Parasitologia, Volume 4, Issue 4 (December 2024) – 10 articles

Cryptosporidium species are protozoan parasites of veterinary and medical importance that infect a wide range of vertebrates globally. Primarily, the mode of infection is typically ingestion of sporulated oocysts, and the risk of transmission to susceptible host is increased by environmental contamination with sporulated oocysts. This systematic review aims to provide a summary of the available data on Cryptosporidium genotypes in Africa. A systematic research of literature on four electronic databases, including Scopus Web of Science, Science Direct, and AJOL, was performed for the determination of Cryptosporidium genotypes in animal and human hosts across Africa between January 2000 to August 2023. All published studies were screened based on the inclusion and exclusion criteria. Overall, 131 Cryptosporidium genotypes were generated from the 47 articles included in this study, which cut across 14 African countries. Cryptosporidium genotypes were reported across all regions within the African continent, such as northern, eastern, western, central, and southern Africa. Cryptosporidium hominis (Ia, Ib, Id, Ie, If, Ih, Ii, and Ik) genotypes were the most dominant, with C. hominis subfamily Ia genotypes reported across all African regions, which indicates high diversity of these subfamilies on the continent. Cryptosporidium parvum (IIa, IIb, IIc, IId, IIe, IIm, and IIi) genotypes were the second dominant genotypes reported, with C. parvum subfamily IIa genotypes having a high diversity across all the African regions with the exception of southern Africa. C. parvum subfamily IIc (IIcA5G3b), which is known to circulate among humans, was reported in a study on dogs in Nigeria. Other documented species of Cryptosporidium with known subtypes in Africa include C. meleagridis (IIIb, IIId, and IIIg), C. cuniculus (Vb), C. ubiquitum (XIIa), C.), and C. erinacei (XIIIa) genotypes. In conclusion, findings from this review have elucidated the Cryptosporidium species and subtypes within the African continent across humans and multiple animal hosts, implying the diversity of this parasites and its ability to infect wide host ranges. Full article

Trypanosoma vivax displays distinct mitochondrial genomes: intact in Africa and degraded in South America. This finding, formerly reported from four isolates, suggested an association between mitochondrial mutations and adaptation to exclusive mechanical transmission outside Africa, circumventing mitochondrial activity essential for cyclical transmission by tsetse flies. Here, we characterized the mitochondrial ND7 and COIII genes in 25 South American isolates of T. vivax from livestock from Argentina, Brazil, Colombia, Ecuador, and Venezuela, as well as in 11 African isolates from Mozambique, Ethiopia, Uganda, Nigeria, and Burkina Faso from tsetse flies, antelopes, and cattle. Phylogenetic inference supported the lineages TVV (Trypanosoma vivax vivax) and TVL (Trypanosoma vivax-like), predominant in South America/West Africa and East Africa, respectively. Both ND7 and COIII genes were intact in all African TVV and TVL isolates and, for the first time, in 10 South American isolates from Brazil. Remaining South American isolates exhibited some degree of gene erosion, including ~142 bp deletion at the 3′ end of ND7 disclosed in Venezuela and Colombia, ~163 bp deletion at the 3′ end of ND7 in Brazil and Argentina, and ~750 bp deletion from the 5′ end of ND7 to the 3′ end of COIII in Venezuela. Comprehensive analyses of whole mitochondrial genomes from additional South American and African isolates are crucial for formulating reliable hypotheses regarding the origin, absence, and rapid mitochondrial degradation observed in South American T. vivax. Full article

Female Genital Schistosomiasis (FGS) is caused by Schistosoma haematobium, which causes chronic gynecological conditions that lead to substantial morbidity and infertility. This study’s objective is to determine the prevalence and burden of FGS based on the presence of S. haematobium-specific DNA in females across age groups using our previously field-acquired filtered human urine samples from Zambia, Tanzania, and Ghana, collected over multiple years. For Ghana (2013), 39 out of 90 samples were from females, of which 31 (79.5%) were positive and 8 (20.5%) were negative. In Zambia (2016), 80 out of 133 samples were from females, of which 46 (57.5%) tested positive and 34 (42.5%) were negative. For Zambia (2017), 60 out of 110 samples were from females, of which 45 (75%) tested positive and 15 (25%) tested negative. In Tanzania (2018), 70 out of 104 samples were from females, of which 43 (61.4%) tested positive and 27 (38.6%) tested negative. FGS prevalence ranged from 57.5% (Zambia in 2016) to 79.5% (Ghana in 2013) and was found predominantly among the 11–20 years age group. The analytical outcome highlights that FGS is predominant among females in different endemic countries and in the age range of pre-teen to young adult. Full article

According to the Host Manipulation Hypothesis, parasites modify the phenotype of their host to enhance host–host transmission and thereby increase fitness. Metacercarial infection of some amphibians changes host behavior, including locomotion, and thereby enhances predation by the definitive host. To further test this hypothesis, it is first necessary to determine whether a parasite actually modifies a host’s phenotype. In the southern Appalachian Mountains of the US, metacercariae of the trematode Metagonimoides oregonensis (Price, 1931) encyst in the musculature of its second intermediate host, the salamander Desmognathus amphileucus Bishop, 1941. Metacercarial infections of musculature in fish negatively affect host swimming performance. Therefore, we tested the hypothesis that infection by M. oregonensis affects walking in the aquatic larvae of D. amphileucus. We compared this mode of locomotion between infected and uninfected larvae by placing them in 1 m troughs of water and allowing them to wander freely until they stopped. Non-parametric (Kaplan–Meier) survival analysis determined that infected salamanders stopped significantly sooner than uninfected ones. Because infected salamanders move less, the presence of this parasite may contribute to genetic divergence in these salamanders by slowing dispersal and concomitant gene flow. Our results suggest that macroparasites can potentially modify a host’s behavior with biological consequences beyond enhancement of parasite transmission. Full article

The finding also represents the first detection of this trematode on the Balkan Peninsula. The study was conducted between 2014 and 2023. Nineteen road-killed polecats, mainly from southern Bulgaria, were examined. A four-year-old male polecat road-killed near Chepelare, a town in the Somlyan Province in the Rhodope Mountains, was infested with six adult Troglotrema acutum within its frontal sinus. The skull exhibited only weakly developed lesions. The prevalence of 5.26% observed in this sample was lower than values reported from other European countries. This finding extends the known southeastern distribution range of T. acutum by over 700 km. Full article

Biological control of undesirable organisms and pathogens often involves the introduction of alien species into new regions. However, alien species themselves pose a potential threat to local ecosystems and economies. The Eastern mosquitofish Gambusia holbrooki is recognised as a dangerous invasive species, but despite this, it is still used for biological control of mosquito larvae, a potential vector of malaria plasmodium transmission to humans, on the Black Sea coast of the Caucasus. We focused on the species composition of helminths in this fish species. We detected adult nematodes Pseudocapillaria (Pseudocapillaria) tomentosa and cestodes Schyzocotyle acheilognathi (formely Bothriocephalus acheilognathi). The above nematode was observed for the first time in fish of the genus Gambusia. Importantly, the cestode S. acheilognathi, which we found in G. holbrooki, is the most successful invasive alien parasite species in freshwaters of the planet and is extremely hazardous to natural ecosystems and aquaculture as it can cause mass mortality of young fish. Thus, the current practice of transferring mosquitofish between water bodies on the Black Sea coast of the Caucasus to control mosquito larvae may contribute to the undesirable spread of a harmful quarantine fish parasite. Full article

Soil-transmitted helminths (STHs), including Ascaris lumbricoides, hookworm species, and Trichuris trichiura, cause significant morbidity worldwide. For an effective proper control of their morbidity, accurate diagnosis method is needed. To this end, a polymerase chain reaction (PCR) method has been developed, but its use remains limited due to the high cost of its implementation, the resources required, and the lack of qualified technicians. The objective of the present analysis is to assess the agreement between the Kato–Katz microscopy method and quantitative real-time PCR (RT-PCR) in the diagnostic of STHs before and after treatment, to decipher the usefulness of either technique for evaluation of the treatment. Methods: Stool samples were collected before and after three- or six-weeks post-treatment from study participants and analyzed using Kato–Katz and RT-PCR methods for the diagnosis of STHs infections. The cure rate (CR) was estimated according to each diagnostic method. Agreement between CRs was tested using the Kappa statistical test. Results: Agreement between Kato–Katz and RT-PCR methods varied regarding the STH species targeted and was different after treatment compared with before treatment. At baseline, the two diagnostic methods showed a moderate agreement (0.45 < K < 0.5) for all STH species, whereas after treatment, concordance decreased slightly (0.11 ≤ K ≤ 0.14) for A. lumbricoides, remained moderate (0.5 ≤ K ≤ 0.53) for T. trichiura, and went from moderate to absent for hookworms. Conclusion: Our findings showed basically a moderate agreement between the Kato–Katz method and RT-PCR. There is a likely association with a moderate proportion of microscopy-positive cases. Reciprocally, a decrease in agreement after treatment was observed with low microscopy-positive cases after treatment, whereby RT-PCR was more likely to detect positive cases than microscopy. Therefore, the agreement is positively associated with an increasing in the number of samples testing positive. Full article

Vector-borne infections persist as a significant issue in both human and animal health. Many of the most common vector-borne infections in the USA, especially tick-borne infections, are known to be zoonotic, including Lyme disease, anaplasmosis, and ehrlichiosis, and these infections may also negatively impact the health of infected animals. Convenient patient-side assays for the detection of antibodies to Borrelia burgdorferi, Anaplasma spp., and Ehrlichia spp., and antigen of Dirofilaria immitis have allowed for the generation of robust and large-scale prevalence data in dogs. Data of similar scale and distribution are not available in cats, and most feline prevalence studies have evaluated a small sample size with limited geographic distribution. The objective of this study was to evaluate the prevalence of antibodies to B. burgdorferi, Anaplasma spp., and Ehrlichia spp., and D. immitis antigen among shelter cats across the USA, a population that is presumably at high risk for ectoparasitism and, consequently, exposure to vector-borne infections. In total, 2232 whole blood samples were collected from shelter cats across four regions of the USA—South, Northeast, Midwest, and West—and were evaluated using the Idexx SNAP^® 4Dx^® Test. Ectoparasites were also opportunistically collected from cats during blood collection and morphologically identified. The prevalence of at least one vector-borne infection was 2.60%, and the nationwide prevalence was 1.88% for B. burgdorferi, 0.54% for Anaplasma spp., 0.09% for Ehrlichia spp., and 0.55% for D. immitis. A total of 1120 ectoparasites were collected from 423 cats, including 27 ticks and 1093 fleas. Although the overall prevalence of the pathogens in this survey is relatively low, we observe that there is an increased exposure risk regionally for some agents, with geographic distributions in this study mostly coinciding with established human and canine distributions. Understanding these findings in an assumed non-protected population of cats allows us to extrapolate the risk to pet cats if they are not provided routine veterinary care, including a broad-spectrum parasite prevention program. Full article

Helminth infections pose a significant global health challenge, as existing drugs often lack efficacy and may be contraindicated in some populations. Progress in the development of new drugs is hindered by the lack of innovative models for use in drug research. Metarhabditis blumi nematodes, which are associated with parasitic otitis in cattle, can severely affect the nervous system, leading to death. The treatment and control of this pathology face similar limitations to those for other parasitic diseases. Our study aimed to standardize M. blumi as a model for evaluating the anthelmintic activity of new drugs. Larvae (L3) and adult worms were treated with the reference drugs albendazole (16 µM) and ivermectin (2.5 µM) diluted in an NGM medium for 24 h, and various parameters were evaluated. Motility and mobility were analyzed using a video tracking and analysis program. Morphological and ultrastructural characterizations were performed after chemical fixation using light and scanning electron microscopy (SEM). The results showed that ivermectin was more effective than albendazole in treating M. blumi adults and L3. The SEM images revealed drug-induced ultrastructural changes. Compared to previous studies using the established Caenorhabditis elegans model, M. blumi demonstrated greater resistance to both albendazole and ivermectin. We conclude that M. blumi is a viable model for drug discovery assays and a valuable new experimental model for various biological studies, highlighting that, unlike C. elegans, M. blumi is associated with parasitism. Full article

The quest for new drug candidates targeting neglected parasitic diseases has become increasingly urgent over the past decades. Advancements in formulating and optimizing drug delivery systems begin with basic research, including direct assays to evaluate the activity of molecules against parasitic stages maintained in laboratories; i.e., promastigotes. In the context of leishmaniasis, an endemic disease worldwide, the cultivation of Leishmania parasites can vary significantly across different laboratories. Factors such as culture media composition, pH, supplementation, and temperature can lead to varied drug responses in in vitro activity assays. This study aims to compile the parameters used in Leishmania spp. promastigotes cultivation protocols described in scientific articles published in indexed journals over the past ten years. The data reveal a lack of uniformity among Leishmania culture protocols, suggesting a potential bottleneck in comparing the leishmanicidal potential of in vitro drug candidates reported by different research groups. This condition is crucial to consider, because viability/inhibition assays should begin with fully-grown, healthy promastigote cultures capable of homogeneous division, thereby producing more reproducible results. Full article