Blood parasites of dogs in Ibadan

Between March, 1974 and February, 1975, blood smears made from 500 of the dogs brought to the small animal clinic of the University of Ibadan and the state owned veterinary clinic in the same town were stained with Giemsa and examined for blood parasites. Forty-nine per cent of the dogs carried blood parasites, the commonest of which was Babesia cards. Others were B. gibsoni, Haemobartonella canis, Trypanosoma congolense, Eperythrozoon and Microfilaria. The parasitaemia due to these parasites in the dogs examined was mostly light, although a substantial number of dogs had medium and heavy parasitaemias. No significant difference was found in the susceptibility of the local and exotic breeds to infection with the parasites.     

Parasite population dynamics in pigs infected with Trichuris suis and Oesophagostomum dentatum

The aim of the present study was to investigate the population dynamics and potential interactions between Trichuris suis and Oesophagostomum dentatum in experimentally co-infected pigs, by quantification of parasite parameters such as egg excretion, worm recovery and worm location. Forty-eight helminth naïve pigs were allocated into four groups. Group O was inoculated with 20 O. dentatum L₃/kg/day and Group T with 10 T. suis eggs/kg/day. Group OT was inoculated with both 20 O. dentatum L₃/kg/day and 10 T. suis eggs/kg/day, while Group C was kept as an uninfected control group. All inoculations were trickle infections administered twice weekly and were continued until slaughter. Faecal samples were collected from the rectum of all pigs at day 0, and twice weekly from 2 to 9 weeks post first infection (wpi). Six pigs from each group were necropsied 5 wpi and the remaining 6 pigs from each group were necropsied 10 wpi. The faecal egg counts (FEC) and total worm burdens of O. dentatum were dramatically influenced by the presence of T. suis, with significantly lower mean FECs and worm burdens at 5 and 10 wpi compared to single infected pigs. Furthermore, in the presence of T. suis we found that O. dentatum was located more posteriorly in the gut. The changes in the Trichuris population were less prominent, but faecal egg counts, worm counts 5 wpi (57% recovered vs. 39%) and the proportion of infected animals at 10 wpi were higher in Group OT compared to Group T. The location of T. suis was unaffected by the presence of O. dentatum. These results indicate an antagonistic interaction between T. suis and O. dentatum which is dominated by T. suis.     

Comparison of experimental models for Streptococcus suis infection of conventional pigs

Four different experimental models for Streptococcus suis-induced disease were compared to find a model that closely mimics naturally occurring disease in conventional pigs. Fourteen, 2-week old pigs free of S. suis type 2 were used in 2 experiments. In experiment 1, 3 pigs were inoculated intravenously (IV) and 3 pigs intranasally (IN) with S. suis. Two out of 3 of the IV-inoculated pigs exhibited signs of severe central nervous system disease (CNS) and were euthanized. Streptococcus suis type 2 was isolated from whole blood, joints, and serosal surfaces of both pigs. No clinical signs and no growth of S. suis were detected in the IN-inoculated pigs. In experiment 2, 4 pigs were inoculated IV and another 4 were inoculated IN with the same isolate as in experiment 1. One hour before inoculation the IN-inoculated pigs were given 5 mL of 1% acetic acid intranasally (IN-AA). All the IV-inoculated pigs showed CNS disease and lameness, and 2 of the pigs became severely affected and were euthanized. All the IN-AA inoculated pigs exhibited roughened hair coats and 2 pigs developed severe CNS disease and were euthanized. Streptococcus suis was isolated from the joints and blood of 3 pigs in the IV-inoculated group. Streptococcus suis was isolated from blood of 2 pigs, meninges of 3 pigs, and joints of 1 pig in the IN-AA inoculated group. Natural exposure to S. suis most likely occurs by the intranasal route. The IN-AA model should serve as a good model for S. suis-induced disease, because the natural route of exposure is intranasal and the IN-AA model was effective in inducing disease that mimics what is observed in the field.     

Studies ofStreptococcus suis type 2 infection in pigs

Investigations into the immunology, pathogenesis and epidemiology ofStreptococcus suis type 2 infections were carried out in experimental pigs and in naturally-occurring field outbreaks of disease.The capsular polysaccharide fromStr. suis type 2 was shown to induce opsonic antibodies in pigs when injected with Freund's incomplete adjuvant, but difficulties encountered in experimental production of the disease prevented a study of their protective effects.Problems with the bactericidal tests led to an investigation of other assays for antibodies againstStr. suis type 2, namely, a phagocytic test with pig neutrophils, a mixed reverse passive antiglobulin haemagglutination test and an indirect haemagglutination test. There was evidence that with modifications both the latter tests would be useful.Transmission studies in 39 conventionally-reared and 7 hysterectomy-derived, colostrum-deprived pigs yielded interesting results with regard to the distribution of the organism in relation to the disease process.Tonsil carriage in clinically-healthy pigs was demonstrated after experimental and natural infection. Detectable carrier rates varied between 0 and 59%. The organism was shown to persist in the presence of circulating opsonic antibodies and in pigs on penicillin-medicated feed. Attempts to isolate the organism from the genital tract were unsuccessful.Medicated early weaning and classical SPF techniques applied to infected herds appeared to be effective in producing pigs free fromStr. suis type 2 infection.     

Prevalence of gastrointestinal nematodes in growing pigs in Kabale District in Uganda

During the last 30 years, pig production in Uganda and neighbouring counties has increased markedly. Pigs are mainly kept as a source of income for small-scale farmers; however, the pig production is subject to several constraints, one of them being worm infections. A study was carried out in rural communities in Kabale District in the South Western part of Uganda in September and October 2007 in order to estimate the prevalence of gastrointestinal nematode parasites in pigs based on coprological examination. Fifty-six households were randomly selected and visited. Housing system and deworming history were recorded. Faeces was sampled from rectum of one to five pigs (age, 3–12 months) per household. A total of 106 pigs were examined coprologically of which 91% excreted nematode eggs. The following prevalences of nematode eggs were recorded: strongyles (89%), Ascaris suum (40%), Trichuris suis (17%) and spiruroid eggs (48%). On household level, rearing pigs on slatted floors in pens significantly reduced the faecal egg excretion of strongyle eggs with almost 80% (p = 0.010) and a significant interaction between floor type and anthelmintic treatment was found for spiruroids (p = 0.037). Fifteen T. suis egg positive pigs were selected for post-mortem examination of the gastrointestinal tract. The post-mortem examinations revealed that 93% pigs were infected with Oesophagostomum spp. (worm burden, min–max 10–2,180), 73% with A. suum (1–36), 67% with T. suis (6–58), and 20% with Hyostrongylus rubidus (worms not quantified). In general, nematode infections were widespread and polyparasitism common in pigs in Uganda. However, worm burdens were moderate which may be related to recent deworming or to the practice of rearing pigs on slatted floors in wooden elevated pens.     

Breed and sex influences on porcine haematological picture under hot humid climatic conditions

An investigation was undertaken of some haematological characteristics of one indigenous and five exotic breeds of pigs kept on a farm in the hot, humid climate of Ibadan, Nigeria. The total white blood cell counts were not affected by breed and sex but the other parameters exhibited various degrees of response to these two variables, the males of each breed tending to have higher values than the females. The indigenous pigs generally had higher values than the exotic breeds. Of the latter, only the Landrace and Large White had haematological values somewhat similar to those of the West African indigenous pig. This suggests that the Landrace and Large White breeds may be more suited than the other exotic breeds investigated to the climatic conditions prevalent in Ibadan.     

The incidence of adult and larval stage Taenia hydatigena in Uttar Pradesh (India)

A total of 1023 dogs of different breeds from different parts of Uttar Pradesh State were examined for the presence of Taenia hydatigena, and 810 sheep, 1015 goats and 1040 pigs were examined for the presence of Cysticerus tenuicollis, to determine the incidence of these parasites. In dogs, the incidence of T. hydatigena was found to be 40.95%. The rate of infection was higher in street dogs than in dogs kept indoors.Cysticercus tenuicollis was found in 37.03% of sheep, 27.29% of goats and 8.30% of pigs. The rate of infection was higher in sheep than in goats or pigs. A high incidence of infection was found in the rainy season. The intensity of infection was higher in old than in young animals.     

Breed and sex influences on porcine haematological picture under hot humid climatic conditions

An investigation was undertaken of some haematological characteristics of one indigenous and five exotic breeds of pigs kept on a farm in the hot, humid climate of Ibadan, Nigeria. The total white blood cell counts were not affected by breed and sex but the other parameters exhibited various degrees of response to these two variables, the males of each breed tending to have higher values than the females. The indigenous pigs generally had higher values than the exotic breeds. Of the latter, only the Landrace and Large White had haematological values somewhat similar to those of the West African indigenous pig. This suggests that the Landrace and Large White breeds may be more suited than the other exotic breeds investigated to the climatic conditions prevalent in Ibadan.     

A comparison of the infectivity of Trichuris suis ova embryonated by four different methods

Four methods for embryonating the eggs of Trichuris suis in the laboratory were compared. Eggs were mixed with moist vermiculite (method 1) or were suspended in a 0.2% potassium dichromate solution that was either aerated (2), non-aerated (3) or deoxygenated (4). It was shown that differences in the method of culture profoundly affected the ability of the fully developed eggs to hatch and the parasites to become established in pigs. Of the four methods compared, ova of highest infectivity were produced after culture in moist vermiculite.     

Opportunities for conservation and utilisation of local pig breeds in low-input production systems in Zimbabwe and South Africa

Purpose and methods

In situ conservation of pig genetic resources requires understanding of the farming systems under which the pigs are kept. The objective of the study was to characterise smallholder pig production systems where indigenous pigs are kept in order to assess opportunities for in situ conservation of these pigs. Factors influencing pig herd sizes, ranking of pigs in smallholder production systems, breeds and breed preferences, pig ownership patterns, traits preferred by farmers and constraints to production were investigated in a survey involving 199 farmers from Chirimhanzu District of Zimbabwe, Vhembe, Alfred Nzo and O. R. Tambo Districts of South Africa.

Results

Income was the major factor influencing most pig production related parameters. Most pigs (69.67 %) were owned by women, with most of the women falling into the very low income group. Farmers kept pigs for several reasons that were common across geographical zones and income groups. The odds of a farmer ranking pigs first in the production system depended on the absence of other livestock (P?<?0.05). Farmers in the higher income group tended to mention poor feed resources and access to information as constraints (P?<?0.05) compared to the very low income group. There was preference heterogeneity in the breeds kept and the reasons for breed choice across the income groups and geographical zones. Fewer farmers in the very low income group (42.62 %) recognised the need to conserve local pigs compared to the low income group (80.49 %), the medium income group (50.00 %) and the high income group (100.00 %; χ ²?=?19.14; P?<?0.001).

Conclusions

It was concluded that farmers see value in local pigs and are willing to conserve them. In situ conservation programmes are possible and these should recognise the role of poor women in conserving and enhancing indigenous pig genetic resources.     

Aegyptianellosis,eperythrozoonosis, grahamellosis and haemobartonellosis

Aegyptianellosis, eperythrozoonosis, grahamellosis and haemobartonellosis are diseases caused by procaryotic microorganisms which parasitize the erythrocytes of a variety of animals. Differentiation between Eperythrozoon and Haemobartonella is difficult. The parasites are similar in the living state, being small cocci or rods. In stained preparations Eperythrozoon may appear to be annular. The major criterion for differentiation is the relation of the parasite to the erythrocyte. Haemobartonellae are tightly attached to the erythrocyte and are rarely seen free in the plasma. Eperythrozoa are loosely attached to the erthrocyte, can be readily disloded and are often seen free in the plasma. Aegyptianella which occurs intracellularly in an inclusion is easily differentiated from the others while Grahamella, which is rod shaped, is always intracellular and is not in an inclusion but is scattered throughout the erythrocyte's cytoplasm. These organisms are not generally pathogenic. A slight parasitemia, mild anemia and slight fever may follow infection in the intact animal. Most infected animals remain nonclinical carriers. Splenectomy of a carrier animal or infection of a splenectomized animal will produce high parasitemia; even then, the physiological disturbance is mild. The only exceptions to the general rule that infection with these organisms produces a mild disease in intact animals are infections with Aegyptianella pullorum, Eperythrozoon suis and Haemobartonella felis. Aegyptianella pullorum produces aegyptianellosis of fowl, a disease characterized by anemia, E. suis produces “icteroanemia of swine” and H. felis produces “filine infectious anemia”.     

The immune response against Chlamydia suis genital tract infection partially protects against re-infection

The aim of the present study was to reveal the characteristic features of genital Chlamydia suis infection and re-infection in female pigs by studying the immune response, pathological changes, replication of chlamydial bacteria in the genital tract and excretion of viable bacteria. Pigs were intravaginally infected and re-infected with C. suis strain S45, the type strain of this species. We demonstrated that S45 is pathogenic for the female urogenital tract. Chlamydia replication occurred throughout the urogenital tract, causing inflammation and pathology. Furthermore, genital infection elicited both cellular and humoral immune responses. Compared to the primo-infection of pigs with C. suis, re-infection was characterized by less severe macroscopic lesions and less chlamydial elementary bodies and inclusions in the urogenital tract. This indicates the development of a certain level of protection following the initial infection. Protective immunity against re-infection coincided with higher Chlamydia-specific IgG and IgA antibody titers in sera and vaginal secretions, higher proliferative responses of peripheral blood mononuclear cells (PBMC), higher percentages of blood B lymphocytes, monocytes and CD8⁺ T cells and upregulated production of IFN-γ and IL-10 by PBMC.

Electronic supplementary material

The online version of this article (doi:10.1186/s13567-014-0095-6) contains supplementary material, which is available to authorized users.     

Recurrence of Chlamydia suis infection in pigs after short-term antimicrobial treatment

The effect of short-term antimicrobial treatment on natural excretion of Chlamydia suis in rectal swabs and C. suis and Chlamydophila psittaci in nasal swabs was investigated in 47 clinically normal piglets by quantitative real-time PCR. Pigs were treated IM with 4 mg/kg enrofloxacin for 5 days (n = 22) or 2.5 mg/kg enrofloxacin for 3 days followed by 100 mg/mL tiamulin (n = 25). Antimicrobial treatment reduced the number of pigs positive for chlamydiae and the quantity of chlamydial DNA in positive swabs for a few days, but chlamydial excretion recurred in both groups. Short-term antimicrobial treatment at dosages recommended for treatment of other bacterial infections in pig herds was not effective in eliminating naturally occurring subclinical chlamydial infection in pigs.     

Comparison of blood smear and indirect fluorescent antibody techniques in detection of haemoparasite infections in trade cattle in Nigeria

The incidence of blood parasites in trade cattle was surveyed with emphasis on tick-borne parasites, using blood smears and immunofluorescent antibody (IFA) techniques. With the blood smear method, about 9 and 8.9% of cattle examined were found positive for Babesia bigemina and Anaplasma marginale, respectively. Percentage infections with other parasites were 3.33, 1.92, 0.75, 0.75 and 0.58, respectively, for Babesia bovis, Trypanosoma brucei, Anaplasma centrale, Eperythrozoon and Theileria species as well as Trypanosoma congolense. The incidence of A. marginale infection was at its peak during the rainy season while B. bigemina was most prevalent during the dry season. There were mixed infections of Anaplasma and Babesia (1.42%); Babesia and trypanosomes (1.00%); Babesia and Eperythrozoon (0.75%) and Babesia and Theileria (0.75%). Using the indirect fluorescent antibody test, 93, 55 and 68% of cattle sera examined were found to be positive for B. bigemina, B. bovis and A. marginale, respectively. Forty-nine percent of the positive sera of B. bigemina had highest titres. The importance of using serological means for determining the endemic levels of tick-borne diseases in cattle in Nigeria is discussed.     

Effect of an Immunosuppressor (Dexamethasone) on <Emphasis Type="Italic">Eperythrozoon</Emphasis> Infection

The aim was to study the relationship between the infection rate of Eperythrozoon suis and the status of the immune system. Four pigs with chronic eperythrozoonosis were divided into experimental and control groups. Immunosuppression of the experimental group was accomplished by injecting with high-dose glucocorticoid (dexamethasone) on 3 consecutive days. Microscopic examination of blood smears was performed to observe the change of infection rate after administration. The blood samples of each group were collected on day 7 after administration for half-nested PCR assay. The microscopic results showed that the infection rate of the experimental group rose distinctly by 40 h late and remained at 90% in the days following administration. No changes were observed in the control group. PCR results showed a single expected 250 bp fragment in each group, which validated the positive microscopic results. This study demonstrated the significant effect of dexamethasone (DEX) on Eperythrozoon infection.     

Immune and inflammatory responses in pigs infected with Trichuris suis and Oesophagostomum dentatum

The aim of the present study was to investigate parasite induced immune responses in pigs co-infected with Trichuris suis and Oesophagostomum dentatum as compared to mono-species infected pigs. T. suis is known to elicit a strong immune response leading to rapid expulsion, and a strong antagonistic effect on O. dentatum populations has been observed in co-infected pigs. Forty-eight helminth naïve pigs were allocated into 4 groups in a 2-factorial design. Two groups were trickle inoculated with either 10 T. suis eggs/kg/day (Group T) or 20 O. dentatum L3/kg/day (Group O). Group OT was infected with same levels of both T. suis and O. dentatum (Group OT) and Group C remained uninfected. In each group, six pigs were necropsied after 35 days and the remaining pigs after 71 days. Parasite E/S-antigen specific serum antibodies were quantified by an in-direct ELISA. qPCR was used to measure the expression of immune function related genes in the mucosa of proximal colon and the draining lymph node. Highly significant interactions were identified for O. dentatum specific IgG1 (p < 0.0001) and IgG2 (p < 0.0006) antibodies with a remarkable 2-fold higher antibody response in group OT pigs as compared to group O. These findings indicated that T. suis enhanced the antibody response against O. dentatum in Group OT. The gene expression data confirmed a strong Type 2 response to T. suis (e.g. marked increase in IL-13, ARG1 and CCL11) and clearly weaker in amplitude and/or delayed onset response to O. dentatum in the single infected group. Interactions were found between the two nematodes with regard to several cytokines, e.g. the increase in IL-13 observed in Group T was absent in Group OT (p = 0.06, proximal colon mucosa, 35 and 71 p.i.). Some of these immune response-related interactions may support, or even partially explain, the observed interactions between the two worm populations in co-infected pigs.