Teat onchocercosis in cows with reference to prevalence, species involved and pathology

The present study reports teat onchocercosis in cows in the province of Kars in north eastern Turkey with reference to the prevalence, species involved and pathological findings. In the study, 600 cows of various breeds and ages slaughtered in the local abattoir were examined and 145 (24%) were found to have various lesions on their teats, of which 45 (31%) were infected with three Onchocerca species (Onchocerca gutturosa, O. lienalis and an unidentified Onchocerca spp.), identified according to their morphological characteristics. Gross pathological examination of the teats with lesions revealed scabies and chaps of varying sizes, healed sores and small nodules. Histopathologically, large numbers of microfilariae were commonly observed within the collagenous fibre bundles of the dermis, with only a few microfilariae in the dermis in some cases. The microfilariae were also often found to have accumulated around the perivascular spaces and were frequently associated with infiltration by inflammatory cells, predominantly eosinophil leukocytes and mononuclear cells. In two cases, microfilariae were discovered exclusively in the lumen of the capillaries of the dermal papillaries. In one case, in which microfilarae were not encountered, sections of adult worms surrounded by neutrophil leukocytes were detected free in the teat canal. The presence of extensive teat lesions along with microfilariae of the Onchocerca species as found in this study warrants further assessment of the impact of onchocercosis on dairy farming.     

Trypanosomosis prevalence in cattle on Mafia Island (Tanzania)

During two consecutive surveys (February and August/Sept 2002), a total of 970 cattle from the cattle population of Mafia Island (United Republic of Tanzania) were blood-sampled. All blood samples were microscopically screened for the presence of trypanosomes and a portion of these were checked for antibodies with an Ab-ELISA and for the presence of trypanosomal DNA with PCR. Microscopic evidence of trypanosomes of the congolense group (sub-genus Nannomonas) was found in 0.8% of the animals (8/970) and in two cases the species identified was confirmed by PCR as Trypanosoma congolense savannah type. Non-pathogenic Trypanosoma theileri were detected in 3.2% (31/970) of the samples using the Dark Ground-Buffy Coat (DG-BC) technique. For survey 1 (S1), detection of antibodies (Ab-ELISA) against pathogenic trypanosomes indicated a seroprevalence of 14.2% (68/480). Of the samples, either DG positive or with a PCV lower then 25, examined by PCR, a total of 8.4% (5/59) (selected from 970 samples), were found positive for T. congolense. The low prevalence of pathogenic trypanosomes on Mafia Island is intriguing, especially in view of the omnipresence of the tsetse fly Glossina brevipalpis. Although the presence of detected trypanosomal antibodies does not necessarily indicate a current infection, the combination of serological/parasitological examinations and the results of the PCR do support this low prevalence of trypanosomosis in cattle. Despite the low prevalence, pathogenic trypanosomes are present on Mafia Island and possible reasons for this low infection rate, taking account of the relation between Glossina species present, transmission risk and trypanosomes found in cattle, are discussed also in view of a future appropriate intervention strategy.     

A review of pig pathology in Tanzania

The approximately 1.58 million pigs in Tanzania represent 3.7 % of the national population of quadruped meat-producing animals. Pigs are kept mainly by small producers who own 99.5 % of the national stock in units that average 3.04 animals (range 2–48). Government policy has had little practical application. African swine fever, foot-and-mouth disease and Cysticercosis are important diseases. The first two are notifiable diseases under Tanzania legislation; the last has widespread distribution and relevance as a major zoonosis. Ascariasis (Ascaris suum), hydatidosis (Echinococcus granulosus), leptospirosis (Leptospira interrogans) and thermophilic Campylobacter are other zoonoses associated with pigs. Gastrointestinal helminths and external parasites, especially Sarcoptes scabiei, are common. Risk factors associated with cysticercosis for humans working with pigs or eating their meat include the free-range or semi-confined management systems, the use of rivers or ponds as a source of water, lack of household sanitation, informal home slaughter, pork not being inspected at slaughter slabs and undercooked and barbecued meat. Pigs are a minor component of Tanzania’s livestock sector but there is potential for increasing their contribution to human welfare. Prospects are enhanced by the shorter life cycle, greater number of young produced per year and the possibility of producing high-quality animal protein at a lower cost than meat produced by cattle and small ruminants.     

Ocular onchocercosis in dogs: a review

In recent decades, sporadic cases of ocular Onchocerca species infection have been reported in dogs in the USA and Europe. In the acute stage of the disease severe inflammation of the ocular and periocular tissues was observed. In chronic cases, the strongly coiled, gravid nematodes were incorporated in pea- to bean-sized granulomatous nodules in various parts of the eye, including the retrobulbar space, orbital fascia, eyelid, third palpebra, conjunctiva and sclera. Apart from the ophthalmological significance of the disease, the large number of microfilariae in the skin may be responsible for acute and chronic dermatological problems. The geographical distribution and prevalence of the infection may be greater than currently thought, because the lesions may have been erroneously regarded as other ocular diseases. Onchocerciasis is the world's second most prevalent infectious cause of blindness in human beings and parasitologists have long searched for an experimental model of human onchocerciasis; ocular onchocercosis infections in dogs may provide a useful experimental system.     

Bovine trypanosomiasis in Southern Tanzania: Parasitological and serological survey of prevalence

In a survey for bovine trypanosomiasis blood smears from 1,617 cattle at 72 sites were examined. Trypanosomes were found in 93 cattle, representing 16% of the cattle in herds in which trypanosomiasis was confirmed. Of the positive cattle 56% had infections with T. congolense, 17% T. vivax and 2.2% T. brucei. Five cattle had mixed infections and in 18 cattle the species was not identified. Sera from 1,352 cattle were tested using microelisa. Ten out of 16 sites, at which no trypanosomes were found in blood smears and at which trypanocides were in use, had over 15% seropositive cattle compared with five of 19 sites at which trypanocides were not in use. It was concluded that the microelisa was a useful aid to the diagnosis of bovine trypanosomiasis and that there is a need for accurate records of drug use and livestock movements to be kept. The serious risk of drug resistant strains of trypanosomes emerging due to the uncontrolled use of trypanocides is emphasised.     

A review on prevalence,control measure,and tolerance of Tanzania Shorthorn Zebu cattle to East Coast fever in Tanzania

In Tanzania, control of East Coast fever (ECF) has predominantly relied on tick control using acaricides and chemotherapy, little on ECF vaccination, and very little on dissemination regarding animal immunization. In this paper, the prevalence, control measure, and tolerance of Tanzania Shorthorn Zebu (TSHZ) cattle to ECF are reviewed. In addition, the opportunities available for reducing the use of acaricides for the benefit of the farmers in terms of reduction of costs of purchasing acaricides and environmental pollution are described. The tick distribution and epidemiological factors for ECF such as the agro-ecological zones (AEZ), livestock production systems (LPS), strain, and age of the animals are also described. These factors influence the epidemiology of ECF and the distribution of TSHZ strains in different geographic locations of Tanzania. We have further showed that there is a tendency of farmers to select among the strains of TSHZ for animals which can tolerate ticks and ECF and crossbreed them with their local strains with the aim of benefiting from the inherent characteristics of the most tolerant strains. Generally, many strains of TSHZ cattle are tolerant to tick infestation and ECF infection and can be bred to respond to the needs of the people. In this review paper, we recommend that in future, ECF epidemiological studies should account for factors such as livestock production system, agro-climate, breed of animal, tick control strategy, and the dynamic interactions between them. In conclusion, we have demonstrated that an integrated control method involving use of acaricides, immunization, and ECF-tolerant/-resistant animals is required.     

Lungworms (Dictyocaulus arnfieldi): prevalence in live equids in Kentucky

Prevalence of natural infections of the lungworm, Dictyocaulus arnfieldi, was investigated in Kentucky in 5,437 live equids (horses, ponies, and asses) on 91 farms by examination of fecal samples over a 15-month-period from January 28, 1983 to April 19, 1984. For the 91 farms investigated, asses only were examined on 1 farm; for the other 90 farms, examinations were made of horses on all of them, of ponies on 4 farms, and of asses on 9 farms. Larvae of D arnfieldi were found in fecal samples of 112 (2%) of 5,379 horses on the 90 farms of which 38% had greater than or equal to 1 infected animal; none of 19 ponies examined was infected. For 39 asses (donkeys and mules) examined, 21 (54%) were infected; infected asses were present on 80% of the 10 farms on which they were examined. The equids, excluding asses, that were examined and the percentage (in parentheses) infected with D arnfieldi included 4,329 (2%) Thoroughbreds, 684 (2%) Standardbreds, 78 (0%) American Saddle Horses, and 307 (3%) miscellaneous (other breeds or mixed breeds of horses and ponies). Equids were separated into 3 categories relative to previous treatment with ivermectin: A (no treatment), B (treatment), and C (treatment unknown).(ABSTRACT TRUNCATED AT 250 WORDS)     

Risk factors for the prevalence of porcine cysticercosis in Mbulu District, Tanzania

To estimate prevalence of and risk factors for the prevalence of porcine cysticercosis in Mbulu District, Tanzania, 770 live pigs were examined by lingual examination in 21 villages. Structured observations and questionnaire interviews were used to assess pig rearing practices and household use of latrines. Associations between factors were analyzed using a Bayesian hierarchical model to obtain prevalence odds ratio (OR) and 95% Bayesian Credible Intervals (95% BCI). Prevalence was 17.4% (village-specific range 3.2–46.7%). Prevalence of porcine cysticercosis was considerably higher in pigs reared in households lacking latrines than in those reared in households that were using latrines (OR=2.04; 95% BCI=1.25, 3.45). About 96% of the pigs were kept under free-range conditions. This study suggests the need for further studies in order to design and implement effective prevention and control measures for porcine cysticercosis in Mbulu District, Tanzania.     

The prevalence of serum antibodies to Ehrlichia ruminantium infection in ranch cattle in Tanzania: a cross-sectional study

Serum samples collected in a cross-sectional survey of grazing cattle on Manyara Ranch, Monduli district, Tanzania, were tested by indirect major antigenic protein 1 fragment B (MAP 1-B) ELISA to determine the seroprevalence of Ehrlichia ruminantium and to assess ranch-level risk factors for heartwater. Heartwater-exposed cattle were widespread on the ranch and overall seroprevalence was 50.3% (95% CI, 44.9-55.6), enough to indicate an endemically unstable situation. Multivariate logistic regression modelling was used to identify risk factors associated with seropositivity. Two factors appeared to increase the herd's risk for contracting heartwater. Seroprevalence increased significantly with age (beta = 0.19 per year of age, P < 0.001) and animals carrying ticks of any species were associated with an increased risk of infection with E. ruminantium (Odds ratio, OR = 3.3, P < 0.001). The force of infection based on the age seroprevalence profile was estimated at 18 per 100 cattle year-risk. The current tick control measures on the ranch were associated with a decreased risk of infection with E. ruminantium (OR = 0.25 for no dipping and OR = 0.31 for low dipping, P < 0.001). Six tick species were identified; in order of frequency these were: Ambylomma variegatum 59.9%, Rhipicephalus evertsi evertsi 13.9%, Rhipicephalus pulchellus 12.5%, Hyalomma truncatum 7.03% and Rhipicephalus appendiculatus 6.07%. The least encountered tick was Rhipicephalus simus, which accounted for 0.38%. The cattle seemed well adapted to their environment and capable of resisting the tick burden under this extensive wildlife/livestock grazing and interaction system.     

Spontaneous Aortic Lesions in Reindeer (Rangifer Tarandus L)

Aortas of 20 reindeer, aged from 1.5 to 8.5 years, were studied. Fatty streaks were seen in 9, a fibrous plaque in 1, and elastic tissue degeneration in the tunica media in 4 of the aortas.     

Worm control practices and anthelmintic usage in traditional and dairy cattle farms in the southern highlands of Tanzania

Worm control practices and anthelmintic usage in 177 cattle farms in Iringa district in the southern highlands of Tanzania was determined through a questionnaire survey. A total of 76 traditional, 92 small-scale dairy and 9 large-scale dairy cattle farms were included in the survey. Results indicated that 87.7% traditional, 97.8% small-scale dairy and 100% large-scale farmers relied solely on the use of anthelmintics, 2.7% traditional farmers used traditional medicines while 9.6% traditional farmers had not any form of worm control practice. Worm infection was ranked the second most important constraint of productivity in cattle in the three production systems. Most farms (57.6% traditional, 35.8% small-scale dairy, 66.7% large-scale dairy) used anthelmintics with a combination of levamisole and oxyclozanide. Benzimidazoles were used only in traditional (25.4%) and small-scale dairy (32.1%) farms while nitroxynil (Trodax) was mostly used in large-scale dairy farms (33.3%). Generally, 40% of farmers treated three or four times a year and the frequency in some farms was surprisingly high for resource poor small-scale farmers. The frequency of anthelmintic treatment was mostly the same regardless of the management system. Treatments in most farms depended on availability of money and drugs and not the epidemiology of parasites. A significant proportion (46.3%, P=0.007) of farmers especially in rural areas failed to follow their pre-planned treatment schedules due to lack of money (86%) and unavailability of drugs (6.6%). Many farmers (58.9%) had used the same type of anthelmintic for four or more consecutive years and 85.3% of them would continue with the same anthelmintic. Farmers in all management systems mostly purchased anthelmintics from private veterinary drug shops and about 43% traditional and 33.3% small-scale dairy farmers mostly in rural areas obtained anthelmintics from village extension officers. Despite the fact that all farmers were aware of worm infection and the associated signs in cattle, 42.5% had poor knowledge on the source of worm infection. Small-scale dairy farmers allowed only a 1-day withdraw period for milk regardless of the type of anthelmintic used and there was no milk and slaughter clearance in traditional farms. It was concluded from this study that worm control in Iringa faces serious constrains and that education of farmers and farm hands is not adequate. Moreover, poor quality control and high price of potent anthelmintics, few extension workers, low income and low education among farmers contributed significantly to erratic worm control practices and anthelmintic usage in peri-urban and rural areas.     

Cross-sectional estimation of Babesia bovis antibody prevalence in cattle in two contrasting dairying areas in Tanzania

The crude prevalence of antibodies to Babesia bovis infection in cattle was estimated by serology using indirect ELISA during the period January to April, 1999. Sera were obtained from 1,395 dairy cattle (of all ages, sexes and breeds) on smallholder farms, the majority being kept under a zero grazing regime. The crude prevalence of antibodies to Babesia bovis was 6 % for Tanga and 12 % for Iringa. The forces of infection based on the age sero-prevalence profile, were estimated at six for Iringa and four for Tanga per 100 cattle years-risk, respectively. Using random effect logistic regression as the analytical method, the factors (variables) of age, source of animals and geographic location were hypothesised to be associated with sero-positivity of Babesia bovis in the two regions.     

Spontaneous pathology of the thymus in aging Wistar (Cpb:WU) rats

Spontaneous thymic lesions were investigated in Wistar (Cpb:WU) rats. Thymic tumors were not uncommon and most showed medullary differentiation. Thymic involution was investigated in a limited group of animals in which the survival rate for males and females was similar. The histological pattern of thymic involution differed between sexes. Severe thymic involution occurred more frequently in males than in females and at an earlier age.     

Tick burden and prevalence of Theileria parva infection in Tarime zebu cattle in the lake zone of Tanzania

This study was carried out to assess the distribution, abundance of different tick genera and prevalence of Theileria parva infection in Tarime zebu cattle kept in selected wards of Serengeti and Tarime districts in Mara region. Adult ticks were identified and counted from half body parts of 360 animals which were extensively managed in communal land with natural pastures. Concurrently, blood samples were collected and thereafter DNA extracted and a nested polymerase chain reaction (nPCR) was done using primers specific for p104 gene to detect the presence of T. parva DNA. Ticks were identified into four groups: Amblyomma genus, Boophilus sub-genus of Rhipicephalus genus, other species of Rhipicephalus, and Hyalomma genus. Rhipicephalus genus accounted for 71.8 % of the total ticks, whereas Amblyomma, Boophilus sub-genus of Rhipicephalus genus and Hyalomma constituted 14.1, 14.0 and 0.1 %, respectively. There were more animals (p?p?T. parva was 27.7 % and was higher (p?T. parva did not show any clinical signs of East Coast fever (ECF), suggesting the existence of subclinical infection in Tarime zebu. These results suggest that Tarime cattle can tolerate ECF infection and are likely to serve as potential carriers of T. parva to other less-tolerant cattle breeds in mixed herds. Since Tarime cattle are preferred by most farmers with mixed herds, routine screening for T. parva is highly recommended to minimize introduction of infected cattle into an immunologically naive population.     

Sero-epidemiological investigation of bovine toxoplasmosis in traditional and smallholder cattle production systems of Tanga Region,Tanzania

In view of the worldwide importance of Toxoplasma gondii and the fragmented information on the seroprevalence of the disease in animals in Tanzania, a study, using the modified Eiken latex agglutination test (LAT), was conducted from May 2003 to January 2004 to determine the prevalence of antibody to T. gondii in 130 randomly selected farms comprising 655 cattle. The overall seroprevalence of T.gondii antibodies in cattle and farms were 3.6% and 13%, respectively. Risk factors for animal and herd-level toxoplasmosis seropositivity were tested using multivariable logistic regression to control for confounding factors. Cattle managed under traditional husbandry practises were more likely to be seropositive than those managed under smallholder practises (48% versus 4.7%; p < 0.01). Herd size of ≥ 9 cattle were at greater risk of acquiring infection than herds holding fewer animals [≤ 9 cattle], (odd ratio [OR] = 3.99; 95% confidence interval [CI], 0.97–16.48; P = 0.001). We concluded that seroprevalence at herd level was high and relatively low at animal level, possibly due to the reduced susceptibility of cattle to T.gondii infection as compared to goats and sheep. The high seroprevalence in animals managed by traditional husbandry practise suggests that the parasite is widely distributed in the environment and could pose a public health threat to the people living in those areas.