Parasites have a significant impact on the neurological, cognitive, and mental well-being of humans, with a global population of over 1 billion individuals affected. The pathogenesis of central nervous system (CNS) injury in parasitic diseases remains limited, and prevention and control of parasitic CNS infections remain significant areas of research. Parasites, encompassing both unicellular and multicellular organisms, have intricate life cycles and possess the ability to infect a diverse range of hosts, including the human population. Parasitic illnesses that impact the central and peripheral nervous systems are a significant contributor to morbidity and mortality in low- to middle-income nations. The precise pathways through which neurotropic parasites infiltrate the CNS by crossing the blood-brain barrier (BBB) and cause neurological harm remain incompletely understood. Investigating brain infections caused by parasites is closely linked to studying neuroinflammation and cerebral impairment. The exact molecular and cellular mechanisms involved in this process remain incomplete, but understanding the exact mechanisms could provide insight into their pathogenesis and potentially reveal novel therapeutic targets. This review paper explores the underlying mechanisms involved in the development of neurological disorders caused by parasites, including parasite-derived elements, host immune responses, and modifications in tight junctions (TJs) proteins.
Interleukin 18 (IL-18) exerts pleiotropic roles in many inflammatory-related diseases including parasitic infection. Previous studies have demonstrated the promising therapeutic potential of modulating IL-18 bioactivity in various pathological conditions. However, its involvement during malaria infection has yet to be established. In this study, we demonstrated the effect of modulating IL-18 on the histopathological conditions of malaria infected mice.
Snapper had been cultured in Malaysia since 1980 due to the fry availability and the high demand. However, details on the caligids infestation were not properly documented. This study was carried out to determine the prevalence, mean intensity and site preference of Caligus rotundigenitalis (Caligidae, Siphonostomatoida) a parasitic copepod on cage cultured crimson snapper, Lutjanus erythropterus from Bukit Tambun, Penang, Malaysia. A total of 70 specimens of cultured snapper were examined based on different infestation sites such as head, body as well as operculum. The specimens were separated into three groups according to the size of the fish. C. rotundigenitalis was found to be the only species infesting L. erythropterus with the prevalence and the mean intensity of 81.4% and 5.6±4.4, respectively. There was a significant difference between the prevalence of site infestation of the body and inner operculum sites. The prevalence of C. rotundigenitalis was highest on inner operculum of the fish followed by the body and head. However, there was no significant difference in the distribution of C. rotundigenitalis over the different infestation sites derived from the three groups. The information obtained from this study can be used for more effective control measures of ectoparasitic copepod infestation in floating cages.
Mariculture in Southeast Asia began in the 1970s and expanded rapidly during the 1980s, with the commercial hatchery production of the seabass Lates calcarifer. Other important cultured species were Epinephelus coioides, Epinephelus malabaricus, Lutjanus johni, and Lutjanus argentimaculatus. Intensification in the polyculture of these species and the large-scale international movement of fingerlings or juveniles, as well as the rapid expansion and concentration of fish farms, have caused severe problems resulting from parasitic infections. Infections in maricultured fish are predominantly caused by monoxenous parasites, in particular the capsalid and diplectanid monogeneans. Heteroxenous blood parasites also successfully maintained transmission in the culture system despite their requirement for an intermediate host. Prophylactic chemical treatments helped to reduce parasitic infection but did not eliminate them and once introduced into the floating netcage culture system, these parasites managed to maintain their transmission successfully. Despite the current lack of information regarding the biology of many parasites affecting cultured marine fishes, it nevertheless is possible to develop methodologies to produce an integrated health management system specifically designed to the needs of the mariculture practiced in the Southeast Asian region. This system is important and should include a sequence of prophylaxes, adequate nutrition, sanitation, immunization and an effective system of marketing for farmed fishes.
Nine soil samples from nine buildings infested with Coptotermes gestroi in Pulau Pinang, Malaysia, were tested for the type of soil texture. The soil texture analysis procedures used the hydrometer method. Four of nine buildings (44%) yielded loamy sand-type soil, whereas five of nine buildings (56%) contained sandy loam-type soil.
Tilapia is one of the commercially important fish in Malaysia as well as in other parts of the world. An understanding of monogenean infection dynamics in tilapia fish may assist us in searching for some intervention measures in reducing the loss of fish caused by parasitic diseases. The present study aimed (1) to compare infection level of monogeneans between the wild and cultured Oreochromis niloticus, and between the cultured O. niloticus and cultured red hybrid tilapia, and (2) to examine the spatial distribution of monogenean species over the gills of the different host species. From a total of 75 fish specimens, six species of monogeneans from two genera: Cichlidogyrus (C. halli, C. mbirizei, C. sclerosus, C. thurstonae, C. tilapiae) and Scutogyrus (S. longicornis) were identified. Data showed that the infection level of cultured O. niloticus was higher than that of the wild O. niloticus, however, the former was lower than that of the cultured red hybrid tilapia. Higher species richness of monogeneans was observed in the cultured red hybrid tilapia as compared to the others. Results for spatial distribution showed that the monogeneans have no preference on the left or right sides of the gills. However, C. halli, C. mbirizei, and C. tilapiae showed preferences on specific gill arches in the cultured O. niloticus and red hybrid tilapia. In general, the gill arch IV harboured the least number of monogeneans. The susceptibility of monogenean infection between the different types of tilapia is discussed.
This study investigated the prevalence of parasitic infections among aborigine children at Post Brooke, Kelantan. Eighty-four formalin-fixed specimens and 78 PVA-fixed specimens were obtained. 79.8% and 35.9% of the samples were positive for helminth ova and protozoa respectively. The parasites detected (single plus mixed infections) were A. lumbricoides (50/84, 59.5%), T. trichiura (35/84, 41.7%), hookworm (5/84, 6.0%), S stercoralis (1/84, 1.2%), G. intestinalis (18/78, 23.1%), E. histolytica (7/78, 9.0%) and E. coli (7/78, 9.0%). Two hundred thick blood film examinations detected only one case of Plasmodium falciparum infection. A high prevalence of intestinal parasitic infections among the children at Post Brooke was demonstrated in this study; thus there is an urgent need to improve the hygiene, education and living standards of this population.
Ethnic minority groups (EMGs) are often subject to exclusion, marginalization and poverty. These characteristics render them particularly vulnerable to neglected diseases, a diverse group of diseases that comprise bacteria, ecto-parasites, fungi, helminths and viruses. Despite the health policy relevance, only little is known of the epidemiological profile of neglected diseases among EMGs. We reviewed country data from Australia, Cambodia, Lao People's Democratic Republic, Malaysia, the Philippines and Vietnam and found several overlaps between regions with high proportions of EMG population and high prevalence rates of neglected diseases (infections with soil-transmitted helminths, filarial worms, schistosomes, food-borne trematodes and cestodes). While the links are not always clearly evident and it is impossible to establish correlations among highly aggregated data without control variables-such as environmental factors-there appear indeed to be important linkages between EMGs, socio-economic status and prevalence of neglected diseases. Some determinants under consideration are lack of access to health care and general health status, poverty and social marginalization, as well as education and literacy. Further research is needed to deepen the understanding of these linkages and to determine their public health and socio-economic significance. In particular, there is a need for more data from all countries in the Western Pacific Region that is disaggregated below the provincial level. Selected case studies that incorporate other control variables-such as risk factors from the physical environment-might be useful to inform policy makers about the feasibility of prevention and control interventions that are targeted at high-risk EMGs.
We report a case of visceral pentastomiasis caused by Armillifer moniliformis in a 70-year-old aboriginal farmer from rural Malaysian Borneo. The patient complained of upper abdominal pain, jaundice, and loss of weight. Radiological investigations and subsequent histopathological examination revealed an adenocarcinoma of the pancreas with an adjacent liver nodule containing a nymph of A. moniliformis. This report constitutes the first documented human pentastomid infection in the whole of Malaysia after nearly 40 years, and it is the third description from Malaysian Borneo. Cases of human and animal pentastomiasis in Malaysia are discussed.
Malaria is the most important parasitic disease with global concern. Plasmodium knowlesi recently has emerged from its natural simian host as a significant cause of human malaria, particularly in Malaysian Borneo. Therefore, it has been added as the fifth human Plasmodium specie which is widely distributed in Southeast Asia. Recent developments of new molecular tools enhanced our understanding about the key features of this malaria parasite. Here, we review some of the ways in which molecular approaches might be used for epidemiology of P. knowlesi and finally lead to an efficient control of malaria.
Direct microscopy is widely used for the diagnosis of parasitic infections although it often requires an experienced microscopist for accurate diagnosis, is labour intensive and not very sensitive. In order to overcome some of these shortcomings, molecular or nucleic acid-based diagnostic methods for parasitic infections have been developed over the past 12 years. The parasites which have been studied with these techniques include the human Plasmodia, Leishmania, the trypanosomes, Toxoplasma gondii, Entamoeba histolytica, Giardia, Trichomonas vaginalis, Cryptosporidium parvum, Taenia, Echinococcus, Brugia malayi, Wuchereria bancrofti, Loa loa and Onchocerca volvulus. Early methods, which involved hybridisation of specific probes (radiolabelled and non-radiolabelled) to target deoxyribonucleic acid (DNA), have been replaced by more sensitive polymerase chain reaction (PCR)-based assays. Other methods, such as PCR-hybridisation assays, PCR-restriction fragment length polymorphism (PCR-RFLP) assays and random amplified polymorphic DNA (RAPD) analysis have also proved valuable for epidemiological studies of parasites. The general principles and development of DNA-based methods for diagnosis and epidemiological studies will be described, with particular reference to malaria. These methods will probably not replace current methods for routine diagnosis of parasitic infections in developing countries where parasitic diseases are endemic, due to high costs. However, they will be extremely useful for genotyping parasite strains and vectors, and for accurate parasite detection in both humans and vectors during epidemiological studies.
Twenty Asian sea bass Lates calcarifer from a floating cage in Bt. Tambun, Penang were examined for the presence of parasitic gill copepod, Lernanthropus latis. The prevalence of L. latis was 100% with the intensity of infection ranging from 1 to 18 parasites per host or 3.75 of mean intensity. Female parasites having oblong cephalothorax and egg-strings were seen mainly on the entire gill of examined Asian sea bass. The infected gill of Asian sea bass was pale and had eccessive mucus production. Under light and scanning electron microscopies (SEM), L. latis was seen grasping or holding tightly to the gill filament using their antenna, maxilla and maxilliped. These structures are characteristically prehensile and uncinate for the parasite to attach onto the host tissue. The damage was clearly seen under SEM as the hooked end of the antenna was embedded into the gill filament. The parasite also has the mandible which is styliform with eight teeth on the inner margin. The pathological effects such as erosion, haemorrhages, hyperplasia and necrosis along the secondary lamellae of gill filaments were seen and more severe at the attachment site. The combined actions of the antenna, maxilla and maxilliped together with the mandible resulted in extensive damage as L. latis attached and fed on the host tissues.
A gastrointestinal parasite survey of 411 stray and refuge dogs sampled from four geographical and climactically distinct locations in India revealed these animals to represent a significant source of environmental contamination for parasites that pose a zoonotic risk to the public. Hookworms were the most commonly identified parasite in dogs in Sikkim (71.3%), Mumbai (48.8%) and Delhi (39.1%). In Ladakh, which experiences harsh extremes in climate, a competitive advantage was observed for parasites such as Sarcocystis spp. (44.2%), Taenia hydatigena (30.3%) and Echinococcus granulosus (2.3%) that utilise intermediate hosts for the completion of their life cycle. PCR identified Ancylostoma ceylanicum and Ancylostoma caninum to occur sympatrically, either as single or mixed infections in Sikkim (Northeast) and Mumbai (West). In Delhi, A. caninum was the only species identified in dogs, probably owing to its ability to evade unfavourable climatic conditions by undergoing arrested development in host tissue. The expansion of the known distribution of A. ceylanicum to the west, as far as Mumbai, justifies the renewed interest in this emerging zoonosis and advocates for its surveillance in future human parasite surveys. Of interest was the absence of Trichuris vulpis in dogs, in support of previous canine surveys in India. This study advocates the continuation of birth control programmes in stray dogs that will undoubtedly have spill-over effects on reducing the levels of environmental contamination with parasite stages. In particular, owners of pet animals exposed to these environments must be extra vigilant in ensuring their animals are regularly dewormed and maintaining strict standards of household and personal hygiene.
In April 2004, an outbreak of acute diarrheal illness occurred among the Orang Asli (aborigine) in the Cameron Highlands, Pahang State, Peninsular Malaysia, where rotavirus was later implicated as the cause. In the course of the epidemic investigation, stool samples were collected and examined for infectious agents including parasites. Soil transmitted helminthes (STH), namely Ascaris lumbricoides (25.7%), Trichuris trichiura (31.1%) and hookworm (8.1%), and intestinal protozoa, which included Giardia lamblia (17.6%), Entamoeba histolytica/E. dispar (9.4%), Blastocystis hominis (8.1%) and Cryptosporidium parvum (2.7%), were detected. Forty-four (59.5%) were infected with at least one parasite, 24 (32.4%), 12 (16.2%) and 8 (10.8%) had single, double and triple parasitic infections, respectively. STH were prevalent with infections occurring as early as in infancy. Giardia lamblia, though the most commonly found parasite in samples from symptomatic subjects, was within the normally reported rate of giardiasis among the various communities in Malaysia, and was an unlikely cause of the outbreak. However, heavy pre-existing parasitic infections could have contributed to the severity of the rotavirus diarrheal outbreak.
Food-borne parasitic zoonoses have emerged as a major public health problem in many countries and are posing a medical challenge. They are not only important from the economic point of view but also because of their severe sequelae. In Malaysia, these parasitoses are a tip of an iceberg problem. The article documents all the food-borne parasitic zoonoses reported in Malaysia. An epidemiological assessment of the diseases with research needs is highlighted.
Food-borne parasitic zoonoses are emerging as major public health problems in most countries because they are widespread and pose a medical challenge. Not only are they important from an economic standpoint, but they also cause severe sequalae in all those affected. The extent of parasitic zoonoses in Malaysia is considered a "tip of the iceberg" problem. Cases of zoonotic diseases, like porocphaliasis, sarcocystosis, toxoplasmosis, cysticercosis, hydatidosis, echinostomiasis, and gnathostomiasis are traced and documented. An epidemiologic reassessment of methods is suggested to determine the extent of these parasitoses in Malaysia.
Matched MeSH terms: Parasitic Diseases/epidemiology*; Parasitic Diseases/prevention & control
In January 2016, a 20-year-old female oriental small-clawed otter (Aonyx cinereus) from Night Safari in Singapore was euthanized and diagnosed with a thyroid gland carcinoma. Postmortem examination and histology also revealed metastasis to the regional lymph nodes and severe visceral pentastomiasis. Grossly, the lymph nodes were infested, and encapsulation was observed on the visceral serosal surface. Histopathologically, the lymph nodes were encysted by a thick fibrous connective capsule with minimal inflammatory response. Pentastomiasis has been previously reported in the smooth-coated otter (Lutrogale perspicillata) in Malaysia. This report is the first case of severe visceral pentastomiasis in an oriental small-clawed otter with functional thyroid carcinoma.