Dracunculiasis: water-borne anthroponosis vs. food-borne zoonosis.

Dracunculiasis is the first parasitic disease set for eradication. However, recent events related to the Dracunculus medinensis epidemiology in certain African countries are apparently posing new challenges to its eradication. Two novel facts have emerged: the existence of animal reservoirs (mainly dogs but also cats and baboons), and possibly a new food-borne route of transmission by the ingestion of paratenic (frogs) or transport (fish) hosts. Therefore, instead of being exclusively a water-borne anthroponosis, dracunculiasis would also be a food-borne zoonosis. The existence of a large number of infected dogs, mainly in Chad, and the low number of infected humans, have given rise to this potential food-borne transmission. This novel route would concern not only reservoirs, but also humans. However, only animals seem to be affected. Dracunculus medinensis is on the verge of eradication due to the control measures which, classically, have been exclusively aimed at the water-borne route. Therefore, food-borne transmission is probably of secondary importance, at least in humans. In Chad, reservoirs would become infected through the water-borne route, mainly in the dry season when rivers recede, and smaller accessible ponds, with a lower water level containing the infected copepods, appear, whilst humans drink filtered water and, thus, avoid infection. The total absence of control measures aimed at dogs (or at other potential reservoirs) up until the last years, added to the stimulating reward in cash given to those who find parasitized dogs, have presumably given rise to the current dracunculiasis scenario in Chad.

The helminth community of the wood mouse Apodemus sylvaticus from the Erro River valley, Navarre, Spain.

The helminth fauna of the wood mouse, Apodemus sylvaticus, in the Erro River valley (Navarre, Spain) was investigated from a total of 150 mice between February 2001 and July 2002. An overall prevalence of 90.7% was recorded and up to 14 helminth species identified. The most prevalent species was the nematode Heligmosomoides polygyrus (78.0%), whereas Syphacia stroma was the species with the highest median abundance (19.8). The detection of Calodium hepaticum, Rodentolepis straminea and the larvae of Hydatigera taeniaeformis are significant, since these helminth species could be considered potential human parasites. The helminth infracommunity comprised no more than five species. A significant predominance of monoxenous species was detected. Statistically significant differences were also found between prevalences, helminth abundance, species richness and helminth diversity of sub-populations of the wood mouse determined by host age and season of capture, which agree with most of the studies carried out on this host. This study will shed light on the helminth community of the wood mouse from a region of Spain which has not previously been documented.

The helminth community of the wood mouse Apodemus sylvaticus in a Mediterranean ecosystem in regeneration ten years after a wildfire.

This study was carried out 10 years after a wildfire in the Spanish Serra Calderona Natural Park, following a previous analysis comprising the first 5 years after the fire. Its primary aim was to elucidate the impact of this perturbation on the population biology of the wood mouse Apodemus sylvaticus, and the repercussions on its helminth community in this regenerating Mediterranean ecosystem. Second, confirmation of the ability of the parasites to tolerate environmental stressors and the effects on their transmission strategies was sought. Five hundred and sixty-four individuals of A. sylvaticus were studied in a 9-year period, from the second to the tenth post-fire year: 408 mice from the burned area and 156 from the control--non-burned--area. The helminth community for both areas and the effect of intrinsic (host age and sex) and extrinsic (site, period and year of capture) factors on helminth prevalence, abundance and diversity, and species richness were analysed. Our findings show that, after an environmental disaster, the behaviour of helminth species might be related to their pre-catastrophe presence, their biological cycles, the host's immunological condition, the change of host dynamics, the direct effects of the perturbation, and the processes related to the re-establishment of the ecological balance of a devastated ecosystem.

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.

Morphology of Bertiella studeri (Blanchard, 1891) sensu Stunkard (1940) (Cestoda: Anoplocephalidae) of human origin and a proposal of criteria for the specific diagnosis of bertiellosis.

Human material of an African specimen of Bertiella studeri (Blanchard, 1891), a typical intestinal cestode of monkeys, is described. Mature, postmature and gravid proglottides, and eggs, previously inadequately figured, are illustrated and photographed. The description of the species agrees with that provided by Stunkard (1940). A comparative study with other descriptions of the species is made in an attempt to clarify previous findings. The morphological differences reported in various earlier descriptions of the species suggest that B. studeri should be regarded as a "B. studeri species complex" Improvements are required in the descriptions of new future findings in order to clarify the specific diagnosis of human bertiellosis. Evidence suggests that a generalised diagnosis exclusively based on egg size and geographical distribution is insufficient to differentiate B. studeiri and Bertiella mucronata (Meyner, 1895), or additional species may be affecting humans.

The Asian Taenia and the possibility of cysticercosis.

In certain Asian countries, a third form of human Taenia, also known as the Asian Taenia, has been discovered. This Asian Taenia seems to be an intermediate between Taenia solium and T. saginata since in morphological terms it is similar to T. saginata, yet biologically, as it uses the same intermediate host (pigs), it is more akin to T. solium. Taenia solium causes human cysticercosis, while T. saginata does not. It is not known whether the Asian taeniid is able to develop to the larval stage in humans or not. The arguments proposed by those authors who consider it unlikely that the Asian Taenia causes human cysticercosis are: (a) its molecular similarities with T. saginata; (b) the absence of cases of human cysticercosis in populations where the Asian adult is highly prevalent; and (c) the unsupporting results derived from an experimental infestation study. These three arguments are debated, although bearing in mind that at present there is still no clear scientific data to support that human cysticercosis can be caused by the Asian Taenia.

Human Bertiella studeri in Spain, probably of African origin.

A mature tapeworm and gravid proglottids of Bertiella studeri were reported from the stools of a 33-year-old pregnant Spanish woman. The patient had spent the six months preceding this discovery in Kenya. The evidence suggests a case of parasitism imported to Spain from the African continent. The patient presented no symptoms related to the parasite and the discovery in stools of a number of active, white structures led her to collect them. A morphologic and morphometric description of the material obtained is presented. Mebendazole failed to remove the parasite but niclosamide was effective.