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PubMed1990

Molecular characterization of the surface and cyst fluid components of Taenia crassiceps.

Information relating to the characterization of cestode surface macromolecules is limited. This is especially the case with Taenia crassiceps, a well-recognized model for the study of larval cestodiasis. Here, the protein and glycoprotein composition of the tegumental surface and cyst fluid of the metacestode have been investigated using radio-isotope labelling, immunoprecipitation, SDS-PAGE and lectin affinity chromatography. A restricted number of surface proteins was labelled with the 125I/Iodogen method although the majority were immunogenic; in contrast an array of cyst fluid antigens were labelled. Host serum proteins, including immunoglobulins, were identified on the surface and in the cyst fluid. Some of the 125I-labelled surface proteins, including a 37 kDa molecule, have been shown to be glycoproteins and probably contain-D-mannose and/or D-glucose; there is limited or no N-acetylglucosamine and no terminal galactose present on these components. A 37 kDa surface molecule, possibly the same glycoprotein, was also precipitated by infection sera and this may endorse the theory that highly immunogenic carbohydrates are continuously shed by T. crassiceps as a mechanism for diverting the immune response of the host. Radio-iodinated and biosynthetically labelled T. crassiceps antigens were highly cross-reactive with antibody raised to other cestodes and not one antigen was identified as a possible candidate for use in specific immunodiagnosis of any of the important taeniid infections.

Animals↗
PubMed1988

Excretory-secretory products of helminth parasites: effects on host immune responses.

Parasitic helminths excrete or secrete (ES) a variety of molecules into their mammalian hosts. The effects of these ES products on the host's immune responses are reviewed. Investigations into the source of antigenic or immunoregulatory ES products have identified the cuticular and tegumental surfaces of some nematodes and trematodes respectively as being important sources of ES products; other ES molecules are released through specialized excretory or secretory organs. It is proposed that the active shedding of surface antigens may serve as an important source of parasite antigens available to the immune system in a form in which they can be taken up and processed by antigen-presenting dendritic cells, macrophages and certain B cells for presentation to T helper cells. The ES products of nematodes, trematodes and cestodes contribute to immune evasion strategies of the parasites through mechanisms including shedding of surface-bound ligands and cells, alteration of lymphocyte, macrophage and granulocyte functions and modulation of complement and other host inflammatory responses. Immunopathology may be induced by ES products as in the development of granulomas around entrapped schistosome eggs. In some host-parasite systems ES antigens may induce host-protective immune responses and this source of protective antigens has been utilized in the successful vaccination against helminth infections, particularly against infection with trichurid nematodes and the metacestode stage of cestode parasites. The use of ES antigens in immunodiagnosis of helminth infection is also briefly discussed.

Animals↗
PubMed2003

Lead concentrations in Hymenolepis diminuta adults and Taenia taeniaeformis larvae compared to their rat hosts (Rattus norvegicus) sampled from the city of Cairo, Egypt.

Concentrations of lead, determined by electrothermal atomic absorption spectrometry, were compared between the cestodes Hymenolepis diminuta and Taenia taeniaeformis and its host rat (Rattus norvegicus). Rats were sampled at 2 sites, which differed in respect to lead pollution as quantified from road dust, adjacent to the city of Cairo, Egypt. Comparing lead levels among host tissues and the parasites the significantly highest accumulation was found in H. diminuta, followed by rat kidney and larvae of T. taeniaeformis. Calculation of bioconcentration factors showed that H. diminuta contained 36-, 29-, 6- and 6-fold higher lead levels than intestinal wall, liver, kidney and larvae of T. taeniaeformis, at the more polluted site. At the less contaminated site lead bioconcentration factors for H. diminuta were found to be 87, 87 and 11 referred to intestine, liver and kidney of the host. Due to a high variability of the lead concentrations in H. diminuta it was not possible to indicate differences in metal pollution between both sampling sites. This variability may be influenced by different age structures of cestode infrapopulations. It is likely that younger worms contain lower metal levels than older worms due to a shorter exposure period. Thus, it is necessary to standardize the sampling of worms which should be used for indication purposes. Due to a lack of adequate sentinel species in terrestrial habitats more studies are required to validate and standardize the use of helminths as accumulation bioindicators in order to obtain mean values with low standard deviations. The host-parasite system rat-H. diminuta appears to be a useful and promising bioindication system at least for lead in urban ecosystems as rats as well as the tapeworm are globally distributed and easily accessible.

Animals↗
PubMed2004

Variation in the helminth community structure in spiny mice (Acomys dimidiatus) from four montane wadis in the St Katherine region of the Sinai Peninsula in Egypt.

We compared helminth communities in spiny mice (Acomys dimidiatus) from 4 wadis in the arid montane region of the southern Sinai in Egypt, in a 4-week period in late summer. Total helminth species richness was 14 (8 nematodes, 5 cestodes and 1 acanthocephalan) with 94% of mice carrying at least 1 species and an overall mean species richness of 1.85. The most prevalent parasites were Protospirura muricola (47.8 %) and Dentostomella kuntzi (46.3%). One larval cestode, Joyeuxiella rossicum, represents a new host record. The helminth community was dominated by intestinal nematodes (88.7%) of which 58.2% were arthropod-transmitted heteroxenic species. At the component community level, 70% of the worms were recovered from mice in just two wadis (Gharaba and Tlah) and 48.6 % of intestinal nematodes were from Wadi Gharaba. Although only 7 species of helminths were recorded from Wadi Gharaba, this site gave the highest Berger-Parker dominance index because of P. muricola. P. muricola was also dominant in Wadi El Arbaein whilst Syphacia minuta was the dominant species in Wadis Gebal and Tlah. At the infracommunity level, mean species richness and Brillouin's index of diversity were highest in Wadi Tlah and lowest in Wadi Gebal, and the former was age dependent. Whilst mice from different wadis differed in the nematodes that were most common, those from Wadi Gharaba carried the highest mean number of worms/mouse. The abundance of P. muricola in particular varied markedly between sites: Wadi Gharaba was distinct as the site showing the highest mean worm burden whereas mice from Wadi Gebal were uninfected. None of the directly transmitted oxyuroid nematodes showed significant variation in abundance between wadis, or host sex or age classes. Overall, the single extrinsic factor in the study, site of capture, was more important than the intrinsic factors in explaining variation in helminth communities in the region. We conclude that in the high mountains of southern Sinai, each wadi is distinct in terms of its rodent parasites, and hence we expect spatially different coevolutionary pressures on their hosts, with resultant variation in life-histories.

Age Factors↗
PubMed2005

Complete sequence and structure of the mitochondrial genome of the human tapeworm, Taenia asiatica (Platyhelminthes; Cestoda).

The complete Taenia asiatica mitochondrial genome was amplified by long extension polymerase chain reaction (long PCR) to yield overlapping fragments that were then completely sequenced. The whole mitochondrial genome was 13 703 bp long and contained 12 protein-encoding, 2 ribosomal RNA (small and large subunits), 22 transfer RNA genes and a short non-coding region. Thus, its gene contents are like those typically found in metazoan animal mitochondrial genomes (apart from the absence of atp8). All the genes were transcribed from the same strand. The 3' end 34 bp region of nad4L overlapped with the 5' end portion of nad4. The tRNA genes were 61-69 bp long, and the secondary structures of 18 tRNAs had typical clover-leaf shapes with paired DHU arms. However, trnC, trnS1, trnS2 and trnR had unpaired DHU arms that were 7-12 bp in length. The tRNAs that transferred serine lacked a DHU arm, as is also observed in a number of parasitic platyhelminths and metazoans. However, the trematode trnRs have paired DHU arms. The T. asiatica mtDNA non-coding region was like that in other cestodes since it was composed of a short non-coding region of 72 nucleotides and a long non-coding region of 176 nucleotides separated by a trnL1/, trnS2/, trnL2/, trnR/, nad5 gene cluster. The sequences of the cox1 genes between T. asiatica and T. saginata differ by 4.6%, while the T. asiatica cob gene differs by 4.1% and 12.9% from the cob genes of T. saginata and T. solium, respectively. In conclusion, the T. asiatica mitocondrial genome should provide a resource for comparative mitochondrial genomics and systematic studies of parasitic cestodes.

Animals↗
PubMed2005

Temporal host-parasite relationships of the wild rabbit, Oryctolagus cuniculus (L.) as revealed by stable isotope analyses.

Natural abundances of the stable isotopes, 15N/14N (delta15N) and 13C/12C (delta13C), were used to study temporal host-parasite relationships of the wild rabbit, Oryctolagus cuniculus (L.). During the 12-month sampling period, temporal isotopic shifts in delta15N were noted for dietary vegetation, host rabbit faeces and fur, but not for muscle or stomach contents. delta15N varied temporally for the parasitic cestode species, Mosgovoyia pectinata but not for Cittotaenia denticulata. Similarly, intestinal parasitic nematodes had apparent species-specific delta15N patterns. Only rabbit fur and intestinal parasitic nematodes did not exhibit temporal shifts in delta13C. Overall, host faeces and stomach contents were isotopically indistinct as a likely consequence of coprophagy. Relative to their host, parasitic nematodes were 15N-enriched, consistent with an increase in trophic level status. Conversely, cestodes were 15N-depleted. Isotopically, each parasite reflected a species-specific relationship with their rabbit host. This technique could be utilized to integrate parasites into food-web studies.

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PubMed2004

A taxonomic study of species of Bothriocephalus Rudolphi, 1808 (Cestoda: Pseudophyllidea) from eels in Japan: morphological and molecular evidence for the occurrence of B. claviceps (Goeze, 1782) and confirmation of the validity of B. Japonicus Yamaguti, 1934.

A taxonomic study of specimens of Bothriocephalus from eels ( Anguilla spp.) in Japan has demonstrated the occurrence of two species, B. claviceps (Goeze, 1782) and B. japonicus Yamaguti, 1934. The former species is a parasite of eels ( A. anguilla and A. rostrata ) in the Holarctic Region and was recently reported from A. marmorata in Japan. The conspecificity of tapeworms newly found in an eel ( A. ? japonica ) from Lake Biwa, central Japan, with B. claviceps has been confirmed by the great similarity of their ITS-2 gene sequences (similarity 95.3% and 95.2%). However, the sequences of worms identified as B. claviceps from A. marmorata differed considerably from those of B. claviceps from two populations of A. anguilla from Europe and the above-mentioned one from Japan (similarity 66.3%, 67.1% and 65.1 %, respectively), thus indicating that the former cestodes may have been misidentified. This assumption was confirmed by morphological evaluation of a voucher specimen from A. marmorata. The morphology of this cestode, as well as those from A. japonica from two localities in Japan (Lakes Biwa and Suwa), indicates their conspecificity with B. japonicus. The validity of this taxon has been confirmed on the basis of a re-examination of the type-specimens. The two taxa, B. japonicus and B. claviceps, differ from each other in the shape and length of the scolex (619-730 microm in B. japonicus versus 1,180-2,100 microm in B. claviceps ), the relative position of the cirro-vaginal and uterine pores (opposite each other in relation to the median line of the body in B. japonicus versus tandem or slightly offset along the median line in the latter species), and the size of the eggs (41-52 x 28-35 microm in B. japonicus versus 50-70 x 31-43 microm in B. claviceps ).

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PubMed2001

Characterization of two monoclonal antibodies raised in Btk(xid) mice that recognize phosphorylcholine-bearing antigens from Trichinella and other helminths.

This study investigated the binding properties of two monoclonal antibodies (mAbs US1 and US2) raised in (CBA/n x BALB/c)F1 (NBF1) Btk(xid) male mice. Both mAbs show unusual specificity for phosphorylcholine (PC)-containing TSL4 antigens of Trichinella. Specifically, and in contrast to mAbs raised in normal mice, US1 and US2 mAbs do not bind to artificial PC-protein conjugates and are not inhibited by either free PC or NPPC, although US2 was partially inhibited by NPPC at high concentration (10(-2) M). However, both mAbs completely abrogate the binding to Trichinella antigens of other anti-PC mAbs (e.g. BH8 and Mab-2). These results suggest that both US1 and US2 recognize complex PC-containing epitopes. The patterns of recognition of PC-bearing antigens from different helminths by US1, US2, Mab-2 and BH8 were broadly correlated with phylogenetic proximity. The closest similarities were observed between the members of the Trichinelloidea superfamily (Trichinella spiralis and Trichuris muris) and among the ascarids (Toxocara canis, Anisakis simplex, Hysterothylacium aduncum and Ascaris lumbricoides). However, US1 did not react with the filarial nematode Onchocerca volvulus and reacted only weakly with Onchocerca gibsoni, while US2 reacted only weakly with both species. Only BH8 recognized PC-bearing antigens from the trematode Fasciola hepatica and the cestode Bothriocephalus scorpii. These results suggest that PC is attached to identical or very similar structures on most different nematode species, although major differences exist with respect to helminth species from groups such as the trematodes and cestodes that are phylogenetically distant from the nematodes.

Animals↗
PubMedDate not supplied

The genera Paranoplocephala Lühe 1910 and Anoplocephaloides Baer, 1923 (Cestoda: Anoplocephalidae), with particular reference to species in rodents.

The present study redefines the systematic arrangement and taxonomic status of some anoplocephaline cestodes previously allocated among the genera Andrya Railliet, 1893. Paranoplacephala Lühe, 1910, and Aprostatandrya Kirshenblat, 1938. Comparisons indicated that Paranoplocephala omphalodes (Hermann, 1783), type species of Paranoplocephala, differs morphologically from its congeners, all of which conform to the diagnosis of the genus Anoplocephaloides Baer, 1923, hitherto considered a synonym of Paranoplocephala, and that it cannot be distinguished at the generic level from Aprostatandrya macrocephala (Douthitt, 1915), type of the genus Aprostatandrya. The distinction between Andrya and Aprostatandrya based on the presence or absence of a "prostate gland" does not exist, for neither the type species of Andrya, A; rhopalocephala (Riehm, 1881), nor A. cuniculi (Blanchard, 1891) possesses such an organ; rather, the structure of the external seminal vesicle in these cestodes does not differ fundamentally from that in P. omphalodes or in species of Aprostatandrya. Based on these findings, Aprostatandrya Kirshenbalt, 1938 is placed in synonymy with Paranoplocephala Lühe, 1910, and Anoplocephaloides Baer, 1923 is restored to contain all species other than P. omphalodes formerly allocated to the genus. Paranoplocephala. If the pattern of development of the uterus in A. rhopalocephala is found to be like that in P. omphalodes, Paranoplocephala Lühe, 1910 will in turn also become a synonym of Andrya Railliet, 1893. Three additional species of Anoplocephaloides are described, and the zoogeography of Anoplocephaloides spp. and their mammalian hosts is briefly discussed.

Animals↗
PubMedDate not supplied

The genus Clelandia Johnston, 1909 and its affinities with Parvitaenia and Neogryporhynchus (Cestoda, Dilepididae).

The diagnosis of Clelandia has been amended. The validity of the genus and its closeness to Parvitaenia and Neogryporhynchus are discussed. On the basis of its morphology and of the specificity of the dilepidid cestodes within the order Ciconiiformes, one many admit that its host belongs to the suborder Ardeae, and that the original doubtful diagnosis of the host was wrong. Clelandia seems to confirm that the genus Parvitaenia is a nucleus of evolutionary radiation among cestodes of the Ciconiiformes, with peculiar traits in the Australian region, and that it isn't a homogeneous unit.

Animals↗
PubMed1988

Postoncospheral development and cycle of Taenia polyacantha Leuckart, 1856 (Cestoda: Taeniidae). First part.

The postoncospheral development and cycle of Taenia polyacantha Leuckart, 1856, an holarctic species of cestode, were investigated in the laboratory as well as in the tundra of northern Alaska. Foxes, Alopex lapogus (L.) and Vulpes vulpes (L.), serve as final host of T. polyacantha; the northern vole, Microtus oeconomus (Pallas), and the brown lemming, Lemmus sibiricus (Kerr), are important as the intermediate host. As determined in experimentally infected voles and lemmings, the oncosphere of T. polyacantha transformed to a primary vesicle in the liver. On the 6th day postexposure, coinciding with its migration to the peritoneal cavity, the larval cestode consisted of a minute aggregation of secondary vesicles. By 9-10 days postexposure, the secondary vesicles dissociated, thereafter developing independently to infective cysticerci by 30-40 days postexposure. At an age of about 60 days, the infective larvae began to undergo further growth and morphological modification, which led to acquisition of some strobilar characteristics by the forebody. Such late transformation of a cysticercus to a more advanced form of larva is known otherwise only in Taenia martis (Zeder, 1803). Differences in numbers and sizes of rostellar hooks provided the basis for recognition of two taxa at the infraspecific level: Taenia p. polyacantha Leuckart, 1856, distributed in Eurasia to the south of the zone of tundra, and T. p. arctica ssp. nov., present throughout the holarctic tundra. Observations concerning interactions of T. polyacantha and its hosts are discussed.

Animals↗
PubMed1990

Reproductive anatomy and gametogenesis in Shipleya inermis (Cestoda: Dioecocestidae).

Study of the reproductive anatomy in 65 strobilae of the dioecious cestode Shipleya inermis Fuhrmann, 1908 (Acoleata: Dioecocestidae) showed that a common genital duct, probably arising through fusion of the vas deferens and the proximal portion of the vaginal duct, compensated functionally for the loss of a patent vagina. Gonochorism was characteristic, but rudimentary genital organs of the opposite sex were present in 26% of males and 9% of females; two strobilae (3%) were hermaphroditic. Hermaphrodites had normally developed male organs and were capable of cross-fertilization as males; their female organs were much reduced in size but were functional, and eggs or fertilized ova in the uteri indicated that self-fertilization occurred. Gametogenesis was traced, mainly in chromosomal preparations. The diploid chromosomal complement in embryos and germ-line cells consisted of four pairs of homologues (2n = 8, n = 4, FN = 14). Based on observation in female cestodes of one pair of chromosomes having non-homologous or non-pairing segments due to influence of heterochromatin, the authors suggest that females produce gametes of two types relative to heterochromatic DNA, while males are homogametic, and that sex-determining effects are associated therein. In males, meiosis included chromosomal pairing and recombination, after which heterochromatin was eliminated from germline cells through fragmentation. Other biological characteristics of S. inermis in the hosts, Limodromus spp. (Charadriiformes), are briefly discussed.

Animals↗
PubMed2004

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.

Animals↗
PubMed2005

Gastrointestinal helminths of the lizard Chalcides ocellatus from Benghazi, Libya.

Chalcides ocellatus, a scincid lizard, sampled during October 1998 to December 1999 from Benina (farmland) and Al-Kueffia (a rocky area) in Benghazi, Libya, was found to harbour three intestinal nematodes, Pharyngodon mamillatus, Thelandros alatus and Parapharyngodon micipsae, and an intestinal cestode, Oochoristica tuberculata. Thelandros alatus, P. micipsae and O. tuberculata were recorded for the first time in C. ocellatus. Parapharyngodon micipsae was detected in C. ocellatus from Benina and O. tuberculata from lizards in Al-Kueffia. The majority (87.6%) of C. ocellatus were infected with helminth parasites and the levels of infection were higher in males than in females but this difference was not significant. Pharyngodon mamillatus recorded the highest number of nematode parasites in C. ocellatus, although there was no relationship between the number of nematode parasites recovered and host density. In lizards infected with the cestode O. tuberculata, males had shorter snout-vent lengths than females. From a total of 153 C. ocellatus, 120 (78.4%) showed single and 14 (9.2%) showed mixed parasitic infections. Mixed infections between different species of nematodes were not observed.

Animals↗
PubMed2005

Parasite populations in the brown rat Rattus norvegicus from Doha, Qatar between years: the effect of host age, sex and density.

A total of 179 urban rats were sampled in the city of Doha in Qatar across the winter seasons (February-April) of 2002 and 2003. Only two parasites were identified, with overall prevalences of 35.8% and 41.3% for the cestode Hymenolepis diminuta and the flea Xenopsylla astia respectively. The prevalence of H. diminuta was markedly influenced by both year of study and host age, being higher in 2003 and amongst older rats. The abundance of infection of H. diminuta was influenced by the year of study, host age and sex. Worm burdens in adult rats were almost twice as heavy in males compared with females and adults of both sexes harboured heavier infections than juveniles. The prevalence of X. astia was influenced by both year and host age, being higher in juvenile rats in 2002 and in adults in 2003. The abundance of X. astia was significantly higher in 2003 and both male and female rats showed similar abundances, but in 2003 females were more heavily infested. Reasons for this are discussed in relation to the differing foraging strategies shown by male and female rats. The prevalence and abundance profiles for both H. diminuta and X. astia were higher overall in 2003 due to a significant increase in the rat population density, although this did not reflect in any increase in parasite species richness. Rats that were infected with H. diminuta were almost twice as likely to be infected with X. astia than those without the cestode, but when controlled for the effects of year, host age and sex, no quantitative interactions were detected between the two parasite species.

Age Factors↗
PubMed2006

Plasma etching and ashing: a technique for demonstrating internal structures of helminths using scanning electron microscopy.

Plasma etching and ashing for demonstrating the three-dimensional ultrastructure of the internal organs of helminths is described. Adult worms of the cestode Caryophyllaeides fennica were dehydrated through an ethanol series, critical point dried (Polaron E3000) and sputter coated with 60% gold-palladium (Polaron E5100) and glued to a standard scanning electron microscope (SEM) stub positioned as required for ashing. After initial SEM viewing of worm surfaces for orientation, stubs were placed individually in the reactor chamber of a PT7150 plasma etching and ashing machine. Worms were exposed to a radio frequency (RF) potential in a low pressure (0.2 mbar) oxygen atmosphere at room temperature. The oxidation process was controlled by varying the times of exposure to the RF potential between 2 to 30 min, depending on the depth of surface tissue to be removed to expose target organs or tissues. After each exposure the oxidized layer was blown from the surface with compressed air, the specimen sputter-coated, and viewed by SEM. The procedure was repeated as necessary, to progressively expose successive layers. Fine details of organs, cells within, and cell contents were revealed. Ashing has the advantage of providing three dimensional images of the arrangement of organs that are impossible to visualize by any other procedure, for example facilitating testes counts in cestodes. Both freshly-fixed and long-term stored helminths can be ashed. Ashing times to obtain the desired results were determined by trial so that some duplicate material was needed.

Animals↗
PubMed1983

Isoelectric focusing in agarose: a highly discriminatory method for the detection of enzyme heterogeneity.

A comparison was made of the effectiveness of starch gel electrophoresis and isoelectric focusing in agarose for the separation of isoenzymes. Lactate dehydrogenase (LDH) of Theileria parva and glucose phosphate isomerase (GPI) of various cestodes were examined by the two techniques. Isoelectric focusing proved to be highly discriminatory, clearly distinguishing cestode orders and Taenia spp. which were closely similar by starch gel electrophoresis, and separating seven bands of Theileria-specific LDH activity which were not separable from normal bovine control bands on starch gels. The routine use of isoelectric focusing in agarose is therefore recommended for isoenzyme analysis.

Animals↗
PubMed1990

Hydatid disease in the Turkana District of Kenya, VII: analysis of the infection pressure between definitive and intermediate hosts of Echinococcus granulosus, 1979-1988.

The rate of acquisition of Echinococcus granulosus and Taenia hydatigena was examined in dogs treated with praziquantel in northwestern Turkana District of Kenya. An attempt was also made to assess the effect of drought on the prevalence of E. granulosus. The infection pressure to dogs with the cestodes was shown to be high, and the prevalence returned to pretreatment levels within six months. The unreliability of arecoline purging in prevalence studies of dog cestodes is shown by mathematical contrast to the results of autopsy. Arecoline purge may underestimate the real prevalence by 10-fold. Dosing intervals in hydatid control programmes utilizing mass dog-purging to estimate re-infection rates should therefore take this factor into consideration. It is proposed that a mass dog-dosing schedule in Turkana, using praziquantel, should take into consideration the short prepatent period of E. granulosus, the financial constraints, and the slaughter practices in the area. During the prolonged droughts which occur approximately every 10 years, the programme will be adjusted accordingly to cater for the initial increase in infection intensity to dogs.

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