Role of mastitis in on-farm deaths of Finnish dairy cows.

According to our recent necropsy-based study, mastitis is the most common underlying diagnosis of on-farm deaths in Finnish dairy cows. However, it remained unanswered to what extent mastitis has contributed to death of all necropsied cows. In the present study, based on histopathology we detected one third of the necropsied dairy cows having active inflammatory udder lesions (n = 110). The role of mastitis varied and was interpreted by causes of death (underlying, intermediate, immediate, other significant). Mastitis was most commonly either the underlying (28%) or both immediate and underlying cause of death (48%), and only seldom the immediate (4%) or intermediate (4%) cause of death. Mastitis occurred either as the only cause leading to death (mastitis only, MO, 39%), or with many other contributing diseases (multiple diseases, MD, 61%) which were interacting with mastitis and together leading to death. Between these groups (MO vs. MD), time of mastitis occurrence during lactation, producer-reported duration of illness, clinical signs, and medication differed, as well the histopathological severity of mastitis. The cases, where mastitis was the only initial insult, occurred evenly throughout the entire lactation, but the cases with many interacting diseases clustered in early lactation. In multiple diseases -cases mastitis occurred concurrently with metritis (31%), aspiration pneumonia (24%), acute trauma/dystocia (15%), or with other diseases, such as ketosis, hepatic lipidosis, rumenitis, and abomasal diseases. For a pathologist, the gross mastitis diagnosis was most challenging at the beginning of the lactation, especially if inflammation was mild to moderate, suggesting the value of histopathological examination being highest at that time. Also, producers reported mastitis signs less frequently if cow had many simultaneously occurring diseases. Therefore, even if clinical signs of other diseases are present, the udder should be considered a potential cause of illness, and it should be examined, especially in dry and transition period cows.

Necropsy-based study on dairy cow mortality-Underlying causes of death.

The worldwide problem of increasing dairy cow mortality is widespread in modern production systems, it causes economic losses, and indicates problems with herd health and welfare. Most studies on causes of dairy cow mortality are limited as they are based on secondary register data, or questionnaires for producers or veterinarians, and neither necropsies nor histopathologic analyses are usually performed. For this reason, no definite causes for dairy cow deaths have been determined making it difficult or impossible to implement effective preventive measures. The objectives of this study were to (1) determine the causes of on-farm mortality of Finnish dairy cows, (2) determine the usefulness of routine histopathologic analysis in bovine necropsies, and (3) assess how reliable producers' perception about the cause of death is. Underlying diagnoses of on-farm deaths were determined through necropsy of 319 dairy cows at an incineration plant. The necropsy data were combined with background information obtained from online questionnaires covering cow and herd records. Mastitis was the most common underlying diagnosis of death (26.6%), followed by digestive disorders (15.4%), other known disorders (13.8%), calving-associated disorders (12.2%), and locomotion disorders (11.9%). The underlying diagnoses of death varied during different stages of lactation and with parity. A large proportion of the study cows (46.7%) died during the first 30 d after calving, and of those, 63.6% died during the first 5 d. A routine histopathologic analysis was performed in every necropsy, and it changed the preliminary gross diagnosis in 18.2% of the cases. Producers' perception about the cause of death agreed with the necropsy-based underlying diagnosis of death in 42.8% of the cases. It was most consistent for mastitis, calving disorders, locomotion diseases, and accidents. In cases where producers had no insights about the cause of death, necropsy revealed the final underlying diagnosis in 88.2% of cases, demonstrating the usefulness of necropsy. Based on our findings, necropsies provide useful and reliable information to develop control programs for cow mortality. Including routine histopathologic analysis in necropsies, more accurate information may be obtained. Furthermore, targeting preventive measures on transitional cows may be most effective, as the number of deaths was highest at this time.

Botfly Cephenemyia ulrichii larvae in the nasal cavity and nasopharynx of a dog with respiratory signs.

A Finnish Lapphund dog with acute upper respiratory signs and gagging was presented at veterinary clinic. During rhinoscopy, ten 1- to 2-mm long, actively moving larvae were found in the dog's nasal cavity and nasopharynx and identified as Cephenemyia ulrichii (Diptera: Oestridae). This moose (Alces alces) parasite is widespread in Finland but has not been reported before from an accidental canine host. Clinical signs resolved with imidacloprid/moxidectin spot-on formulation.

Sexual Orientation Among Unmarried Final Year University Students in Osun State: Distribution, Determinants and Level of Satisfaction.

BACKGROUND: Sexual Orientation is an enduring pattern of romantic or sexual attraction, with the attractions broadly incorporated under heterosexuality and non-heterosexuality. Societal and other factors seem to affect individuals' perception of their self-identified orientation. Thus, this study sets out to document the distribution of sexual orientation, level of self-reported satisfaction, and factors associated with sexual orientation among unmarried university students. METHODS: A cross-sectional study involving 550 respondents sampled using a multi-stage sampling technique. Data collected via a self-administered questionnaire and analyzed via IBM SPSS version 20.0. RESULTS: Most respondents (93.6%) were heterosexuals, 4.7% bisexuals, 1.3% lesbian women and 0.40% gay men. More heterosexuals (80.4%) were fully satisfied with their self-identified sexual orientation compared to 57.2% of non-heterosexuals. Respondents who had religious upbringing and those whose parents were currently married were less likely to have sexual orientation outside of heterosexuality. CONCLUSION: The most prevalent sexual orientation was heterosexuality, with more heterosexuals also expressing satisfaction than others. With the level of dissatisfaction expressed by those who are not heterosexuals as well as the factors associated with heterosexuality, it is plausible to conclude that societal values and/or prejudices constitute major factors in individuals self-identifying with some particular sexual orientation and the satisfaction derived therein.

Non-tuberculous Mycobacteria can Cause Disseminated Mycobacteriosis in Cats.

Mycobacteriosis caused by non-tuberculous mycobacteria (NTM) is a rising concern in human medicine both in immunocompromised and immunocompetent patients. In cats, mycobacteriosis caused by NTM is considered mostly to be a focal or dermal infection, with disseminated disease mostly caused by Mycobacterium avium. We describe three cases of disseminated mycobacteriosis in cats, caused by Mycobacterium malmoense, Mycobacterium branderi/shimoidei and M. avium, with no identified underlying immunosuppression. In all cases, extracellular mycobacteria were seen in the pulmonary epithelium, intestinal lumen and glomerular tufts, which could affect the shedding of the organism. The present study highlights the importance of mycobacteriosis as a differential even in immunocompetent animals. Considering the close relationship of owners and pets and the potential presence of free mycobacteria in secretions, cats should be considered as a possible environmental reservoir for mycobacteria.

Fertility and growth of nulliparous ewes after feeding red clover silage with high phyto-oestrogen concentrations.

The study aimed to determine the effects of red clover (Trifolium pratense) silage with high phyto-oestrogen content on ewe performance during their first breeding season. Red clover silage containing formononetin, biochanin A, genistein, and daidzein was fed to 10 nulliparous ewes of the prolific Finnish Landrace breed before, during and after the breeding season, for a total of 5 months. A control group of 10 ewes was fed with grass silage. The mean numbers of foetuses per pregnancy were 2.1±0.7 and 2.2±0.8 for the red clover and control groups, respectively. The total mass of the uterus with its contents was significantly greater in ewes of the red clover group compared with those of the control group. This difference was mainly explained by the greater volume of foetal fluids. Serum progesterone concentration in the red clover group was significantly lower over the entire period analysed than in the control group. In conclusion, the fecundity of the ewes was not reduced by red clover feed with high phyto-oestrogen concentrations. The volume of foetal fluids increased that could increase the risk for vaginal prolapse before the term.

Osteoarthritic cartilage lesions in the bovine patellar groove: a macroscopic, histological and immunohistological analysis.

A high percentage of osteoarthritis (OA)-like patellar groove lesions in the stifle joint in calcium-deficient bulls has been recently reported. The prevalence of these lesions in bulls deficient in or supplemented with calcium was compared to findings in culled and healthy bulls to determine whether they represent normal anatomical variations, developmental anomalies or OA. It was hypothesized that the patellar groove lesions may represent OA. Distal cartilage samples from 160 femurs were analysed using a macroscopic Société Française d'Arthroscopie (SFA) OA grading system. Samples representing different SFA grades were subjected to Osteoarthritis Research Society International (OARSI) histological and high-mobility group box 1 (HMGB1) immunohistological OA grading. For a qualitative analysis three OA samples were immunostained for interleukin (IL)-1ß, matrix metalloproteinase (MMP)-13 and collagenase-produced COL2-3/4M neoepitopes. Patellar groove lesions were found in 48% of the femurs and were highest in calcium-deficient animals (71%, P<0.001). All three different grading systems disclosed OA in culled bulls, but no focal areas of cartilage necrosis. OARSI and HMGB1 grades were fairly concordant (Spearman's ρ=0.95, P<0.001; Cohen's κ=0.23, P<0.005), both with a slight disparity with the SFA grade (ρ=0.80 and 0.87, P<0.01; κ=0.36 and 0.46, P<0.001). IL-1ß, MMP-13 and COL2-3/4M staining patterns were compatible with OA. The study showed that patellar groove lesions are common in bulls. In all SFA, OARSI and HMGB1 graded samples the lesions clearly demonstrated OA and showed OA-typical pathophysiology. Arthroscopic SFA grading showed similar changes in calcium-deficient and calcium-supplemented bulls, but in the absence of a time course study and histological data the primary nature of these lesions could not be established with certainty.

Molecular identification of Taenia spp. in the Eurasian lynx (Lynx lynx) from Finland.

Cestodes of the genus Taenia are parasites of mammals, with mainly carnivores as definitive and herbivores as intermediate hosts. Various medium-sized cats, Lynx spp., are involved in the life cycles of several species of Taenia. The aim of the present study was to identify Taenia tapeworms in the Eurasian lynx (Lynx lynx) from Finland. In total, 135 tapeworms from 72 lynx were subjected to molecular identification based on sequences of 2 mtDNA regions, the cytochrome c oxidase subunit 1 and the NADH dehydrogenase subunit 1 genes. Available morphological characters of the rostellar hooks and strobila were compared. Two species of Taenia were found: T. laticollis (127 samples) and an unknown Taenia sp. (5 samples). The latter could not be identified to species based on mtDNA, and the rostellar hooks were short relative to those described among other Taenia spp. recorded in felids from the Holarctic region. In the phylogenetic analyses of mtDNA sequences, T. laticollis was placed as a sister species of T. macrocystis, and the unknown Taenia sp. was closely related to T. hydatigena and T. regis. Our analyses suggest that these distinct taeniid tapeworms represent a putative new species of Taenia. The only currently recognized definitive host is L. lynx and the intermediate host is unknown.

Bovine chronic osteoarthritis causes minimal change in synovial fluid.

Chronic osteoarthritis (OA) is a degenerative disease of the articular cartilage. DNA-binding high mobility group protein B1 (HMGB1) is released on cellular death/activation and acts as an endogenous danger signal and a proinflammatory cytokine. Matrix metalloproteinase (MMP)-2 and in MMP-9 are induced to mediate proteolytic degradation/remodelling of joint tissues. Collagen degradation in the bone and synovium leads to release of type I collagen-derived cross-linked carboxy-terminal telopeptide (ICTP). These molecules have been linked to the pathogenesis of OA and could have potential as synovial fluid (SF) biomarkers in OA. Cartilage and SF were obtained from 27 dairy bulls (30-61 months old) and control cartilage from six young healthy dairy bulls. OA lesions were evaluated grossly (five grades), histologically (seven Osteoarthritis Research Society International [ORSI] grades) and immunohistochemically (four HMGB1 grades). The OARSI lesion score was calculated as the product of the OARSI grade and the OARSI score (the total area of the lesions). SF concentrations of HMGB1, MMP-2 and -9 and ICTP were measured by enzyme-linked immunosorbent assay, gelatin zymography and radioimmunoassay, respectively. Seventy-two percent (39/54) of stifle joints and 85% (23/27) of the dairy bulls had at least one gross OA lesion and 94% of the lesions were localized to the distal end of the femur, with the patellar groove and the lateral trochlear ridge being predilection sites. Gross and histological grades correlated with the HMGB1 grade, but SF total cell count, percent neutrophils or the measured biomarkers did not correlate with the tissue lesions, with the exception of ICTP concentration, which correlated with the total joint score. The switch of HMGB1 from DNA-binding nuclear protein to an extracellular alarmin/cytokine correlates with the gross and histological grades of OA tissue lesions. However, the activity and extent of the tissue lesions did not correlate with other SF biomarkers, perhaps because the histological grades represent outcome measures, while SF reflects process parameters. The only exception was ICTP concentration, which reflects enhanced destruction/remodelling.

High mobility group box-1 (HMGB-1) in osteoarthritic cartilage.

OBJECTIVES: Nucleosomal high mobility group box-1 (HMGB-1) is translocated and released from necrotic and activated cells as an endogenous danger signal (alarmin) and cytokine. It was hypothesised that it plays a role in osteoarthritis (OA). characterised by cellular activation, inflammation and enchondral bone formation. METHODS: Bovine knee joint samples, collected from culled animals, were scored using histologic/histochemical grading to intact looking, mild, moderate or severe and immunohistochemically stained for HMGB-1. Chondrocyte pellets, produced from human bone marrow-derived mesenchymal stem cells and stimulated with tumour necrosis factor-a (TNF-alpha), were similarly stained. RESULTS: In healthy looking OA cartilage chondrocyte nuclei were usually HMGB-1 negative and in mild OA staining was restricted to nuclei. In moderate OA lesions HMGB-1 was also seen in the cytoplasm and occasionally pericellular matrix and in severe OA lesions often also in intra- and inter-territorial matrix. The tidemark in healthy cartilage did not contain HMGB-1, which however was seen at this interface as linear deposits even in intact-looking and mild OA lesions, as multiple wave-like deposits in moderate and as heavy granular deposits in severe lesions. TNF-alpha stimulation of chondrocytes caused translocation of HMGB-1 from the nucleus to the cytoplasm. CONCLUSIONS: In resting chondrocytes tight nucleosomal HMGB-1 binding might cause steric hindrance of immunostaining. TNF-alpha- or OA-mediated activation leads to nuclear staining and cytoplasmic translocation. Advancing OA leads to increasingly intense extra-/pericellular deposition of HMGB-1 alarmin, indicating local chondrocyte activation and/or necrosis. In particular, HMGB-1 at the tidemark might play a role in the pathological thickening of subchondral bone plate/osteophyte formation.

Setaria tundra microfilariae in reindeer and other cervids in Finland.

Harmful parasites of the wild northern boreal mammals are still surprisingly poorly studied. In 2003-2006, a peritonitis outbreak caused by the filarioid nematode, Setaria tundra, emerged in Finland's reindeer population. In order to gain knowledge about the basic biology, epidemiology, and transmission dynamics of this parasite, samples for S. tundra were collected from reindeer and other cervids during the follow-up period 2004-2006. Using morphology and molecular biology methods, we describe here S. tundra's first larval stage, microfilaria (smf), for the first time scientifically. The prevalence and densities of smf were higher in reindeer calves than in adults, overall prevalence being 42%. The overall smf prevalences for moose, wild forest reindeer and roe deer were 1.4-1.8%, 23%, and 39%, respectively. The focus of microfilaremia moved north and settled down in the south simultaneously with the peritonitis outbreak. The peak microfilaremia occurred in the first summer after the infection, and smf disappeared from the blood after 2 years. Captive reindeer were smf positive over the year. The prepatent period of S. tundra was estimated to be about 4 months, and the life span at least 14 months. This parasite likely has an important impact on boreal ecosystems.

Diagnostic exercise: Tyzzer's disease, distemper, and coccidiosis in a pup.

A 2-month-old mongrel dog had multifocal necrotizing hepatitis, interstitial pneumonia, and hemorrhagic enteritis. Immunohistochemistry detected antigens of Clostridium piliforme in the intestine and liver, and antigens of canine distemper virus within the lung, urinary bladder, brain, spleen, and liver. Furthermore, uncharacterized intralesional coccidian protozoa were observed within the intestine.

Type C bovine botulism outbreak due to carcass contaminated non-acidified silage.

The first reported bovine botulism outbreak in Finland is described. Nine out of 90 cattle on a dairy farm died after being fed non-acidified silage contaminated by animal carcasses. Type C botulinum neurotoxin gene was detected in one heifer by polymerase chain reaction (PCR) and the neurotoxin was detected by the mouse bioassay. Clostridium botulinum type C was isolated from liver samples. The isolated strain was identified with amplified fragment length polymorphism (AFLP) analysis as group III C. botulinum. To our knowledge, this is the first time that a type C bovine botulism outbreak has been diagnosed by PCR and confirmed by subsequent isolation and AFLP identification of the disease strain. The importance of the acidification process in silage production to inhibit C. botulinum toxin production in silage and thus to prevent further botulism outbreaks is emphasized. Nevertheless, preformed toxin in the carcass is not destroyed by acid.

Central primitive neuroectodermal tumour with ependymal differentiation in a dog.

A central primitive neuroectodermal tumour (PNET) with ependymal differentiation was identified in an 18-month-old female Australian terrier dog that died following signs of central nervous system disease. A large space-occupying haemorrhagic mass replaced the thalamus and part of the hypothalamus of the brain. Microscopical examination revealed a tumour formed by a compact sheet of small cells that contained ependymal and perivascular pseudorosettes. Immunohistochemically, the neoplastic cells variably expressed glial fibrillary acidic protein, neuron-specific enolase, vimentin and cytokeratin, consistent with divergent differentiation of the tumour. This case is thought to represent the first description of PNET with ependymal differentiation in a dog.

Infertile boars with knobbed and immotile short-tail sperm defects in the Finnish Yorkshire breed.

In the period 1996-2006 two specific sperm defects, the knobbed acrosome (KA) defect and the immotile short-tail sperm (ISTS) defect, showed a strong negative association with fertility in Finnish breeding boars. In this study, we examined the incidence of these two sperm defects in two pig breeds, their effects on fertility and their associations with sperm morphology and testicular histology. Semen samples from 2048 (1097 Yorkshire, 951 Landrace) boars were collected. None of the Landrace boars revealed either the KA defect or the ISTS defect. Of the Yorkshire boars, 0.8% were afflicted with the KA defect and 7.6% with the ISTS defect. Boars diagnosed with the ISTS defect produced no litters. Fertility data were available from two artificially inseminated (AI) boars and six farm breeding boars affected with the KA defect. Breeding boars with 45-81% knobbed spermatozoa (n = 6) did not produce any litters out of 71 sows bred. AI boars with 25-30% knobbed spermatozoa had a poor non-return rate (on average 47% compared with 85% for normal control boars) and produced small litters, on average 2.5 piglets less than other boars of the same breed. Morphometry of testicular tissue and distribution of different cells in the seminiferous tubules were examined in nine boars. Boars with the KA defect had a smaller diameter of the seminiferous tubules (p < 0.05) and a lower number of Sertoli cells (p < 0.05) than controls. ISTS boars, in turn, had a significantly lower number of elongated spermatids (p < 0.05), and they also produced on average only 12% of the spermatozoa of normal boars. The ISTS defect is a manifestation of an autosomal recessive disease caused by an insertion in the KPL2 gene in porcine chromosome 16. Although we tried to map the KA defect, its aetiology remains unclear.

Expression of vascular endothelial growth factor receptors coincide with blood vessel in-growth and reactive bone remodelling in experimental intervertebral disc degeneration.

OBJECTIVE: To analyze immunohistochemically the localization of the VEGF receptors in experimental intervertebral disc degeneration tissues in a pig model. MATERIALS AND METHODS: In six domestic pigs, the cranial bony endplate of the L4 vertebra were perforated into the nucleus pulposus. Three months postoperatively, the animals were sacrificed and the experimental and control vertebrae, complete with intervertebral discs, were excised and subjected for immunohistochemical staining of vascular endothelial growth factor receptors (VEGFR) along with VEGF - A, -C, -D and blood and lymphatic vessel markers vWF and LYVE-1. RESULTS: The results of immunohistochemical analysis of experimental samples showed VEGFR-1 (Flt-1) expression in intervertebral disc and all paradiscal tissues studied. In control samples expression of VEGFR-1 was lower and absent in the intervertebral discs. Comparatively less of VEGFR-2 (KDR/Flk-1) and VEGFR-3 (Flt-4) than VEGFR-1was found in degenerated intervertebral discs and paradiscal tissues. In contiguous control intervertebral discs and control paradiscal tissues VEGFR-2 and-3 receptors were expressed to a lower extent than in experimental tissues or were even totally absent. Also growth factors VEGF-A, -C, -D, as well as von Willebrand factor and to a much lower extent LYVE-1 were differently expressed in experimental and control intervertebral discs. CONCLUSION: In experimental intervertebral disc degeneration, VEGF receptors were expressed in the damaged disc and paradiscal tissues. In the same tissues, VEGF-A, -C, and -D, signs of blood and lymphatic vessel in-growth and reactive/adaptive vertebral bone remodelling were found.

Providing high-quality research training for veterinary pathologists in Europe.

Despite their key role in a wide range of fields relating to animal and public health, there is currently a lack of veterinary pathologists in Europe. In 1999, to help address the problem, the European College of Veterinary Pathologists (ECVP) and the European Society of Veterinary Pathology (ESVP) established a joint Education Committee. In this Special Article, Professor Anja Kipar and colleagues, all members of the committee, describe the ECVP/ESVP Summer Schools in Veterinary Pathology programme, which aims to provide high-quality research training for veterinary pathologists from all over Europe and beyond.

Multinuclear-multiflagellar sperm defect in a bull--a new sterilizing sperm defect.

The development and use of modern techniques, such as intracytoplasmic sperm injection (ICSI), gene knockout and sperm fluorescence in situ hybridization with chromosome- specific probes, have significantly increased our knowledge about sperm defects. We describe a new oligoasthenoteratozoospermic defect in a bull. Because of its morphological characteristics the defect was named the multinuclear-multiflagellar sperm defect. All spermatozoa in the ejaculate were abnormal. Many of the spermatozoa had multiple nuclei and multiple sperm tails. All spermatozoa lacked an acrosome, and only seldom did spermatozoa have a mitochondrial helix in the midpiece area. Meiosis and spermiogenesis were severely affected in this otherwise phenotypically normal bull. The sperm defects resembled the phenotype of a targeted gene knockout Hrb(-/-) (HIV-1 Rev-binding/interacting protein) mutant mouse strain, which is expressed as sterility in males, while females remain fertile. Since the father of this bull has been extensively used in at least three countries the defective gene has possibly become widespread in the red and white breeds (Ayrshire, Swedish Red and White, Norwegian Red) in the Nordic countries. However, it is not proved that the father of this bull is a carrier of this defect.

RANKL and cathepsin K in diffuse sclerosing osteomyelitis of the mandible.

BACKGROUND: Diffuse sclerosing osteomyelitis (DSO) of the mandible is characterized by mixed bone resorption and formation. METHODS: Immunohistopathology of DSO in the clinically acute and subacute phases was compared with healthy bone. RESULTS: Receptor activator of nuclear factor kappaB ligand (RANKL) was found in DSO lesions. When it was used in vitro to stimulate monocytes, cathepsin K expression was observed in mononuclear prefusion precursors and in multinuclear giant cells. Similarly, exacerbations of DSO were characterized by RANKL and induction of cathepsin K in mononuclear precursor cells, which subsequently seem to differentiate into osteoclasts or foreign body giant cells. The proportion of bone to soft tissue increased with the duration of disease. CONCLUSIONS: RANKL-driven osteoclastogenesis and acidic cysteine endoproteinase cathepsin K seem to play important roles in DSO as osteoclast-mediated bone resorption may represent the primary disease process later followed by new bone formation.

Canine intestinal helminths in Finland: prevalence, risk factors and endoparasite control practices.

In this survey, the prevalence of canine gastrointestinal helminths in Finland was investigated by coprological examination (n = 541) and possible risk factors for helminth infections in dogs were analysed. In addition, the dog owners (n = 296) completed a questionnaire about use of anthelmintics, sources of information about parasites and antiparasitic treatments and reasons for choosing the drugs. The prevalence of gastrointestinal helminths was 5.9%. Eggs from four different species were identified in the faecal samples. Toxocara canis eggs were present in 17 dogs (3.1%), Uncinaria stenocephala eggs in 14 dogs (2.6%) and Diphyllobothrium latum eggs in 2 dogs (0.4%). Moreover, one sample contained eggs of Trichuris vulpis (0.2%). Kennel housing and visits abroad were identified as risk factors for T. canis and U. stenocephala infections. Most dogs (86.0%) received anthelmintic treatment at least once a year. Hunting dogs were dewormed least; one-third was treated less than once a year. Approximately, half of the owners occasionally changed the anthelmintic used. The most important trait of the anthelmintic was its broad spectrum, fenbendazole being the most commonly chosen. Veterinarians, dog magazines and dog breeders were the predominant sources of information concerning parasites and deworming strategies.