Effect of Soil Temperature on Canine Soil-Transmitted Nematodes in Kandy District with the First Record of Hookworm, Ancylostoma tubaeforme from Sri Lanka

PURPOSE

Soil-transmitted nematodes (STNs) are widespread in tropical and subtropical regions, particularly where the communities are socio-economically challenged. We investigated the effect of soil temperature on the prevalence and intensity of STN infection in free-roaming dogs.

METHODS

Fresh faecal samples collected from free-roaming dogs in Digana and Pussellawa town areas in the Kandy District, Sri Lanka, were microscopically analysed for canine STNs. Soil temperature was measured at each sampling site. Highly prevalent canine hookworm Ancylostoma, was further studied using PCR and sequencing, followed by phylogenetic analysis.

RESULTS

The soil temperature ranged between 28 and 31 °C (mean = 29.79 °C) and 18-21 °C (mean = 19.52 °C) in Digana and Pussellawa, respectively, showing a significant difference in the two sites (Students t-test t = 1.68, p < 0.0001). Of the total 44 dogs sampled, 41 (93.2%) were positive for STNs. During microscopic analysis, five nematodes: Ancylostoma spp., Capillaria sp., Strongyloides sp., Toxocara canis, and Trichuris sp., were identified. Ancylostoma species (93.2%) were the most prevalent, followed by Strongyloides sp. (22.7%) and Toxocara canis (15.9%). Infection prevalence of Strongyloides sp. was higher in Digana (40.9%) compared to that in Pussellawa (4.5%; Chi-square test, χ2 = 8.28, p = 0.004) and also the infection intensity from Digana (EPG = 8.02 ± 20.2) compared to that from Pussellawa (0.45 ± 2.1; Mann Whitney U test, p = 0.006). Amplicons (ITS1-5.8S-ITS2) of the expected size for A. caninum, and A. tubaeforme were produced. An A. caninum sequence reported here (OQ101719) illustrated the highest similarity of 99.2% to one of the local sequences (MZ707153) upon pairwise comparison.

CONCLUSION

Digana, with a higher soil temperature than Pussellawa, had a significantly higher prevalence and infection intensity, particularly Strongyloides sp. This study also signifies the first molecular identification of hookworm species A. tubaeforme in Sri Lanka.

Polyphyly of the Dinurinae Looss, 1907 (Digenea: Hemiuridae) and resurrection of the Mecoderinae Skrjabin & Guschanskaja, 1954 based on novel collection of Tubulovesicula laticaudi Parukhin, 1969 from marine elapid snakes in Sri Lanka

With one exception, the only known hemiurid trematodes that do not use teleost fishes as definitive hosts instead occur in marine elapid snakes. These comprise six species across four genera and three subfamilies, and so presumably indicate at least three independent invasions of marine snakes from teleost fishes. Here, one of these taxa, Tubulovesicula laticaudi Parukhin, 1969 (= T. orientalis Chattopadhyaya, 1970 n. syn.) is reported from Sri Lanka, collected from Shaw's sea snake Hydrophis curtus (Shaw) (Elapidae: Hydrophiinae: Hydrophinii), the annulated sea snake H. cyanocinctus Daudin and the yellow sea snake H. spiralis (Shaw) off Nayaru in the Bay of Bengal, and from H. spiralis in Portugal Bay, Gulf of Mannar. Novel molecular data, for COI mtDNA and ITS2 and 28S rDNA, are the first for a species of Tubulovesicula Yamaguti, 1934. Nominally, Tubulovesicula belongs in the Dinurinae Looss, 1907, but in phylogenetic analyses based on 28S rDNA, our sequences for T. laticaudi resolved relatively distant from that for representatives of Dinurus Looss, 1907, the type-genus, rendering the subfamily polyphyletic. Tubulovesicula laticaudi resolved closest to data for the type-species of the Plerurinae Gibson & Bray, 1979, but that subfamily is also polyphyletic. These findings lead us to re-evaluate an alternative classification considered by Gibson & Bray (1979). We propose restricting the Dinurinae for forms with a permanent sinus-organ (Dinurus, Ectenurus Looss, 1907; Erilepturus Woolcock, 1935; Paradinurus Vigueras, 1958; Qadriana Bilqees, 1971) and resurrect the Mecoderinae Skrjabin & Guschanskaja, 1954 for forms with a temporary sinus-organ (Mecoderus Manter, 1940, Allostomachicola Yamaguti, 1958, Stomachicola Yamaguti, 1934 and Tubulovesicula).

Comparative analysis of proximate compositions, mineral and functional chemical groups of 15 different seaweed species

Seaweed is a popular edible source and is associated with many foods and pharmaceutical industries around the world. The current research aims to provide information on the chemical composition of 15 seaweed species, consisted of Chlorophyta, Ochrophyta/Phaeophyceae, and Rhodophyta macroalgae, collected from coastal areas of Sri Lanka. Seaweed samples were subjected to the analysis of lipids, proteins, ash and macro, micro, trace and ultra-trace elements. The highest protein content was recorded in the brown algae. Maximum dietary fiber and ash contents were recorded from green algae. The highest predominant fatty acids were observed from green seaweeds (Caulerpa racemosa); however, linoleic acid (C18:2n6) is the dominant fatty acid of all macroalgae. Mineral contents were highest in the red macroalga; however, copper, zinc and magnesium were also comparatively higher in green alga Ulva lactuca. In conclusion, 15 seaweed species belonging to the three different classes of seaweeds are investigated in details to obtain their biochemical, mineral and fatty acid compositions for the synthesis of novel therapeutic agents. In order to explore biorefinery processes for these seaweeds, as well as how they can potentially be cultivated, more extensive studies are required. Studying and determining the nutritional values of seaweeds will be beneficial with the potentials for future industrial uses and research.

Hepatic trematode Platynosomum sp. (Dicrocoeliidae) from a domestic cat in Colombo, Sri Lanka: Case report and molecular identification

Platynosomum is a digenean trematode causing hepatobiliary disease in cats in tropical and subtropical regions. The presence of Platynosomum species in Sri Lanka has not been previously reported or investigated. In the current study, we report a clinical case of a cat suffering from hepatic and biliary complications. Fine-needle aspiration of the biliary extract revealed a large number of parasite eggs, and the morphological and molecular identification of eggs was carried out. Molecular phylogenetics was performed using the nuclear ribosomal Internal Transcribed Spacer 2 (ITS2) and a portion of a mitochondrially encoded gene; Cytochrome C Oxidase subunit 1 (COX1). Through a combination of history, clinical signs, blood reports, ultrasound scanning, light microscopy of eggs from biliary aspirate and molecular studies, the disease was confirmed as parasitism caused by a Platynosomum like species. The Platynosomum species in Sri Lanka is phylogenetically related to Platynosomum illiciens reported from Costa Rica, Central America. This case emphasizes the importance of future studies in Sri Lanka regarding the prevalence and distribution of Platynosomum among cat populations. Further, the inclusion of feline platynosomiasis in the differential diagnoses list for hepatobiliary diseases is required.

Human Otoacariasis in Two Climatically Diverse Districts in Sri Lanka: Seasonality, Risk Factors, and Case Notes

PURPOSE

Otoacariasis is a parasitic otopathy reported in many parts of the world. This study presents the seasonal pattern, risk factors, and case notes on human otoacariasis in two climatically different districts: Anuradhapura and Kandy in the Dry and Wet/Intermediate zone of Sri Lanka, respectively.

METHODS

Ticks removed from the ear canal of patients were collected. Risk factors of otoacarisis were determined by a case/control follow-up study.

RESULTS

Nymphal Dermacentor auratus (90.8%) was the main tick species associated otoacariasis. In the Kandy District, infestation was year-round, while in the Anuradhapura District, it was seasonal with a peak in December-February. Children < 10 years were a risk group in both districts. Females were a risk group in the Kandy District. Engagement in outdoor activities was a risk factor in both districts. In addition, the presence of wildlife and domesticated animals were risk factors in the Kandy and Anuradhapura districts, respectively. The treatment protocols in the two hospitals were different. An infant with otoacariasis from the Anuradhapura District developed rickettsia.

CONCLUSIONS

Although the tick species was the same, seasonality, risk groups, and risk factors in the two districts were different which could be due to the establishment and persistence of tick populations influenced by biotic and abiotic factors.

The role of cortisol in the association of canine-companionship with blood pressure, glucose, and lipids: a systematic review

INTRODUCTION

The dog is known as man's best friend and canine-companionship is associated with positive effects on cardiovascular health.

AIM

We aim to review the role of cortisol in the association of canine-companionship with human blood pressure, glucose and lipid profile.

METHODS

Electronic databases, and reference lists of the selected articles were searched for original articles in English which evaluate the role of cortisol in the association of canine-companionship with human blood pressure, glucose and lipid profile. Appropriate tools from the National Institute of Health were used for the quality assessment.

RESULTS

Of the 2108 articles included for screening, 6 studies fulfilled the selection criteria. The USA had produced the highest number of studies (50%, 3/6). Pre-post studies (83%, 5/6) were the predominant type, and the overall quality of the selected studies was acceptable. The majority of studies showed a significant reduction of cortisol with dog companionship or therapy (67%, 4/6) along with a significant reduction of heart rate (2/4), systolic blood pressure (1/4), mean arterial blood pressure (1/4), or total cholesterol level (1/4). The role of cortisol in the association of canine-companionship with human blood pressure, glucose and lipid profile was scarcely studied with no studies from lower-middle-income countries, where the disease burden is on the rise.

CONCLUSION

A significant reduction of few cardiovascular risk factors was found along with a significant reduction of cortisol in canine companionship in few studies. Future comparative or higher-level studies are essential on the association between canine companionship, cortisol and cardiovascular risk factors, especially in lower-middle-income countries.

Gastro-intestinal parasites in two subspecies of toque macaque (Macaca sinica) in Sri Lanka and their zoonotic potential

Gastro-intestinal (GI) parasites of primates have a greater potential of becoming zoonotic. This potential may vary in different primates based on multiple factors such as proximity to human settlements and the climate of their habitat. We examined the GI parasites in two subspecies of toque macaque: Macaca sinica sinica (confined to the dry zone) and Macaca sinica aurifrons (confined to the wet zone) of Sri Lanka. Fresh faecal samples were collected and analysed following a modified Sheather's sucrose floatation method. A total of 90.8% (89/98) macaques were infected with one or more parasite species. There was no difference in the overall prevalence of GI parasites between the two subspecies, M. s. aurifrons (95.9%) and M. s. sinica (85.7%; χ²;χ = 3.059, p = 0.080). Sixteen parasite species were recorded including, 15 species in the M. s. sinica and 12 species in the M. s. aurifrons. Among the helminths identified, Anatrichosoma sp., Ancylostoma spp., Capillaria spp., Oesophagostomum /Bunostomum spp. and Physaloptera spp. are known to be zoonotic while Ascaris spp., Enterobius sp., Strongyloides spp. and Trichuris spp. have both zoonotic and anthroponotic potential. Among the protozoans, Balantidium coli and Buxtonella sp. are known to be zoonotic, while Entamoeba spp. and Cryptosporidium spp. have both anthroponotic and zoonotic potential. This study provides the first record of Anatrichosoma sp. and Buxtonella sp. in Sri Lanka and the first record of Cryptosporidium spp. in M. s. aurifrons. The molecular data allowed further identification and differentiation of Entamoeba nuttalli and E. coli that are known to be zoonotic and anthroponotic, respectively. The two subspecies of macaques have close interactions with humans; hence, in-depth epidemiological studies are required to understand the potential public-health risks to humans and conservation implications for macaque populations.

Preliminary screening of the aqueous extracts of twenty-three different seaweed species in Sri Lanka with in-vitro and in-vivo assays

Background

Seaweeds are an important source of bioactive compounds which are applied in various aspects of medicinal investigations. The present study was conducted to investigate cytoxicity (in-vitro and in-vivo) and wound healing activity of different seaweed species in Sri Lanka.

Methods

Twenty-three seaweed samples, belonging to Phaeophyta (Brown), Chlorophyta (Green) and Rhodophyta (Red) were used for the experiments. Samples were collected from the inter-tidal and the sub-tidal habitats around Sri Lankan coast (Southern, Northern and North-western). Aqueous seaweed extracts were tested for cytotoxic and wound healing activity; in-vitro and in-vivo. To determine toxicity of aqueous seaweed extracts, brine shrimp lethality assay and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) colorimetric assay on mouse fibroblasts (L929) cell line were performed. Cell migration induction of seaweed extracts was assessed by scratch wound healing assay using L929 cell line. Based on the our previous experiments S.ilicifolium (SW23) was selected for the in vivo study to confirm our hypothesis. Albino mice (BALB/c) were divided into three groups (12 in each) and a circular area (44.07 ± 02.51 mm²) of full skin was excised to create a wound in mice group II and III. Group III received aqueous extract of Sargasum illicifolium (400 mg/kg BW/day for 12 days, orally), Group II received distilled water for 12 days whereas Group I was used as the control group and it was tested without forming wounds and without providing any treatment. Further, the expression level of Tumor Necrosis Factor (TNF-α) and Transforming Growth Factor-β (TGF-β) via RT-PCR were measured every three days until the end of the experiment.

Results

Phytochemical tests showed positive results to flavonoids in all the selected green seaweeds and alkaloids were observed in red seaweeds. In the toxicity assay, red seaweed, Acanthophora spicifera (SW17) was found to be highly effective on nauplii of brine shrimp (LC₅₀ = 0.072 μg/μl). LC₅₀ value of green seaweed species, Caulerpa racemosa (SW02 and SW08) and Caulerpa sertularioides (SW10) was not found within the tested concentration series. The highest cytotoxic effect on L929 cell line was exhibited by aqueous extracts of red seaweed; Jania adhaereus with 50.70 ± 7.304% cell viability compared with control group. The highest cell migration activity was observed in L929 cell line group treated with extracts of green seaweed namely; Halimeda opuntin (SW07) and extracts of brown seaweed namely; Stoechospermum polypodioides (SW11). Extracts of S. illicifolium (SW23) exhibited a significantly enhanced wound healing activity in mice group III within three days (P < 0.05) with an open wound area of 17.35 ± 1.94 mm² compared with control group (26.29 ± 2.42 mm²). TGF-β gene expression peaked on 6^th day of post-wound and subsequently decreased on 9^th day of post-wound in mice group III. TNF-α expression was suppressed in mice group III whereas it was elevated in group II. TGF-β expression is enhanced in the treatment group compared to the control group.

Conclusions

Aqueous extracts of selected seaweeds are a significant source of potential compounds with wound healing properties, which might be helpful in the healing of various wounds. This also infers that many species of brown and red seaweeds have the potential of wound healing, specifically, Sargasum illicifolium and Jania adhaereus could be a potential candidate for in-vivo studies related to wound healing and cancer therapy in the near future.

Characterization and phylogenetic properties of the complete mitochondrial genome of Fascioloides jacksoni (syn. Fasciola jacksoni) support the suggested intergeneric change from Fasciola to Fascioloides (Platyhelminthes: Trematoda: Plagiorchiida)

Fascioloides jacksoni (syn. Fasciola jacksoni, Cobbold, 1869) (Platyhelminthes: Echinostomatoidea), is a liver fluke that causes severe morbidity and mortality of Asian elephants (Elephas maximus maximus). Understandings on molecular diagnosis, epidemiology, genetics and evolution of this flatworm are limited. In this study, we present the complete mitochondrial DNA (mt) sequence of 14,952 bp obtained from an individual fluke and comparative characterization of mitogenomic features with fasciolids, primarily, Fascioloides magna and other taxa in the superfamily Echinostomatoidea. Taxonomic relationship within and between Echinostomatoidea, Opisthorchioidea and Paramphistomoidea in the order Plagiorchiida, are also taxonomically considered. The complete circular mt molecule of Fas. jacksoni contained 12 protein-coding, two ribosomal RNA, 22 transfer RNA genes, and a non-coding region (NCR) rich in tandem repeat units. As common in digenean trematodes, Fas. jacksoni has the usual gene order, the absence of atp8 and the overlapped region by 40 bp between nad4L and nad4 genes. The NCR located between tRNA^Glu (trnE) and cox3 contained nine nearly identical tandem repeat units (TRs of 113 bp each). Special DHU-arm missing tRNAs for Serine were found for both, tRNA^S1(AGN) and tRNA^S2(UCN). Base composition indicated that cox1 of Fas. jacksoni showed the lowest (11.8% to Fas. magna, 12.9 - 13.6% to Fasciola spp. and 18.1% to Fasciolopsis buski) and nad6 the highest divergence rate (19.2%, 23.8-26.5% and 27.2% to each fasciolid group), respectively. A clear bias in nucleotide composition, as of 61.68%, 62.88% and 61.54%, with a negative AT-skew of the corresponding values (-0.523, -0.225 and - 0.426) for PCGs, MRGs and mtDNA for Fas. jacksoni and likewise data for the fasciolids. Phylogenetic analysis confirmed the sister branch of Fas. jacksoni and Fas. magna with the nodal support of 100%, clearly separated from the taxonomically recognized Fasciola spp. With the previous studies, mitogenomic data presented in this study are strongly supportive for Fasciola jacksoni reappraisal as Fascioloides jacksoni in the Fascioloides genus.

Morphological and molecular description of Armillifer moniliformis larvae isolated from Sri Lankan brown palm civet (Paradoxurus montanus)

We report Armillifer moniliformis species infecting the endemic Sri Lankan brown palm civet (Paradoxurus montanus) from the Knuckles Range Forest Conservation Area, Sri Lanka. Larval stages of A. moniliformis were found during the postmortem of three civet cats found dead. Morphological studies were done by a light microscope and a scanning electron microscope (SEM). Histopathological examination was conducted using tissue samples obtained from the liver. For the molecular analysis, DNA was extracted from the isolated third-stage larvae. The NADH dehydrogenase subunit 5 (ND5) and the second internal transcribed spacer region (ITS-2), a portion of the large subunit nuclear ribosomal DNA (28S), a portion of 18S ribosomal rRNA gene (18S), and cytochrome c oxidase subunit 1 gene (COX1) were amplified using polymerase chain reaction (PCR). Excysted third-stage larvae were observed in the lungs, omentum, the pleural cavity, the abdominal cavity, and the surface of the spleen and the pericardium. Around 88 third-stage larvae were isolated from three civet cats. First-stage larvae in the liver were surrounded by outer fibrous layer over the inner germinal layer and filled with clear fluid. Slight hemorrhage, leukocyte infiltration, and mild hepatocellular degeneration in the liver were observed. The SEM examination indicated the unique oral apparatus comprises the oval-shaped mouth opening in between two pairs of curved, retractile hamuli. The sequences obtained for ND5, ITS-2, 28S, 18S, and COX1 were 301, 382, 325, 414, and 644 bp in length respectively. Morphology, sequence similarity search, sequence alignment, and phylogenetic analysis identified this parasite as A. moniliformis.

Heart and liver are infected in fatal cases of dengue: three PCR based case studies

Background

Dengue is a global problem mainly in the tropics. Meticulous clinical management of cases has reduced the death rate significantly, but large numbers of people still succumb to severe complications of the infection. Presence of myocarditis is often overlooked leading to a poor outcome. Clinical management guidelines of dengue do not stress the importance of myocarditis as a manifestation in dengue infection. Severe hepatic dysfunction also needs emphasis.

Case presentation

We present three patients who had come to hospital on the 3rd day of fever. Two of them (case 1 and 3) were in shock on admission and case 2, who was stable on the3^rd day, went into the critical phase and developed shock while in the hospital on the 4^thday. All three had tachycardia on admission that got worse with time. The clinical course was unstable with fluctuations in urine output and deterioration of organ function. Despite frequent monitoring and life support they survived only 2–3 days in hospital. All three patients had myocarditis during the critical phase. In the first case, myocarditis was confirmed by troponin estimation and echocardiogram. In the second and third cases, histopathology confirmed myocarditis. Haemorrhagic necrosis of the liver was found in case 2 and 3 with exponential rise of transaminases. In all three cases, viral RNA was detected in both heart and liver tissues by PCR amplification.

Conclusions

We stress that detection of myocarditis and liver involvement in any dengue patient is important from the onset of the illness where treatment should be tailored to prevent development of hypotension. Our findings are novel as PCR and histology are rarely done on tissues of deceased dengue patients in the world. Studies are needed to find therapeutic interventions to reverse cardiac and hepatic dysfunction in dengue infection.

Extensive haemorrhagic necrosis of liver is an unpredictable fatal complication in dengue infection: a postmortem study

Background

Dengue infection carries a potential risk of death despite stringent management of plasma leak and haemorrhage. It appears that the extent of liver dysfunction determines the outcome.

Methods

We present a postmortem study of five patients, died of dengue shock syndrome who had markedly elevated liver enzymes and irreparable circulatory failure.

Results

All were females with a median age of 46 years (range 20–50 years). All had positive NS1 and IgM. Clinically, one patient developed severe degree of hepatic encephalopathy whilst three patients developed uncontrollable bleeding manifestations. Dengue virus was detected in three liver specimens by reverse transcription PCR. Histology of the liver revealed massive necrosis with haemorrhages in these patients with evidence of micro and macrovesicular steatosis with significant periportal inflammatory infiltrate. No significant ischaemic changes or necrosis was observed in the other organs.

Conclusions

Severe haemorrhagic necrosis of the liver was the cause of death in these patients probably due to direct viral infection. Predilection for severe liver disease remains unknown. Therefore, it is prudent to think beyond plasma leak as the main pathology of dengue infection and attempts should be made to develop other treatment modalities to prevent and manage unforeseen fatal complications of dengue infection.

Does Carica papaya leaf-extract increase the platelet count? An experimental study in a murine model

OBJECTIVE

To investigate the potential role of fresh Carica papaya (C. papaya) leaf extract on haematological and biochemical parameters and toxicological changes in a murine model.

METHODS

In total 36 mice were used for the trial. Fresh C. papaya leaf extract [0.2 mL (2 g)/mouse] was given only to the test group (18 mice). General behavior, clinical signs and feeding patterns were recorded. Blood and tissue samples were collected at intervals. Haematological parameters including platelet, red blood cell (RBC), white blood cell (WBC), packed cell volume (PCV), serum biochemistry including serum creatinine, serum glutamic-oxaloacetic transaminase (SGOT) and serum glutamic-pyruvic transaminase (SGPT) were determined. Organs for possible histopathological changes were examined.

RESULTS

Neither group exhibited alteration of behavior or reduction in food and water intake. Similarly, no significant changes in SGOT, SGPT and serum creatinine levels were detected in the test group. Histopathological organ changes were not observed in either group of mice except in three liver samples of the test group which had a mild focal necrosis. The platelet count (11.33±0.35)×10⁵/µL (P=0.00004) and the RBC count (7.97±0.61)×10⁶/µL (P=0.00003) were significantly increased in the test group compared to that of the controls. However, WBC count and PCV (%) values were not changed significantly in the test group. The platelet count in the test group started to increase significantly from Day 3 (3.4±0.18×10⁵/µL), reaching almost a fourfold higher at Day 21 (11.3×10⁵/µL), while it was 3.8×10⁵/µL and 5.5×10⁵/µL at Day 3 and Day 21 respectively in the control. Likewise, the RBC count in the test group increased from 6×10⁶/µL to 9×10⁶/ µL at Day 21 while it remained near constant in the control group (6×10⁶/µL).

CONCLUSIONS

Fresh C. papaya leaf extract significantly increased the platelet and RBC counts in the test group as compared to controls. Therefore, it is very important to identify those chemicals of C. papaya leaves as it can be recommended to be used as a medication to boost thrombopoiesis and erythropoiesis in humans and in animals in which these cell lineages have been compromised.

A case series of spotted fever rickettsiosis with neurological manifestations in Sri Lanka

BACKGROUND

Spotted fever group (SFG) rickettsial infections are increasingly detected in Sri Lanka. We describe 17 patients with SFG who developed neurological manifestations.

METHODS

The cases were studied prospectively from 2008 at the Teaching Hospital, Peradeniya. An immunofluorescent antibody assay (IFA) was used to confirm the diagnosis.

RESULTS

All had an IFA IgG titer ranging from 1/64 to 1/4096 and a positive IFA IgM titer against Rickettsia conorii antigen; in 10 (59%) cases the IgG titers were ≥ 1/256 (definitive cases). The median age of the patients was 62 years (range 26-82 years); 10 were male and seven female. The median duration of fever was 12 days (range 4-35 days). Neurological manifestations on admission were drowsiness or confusion in 14 (82%) and a semi-comatose state in three (18%). Rigidity of the limbs occurred in 14 (82%), bradykinesia and resting tremors in 12 (71%), which persisted after defervescence, neck stiffness in seven (42%), weakness of the limbs in five (29%), deafness in two (12%), and stupor in three (18%). Electroencephalograms in three (18%) showed generalized slow waves. Cerebrospinal fluid examination showed a cellular reaction, predominantly lymphocytes, in three cases. Two patients died (fatality rate 12%).

CONCLUSION

We have documented for the first time the neurological features of SFG rickettsioses in the Central Province, Sri Lanka. These were predominantly extrapyramidal features in patients of older age.

Evidence of acute rickettsioses among patients presumed to have chikungunya fever during the chikungunya outbreak in Sri Lanka

BACKGROUND

Chikungunya fever (CGF) and rickettsioses are known to cause acute onset febrile illnesses associated with severe arthritis. Rickettsial arthritis is curable with the use of appropriate anti-rickettsial antibiotics, however the arthritis of CGF tends to have a prolonged course leading to protracted disability. The aim of this study was to investigate the contribution of CGF and rickettsioses to cases of fever and arthritis during a presumed CGF outbreak in Sri Lanka.

METHODS

Fifty-eight consecutive patients with presumed CGF were further investigated to determine the occurrence of rickettsioses among them, and to identify differences in clinical, hematological, and biochemical parameters between the two diseases.

RESULTS

Nearly a third of the patients had serological evidence of rickettsioses accounting for their illness. The presence of a late onset major joint arthropathy sparing the small joints of the hands and feet, and the occurrence of a late onset discrete maculopapular rash over the trunk and extremities, suggested rickettsioses over CGF. White blood cell count, erythrocyte sedimentation rate, C-reactive protein, and liver function tests were not helpful in differentiating rickettsioses from CGF. Patients with rickettsioses and arthritis who received an empirical course of doxycycline recovered faster than those who did not receive specific treatment.

CONCLUSIONS

The establishment of rapid diagnostic methods able to differentiate the etiological agents of fever and arthritis, such as CGF and rickettsioses, would be beneficial in endemic settings.

The regional sero-epidemiology of rhinosporidiosis in Sri Lankan humans and animals

No data is available in the world literature on serum anti-rhinosporidial antibody levels in animals, and as far as we aware this is the first report. Although rhinosporidiosis in farm and domestic animals has been widely reported from other countries, rhinosporidiosis in animals has not been reported in Sri Lanka, though this country has the highest world-wide prevalence of human rhinosporidiosis on a unit-population basis. Serum IgG titres in 6 species of Sri Lankan animals (buffalo, cat, cattle, dog, goat, horse; total 291) were assayed by the Immuno blot (dot-ELISA) method on nitrocellulose paper and were compared with serum IgG titres in normal Sri Lankan human subjects (total 211) in different geographical areas, and in human Sri Lankan patients with rhinosporidiosis as reference values (total 36). Sensitization to rhinosporidial antigen(s) was detected in all 6 species of animals and the highest titres (1/3200) were found in cats, and free-grazing horses. Cattle showed higher levels of antibody than buffaloes. The titres in these animals are compared with world reports on overt rhinosporidiosis in these species, and with titres in normal Sri Lankan humans. Human, but not animal titres showed variations compatible with the regional prevalence of rhinosporidiosis. The variations in titres in animals especially horses, were probably more related to their mode of feeding, while in humans the titres in normal persons were probably related to the rhinosporidial-endemicity of their respective regions. No conclusions from sero-positivity in animals could be made regarding the absence of reports on rhinosporidiosis as an overt disease in these Sri Lankan animal species but the possibility of a genetically-determined insusceptibility to rhinosporidiosis in Sri Lanka, is considered. Rhinosporidium seeberi-specific PCR positive reactions were obtained with nasal scrapings from cattle that microscopically showed PAS+ bodies that were compatible with rhinosporidial sporangia. Sequence-analysis of the reactions products from five positive R. seeberi-specific PCR samples (four in this study and 1 in a previous study) gave results confirmatory of R. seeberi.

Distribution and ecological aspects of sand fly (Diptera: Psychodidae) species in Sri Lanka

Human indigenous cutaneous leishmaniasis caused by Leishmania donovani complex is endemic in Sri Lanka. We performed an entomological survey to determine the distribution of probable vector species. Sand flies were collected in districts in the dry zone, in the wet zone highlands, and in the wet zone coastal belt of Sri Lanka using CDC light traps, sticky traps and cattle-baited net traps during July, 2005. The survey was reconducted in February, 2006. Overall, 584 sand flies belonging to Phlebotomus (266 specimens, 2 species) and Sergentomyia (318 specimens, 8 species) genera were collected. A total of 266 Phlebotomus was identified as P. argentipes (258/266; 97%) and P. stantoni (8/266; 3%) . The identification studies of Sergentomyia specimens showed that there are at least 8 species in Sri Lanka. Higher number of Phlebotomus sand flies (76/266) were caught in the southern part of the country compared to the other parts probably due to different ecological aspects. P. argentipes were widely distributed throughout the island whereas P. stantoni were collected only in four districts. Since P. argentipes is known to be the vector of L. donovani responsible of visceral leishmaniasis in India, this species may be incriminated as the most possible vector of human cutaneous leishmaniasis in Sri Lanka.

Contribution of rickettsioses in Sri Lankan patients with fever who responded to empirical doxycycline treatment

Twenty-eight febrile Sri Lankan patients with undiagnosed fever for 7 days after hospital admission, who responded to empirical treatment with doxycycline, were retrospectively investigated using microimmunofluorescence assay to verify whether they had rickettsial infection. Eleven (39%) patients were confirmed as having spotted fever group rickettsioses and 10 (36%) as having Orientia tsutsugamushi. Seven were negative for all tests. This suggests that greater use of doxycycline appears justified for patients with undiagnosed fever in settings where rickettsial diseases are endemic or re-emerging with inadequate diagnostic facilities.

The complete mitochondrial genome of Setaria digitata (Nematoda: Filarioidea): Mitochondrial gene content, arrangement and composition compared with other nematodes

In the present study, we determined the complete mitochondrial (mt) genome sequence (13,839bp) of parasitic nematode Setaria digitata and its structure and organization compared with Onchocerca volvulus, Dirofilaria immitis and Brugia malayi. The mt genome of S. digitata is slightly larger than the mt genomes of other filarial nematodes. S. digitata mt genome contains 36 genes (12 protein-coding genes, 22 transfer RNAs and 2 ribosomal RNAs) that are typically found in metazoans. This genome contains a high A+T (75.1%) content and low G+C content (24.9%). The mt gene order for S. digitata is the same as those for O. volvulus, D. immitis and B. malayi but it is distinctly different from other nematodes compared. The start codons inferred in the mt genome of S. digitata are TTT, ATT, TTG, ATG, GTT and ATA. Interestingly, the initiation codon TTT is unique to S. digitata mt genome and four protein-coding genes use this codon as a translation initiation codon. Five protein-coding genes use TAG as a stop codon whereas three genes use TAA and four genes use T as a termination codon. Out of 64 possible codons, only 57 are used for mitochondrial protein-coding genes of S. digitata. T-rich codons such as TTT (18.9%), GTT (7.9%), TTG (7.8%), TAT (7%), ATT (5.7%), TCT (4.8%) and TTA (4.1%) are used more frequently. This pattern of codon usage reflects the strong bias for T in the mt genome of S. digitata. In conclusion, the present investigation provides new molecular data for future studies of the comparative mitochondrial genomics and systematic of parasitic nematodes of socio-economic importance.

Toxocara vitulorum (Ascaridida: Nematoda): mitochondrial gene content, arrangement and composition compared with other Toxocara species

Partial mitochondrial (mt) genome sequence (10,486bp) from the parasitic nematode Toxocara vitulorum was determined and its organization and structure compared with those of T. cati, T. canis and T. malaysiensis. The obtained mt genome sequence of T. vitulorum contains 10 protein-coding genes (cytochrome c oxidase subunits 1-3, Nicotinamide adenine dinucleotide dehydrogenase subunits 1-5, ATP synthase subunit 6 and cytochrome b), 14 transfer RNA genes and the large ribosomal RNA gene (rrnL), non-coding regions. ORF encoding for ATPase subunit 8 is not found in this partial mtDNA sequence. Five translation initiation codons were inferred, ATT, ATG, GTG, GTT and TTG. Most of the genes used TAG or TAA as a stop codon and two genes ended with a T. The gene arrangement and composition of the T. vitulorum mt genome is very similar to that of other Toxocara species mitochondrial genomes sequenced thus far. All genes are transcribed in the same direction, as other Toxocara species. This genome has a high A+T content (67.5%) and low G+C content (32.5%). Phylogenetic reconstruction based on aligned nucleotide sequences of seven taxa provided strong support that Toxocara vitulorum is more closely related to T. malaysiensis than to T. canis and T. cati.

Toxocara canis and Toxocara vitulorum: molecular characterization, discrimination, and phylogenetic analysis based on mitochondrial (ATP synthase subunit 6 and 12S) and nuclear ribosomal (ITS-2 and 28S) genes

Toxocara canis and Toxocara vitulorum are two important parasites of dogs and buffaloes with public health concern. The objectives of the present study are to identify molecular markers to discriminate these closely related parasites and to determine their phylogenetic position and genetic diversity within the genus Toxocara. Thus, two mitochondrial genes (complete ATPase 6 and partial small subunit ribosomal RNA (12S rDNA)), two nuclear ribosomal genes (second internal transcribed spacer region (ITS-2)), and part of the large subunit 28S region were analyzed. Nucleotide sequence (597 bp) and predicted amino acid sequences of the complete ATPase 6 gene (199 amino acids) of both species (T. canis and T. vitulorum) are similar in size with the Toxocara cati and Toxocara malaysiensis. There was 88% nucleotide similarity between T. canis and T. vitulorum and many transversions present in the 12S gene. Analyses of the ITS-2 and 28S regions revealed that the 28S region was more conserved (95% nucleotide similarity between T. canis and T. vitulorum) than the ITS-2 region (85%). This study has provided useful molecular markers for the molecular epidemiological investigation of Toxocara species. Further, phylogenetic analyses of the ITS-2 and 28S genes have indicated that the members of the genus Toxocara form a distinct group with reference to their definitive hosts.

Toxocara canis: Molecular cloning, characterization, expression and comparison of the kinetics of cDNA-derived arginine kinase

Arginine kinase (AK) is a member of a highly conserved family of phosphagen kinases. We determined the cDNA sequence of Toxocara canis AK, cloned it in pMAL plasmid and expressed it in Escherichia coli as a fusion protein with maltose-binding protein. The protein has a theoretical molecular mass of 45,376 Da and an estimated isoelectric point (pI) of 8.38. Alignment of the cDNA-derived amino acid sequence of T. canis AK with other phosphagen kinase sequences showed high amino acid identity with other nematode AKs, and phylogenetic analysis placed it as a distinct branch within a nematode AK cluster. Analysis of the N-terminus sequence of T. canis AK revealed the presence of a signal targeting peptide presumably targeting this protein to cytosol or endoplasmic reticulum (ER). T. canis AK showed high activity for l-arginine. The kinetic constants (K(m) = 0.12 mM, K(cat) = 29.18, and K(d) = 0.23 mM) and V(max) (43.76 micromolPi/min/mg protein) of T. canis recombinant-AK were determined for the forward reaction. It also exhibited a synergism for substrate binding (K(d)(Arg)/K(m)(Arg)=1.96). Comparison of K(cat)/K(m)(Arg) values in various arginine kinases indicates that T. canis AK has a high catalytic efficiency (248.19s(-1)mM(-1)). The present study contains the first description of arginine kinase in a zoonotic nematode. The determination of T. canis AK and its phosphagen biosynthetic pathway, which is completely different from those in mammalian host tissues, suggests this enzyme as a possible novel chemotherapy target for VLM syndrome in humans.

A DNA sequence-based study of theSchistosoma indicum(Trematoda: Digenea) group: population phylogeny, taxonomy and historical biogeography

Partial (DNA) sequences were collected for 2 mitochondrial loci (SrrnaandLrrna, therrnS andrrnL rRNA genes respectively) forSchistosoma indicumgroup species from 4 Southeast Asian countries. The samples included 7 populations, 4 of which were previously unstudied. In 11 cases the combination of locus and population was new. The aim of the study was to provide a phylogeny based on new independent data and multiple populations (earlier studies had mostly used a common set of field samples or laboratory lines) and to examine interrelationships and phylogeography within this species group. Paraphyly of theS. indicumgroup was confirmed, as was the basal position ofSchistosoma incognitumin theSchistosomaphylogeny. Southeast AsianSchistosoma spindaleandS. incognitumpopulations were shown to fall into their respective con-specific cohesive groupings. Estimated divergence times for these taxa were shown to be related to Pleistocene changes in sea level and the radiation of definitive host groups. A revised phylogeographical model is proposed in the light of these findings.

Molecular characterization and phylogenetic analysis of Setaria digitata of Sri Lanka based on CO1 and 12S rDNA genes

The aim of the present research is to determine the phylogenetic position of Setaria digitata of Sri Lanka in the evolutionary tree of filarial worms. DNA sequences of portions of the mitochondrial genes cytochrome c oxidase subunit 1 (CO1) and small subunit ribosomal RNA (12S rDNA) were analysed. Intra-specific variation was observed in CO1 but not in 12S rDNA. Phylogenetic trees inferred from these two genes resembled one another in recognizing monophyly of Setaria. S. digitata and Setaria labiatopapillosa appear to be sister species.

Characterization of a Toxocara canis species-specific excretory-secretory antigen (TcES-57) and development of a double sandwich ELISA for diagnosis of visceral larva migrans

This study describes the isolation of a Toxocara canis species-specific excretory-secretory (ES) antigen and the development of an enzyme-linked immunosorbent assay (ELISA) based on this antigen. Analysis of the ES antigens of T. canis, Toxocara vitulorum, Ascaris lumbricoides and Necator americanus larval antigen was performed by SDS-PAGE followed by western blotting. A 57 kDa T. canis-specific antibody fraction (TcES-57) was identified by western blotting and labelling with anti-Toxocara antibodies (from experimental rabbits and human patients) and tracing with anti-human or anti-rabbit peroxidase conjugate. No protein fraction of 57 kDa was detected in ES or larval antigens collected from T. canis, T. vitulorum, A. lumbricoides and N. americanus. Using TcES-57, a specific antiserum was produced in rabbits and a double sandwich ELISA was developed. This test was validated using known seropositive sera from toxocariasis patients, sera from A. lumbricoides or N. americanus patients, and 50 serum samples from cats. These tests revealed that TcES-57 antigen is specific to T. canis infection and does not cross react with sera of other related infections. Thus, ELISA based on TcES-57 antigen was proven to be an effective tool in the diagnosis of toxocariasis and studies on the role of T. canis in the epidemiology of human toxocariasis.

Prevalence of Toxoplasma gondii in dogs from Sri Lanka and genetic characterization of the parasite isolates

The prevalence of Toxoplasma gondii in 86 street dogs from Sri Lanka was determined. Antibodies to T. gondii were assayed by the modified agglutination test (MAT) and found in 58 (67.4%) of 86 dogs with titers of 1:20 in eight, 1:40 in four, 1:80 in 10, 1:160 in 22, 1:320 in six, 1:640 in five, and 1:1280 or higher in three. Hearts, tongues, and brains (either separately or pooled) of 50 dogs with MAT titers of 1:40 were selected for isolation of T. gondii by bioassays in mice. For bioassays, canine tissues were digested in pepsin and homogenates were inoculated subcutaneously into mice; the mice receiving canine tissues were examined for T. gondii infection. In all, T. gondii was isolated from 23 dogs. Interestingly, dog organs varied in their capacity to induce T. gondii infection in mice, muscles producing more positive results than the brain. The T. gondii isolates obtained from 23 seropositive dogs were PCR-RFLP genotyped using polymorphisms at 10 nuclear markers including SAG1, SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, a new SAG2, and an apicoplast marker Apico. Mixed infection with two genotypes was observed in one dog. Four genotypes were revealed, including three unique genotypes in addition to one belonging to the predominant Type III lineage. The 24 isolates were designated as TgDgSl 1-24.

Seroprevalence of Toxoplasma gondii antibodies in captive elephants (Elephaus maximus maximus) in Sri Lanka

Serum samples collected during August 2003-June 2004 from 45 privately owned captive and 8 elephants from the Pinnawala Elephant Orphanage were tested for the presence of antibodies against Toxoplasma gondii using the direct modified agglutination test (MAT). Antibodies were found in sera of 14 of 45 (32%) privately owned elephants with titers of 1:25 in three, 1:50 in three, 1:100 in three, 1:200 in three, and 1:400 in three elephants. The elephants from Pinnawala Elephant Orphanage were seronegative. This is the first report of T. gondii seroprevalence in elephants in Sri Lanka.

Isolation and Molecular Characterization ofToxoplasma gondiiFrom Chickens From Sri Lanka

The prevalence of Toxoplasma gondii in free-ranging chickens is a good indicator of the prevalence of T. gondii oocysts in the soil because chickens feed from the ground. The prevalence of T. gondii in 100 free-range chickens (Gallus domesticus) from Sri Lanka was determined. Antibodies to T. gondii were assayed by the modified agglutination test (MAT). Antibodies were found in 39 chickens with titers of 1:5 in 8, 1:10 in 8, 1:20 in 4, 1:40 in 5, 1:80 in 5, 1:160 in 5, 1:320 in 2, 1:640 or more in 2. Hearts and brains of 36 chickens with MAT titers of 1:5 or more were bioassayed in mice. Tissues of 3 chickens with doubtful titers of 1:5 were pooled and fed to a cat; the cat shed T. gondii oocysts in its feces. Tissues from 61 chickens with titers of less than 1:5 were pooled and fed to 2 T. gondii-free cats; the cats did not shed oocysts. Toxoplasma gondii was isolated from 11 of 36 seropositive chickens by bioassay in mice. All 12 T. gondii isolates were avirulent for mice. Genotyping of 12 isolates using the SAG2 locus indicated that 6 were type III, and 6 were type II. This is the first report of genetic characterization of T. gondii from any host in Sri Lanka.

Elaboration of a crude antigen ELISA for serodiagnosis of caprine neosporosis: validation of the test by detection of Neospora caninum-specific antibodies in goats from Sri Lanka

The protozoan parasite N. caninum is a major pathogen in cattle and dogs. However, clinical symptoms are occasionally described for other potential hosts. Natural abortion in goats due to N. caninum has been rarely reported and only little data is available on the seroprevalence of N. caninum in this species. In the present study, 486 goats from Sri Lanka were tested in a crude antigen ELISA for the presence of serum antibodies against N. caninum. Additionally, the sera were analysed by N. caninum-Western blot and indirect fluorescence antibody test (IFAT). In all three tests applied, only three sera (0.7%) were scored clearly positive for anti-N. caninum antibodies. The optimal correlation between ELISA, IFAT, and Western blot confirms the suitability of the ELISA for large-scale seroepidemiologic studies, not only in cattle but also in goats.

Seroprevalence of Toxoplasma gondii in Wild Toque Macaques (Macaca sinica) at Polonnaruwa, Sri Lanka

From a natural population that inhabits the dry evergreen forest at Polonnaruwa, serum samples of 170 toque macaques were examined for antibodies to Toxoplasma gondii by the modified agglutination test. Of these, 21 (12%) were found with titers of 1:16 in 9, 1:32 in 9, 1:256 in 1, 1:1,024 in 1, and 1:4,096 in 1. There was no evidence of maternal transmission of antibodies or congenital toxoplasmosis. None of the infected macaques died within 1 yr after sampling. Toxoplasma gondii infection was closely linked to human environments where domestic cats were common. Macaques having frequent contact with human settlements showed a significantly greater (P < 0.0001) prevalence (19% infected) than macaques restricted to forest habitat, none of which was infected. Although infection with T. gondii has been noted in several species of Asian primates, this is the first report of T. gondii antibodies in toque macaques (Macaca sinica) that are endemic to the island of Sri Lanka.

Anti-Rhinosporidial Antibody Levels in Patients with Rhinosporidiosis and in Asymptomatic Persons, in Sri Lanka

The only report hitherto, from India in 1982, on anti-rhinosporidial antibody levels in patients with rhinosporidiosis recorded that antibody was not detected in Indian patients. The present report describes the use of the dot-ELISA assay of serum anti-rhinosporidial IgG, IgM and IgA and salivary sIgA in patients with diverse clinical presentations, in rural asymptomatic persons who had bathed in ground waters that probably harboured the causative pathogen, Rhinosporidium seeberi, and in laboratory persons who were exposed to R. seeberi. Ultrasonic extracts of purified endospores and sporangia of R. seeberi were used as antigen. The geometric mean (reciprocal) titres of serum antibody detected in patients were IgM 142.1, IgG 178.5, IgA 84.6, with ranges of 0-640, 30-960 and 0-160 respectively, salivary sIgA titres ranged from 0 to 18 with a mean of 4.6. The levels of antibody had no correlation with the site, the number of sporangia, duration and recurrence of the disease. Asymptomatic persons from the same endemic area as patients showed mean titres of IgM 89.6, IgG 69.1, IgA 95.5, with salivary sIgA titres of 3.1. Asymptomatic personnel who had been working in a laboratory where rhiniosporidial work was being done, showed mean titres of 169.6 IgM, 62.8 IgG, and 6.5 salivary sIgA. These results indicate that an anti-rhinosporidial antibody response occurs in rhinosporidial patients, as well as in asymptomatic persons who were exposed to R. seeberi in the environment. Anti-R. seeberi antibody does not appear to be protective in rhinosporidiosis since appreciable titres were present in patients with recurrent, single, multiple or disseminated lesions of long duration.

Seroprevalence of Sarcosystis spp. in cattle and buffaloes from the wet and dry zones of Sri Lanka: a preliminary study

An enzyme-linked immunosorbent assay (ELISA) was developed for the detection of antibodies to Sarcosystis infection in cattle and buffaloes. Crude antigens derived from cystozoites of Sarcosystis cruzi and antibodies from the sera of naturally infected cattle and buffaloes were used. The assay was validated by determination of the specificity, sensitivity and negative and positive predictive values. Using ELISA, a sero-epidemiological survey for sarcosystosis was carried out in cattle (n = 215) and buffaloes (n = 123) from the wet and dry zones of Sri Lanka. The prevalence of infection in cattle was 69.3%. Prevalence of the infection collectively in both cattle and buffaloes in the dry zone was significantly higher (P < 0.001) than that in the wet zone. The number of sero-positive cattle and buffaloes in the dry zone was significantly higher than that in the wet zone (P < 0.05). Buffaloes in the dry and wet zones showed a greater prevalence of infection (P < 0.05) than cattle.

Molecular taxonomic position of the elephant schistosome, Bivitellobilharzia nairi, newly discovered in Sri Lanka

Bivitellobilharzia nairi (Mudaliar and Ramanujachar, 1945) Dutt and Srivastava, 1955 was first recorded in India. A number of adult worm specimens of this schistosome species were recovered from a domestic elephant, which died in 1999 in Sri Lanka. This is the first report of this schistosome from Sri Lanka. In the present study, in order to clarify the phylogenetic relationship with other species of schistosomes, sequences from the second internal transcribed spacer (ITS2) of the ribosomal gene repeat, part of the 28S ribosomal RNA gene (28S), and part of the mitochondrial cytochrome c oxidase subunit 1 (CO1) gene from B. nairi were analyzed. Two intraspecific variations were seen within 13 individuals in the ITS2 region. In the CO1 region of the mitochondrial DNA, there were four haplotypes in the nucleotide sequences and two haplotypes in the amino acid sequences. Phylogenetic analysis using the nuclear DNA showed that B. nairi was basal to all of species of the genus Schistosoma. The 28S tree also showed that the mammalian lineage was monophyletic. However, phylogenetic analysis using the mitochondrial DNA showed that B. nairi was nested within the genus Schistosoma. The taxonomical position for this species as well as the contradiction between the results from the nuclear and mitochondrial genes were discussed.

Identities of two Paragonimus species from Sri Lanka inferred from molecular sequences

Metacercariae of Paragonimus spp. were obtained from field-collected freshwater crabs in Sri Lanka. Genomic DNA was extracted from single metacercariae. Two gene regions (partial mitochondrial cytochrome c oxidase subunit 1 (CO1) and the second internal transcribed spacer of the nuclear ribosomal gene repeat (ITS2)) were amplified using the polymerase chain reaction. Two differing sequences were obtained for each of these gene regions. Phylogenetic analyses placed the type 1 sequences as sister to a clade containing P. westermani and P. siamensis whereas the type 2 sequences were close to published sequences of P. siamensis from Thailand. The possible taxonomic status of these two types are discussed. This is the first report of molecular data about Paragonimus from Sri Lanka.

Parasitic infections in freshwater ornamental fish in Sri Lanka

A total of 1520 ornamental fish of 13 species from 26 export farms in Sri Lanka were collected between October 1999 and March 2000 and examined for parasites. Fish species examined were guppy Poecilia reticulata, goldfish Carassius auratus, platy Xiphophorus maculatus, molly Poecilia sphenops, angel Pterophyllum scalare, swordtail Xiphophorus helleri, tetras Hyphessobrycon species, barbs Capeota and Puntius spp., gourami Colisa sp., carp Cyprinus carpio, fighters Betta spelendens and others (Brachydanio and Astronotus spp.). Nine species of monogenean trematodes (Dactylogyrus extensus, Dactylogyrus cf. extensus, D. vastator, Dactylogyrus cf. vastator Dactylogyrus spp., Gyrodactylus turnbulli, G. katherineri, Gyrodactylus cf. katherineri, Gyrodactylus spp.), 7 protozoan species (Trichodina nigra, Trichodina spp., Tetrahymena corlissi, T. pyriformis, Ichthyophthirius multifiliis, Ichthyobodo necator, Piscinoodinium spp.), 3 species of copepod arthropods (Lernaea cyprinacea, Ergasilus ceylonensis, Argulus foliaceus), 1 metacercarial stage of a digenean trematode (Centrocestus spp.) and 1 nematode (Capillaria spp.) were identified. Parasites were found in fish from 23 of the 26 farms with an overall prevalence of parasitism in 45.3% of fish. The variation in farm prevalence among different parasites was significant (p < 0.01). Fish infection rates with monogenean trematodes, protozoans, copepod crustaceans, digenean trematodes and nematodes were 28.3, 18.4, 4.8, 0.8 and 0.4%, respectively. In all, 50 out of 590 (50/590) guppies were infected with Tetrahymena, compared with 13/930 for all other species, which is a statistically significant result (p < 0.01). Similarly, 13/44 and 18/44 carp were infected with Argulus foliaceus and Lernaea cyprinacea, compared with 7/1476 and 15/1476, respectively, for all other species combined (p < 0.01). Capillaria spp. was found only in guppies (4/590) and angel fish (3/92) while Centrocestus spp. was found in goldfish (12/153) only.

Benefit of the control of gastrointestinal nematode infection in goats in the dry zone of Sri Lanka

The benefit of gastrointestinal nematode control in cross-bred goats in the dry area of Sri Lanka was studied throughout 1 year by comparing the performances of three groups: group 1 animals (n = 11) were left untreated against gastrointestinal nematodes; group 2 animals (n = 11) were given monthly anthelmintic treatment. doramectin, at the dose rate of 300 microg/kg bodyweight during the entire study period; group 3 animals (n = 11) were also given monthly doramectin treatment at the dose rate of 300 microg/kg bodyweight but only during the rainy months, October to January and again once in April. All three groups were turned out together on to communal pasture. Tracers were used for the monthly estimation of gastrointestinal nematode burdens. Four untreated animals and a group 3 animal suffered from parasitic gastroenteritis during the study period. When compared with the controls, the treated groups had significantly lower gastrointestinal nematode infection as indicated by faecal egg counts (P<0.01). Faecal egg counts in group 3 were significantly higher than those in group 2 (P < 0.01). When compared with the controls, the treated groups had significantly greater weight gains (P< 0.05). Haemonchus contortus and Trichostrongylus colubriformis were the predominant gastrointestinal nematodes identified from tracers. The worm burden varied according to the rainfall pattern, with very minimal transmission during the dry period which extends from May to August. Under the conditions of this study, the monthly anthelmintic treatments increased weight gains and prevented parasitic gastroenteritis of goats in the dry zone of Sri Lanka.

Affinities between Asian non-human Schistosoma species, the S. indicum group, and the African human schistosomes

Schistosoma species have traditionally been arranged in groups based on egg morphology, geographical origins, and the genus or family of snail intermediate host. One of these groups is the 'S. indicum group' comprising species from Asia that use pulmonate snails as intermediate hosts. DNA sequences were obtained from the four members of this group (S. indicum, S. spindale, S. nasale and S. incognitum) to provide information concerning their phylogenetic relationships with other Asian and African species and species groups. The sequences came from the second internal transcribed spacer (ITS2) of the ribosomal gene repeat, part of the 28S ribosomal RNA gene (28S), and part of the mitochondrial cytochrome c oxidase subunit 1 (CO1) gene. Tree analyses using both distance and parsimony methods showed the S. indicum group not to be monophyletic. Schistosoma indicum, S. spindale and S. nasale were clustered among African schistosomes, while S. incognitum was placed as sister to the African species (using ITS2 and 28S nucleotide sequences and CO1 amino acid sequences), or as sister to all other species of Schistosoma (CO1 nucleotide sequences). Based on the present molecular data, a scenario for the evolution of the S. indicum group is discussed.

Infectivity of Cryptosporidium parvum isolated from asymptomatic adult goats to mice and goat kids

An experimental study was carried out in neonatal goat kids to examine the infectivity of Cryptosporidium oocysts, pattern of oocyst shedding and morphological changes in the intestine during the infection. Cryptosporidium oocysts isolated from adult asymptomatic goats, and identified as C. parvum by polymerase chain reaction (PCR) were used in this study. Of three 4-day-old goat kids, two were orally infected with C. parvum oocysts (10(5) oocysts in 10 ml PBS/kid). One goat kid given 10 ml PBS only by the oral route served as a control. Cryptosporidium oocysts were detected in the faeces of one infected kid on day 3 post-inoculation (pi) whereas in the other 6 days pi. The faecal oocyst counts gradually increased and the peak counts in the two kids were 2 x 10(6)g(-1) (on day 12 pi) and 3.2 x 10(6)g(-1) (on day 14 pi). The increase in faecal oocyst output coincided with diarrhoea in an infected kid from days 10-17 pi. Although the oocyst excretion declined gradually after the peak, both infected kids excreted oocysts until euthanized on days 20 and 22 pi. Light and scanning electron microscopic investigations of the ileum revealed the endogenous stages on the brush border of the enterocytes, infiltration of neutrophils and mononuclear cells into the lamina propria, atrophy, stunting and fusion of villi. For purposes of comparison, goat Cryptosporidium oocysts were inoculated orally (10(3) oocysts/mouse) to eight, 1-week-old mice. All experimental mice excreted oocysts from day 3 pi, and four infected mice continued to excrete oocysts up to day 42 pi. The experimental infection described in goat kids resembled the natural disease in terms of oocyst excretion, clinical signs and intestinal pathology. The ability of oocysts excreted by asymptomatic goats, to infect goat kids and mice is likely to have a major impact on the epidemiology of cryptosporidiosis in livestock and man.