molecular results showed four positive samples for T. canis from Gingindlovu (n = 1), uMzinto (n = 1), and Shongweni (n = 2). The role of FRC consumption in zoonosis transmission is discussed.

The Complete Mitogenome of Toxocara vitulorum: Novel In-Sights into the Phylogenetics in Toxocaridae

Toxocara vitulorum (Ascaridida: Nematoda) is one of the most common intestinal nematodes of cattle and buffalos and, therefore, represents a serious threat to their populations worldwide. Despite its significance in veterinary health the epidemiology, population genetics, and molecular ecology of this nematode remain poorly understood. The mitogenome can yield a foundation for studying these areas and assist in the surveillance and control of T. vitulorum. Herein, the first whole mitogenome of T. vitulorum was sequenced utilizing Illumina technology and characterized with bioinformatic pipeline analyses. The entire genome of T. vitulorum was 15,045 bp in length and contained 12 protein-coding genes (PCGs), 22 transfer RNAs (tRNAs), and two ribosomal RNAs (rRNAs). The gene arrangement (GA) of T. vitulorum was similar to those of other Toxocara species under GA3. The whole genome showed significant levels of AT and GC skew. Comparative mitogenomics including sequence identities, Ka/Ks, and sliding window analysis, indicated a purifying selection of 12 PCGs with cox1 and nad6 having the lowest and highest evolutionary rate, respectively. Whole amino acid sequence-based phylogenetic analysis supported a novel sister-species relationship of T. vitulorum with the congeneric species Toxocara canis, Toxocara cati, and Toxocara malaysiensis in the family Toxocaridae. Further, 12 (PCGs) single gene-based phylogenies suggested that nad4 and nad6 genes shared same topological trees with that of the whole genome, suggesting that these genes were suitable as novel genetic markers for phylogenetic and evolutionary studies of Ascaridida species. This complete mitogenome of T. vitulorum refined phylogenetic relationships in Toxocaridae and provided the resource of markers for population genetics, systematics, and epidemiology of this bovine nematode.

Evaluation of the cytokines response in buffaloes focused on its milk as a newly emerging indicator tracing for toxocariasis

This study aimed to evaluate the immune responses and oxidative stress provoked by Toxocara vitulorum infection in buffaloes with special reference to milk parameters as an emerging tool. The use of the milk tool was reported for the first time in tracing T. vitulorum infection in Egyptian buffaloes. Intestine, milk, serum, and liver samples were gathered from flocks in Cairo and Giza districts to evaluate buffalo immune responses provoked by T. vitulorum. The compositional items and somatic cells of milk were monitored. The intestine and milk were evaluated for interleukin IL-1β, IL-6, and tumor necrosis factor-alpha (TNF-α) by quantitative real-time polymerase chain reaction protocol and the analysis of malondialdehyde (MDA) as an oxidative stress marker. The mean percentages for the total solids, fats, proteins, lactose, salts, pH, and somatic cell count/ml in positive samples were 11.23 ± 0.37, 5.1 ± 0.17, 4.44 ± 0.14, 3.9 ± 0.14, 0.81 ± 0.02, 6.8 ± 0.22, and 4.23 × 10⁶± 1.41 × 10⁵ cells/ml, respectively. A significant difference (p < 0.05) was observed in the mean values of compositional items except for the total protein %, salts %, and pH. For T. vitulorum-contaminated samples, the milk IL-1β, IL-6, TNF-α, and MDA (nmol/ml) were 7 ± 0.23, 18 ± 0.6, 17 ± 0.56, and 3.7 ± 0.12, respectively (which were less than the values for intestinal cytokines). There is a statistical difference (p < 0.05) between positive and negative samples in the intestinal, milk cytokines, and MDA. This study is an initial investigation of the utilization of intestine and milk cytokines in the evaluation of buffalo toxocariasis.

Brain food: rethinking food-borne toxocariasis

Human toxocariasis is a neglected tropical disease, which is actually global in distribution and has a significant impact on global public health. The infection can lead to several serious conditions in humans, including allergic, ophthalmic and neurological disorders such as epilepsy. It is caused by the common roundworm species Toxocara canis and Toxocara cati, with humans becoming accidentally infected via the ingestion of eggs or larvae. Toxocara eggs are deposited on the ground when infected dogs, cats and foxes defecate, with the eggs contaminating crops, grazing pastures, and subsequently food animals. However, transmission of Toxocara to humans via food consumption has received relatively little attention in the literature. To establish the risks that contaminated food poses to the public, a renewed research focus is required. This review discusses what is currently known about food-borne Toxocara transmission, highlighting the gaps in our understanding that require further attention, and outlining some potential preventative strategies which could be employed to safeguard consumer health.