Màrius V. Fuentes

Human and animal fascioliasis in Mazandaran province, northern Iran

The fascioliasis situation in humans and livestock of Iranian Mazandaran is analysed for the first time. Coprological studies showed 7.3% and 25.4% global prevalences in sheep and cattle, respectively. Studies in slaughterhouses indicate that sheep and cattle may be the main reservoir species, buffaloes may play local roles in the transmission, and goats and horses probably only participate sporadically. Morphometric studies by computer image analysis showed that forms intermediate between Fasciola hepatica and F. gigantica appear in addition to both species. A total of 107 infected humans were diagnosed during the 1999–2002 period, which suggests that fascioliasis may be widespread. The absence of differences in human fascioliasis among gender and age groups differs from other human endemic areas. Both human and animal infections show marked differences between western and eastern Mazandaran. Traditions in herbal condiments for human consumption, methods of animal husbandry and annual rainfall may explain the higher prevalences in western Mazandaran.

Validation of a mapping and prediction model for human fasciolosis transmission in Andean very high altitude endemic areas using remote sensing data

The present paper aims to validate the usefulness of the Normalized Difference Vegetation Index (NDVI) obtained by satellite remote sensing for the development of local maps of risk and for prediction of human fasciolosis in the Northern Bolivian Altiplano. The endemic area, which is located at very high altitudes (3800-4100 m) between Lake Titicaca and the valley of the city of La Paz, presents the highest prevalences and intensities of fasciolosis known in humans. NDVI images of 1.1 km resolution from the Advanced Very High Resolution Radiometer (AVHRR) sensor on board the National Oceanic and Atmospheric Administration (NOAA) series of environmental satellites appear to provide adequate information for a study area such as that of the Northern Bolivian Altiplano. The predictive value of the remotely sensed map based on NDVI data appears to be better than that from forecast indices based only on climatic data. A close correspondence was observed between real ranges of human fasciolosis prevalence at 13 localities of known prevalence rates and the predicted ranges of fasciolosis prevalence using NDVI maps. However, results based on NDVI map data predicted zones as risk areas where, in fact, field studies have demonstrated the absence of lymnaeid populations during snail surveys, corroborated by the absence of the parasite in humans and livestock. NDVI data maps represent a useful data component in long-term efforts to develop a comprehensive geographical information system control program model that accurately fits real epidemiological and transmission situations of human fasciolosis in high altitude endemic areas in Andean countries.

Malaria resurgence risk in southern Europe: climate assessment in an historically endemic area of rice fields at the Mediterranean shore of Spain.

BackgroundInternational travel and immigration have been related with an increase of imported malaria cases. This fact and climate change, prolonging the period favouring vector development, require an analysis of the malaria transmission resurgence risk in areas of southern Europe. Such a study is made for the first time in Spain. The Ebro Delta historically endemic area was selected due to its rice field landscape, the presence of only one vector, Anopheles atroparvus, with densities similar to those it presented when malaria was present, in a situation which pronouncedly differs from already assessed potential resurgence areas in other Mediterranean countries, such as France and Italy, where many different Anopheles species coexist and a different vector species dominates.MethodsThe transmission risk was assessed analysing: 1) climate diagrams including the minimum temperature for Plasmodium falciparum and Plasmodium vivax development; 2) monthly evolution of the Gradient Model Risk (GMR) index, specifying transmission risk period and number of potential Plasmodium generations; 3) ecological characteristics using remote sensing images with the Eurasia Land Cover characteristics database and the monthly evolution of the Normalized Difference Vegetation Index (NDVI); 4) evaluation of A. atroparvus population dynamics.ResultsClimatological analyses and GMR index show that a transmission risk presently exists, lasting from May until September for P. falciparum, and from May until October for P. vivax. The GMR index shows that the temperature increase does not actually mean a transmission risk increase if accompanied by a precipitation decrease reducing the number of parasite generations and transmission period. Nevertheless, this limitation is offset by the artificial flooding of the rice fields. Maximum NDVI values and A. atroparvus maximum abundance correspond to months with maximum growth of the rice fields.ConclusionsThe Ebro Delta presents the ecological characteristics that favour transmission. The temperature increase has favoured a widening of the monthly potential transmission window with respect to when malaria was endemic. The combined application of modified climate diagrams and GMR index, together with spatial characterization conforms a useful tool for assessing potential areas at risk of malaria resurgence. NDVI is a good marker when dealing with a rice field area.

The helminth community of the wood mouse, Apodemus sylvaticus, in the Sierra Espuna, Murcia, Spain

The helminth community of the wood mouse, Apodemus sylvaticus, in the Sierra Espuna was characterized after a complete analysis of its helminth community component and infracommunity structure relative to host age, sex and year of capture. The helminth community comprised 13 species: one trematode, four cestodes and eight nematodes. The cestode Pseudocatenotaenia matovi and the nematode Syphacia frederici were the most prevalent and abundant helminth species, respectively. Sixty four percent of mice analysed presented helminths with a direct cycle and 42% presented helminths with an indirect cycle. The helminth community presents a low diversity with infracommunities usually made up of only one or two helminth species. Host age and year of capture seem to play a major role in determining species richness and helminth diversity, but not in determining the abundance of helminths. Host sex does not seem to affect the infection rate nor the diversity. Further studies on more samples of wood mice and other small mammal species in this regional park are needed to explore any possible interactions between helminth communities in the host populations.

Human Cysticercosis and Larval Tropism of Taenia asiatica

Taenia solium, T. saginata and the recently discovered T. asiatica1xTaiwan Taenia and taeniasis. Fan, P.C. Parasitol. Today. 1988; 4: 86–88Abstract | Full Text PDF | PubMed | Scopus (61)See all References, 2xMorphologic descriptions of Taenia asiatica sp. n.. Eom, K.S. and Rim, H.J. Korean J. Parasitol. 1993; 31: 1–6Crossref | PubMedSee all References, 3xMorphological description of Taenia saginata asiatica (Cyclophyllidea: Taeniidae) from man in Asia. Fan, P.C. et al. J. Helminthol. 1995; 69: 299–303Crossref | PubMed | Scopus (44)See all References, are species of taeniid cestodes whose adult stages are known to infect humans. Less clear is whether the eggs of T. asiatica also infect humans (as those of T. solium do, causing cysticercosis and the fatal neurocysticercosis) or whether the species is similar to T. saginata whose eggs do not cause infections in humans.Although evidence does exist in support of infective egg stages4xCysticercosis in Asian-Pacific regions. Ito, A. Parasitol. Today. 1992; 8: 182–183Abstract | Full Text PDF | PubMed | Scopus (17)See all References, 5xTaeniasis/cysticercosis in Indonesia as an emerging disease. Simanjuntak, G.M. et al. Parasitol. Today. 1997; : 321–323Abstract | Full Text PDFSee all References, it is also disputed for two main reasons6xGenetic characterization of the Asian Taenia, a newly described taeniid cestode of humans. Bowles, J. and McManus, D.P. Am. J. Trop. Med. Hyg. 1994; 50: 33–44PubMedSee all References, 7xAsian (Taiwan) Taenia: species or strain?. McManus, D.P. and Bowles, J. Parasitol. Today. 1994; 10: 273–275Abstract | Full Text PDF | PubMed | Scopus (20)See all References, 8xFailure of experimental infection of baboons (Papio hamadryas) with the eggs of Asian Taenia. Fall, E.H. et al. J. Helminthol. 1995; 69: 367–368Crossref | PubMed | Scopus (2)See all References. First, T. asiatica is more closely related to T. saginata at the molecular level than to any other taeniid; if T. saginata does not cause human cysticercosis, then the same could be said of T. asiatica. Second, observations of human populations where T. asiatica adults are highly prevalent show no evidence of human cysticercosis or neurocysticercosis (eg. Taiwan, and Samosir Island, Indonesia). We would like to discuss further reasons why such observations might be incorrect.First, although molecular affinities between T. asiatica and T. saginata are very close, the egg infectivity of the two species is quite different; the natural hosts of T. saginata are cattle, while those of T. asiatica are pigs (the same intermediate host for human cysticercosis-producing T. solium). Second, the absence of cysticercosis or neurocysticercosis in these human populations may merely suggest a low prevalence of T. solium. We, however, believe that it is an erroneous indicator of whether the eggs of T. asiatica can infect humans.So, are there similarities between T. solium and T. asiatica that could be used to indicate whether eggs of T. asiatica infect humans? Again, subtle differences between the two species suggest that this is not the case. First, tropism and size of the larval forms differ between the two species. The larva of T. solium (Cysticercus cellulosae) in pigs exhibits no defined tropism9xExperimental infection of an isolate of Taenia solium from Hainan in domestic animals. Fan, P.C. et al. J. Helminthol. 1994; 68: 265–266Crossref | PubMed | Scopus (11)See all References9 and larval size ranges from 5 to 15 mm (Ref. 10xMorphological types of Taenia solium cysticerci. Rabiela, M.T. et al. Parasitol. Today. 1989; 5: 357–359Abstract | Full Text PDF | PubMed | Scopus (21)See all References10). In contrast, the larva of T. asiatica (C. viscerotropica) in the pig (and other experimental intermediate hosts such as calves, goats and monkeys)1xTaiwan Taenia and taeniasis. Fan, P.C. Parasitol. Today. 1988; 4: 86–88Abstract | Full Text PDF | PubMed | Scopus (61)See all References, 11xStudies on taeniasis in Taiwan. VI. Is Taenia saginata from Taiwan, Korea and Indonesia a new species?. Fan, P.C. et al. Chinese J. Parasitol. 1988; 1: 56–70See all References, exhibits marked liver tropism, while reaching a larval size of approximately 2 mm1xTaiwan Taenia and taeniasis. Fan, P.C. Parasitol. Today. 1988; 4: 86–88Abstract | Full Text PDF | PubMed | Scopus (61)See all References, 2xMorphologic descriptions of Taenia asiatica sp. n.. Eom, K.S. and Rim, H.J. Korean J. Parasitol. 1993; 31: 1–6Crossref | PubMedSee all References. This suggests that if C. viscerotropica follows the same developmental course in humans as in other intermediate hosts, then it would preferentially parasitize the liver, causing hepatic cysticercosis, with smaller larvae being present than if C. cellulosae were the infective agent. Such cases of hepatic cysticercosis could be symptomatic or not, depending on larval number and location within the liver (although hepatic/gastrointestinal manifestations may occur). It could be assumed that such clinical symptoms would be more related to the initial stages of cystic hydatidosis than to the classical cysticercosis or neurocysticercosis caused by T. solium. Therefore, where T. asiatica is prevalent in human populations, the absence of classical evidence of cysticercosis should not be taken as indication of the lack of human cysticercosis caused by this parasite.The clinical risk of this possible larval parasitization by T. asiatica could be similar to that of classical cysticercosis, but only if the larvae also reach other locations within humans (as in the case of T. solium and the larvae of Echinococcus granulosus or E. multilocularis) or develop aberrant forms as in the case of T. solium (the racemose cysticercus). At the experimental level, larvae of T. asiatica have been successfully developed in nonhepatic regions12xExperimental infections of pigs and cattle with eggs of Asian Taenia saginata with special reference to its extrahepatic viscerotropism. Eom, K.S. et al. Korean J. Parasitol. 1992; 30: 269–275CrossrefSee all References12 and can develop larger body sizes in hosts other than pigs13xHuman Taenia eggs develop into cysticerci in SCID mice. Ito, A. et al. Parasitology. 1997; 114: 85–88Crossref | PubMed | Scopus (24)See all References13.Evidence for the infection of humans by eggs of T. asiatica therefore remains contradictory. However, we are of the opinion that C. viscerotropica should be included in the evaluation of liver lesions compatible with the larval development of cestodes, particularly in those Asian countries where the parasite is already known to occur.

Ecological study of the wood mouse helminth community in a burned Mediterranean ecosystem in regeneration five years after a wildfire

Parasites are used as biological tags in environmental impact studies. However, terrestrial systems in general and small mammals in particular are rarely considered in these ecological studies. Based on the effects of a wildfire which occurred in the Spanish Serra Calderona Natural Park — a typical Mediterranean ecosystem — the regeneration process of the wood mouse population and its helminth community is analysed. A total of 217 individuals of Apodemus sylvaticus were studied in a five year period, from the second to the fifth post-fire year: 152 mice originating from the burned area and 65 from the control — non-burned — area. The helminth community for both burned and non-burned areas as well as the effect of intrinsic (host age and sex) and extrinsic (site, period and season of capture) factors on helminth prevalences and abundances were analysed. Taking into account the most important results of this study, various aspects of the helminth community dynamics of the wood mouse are postulated as biological tags of the environmental impact of a wildfire, such as the changes in the frequency distribution of the helminth species, the higher diversity in the burned area, and the prevalences of helminth species having biological cycles directly affected by climatic conditions and the vegetal regeneration process. Consequently, the helminth species of A. sylvaticus should be considered suitable biological tags of environmental perturbations, such as a wildfire, and the wood mouse/helminth model can be applied to predict the consequences for helminth species in general.

Proposal of a Geographic Information System for modeling zoonotic fasciolosis transmission in the Andes

ABSTRACT The present study describes the basis for the development of a Geographic Information System(GIS) for conducting an epidemiological analysis of human and animal fasciolosis in the Andes. Themethodology proposes the use of various data bases - those derived from epidemiologicalmutidisciplinary studies and environmental data derived from terrestrial stations and remote sensing. Key words : Fasciola hepatica, fasciolosis transmission, Andes, geographic information system,model. INTRODUCTIONOver the last decade, the importance of humanand animal fasciolosis in various south Americancountries has been emphasized in the scientificliterature 1-5 ; indeed, human infection by Fasciolahepatica has recently been declared an importantworldwide health problem 6,7 . Of the countrieslocated on the slopes of the Andes, Peru, Boliviaand Chile are the most severely affected by thisliver fasciolosis 2 - though areas of Ecuador,Colombia and Venezuela are also affected. TheNorthern Altiplano, between Bolivia and Peru, isconsidered to be a hyperendemic zone for bothhumans and animals while the central regions ofChile are hyperendemic in terms of domesticcattle

Risk Analysis of Human Anisakidosis Through the Consumption of the Blue Whiting, Micromesistius poutassou, Sold at Spanish Supermarkets

European legislation directed at the catering industry concerning the prevention of anisakidosis proposes efficient measures to avoid human infestation, but this legislation does not directly address the consumer at the household level. Assessing the anisakidosis risk for consumers who buy fresh fish at supermarkets in Spain, 284 blue whiting, Micromesistius poutassou, specimens, originating from two fishing zones and seasons of capture, sold at five nationwide Spanish supermarket chains, were examined to identify the presence of anisakid species and analyze their prevalence and abundance in viscera and flesh. The potential influence of intrinsic (length and weight) and extrinsic (origin, season, and days after catch) factors was statistically analyzed. The only two species detected were Anisakis simplex complex and Hysterothylacium sp. Total anisakid prevalence was 55.6%, with A. simplex being more prevalent (53.9%) and abundant (3.9 helminths/fish), and also carrying the biggest risk for consumers. Origin (Atlantic and Mediterranean) and season (spring and autumn) were the most influential factors among those considered. Results suggest that specimens originating from the Atlantic, of greater weight and length, and caught in spring pose the highest transmission risk of anisakidosis. Moreover, the days passed between the catch and consumption should be considered as a risk factor. Thus, in addition to the recommendation of freezing fish at -20°C for at least 24 h (in case the fish is consumed raw or poorly cooked), new and easy-to-follow recommendations are being proposed to avoid anisakidosis at home, which emphasize the importance of the information provided on fish crate labels.

Interactions between anomalous excretory and tegumental epithelia in aberrant Mesocestoides tetrathyridia from Apodemus sylvaticus in Spain

Tetrathyridia of Mesocestoides sp. (Platyhelminthes: Cestoda) were collected from the body cavities of Apodemus sylvaticus (Rodentia: Muridae) in Murcia, Spain, and processed by routine microscopical and histological techniques, including examination with brightfield, phase-contrast, and differential-interference-contrast optics. All specimens examined had solid hindbodies (i.e., lacked a primary lacuna), thus conforming to the plerocercoid metacestode type. The vast majority of tetrathyridia were highly aberrant, often lacking a scolex, varying greatly in body size, and exhibiting buds or duplexed body forms indicative of asexual proliferation. All of the aberrant forms, including those with normal scoleces and apparent absence of proliferation, possessed anomalous multi-lobed invaginations of the hindbody tegument, which were attached at many points to abnormally dilated excretory ducts. The tegumental and excretory epithelia were joined basally, but did not share a common lumen. These abnormal connections between these aberrant tegumental modifications and the abnormally dilated excretory ducts have not been described previously for any metacestode. This report contributes to understanding previously published reports of abnormalities in other plerocercoid metacestodes, including Mesocestoides spp. and diphyllobothriidean spargana.

Taenia asiatica: left out by globalisation?

A recent review article discusses how globalisation, related to the movement of people, animals, and food, affects the epidemiology of foodborne parasites [1].