Parasitologia, Volume 3, Issue 3 (September 2023) – 9 articles

Trichuriosis is a disease in mammals caused by the whipworms of the genus Trichuris. These worms are known for the high disease burden they cause in humans and domestic animals, especially in sub-Saharan Africa. In this study, we investigated the prevalence and seasonal variations of Trichuris worms in multimammate rats (Mastomys natalensis). The study was conducted between January and November 2021 in Tanzania, in two regions (Morogoro and Iringa) that differ in their eco-climatic conditions. Removal trapping was conducted using Sherman^® live traps during the rainy and dry seasons. The gastrointestinal tracts of captured rodents were screened for the presence of Trichuris worms, which were identified using morphological keys. A total of 200 M. natalensis rats were collected from each of the regions, with 100 animals in each season. For Morogoro, the overall prevalence of Trichuris worms in M. natalensis was 36% (n = 72), of which 42% (n = 42) and 30% (n = 30) were for the rainy and dry seasons, respectively. For Iringa, the overall prevalence was 65% (n = 130), of which there were 80% (n = 80) and 50% (n = 50) for the rainy and dry seasons, respectively. Trichuris worm infections were significantly higher during the rainy season in Iringa than in Morogoro; however, no significant difference in infections between males and females was noted in either region or season. Other helminths detected were Strongyloides spp., Capillaria spp., Hymenolepis spp. and eggs of a helminth that has yet to be confirmed, possibly an Anoplocephalid species. Since M. natalensis is the most important pest species in sub-Saharan Africa, and is a carrier of several zoonotic helminths, there is a need for improved surveillance of helminths infections in the studied regions, in order to establish strategic control programs to reduce their adverse impacts on health. Full article

Theileria orientalis Ikeda, an emerging U.S. bovine hemoparasite, causes anemia, abortion, ill-thrift, and occasionally death. While Haemaphysalis longicornis is the primary vector, it is possible that other U.S. ticks are capable of parasite transmission and may contribute to disease spread. Dermacentor variabilis is highly prevalent in the U.S., exhibits a similar geographical distribution to T. orientalis, and is a competent vector of the related parasite, Theileria equi. Herein, we conducted controlled acquisition and transmission studies using splenectomized calves to assess whether D. variabilis can transstadially transmit T. orientalis. D. variabilis nymphs were applied to an infected, splenectomized calf for parasite acquisition and subsequently incubated to molt into adults. Freshly molted adults were applied to two splenectomized T. orientalis-naïve calves to investigate parasite transmission. Calves were monitored for 59 days, and no evidence of parasite transmission was detected using PCR for the T. orientalis Ikeda major piroplasm surface protein gene, blood smear cytology, complete blood counts, or physical examination. Salivary glands from a subset of D. variabilis adults were assessed for T. orientalis using PCR, and the parasite was not detected. These findings support the conclusion that D. variabilis is not capable of transstadial transmission of the U.S. T. orientalis Ikeda isolate. Full article

Digital PCR (dPCR) is an emerging technology that enables the absolute quantification of the targeted nucleic acids. The body of research on the potential applications of this novel tool is growing in human and veterinary medicine. Most of the research on dPCR applications in veterinary parasitology is concentrated on developing and validating new assays to detect and quantify parasites of great financial impact in the food-producing animal industry. Several studies describe the utility of dPCR for individualized medicine in companion animals. Most frequently, dPCR performance is assessed compared to quantitative PCR or Next Generation Sequencing platforms, while others also compare the accuracy of dPCR with traditional parasitological techniques considered gold standard methods. Other researchers describe dPCR assays for surveillance purposes, species identification, and quantification in mixed parasitic infections, the detection of mutations indicative of anthelmintic resistance, and the identification of new targets for drug development. This review provides an overview of the studies that employed dPCR in investigating animal parasites and parasitic diseases from a veterinary perspective and discusses how this novel technology could advance and facilitate diagnosis, surveillance, and the monitoring of response to treatment, or shed light on current gaps in our knowledge of the epidemiology of significant veterinary parasitic diseases. Full article

Equids can be infected by Neospora spp., and its infection is associated with neurological and reproductive disorders. This systematic review and meta-analysis aimed to assess the prevalence of anti-Neospora caninum antibodies in horses, donkeys and mules worldwide between 2012 and 2022. Five scientific databases were consulted: MEDLINE, ScienceDirect, PubMed, LILACS and SciELO, using the descriptors “protozoan” or “neospora” AND “horses” or “donkeys” or “mules”. A total of 1909 studies were screened, and 25 studies met the inclusion criteria. The pooled prevalence of Neospora spp. infection in equids, based on a total of 11,076, was 8.34% (95% CI: 4.78–14.17%). Further analysis by species revealed no statistically significant difference in the prevalence of Neospora spp. infection across equids: 8.5% (95% CI 5.03–13.99%) in horses, 7.36% (CI 2.08–22.94%) in donkeys and 6.07% (95% CI 0.71–36.83%) in mules. Regarding diagnostic tests, the prevalence of Neospora spp. infection determined by the indirect fluorescent antibody test (IFAT) was 8.08% (95% CI: 3.74–16.61%), by the enzyme-linked immunosorbent assay (ELISA) was 7.91% (95% CI: 3.71–16.08%), and by the modified agglutination test (MAT) was 20% (95% CI: 15.37–25.60%). This meta-analysis provided valuable and comprehensive insights into the prevalence of Neospora spp. infection in horses, donkeys, and mules using serological detection methods. The results highlight the wide distribution of Neospora spp. infection in equids across all continents, indicating the importance of this infection. Transmission of the parasite can occur both horizontally (directly between animals) and vertically (from mother to offspring), further emphasizing the significance of understanding and managing this infection in equid populations. Full article

Although bats can serve as reservoirs for several viruses and bacteria, there is limited knowledge regarding the diversity of apicomplexan protozoan belonging to the Piroplasmida and Haemosporida orders within this group of mammals. The present study aimed to investigate the occurrence and phylogenetic assessment of piroplasmids and hemosporidians in spleen samples collected from 229 vampire bats (228 Desmodus rotundus and 1 Diaemus youngii) in the states of Pará, Roraima, Amapá, and Amazonas, northern Brazil. Out of 229 bat spleen samples, 43 (18.77%) tested positive in a nested PCR for piroplasmids based on the 18S rRNA gene. Thirteen sequences (ranging from 474 to 828 base pairs) of the partial 18S rRNA gene showed 91.04–100% identity to Theileria sp., Babesia sp., and Piroplasmida previously detected in deer, tapirs, opossums, and crab-eating raccoons. The phylogenetic analysis based on the near-complete 18S rRNA gene positioned the obtained sequences from three D. rotundus in distinct clades (Theileria sensu stricto, Tapirus terrestris, and “South America Marsupialia”). All bat spleen DNA samples tested negative in a nested PCR assay for hemosporidians based on the cytB gene. The present study reported, for the first time, the presence Babesia sp. and Theileria sp. DNA in D. rotundus. The distinct positioning of the 18S rRNA gene sequences within different clades demonstrates the occurrence of different piroplasmid species in vampire bats. Full article

Nematodes of the genus Kiluluma (Strongylidae, Cyathostominae) parasitize African rhinoceros. We describe the case of a one-year-old male white rhinoceros calf that presented with colonic inflammation and hemorrhage at necropsy. The animal had died following a neurological episode. We recovered and identified adult nematodes from the colon using morphology and ITS2 gene sequences as Kiluluma ceratotherii. We also generated nuclear ITS1, 5.8S, ITS2, and mitochondrial cox1 sequences for future studies and deposited them in GenBank (OR142644–OR142653). Since the animal was born in the same zoo and never transported, infection likely originated within the herd. This is the first report of this nematode from a white rhinoceros in the United States. Full article

Bubaline sarcocystosis, caused by Sarcocystis levinei, is worldwide in distribution. Yet, very limited reports are available across the globe on the phylogenetic aspects of this particular Sarcocystis spp. Virtually no literature is available on its molecular aspects from India. Thus, the present study was designed to phylogenetically characterize the various isolates of S. levinei based on 18S rRNA and cox 1 mitochondrial genes. A total of 11 isolates of S. levinei from Northern India were characterized for 18S rRNA (MG957189-MG957199) and cox 1 (MH255771-MH255781) genes. PCR products were cloned, sequenced, and compared with other sequences across the world. A phylogenetic tree was constructed based on the maximum likelihood (ML) method. Phylogenetic analysis placed S. levinei and S. cruzi into two monophyletic sister groups. An appreciable amount of genetic variability was noticed between various S. levinei sequences for both the gene loci. A total of three haplotypes were noticed for each gene. The generated sequences showed 99.8–100.0% and 99.7–100.0% nucleotide homologies within themselves with regard to the 18S rRNA and cox 1 genes, respectively. Few of the studied sequences showed marked similarity and closeness with the Egyptian sequences than their Indian counterparts. This is the first report of molecular characterization and sequence phylogenetic study of S. levinei from India. Full article

Thread herrings (Opisthonema spp.) are economically important fish species in the Tropical Eastern Pacific. Knowledge of the parasitofauna of commercially exploited species is useful as it can increase our understanding of fish biology and ecology. However, our knowledge of the parasites of Opisthonema spp. is limited. During a fisheries exploration survey in April 2022, samples of Opisthonema bulleri and O. libertate were collected from three oceanographic stations in the Gulf of Tehuantepec in the Mexican Pacific. Parasitological analysis of these materials uncovered four parasite species: Myosaccium ecaude (Trematoda), Cribromazocraes sp. (Monogenea), Pseudoterranova sp. (Nematoda), and an unidentified crustacean of the family Pennellidae (Copepoda). All these species appeared rarely, except for M. ecaude, which reached a prevalence of 100%. The median intensity of M. ecaude infection was significantly higher in O. bulleri than in O. libertate. We analyzed the relationship between parasitic infection intensity and three host traits (fork length, body weight, and age). Only body weight showed a significant positive association with intensity. Future studies are required to analyze the possible effects of seasonality, locality, and host ontogeny on the occurrence of M. ecaude in thread herrings in the Tropical Eastern Pacific. Full article

Malaria is one of the most important neglected diseases in the world, and Brazil has the largest number of cases on the American continent. In Brazil, this disease is considered to be endemic in the Amazon region, although malaria lethality in extra-Amazonian regions is higher. Recently, it has been shown that malaria cases of autochthonous origin are not uncommon in the southeastern states. Among these states, Espírito Santo (ES) has the highest percentage of reported cases. This study aimed to describe the epidemiological profile and main factors that contribute to the incidence of malaria cases in this region, which corresponded to 4155 notifications in the 2007–2017 period based on data obtained from the Special Center for Epidemiological Surveillance of Espírito Santo. The most affected group was males aged around 40 years old, and most of the cases registered were of autochthonous origin. The number of malaria cases decreased during the period 2007–2017. Among the causative species, P. vivax was predominant, and it was followed by P. falciparum as the second most common species of all malaria cases. The main cities of ES presented high records of malaria disease, with high numbers of malaria cases in Santa Tereza, Domingos Martins, Alfredo Chaves, Santa Leopoldina, and Marechal Floriano. It is up to the local governments to advise the population about the epidemiological situation and to standardize medical care for individuals with suspected malaria. Full article