Sympatric occurrence of Taenia saginata and Sarcocystis spp. in cattle from Narok County, Kenya: meat inspection findings with molecular validation.

The epidemiological picture of Taenia saginata infections in Kenya is fragmented with limited available data. Although Sarcocystis species are significant meat-borne parasites, few studies have explored their occurrence in Kenya. This study aimed to estimate the occurrence of bovine cysticercosis and screen for the presence of Sarcocystis spp. A meat inspection-based survey was conducted in ten abattoirs in Narok County, Kenya, and inspection for T. saginata cysticerci was limited to the Triceps brachii muscle. The apparent occurrence of the parasite was 5.4% (95% CI, 3.8, 7.6, n=573). Molecular confirmation of T. saginata was done via nested polymerase chain reaction targeting the mitochondrial 12S ribosomal RNA gene and restricted fragment length polymorphism. Sarcocystis species were identified using a multiplex polymerase chain reaction method targeting the 18S ribosomal RNA gene sequences and the mitochondrial cytochrome c oxidase subunit I gene. Of the 31 cystic lesions tested, 26/31 (83.9%) were confirmed to be T. saginata.Sarcocystis cruzi and S. hominis were detected in 8/31 (25.8%) and 1/31 (3.2%) of the cystic lesions, respectively. Co-infections of S. cruzi and T. saginata were found in 6/31 lesions (19.4%). The confirmation of bovine cysticercosis and S. hominis is suggestive of the presence of risky culinary and sanitation practices that facilitate transmission. This is the first report and molecular confirmation of Sarcocystis spp. in cattle in the country. The presence of both zoonotic S. hominis and pathogenic S. cruzi highlights an underexplored concern of veterinary and human health significance, warranting further epidemiological investigation.

A study of cystic echinococcosis in slaughter animals in three selected areas of northern Turkana, Kenya.

In an attempt to establish the prevalence of cystic echinococcosis, a study was conducted in slaughter animals in three divisions of northern Turkana, Kenya. A total of 5752 goats, 588 sheep, 381 cattle and 70 camels were examined at slaughter. Echinococcus granulosus metacestodes were found in 19.4% of the cattle, 3.6% of sheep, 4.5% of goats and 61.4% of camels. The prevalence of cystic echinococcosis in cattle, sheep and goats was higher in Lokichogio than in either Kakuma or Central divisions. On the other hand, the prevalence of the disease in camels was higher in Central (84.6%) than either Lokichogio (70.6%) or Kakuma (50%). The differences in prevalence rates in different study areas are attributed to differences in environmental conditions, livestock stocking intensity and cross-border migration of livestock.

Application of ultrasonography in prevalence studies of hydatid cysts in goats in north-western Turkana, Kenya and Toposaland, southern Sudan.

A study was done to determine the prevalence of hydatid cysts in goats using ultrasonography. A total of 1,390 goats were examined, 43,6 % (606/1,390) of them from north-western Turkana, Kenya, and 56,4% (784/1,390) from Toposaland, southern Sudan. Hydatid cysts were visualized in 1,82 % (11/ 606) of the goats from north-western Turkana and 4,34% (34/784) of those from Toposaland. Unlike abattoir surveys, the prevalence data obtained in this study were unbiased because entire flocks were examined. The lower prevalence rate of the disease in goats from Turkana was attributed to the hydatid disease control programme in that area, which is absent in Toposaland.

Prevalence of intestinal parasites among children in southern Sudan.

A study was conducted in southern Sudan to determine the prevalence of intestinal parasites among school children. A total of 275 stool samples which were examined using formol-ether concentration techniques yielded 15 different species of parasites. Hook worm with a prevalence of 13.1% was the predominant nematode followed by Strongyloides stercoralis (3.3%), Trichostrongylus (2.5%), Schistosoma mansoni (2.2%) and Trichuris trichiura (1.8%). Ascaris lumbricoides and cestodes were not detected in this population. Intestinal protozoans were common. Entamoeba coli (37.8%), Entamoeba histolytica (28.4%) and Giardia lamblia (9.8%). Children in the age group 6-10 years old were the most affected followed by the 11-15 year-old age group. The infection rate was slightly higher in males than females.

Oxfendazole treatment for cystic hydatid disease in naturally infected animals.

Few chemotherapeutic agents are available for the medical management of hydatid disease caused by the parasite Echinococcus granulosus. In order to test the potential of oxfendazole for the treatment of infection with this parasite, nine infected goats and four sheep were given oxfendazole twice weekly at a dose of 30 mg/kg of body weight for 4 weeks and monitored by ultrasound for an additional 4 weeks. Efficacy was finally evaluated by postmortem examination, including determination of protoscolex viability and cyst wall histology. In treated animals, protoscolices were dead or absent in 97% of cysts from oxfendazole-treated animals compared to 28% of cysts from untreated control animals. On postmortem examination, 53% of cysts from treated animals were found to be grossly degenerate. A sample of those cysts that appeared potentially viable all demonstrated evidence of severe damage to the cyst wall. By light microscopy, cysts showed severe disorganization of the adventitial layer with invasion of inflammatory cells and in some cases frank necrosis with no apparent adventitial layer. The follow-up period for assessment of the drug's ability to cause complete degeneration and resorption of cysts was relatively short. This study, however, indicates that oxfendazole is at least as effective as and is easier to administer than albendazole for the treatment of hydatid disease.

Evaluation of diagnostic ultrasound as a mass screening technique for the detection of hydatid cysts in the liver and lung of sheep and goats.

Ultrasound examination of the liver and lung followed by post-mortem examination was performed in 16 sheep and 284 goats. Thirty-one (10.3%) were positive for hydatid cysts on ultrasound examination and 46 (15.3%) were positive on post-mortem examination. Twenty-one positive on post-mortem examination were falsely identified as negative on ultrasound examination. Of the 254 animals negative on post-mortem examination, six (2.4%) were falsely identified as positive on ultrasound examination. The sensitivity and specificity of ultrasound examination for detecting hydatid cysts in sheep and goats was 54.36% and 97.64%, respectively (positive predictive value: 80.64%; negative predictive value: 92.19%).

The use of ultrasound to study the prevalence of hydatid cysts in the right lung and liver of sheep and goats in Turkana, Kenya.

Ultrasound examination of the liver and right lung was performed in 260 sheep and 320 goats from the Turkana district of Kenya. Hydatid cysts were visualized in 9.2% of the sheep and 2.5% of the goats. Of the animals positive on ultrasound, 87.5% received post-mortem examinations. Eighteen (6.9%) sheep and 5 (1.5%) goats were positive for hydatid cysts on ultrasound and post-mortem examination. False-positives were a result of Taenia hydatigena cysticerci present in the liver in all but 1 case. Positive predictive value of ultrasound for diagnosis of hydatidosis in sheep and goats was 82.1%.

Prevalence of Oncocerca volvulus in Southern Sudan.

Onchocerciasis is endemic in southern Sudan. The prevalence in human population may range from 10% to 40%. In the Eastern Equatorial Region of Southern Sudan, more cases are found in Nimule on the Sudan-Uganda border than in rural highlands of Labone and Chukudum basins. Onchocerciasis was highest in males (with a prevalence of 70.2% based on data from hospital records)) than in females, with prevalence of 19%. Overall, prevalence of onchocerciasis in children was 10.8%.Considering cost-effectiveness, public health priorities and the security situation in this area, we recommend active search on onchocerciasis cases in the community and treatment.

Prevalence of malaria in southern Sudan.

The prevalence of malaria in the human population of southern Sudan was studied during March to April, 1996. A total of 330 people including adults and children were screened for malaria by microscopic examination of Giemsa stained thick and thin blood smears prepared from a finger prick sample. Plasmodium falciparum was the only malaria parasite detected in blood smears in the present study, even though hospital records indicated presence of P. vivax. About 24.5% of those examined were infected. .

Prevalence of human hydatid disease in southern Sudan.

A total of 3443 people were screened by ultrasound to determine the prevalence of hydatid disease in southern Sudan. Hydatid cysts were found in 16 (0.5%) of the people screened. Thirteen of the 16 hydatid cases were from among the Bouya people who showed an overall hydatid prevalence of 2% by ultrasound. All ultra-sound positive cases were further confirmed by dot-blot ELISA. At the time of the survey, Chukudum Hospital had five cases with histories and clinical manifestations consistent with hydatidosis. However, on scan examination only three of them were confirmed to be cases of hydatid disease. The proportion of hydatid infected women in south-western Sudan was almost twice that of men (M:F ratio of 1:1.7), with most of those infected being women in the child-bearing age bracket. Dogs are common in this area and they could be the main reservoirs of Echinococcus granulosus in the Sudan. Due to the low prevalence of hydatid in humans in the study area, and the dispersed nature of the population, it is recommended that hydatid control measures for south-western Sudan include an educational component coupled with treatment of the infected people.

Intestinal helminths of public health importance in dogs in Nairobi.

In a survey of intestinal canine zoonotic helminths in Nairobi, 156 dogs were autopsied. Of these, 10% were infected with Echinococcus granulosus, 88% with Ancylostoma caninum, 45% with Dipylidium caninum and 3% with Toxocara canis. All the infected dogs with E. granulosus originated from around abottoirs in Dagoretti. The risk of infection in man with hydatid disease is considered to be high around Dagoretti and control measures are recommended.

Molecular examination of the sympatry and distribution of sheep and camel strains of Echinococcus granulosus in Kenya.

Previous studies have shown that camel and sheep strains of the cystic hydatid parasite Echinococcus granulosus occur in Kenya. We examined 208 larval isolates and 40 worm samples of E. granulosus from various hosts in Kenya using restriction fragment length polymorphism analysis of a segment of ribosomal DNA amplified by the polymerase chain reaction. This was in an effort to determine whether additional strains of E. granulosus occur in Kenya, to examine the level of genetic heterogeneity within the sheep/dog and camel/dog strains previously identified, and to map out their intermediate host range and geographic distribution in Kenya. We confirmed the existence of the two strains in Kenya and showed that the distribution of the camel strain appears restricted to the Turkana region, where camels are kept as livestock. The intermediate host range for both strains seems to be similar except that humans appear refractory to infection with the camel strain. We have also shown that although the life-cycle patterns of the two strains overlap both geographically and in intermediate and definitive hosts, the strains maintain their homogeneous genetic identity.

Release and survival of Echinococcus eggs in different environments in Turkana, and their possible impact on the incidence of hydatidosis in man and livestock.

In Turkana, Kenya, a prevalence of hydatidosis of nearly 10% has been recorded among the pastoralists yet their livestock have a much lower prevalence of the disease. The present study investigated the release from dogs and subsequent survival of Echinococcus eggs in Turkana huts, water-holes and in the semi-arid environment. The results were compared with the survival of eggs of Taenia hydatigena and T. saginata. The study was repeated under the cooler and moister conditions found in Maasailand where livestock have a greater incidence of hydatid disease than in Turkana but where the incidence in man is ten times lower. The average number of Echinococcus eggs per proglottid is 823. Nine percent of these remain in proglottids 15 minutes after release from a dog and the released eggs lose their viability in less than two, 48 and 300 hours in the sun, huts and water in Turkana respectively: the major influencing factor being temperature. The greater survival of eggs in the houses, coupled with the fact that dogs congregate for most of the day in the small houses facilitating a close man:dog contact, provide ideal conditions for the transmission of the parasite to man. The hostile environmental conditions and lack of contact between dogs and livestock contributes to the lower infection rate in livestock. Conversely in Maasailand, Echinococcus eggs survive in the environment for longer than three weeks and in addition, dogs are used for herding. This partly explains the higher infection rate among Maasai livestock but the low human infection rate remains arcane and requires further study.(ABSTRACT TRUNCATED AT 250 WORDS)

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

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

Hydatid disease: research and control in Turkana, IV. The pilot control programme.

A pilot programme to control hydatid disease in north-west Turkana district was started in October 1983 with an intensive educational campaign. This was followed by control and treatment of the dog population to reduce the prevalence of Echinococcus granulosus, thereby reducing the infective pressure on man. Surveillance is by mass annual sero-epidemiological and ultrascan surveys of the nomadic Turkana within the control region and by arecoline purging of the dogs. Some of the recent advances in research on hydatid disease in subject areas such as immunodiagnosis, chemotherapy and epidemiology have been incorporated into the present programme, and their relevance to this and other similar programmes is discussed.

Class-specific circulating antibodies in infections with Eimeria tenella.

Using a three-layer immunofluorescent test, class-specific, parasite-specific circulating antibody responses to Eimeria tenella were investigated following oocyst infection, drug-truncated oocyst infection and the injection of non-living antigens. Following all three means of antigenic stimulation, IgG, IgM and IgA antibodies were detected. The response to drug-truncated infections was dose-dependent. The sequence of appearance of antibody was IgM, IgA, IgG, whilst the relative quantities were IgG greater than or equal to IgM greater than IgA.