Parasitologia, Volume 2, Issue 2 (June 2022) – 9 articles

The human parasite Entamoeba histolytica, which causes approximately 100 million cases of amoebic dysentery each year, relies on glycolysis as the major source of ATP production from glucose as it lacks a citric acid cycle and oxidative phosphorylation. Ethanol and acetate, the two major glycolytic end products for E. histolytica, are produced at a ratio of 2:1 under anaerobic conditions, creating an imbalance between NADH production and utilization. In this study we investigated the role of acetate kinase (ACK) in acetate production during glycolysis in E. histolytica metabolism. Analysis of intracellular and extracellular metabolites demonstrated that acetate levels were unaffected in an ACK RNAi cell line, but acetyl-CoA levels and the NAD⁺/NADH ratio were significantly elevated. Moreover, we demonstrated that glyceraldehyde 3-phosphate dehydrogenase catalyzes the ACK-dependent conversion of acetaldehyde to acetyl phosphate in E. histolytica. We propose that ACK is not a major contributor to acetate production, but instead provides a mechanism for maintaining the NAD⁺/NADH balance during ethanol production in the extended glycolytic pathway. Full article

Cerebral coenurosis is a fatal parasitic neurological disease affecting the brain and spinal cord of goats and sheep. Despite the large population of sheep and goats in Africa, there is very little awareness about the scale or effects of the disease. A systematic review was conducted to bridge the gap in the current understanding of the epidemiology of Taenia multiceps coenurosis in Africa. A detailed literature search was conducted in EBSCOhost, Google Scholar, Research4life (AGORA), and PubMed for studies in T. multiceps coenurosis in goats and sheep in Africa for the period spanning January 2000 to December 2019. The search identified 574 publications, of which only 11 studies were eligible, highlighting major gaps in reporting of this disease in Africa. Data were extracted and evidence synthesized in relation to prevalence and determinants for T. multiceps coenurosis. The descriptive summary statistics revealed a median (IQR) prevalence of coenurosis of 22.3% (range: 18.3–26.4 percent) for community based and 14.8% (range: 3.8–45.6) for abattoir-based studies. This high prevalence indicates that Taenia multiceps coenurosis is an important disease for small ruminant productivity in Africa. Knowledge of the determinants of prevalence could be used to inform preventive measures, including behaviour change among livestock keepers and those involved in livestock slaughter to break cycles of transmission between small ruminants and dogs. Full article

An intraneuronal parasite infecting approximately one-third of the world’s population, Toxoplasma gondii has been associated with markers of cardiovascular disease. In this study, we used data from the Center for Disease Control and Prevention’s National Health and Nutrition Examination Survey to investigate associations between T. gondii and blood pressure and hypertension. Multiple regression modelling adjusted for a range of covariates showed that T. gondii was associated with lowered probability of elevated blood pressure, with lower probability of Stages 1 and 2 hypertension, and with lower systolic and diastolic blood pressure. These findings suggest that T. gondii might alter hemodynamic regulation, although the clinical relevance of these associations requires additional investigation. Full article

Onward transmission of Plasmodium falciparum from humans to mosquitoes is dependent upon a specialised transmission stage called the gametocyte. Despite its critical role in transmission, key questions regarding gametocyte biology remain to be answered, and there are no widely prescribed therapeutics to eliminate them. Advances in our understanding of the biology of the gametocyte in combination with growing information regarding the mechanism of action of anti-plasmodial therapies provide an emerging view as to which of the biological processes of the gametocyte present viable targets for drug intervention and explain the variable activity of existing therapies. A deeper understanding of the gametocyte and transmission stages of P. falciparum is a path to identifying and characterising novel drug targets. This review will examine how a selection of current and potential gametocytocidals mediate their effect. Full article

Public spaces such as beaches develop an important role in the welfare of the human population in Brazil, where leisure and safety spaces are increasingly scant. Knowledge about the possible role of contaminated sand of beaches on the health of animals and humans is pivotal to determine risk areas and preventing future cases. Therefore, the aim of this study was to assess the presence of eggs of nematodes of public health interest on tropical beaches. Soil samplings (n = 42) from 10 different beaches located in the Metropolitan region of Recife, Northeastern Brazil, were analyzed through the FLOTAC technique. In 80% (8/10) of beaches, eggs of nematodes were detected. In particular, if we consider each individual sample (n = 42) a positivity rate of 90.4% (38/42) was observed. Eggs belonging to the families Ascarididae (47.6%; 20/42), Ancylostomatidae (26.1%; 11/42), and Trichuridae (11.9%; 5/42) were detected. Based on these data, it is necessary to implement preventive measures and educational actions for the population in order to mitigate the potential risk of exposition to parasites of zoonotic importance. Additionally, the FLOTAC technique has been shown to be a reliable technique for assessing soil contamination by nematode eggs. Full article

Toxocara canis and Toxocara cati are known as common roundworm in dogs and cats, respectively. The objective of the current study was to determine the molecular prevalence and risk factors associated with T. canis and T. cati infections in stray dogs and cats, respectively, in Bangkok, Thailand. In total, 1000 fecal samples (from 500 dogs and 500 cats) were collected from stray dogs and cats residing in Bangkok temples. DNA was extracted and screened for T. canis and T. cati using polymerase chain reaction (PCR) with the internal transcribed spacer (ITS) region. The overall prevalence of T. canis in the stray dogs was 5.4% (27/500) and 0.6% (3/500) for T. cati in the stray cats. Toxocara canis infections were detected in stray dogs from 11 out of 48 districts (22.9%), with Bang Khen district having the highest proportion of infected dogs, whereas T. cati infections were only detected in the stray cats in Lat Krabang district. These results indicated that stray animals residing in Bangkok temples pose a considerable public health risk due to zoonotic parasites, especially T. canis. Full article

Sand flies are a significant public health concern in many parts of the world where they are known to transmit agents of several zoonotic diseases to humans, such as leishmaniasis. Vector control remains a key component of many anti-leishmaniasis programs and probably will remain so until an effective vaccine becomes available. The sand fly gut microbiota has recently emerged as an encouraging field for the exploration of vector-based disease control. In particular, the gut microbiome was previously reported to either enhance or inhibit parasite activity depending on the species of bacteria and, thus, has the potential to alter vector competence. Here, we describe the technological advances that are currently expanding our understanding of microbiota composition in sand flies. The acquisition and composition of microbiomes are influenced by several abiotic and biotic factors, including host immunity, genetics, and the environment. Therefore, the microbiomes of sand flies can vary substantially between individuals, life stages, species, and over geographical space, and this variation likely contributes to differences in host phenotypes, highlighting opportunities for novel vector control strategies. Full article

Internal parasitism, a significant cause of production losses in sheep, is routinely controlled by anthelmintic drenches. A better understanding and alternative control strategies are needed to combat the increasing resistance. This study investigated the presence of resident bacteria in the field strain of Haemonchus contortus. Adult female worms were collected from the abomasa of sheep. DNA was extracted from adult female worms and parasite eggs laid in vitro using long or shorter enzymatic incubation methods. Polymerase Chain Reaction (PCR) was performed using universal bacterial and phylum Firmicutes-specific primers; PCR products were cloned and sequenced. The analysis of the sequences shows a majority of the sequences belong to rumen bacteria, mainly Ruminococcus. Streptococcus was detected in four eggs, and adult worm samples and the sequences had a very high homology to the Streptococcus sequences in the database. Clostridium was detected only in the adult samples, whereas Nevskia and Pseudomonas were detected only in the egg samples. Three antibiotics, Ampicillin (Amp), Gentamycin (Gen) and Tetracycline (Tet), individually or combination, were tested to establish proof of concept that abomasal nematode parasites can be controlled by killing the resident bacteria. A larval migration inhibition assay was used to test the hypothesis. Tet (10 and 20 mM) resulted in around 30% mortality in larvae. Amp and Gen did not result in significant levels of larval mortality but, when given in combination, resulted in significant mortality of the larvae, suggesting the role of antibiotics in controlling the parasites by targeting the resident bacteria. Full article

A cross-sectional study was conducted at Gumbo slaughter slab in Juba, Central Equatoria State (CES) in South Sudan, between October and December 2015, to determine the prevalence of cystic echinococcosis (CE) and to estimate the direct economic losses associated with condemnation of infected organs in slaughtered goats. A thorough postmortem examination was conducted on carcasses of a total of 1126 goats selected by systematic random sampling for detection of CE in the lungs, liver, heart, kidneys, and the spleen. Moreover, CE-related direct financial losses were estimated by using a standardized formula. The overall prevalence of CE was found to be 281 (24.9%, 95% CI 22.5–27.6). Furthermore, old age (OR = 2.61, p value < 0.001), Mubende breed (OR = 2.97, p value < 0.001), and Ugandan geographical origin (OR = 2.97, p value < 0.001) were associated with higher prevalence of CE. The lungs were the most affected organ with a prevalence of 55.2% followed by liver (44.1%), and the spleen (0.07%). A direct CE-related monetary loss of 78,820 South Sudanese Pounds (SSP) per year was estimated. This loss is equivalent to USD 43,788. In conclusion, CE is considerably prevalent and is associated with significant direct financial losses among goats slaughtered at Gumbo slaughter slab in Juba, CES, South Sudan. Full article