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 survey of intestinal helminths in domestic dogs in a human-animal-environmental interface: the Oloisukut Conservancy, Narok County, Kenya.

Dogs living in a domestic-wildlife interface can serve as reservoirs and sentinels of parasites shared among humans, domestic animals and wildlife. In Kenya, the epidemiology of intestinal parasites of dogs and their role as reservoirs of zoonoses is poorly understood, especially in domestic-wildlife interfaces. This study aimed to determine the occurrence of intestinal helminths in domestic dogs in the Oloisukut Conservancy. One hundred dog faecal samples were collected per rectum and examined microscopically following zinc chloride flotation and formal-ether concentration techniques. Genotyping of helminths was achieved by nested polymerase chain reaction of NADH dehydrogenase subunit 1, cytochrome oxidase 1 and partial sequencing. Nine genera were detected by microscopy in 65 (65%) dog faecal samples from 54/76 (71.05%) households. The most frequent helminths were hookworm (39%), Spirometra spp. (17%), taeniids (13%), Toxocara spp. (10%), Trichuris spp. (10%), Spirocerca lupi (5%), Physaloptera spp. (2%), Dipylidium caninum (1%) and Strongyloides spp. (1%). Ancylostoma caninum was the only hookworm species detected in dogs, while Taenia serialis and Taenia madoquae were detected in four and one faecal samples, respectively. This study reports for the first time the molecular detection of the cestodes Spirometra theileri, D. caninum and Mesocestoides sp. in dogs in Kenya. The presence of zoonotic helminths in dogs indicates that the residents of this conservancy are exposed to public health risks. The helminths reported here confirm the interaction of domestic dogs with wildlife. An integrated control programme involving the medical, veterinary and wildlife conservation professionals is needed to avert transmission of infectious diseases to humans, domestic animals and wildlife.

Prevalence and genotyping of Echinococcus granulosus sensu lato from livestock in north-eastern Kenya.

Cystic echinococcosis (CE) is a zoonotic disease of cosmopolitan distribution and caused by the larval stage of the dog tapeworm, Echinococcus granulosus sensu lato (s.l.). CE occurs in the wider African continent and in Kenya, notably in the Maasailand and Turkana regions; however, recent studies demonstrate its presence in other parts of Kenya. This study determined the occurrence of CE in livestock (camels, goats, sheep and cattle) in Isiolo, Garissa and Wajir counties, and characterized the species of E. granulosus s.l. present. An abattoir survey was used to determine the presence of CE in various organs in livestock. Polymerase chain reaction-restriction fragment length polymorphism and sequencing of the mitochondrial NADH dehydrogenase subunit 1 gene was used for genotyping. A total of 1368 carcasses from 687 goats, 234 camels, 329 sheep and 118 cattle were inspected for the presence of hydatid cysts. The overall proportion of infections was 29.1% in camels, 14.4% in cattle, 9.9% in goats and 8.2% in sheep. The liver was the most infected organ, while only the lung of camels harboured fertile cysts. Of the 139 cysts genotyped, 111 (79.9%) belonged to Echinococcus canadensis (G6/7) and 20 (14.4%) to E. granulosus sensu stricto. One and two cysts were identified as Taenia saginata and unknown Taenia species, respectively. There was a significant association between county of origin and species of the animal with occurrence of CE. This study reports, for the first time, the characterization of Echinococcus species in livestock from Garissa and Wajir counties, and the current situation in Isiolo county. The fertility of cysts in camels and frequency of E. canadensis (G6/7) in all livestock species indicate that camels play an important role in the maintenance of CE in the north-eastern counties of Kenya.

Molecular identification of zoonotic hookworms in dogs from four counties of Kenya.

All canine hookworms are known to be zoonotic, causing infections ranging from transient skin irritations to prolonged 'creeping eruptions', eosinophilic enteritis and even patent intestinal infections. There is little information on canine hookworm species and their public health significance in sub-Saharan Africa. This study determined the prevalence and species of hookworms in dogs from different climatic zones of Kenya. Dog faecal samples were collected from the environment, and hookworm eggs were isolated by zinc chloride flotation and subjected to DNA extraction. Polymerase chain reaction (PCR) assays targeting the internal transcribed spacer (ITS) 1 and 2, 5.8S and 28S ribosomal RNA of Ancylostoma spp. and Uncinaria stenocephala were performed, and hookworm species were identified by PCR-restriction fragment length polymorphism (RFLP) or DNA sequencing. Hookworm eggs were detected by microscopy in 490/1621 (30.23%, 95% CI 28.01-32.54) faecal samples. Estimates of faecal prevalence were high in counties receiving higher rainfall (Narok 46.80%, Meru 44.88%) and low in those with a more arid climate (Isiolo 19.73%, Turkana 11.83%). In a subset of 70 faecal samples, Ancylostoma caninum (n = 59) was the most common species, followed by A. braziliense (n = 10) and A. cf. duodenale (n = 1). This study reports for the first time the detection of A. cf. duodenale in dog faeces and zoonotic hookworm species in Kenyan dogs. These findings emphasize the need for control measures such as enforcing laws for restraining stray dogs, regular deworming of dogs, and public health awareness programmes aimed at informing communities on outdoor use of footwear.

Prevalence and genotyping of Echinococcus granulosus in sheep in Narok County, Kenya.

Cystic echinococcosis (CE) is a zoonotic disease caused by the larval stage of Echinococcus granulosus species (sensu lato, s.l.). In East Africa, several species/strains occur in livestock, wildlife, and humans, but there is limited information on frequencies of infection by different genotypes in the various mammalian hosts. We have obtained data on E. granulosus infection prevalence in sheep sampled from abattoirs in Narok County, southern Kenya. We inspected carcasses for the presence of hydatid cysts in 180 sheep randomly selected in five sub-locations. The overall prevalence was 16.0% (144/900 animals), with the majority of cysts (50.7%) found in the liver, followed by the lungs (36.8%), while infections involving the liver and lungs were detected in 12.5% of the sheep. PCR-RFLP genotyping of the mitochondrial nad-1 gene in all the 343 cysts identified E. granulosus G1-G3 (sensu stricto, s.s.) as the only genotype. The majority of the cysts (62.1%) were fertile, and 35.2% were sterile, while 2.7% were calcified. Considering cyst fertility, 73.02% of lung cysts were fertile compared to 53.4% in liver cysts. Our data extends previous CE studies in livestock and indicates a high level of CE infection of sheep in Narok, with a predominance of E. granulosus s.s., which is highly pathogenic and commonly infects humans. Given the high fertility rates observed in the cysts, there is an urgent need to determine whether there is a significant incidence of human infection in Narok, and initiate "One Health" control measures.

Echinococcus spp. in central Kenya: a different story.

Research on cystic echinococcosis (CE) has a long history in Kenya, but has mainly concentrated on two discrete areas, Turkana and Maasailand, which are known to be foci of human CE in Africa. Here, we report on a survey for CE in livestock from central to northeastern Kenya, from where no previous data are available. A total of 7,831 livestock carcasses were surveyed. CE prevalence was 1.92% in cattle (n = 4,595), 6.94% in camels (n = 216), 0.37% in goats (n = 2,955) and 4.62% in sheep (n = 65). Identification of the parasite was done using an RFLP-PCR of the mitochondrial nad1 gene, which had been validated before against the various Echinococcus taxa currently recognized as distinct species. From a total of 284 recovered cysts, 258 could be identified as Echinococcus granulosus sensu stricto (n = 160), E. ortleppi (n = 51) and E. canadensis (n = 47) by RFLP-PCR of nad1. In cattle, fertile cysts occurred mostly in the lungs and belonged to E. ortleppi (31 of 54), while the vast majority were sterile or calcified cysts of E. granulosus s.s.. Most fertile cysts in camels belonged to E. canadensis (33 of 37); sterile or calcified cysts were rare. Goats harboured fertile cysts of E. ortleppi (n = 3)--which is the first record in that host species--and E. canadensis (n = 1), while all cysts of E. granulosus were sterile. Only sterile cysts were found in the three examined sheep. Typically, all cysts in animals with multiple infections belonged to the same species, while mixed infections were rare. Our data indicate that the epidemiological situation in central to northeastern Kenya is clearly different from the well-studied pastoral regions of Turkana and Maasailand, and the apparently low number of human CE cases correlates with the infrequent occurrence of E. granulosus s.s.

MOLECULAR CHARACTERISATION OF ECHINOCOCCUS GRANULOSUS SPECIES/STRAINS IN HUMAN INFECTIONS FROM TURKANA, KENYA.

BACKGROUND: Cystic echinococcosis (CE) or hydatid disease is a neglected, economically important zoonotic disease endemic in pastoralist communities, in particular the Turkana community of Kenya. It is caused by the larval stage of the highly diverse species complex of Echinococcusgranulosus sensu lato (s.l). The situation on the genetic diversity in humans in Kenya is not well established. OBJECTIVE: To characterise Echinococcus granulosus (s.1) species/strains isolated from humans undergoing surgery in Turkana, Kenya. DESIGN: A Cross sectional study. SETTING: The Kakuma Mission Hospital and Centre for Microbiology Research, Kenya Medical Research Institute. SUBJECTS: Eighty (80) parasite samples from 26 subjects were analysed by Polymerase chain reaction--Restriction fragment length polymorphism (PCR-RFLP) targeting the nad 1 gene for molecular characterization. RESULTS: Two different genotypes of E. granulosus were identified from the samples analysed: E. granulosus sensu stricto (G1-G3) 85% of the samples analysed and E. canadensis G6/7 (15%). Most of the hydatid cysts (35%) were isolated from the liver. Other sites where cysts were isolated from include: kidney, abdomen, omentum, retroperitonium and the submandibular. Majority of cysts presented as CE1 (50%) and CE3B (42%) images according to WHO ultrasound classification. Both males and females were infected with E. granulosus s.s but only the females showed infection with E. canadensis G6/7. Chi-square test revealed significant difference between age of individuals and cysts classification by ultrasound. In addition, there was an association between cyst presentation (single or multiple) and genotype whereby all the E. canadensis G6/7 cases presented as single cysts in the infected persons. CONCLUSION: This study corroborates previous reports that E. canadensis G6/7 strain is present in Turkana, a place where initially only E. granulosus s.s (G1-G3) was known to be present and that E. granulosis (G1-G3) remains the most widespread genotype infecting humans in the Turkana community.

Cystic echinococcosis in Turkana, Kenya: 30 years of imaging in an endemic region.

Cystic echinococcosis (CE), a widespread, complex zoonosis, causes chronic disease associated with high morbidity. The pastoral Turkana people of Kenya have one of the highest prevalence rates of CE in the world. Between 1983 and 2015, a CE control program in the Turkana region used ultrasound (US) screening surveys and surgical outreach visits to evaluate CE prevalence and treat those with the disease. As the gold standard modality for diagnosing CE, US reveals a great deal of information about the disease in affected populations. The aim of this study is to discuss the characteristics of untreated CE in the Turkana people as revealed by US data collected during the CE control program and evaluate disease presentation, factors influencing the risk of transmission, and the timeline of disease progression. Data were obtained from written patient notes from US screenings and images; cysts were classified using the World Health Organization (WHO) standardized US classification of CE. Findings include greater prevalence of cysts, later stages of cysts, and multiple cysts in older age groups, with no multiple cysts occurring in patients under six years of age, which are consistent with the assertion that rates of exposure, transmission, and infection increase with age in endemic regions. Findings also raise questions regarding the timeline of disease progression, and factors potentially influencing disease transmission within this and other endemic populations. A comprehensive survey focusing on cultural and community observations (e.g., changing behaviors, hygienic practices, etc.) may provide more detailed information regarding factors that facilitate transmission.

The natural history of cystic echinococcosis in untreated and albendazole-treated patients.

The World Health Organization (WHO) treatment protocols for cystic echinococcosis (CE) are based on the standardized ultrasound (US) classification. This study examined whether the classification reflected the natural history of CE in untreated and albendazole-treated patients. Data were collected during mass US screenings in CE endemic regions among transhumant populations, the Turkana and Berber peoples of Kenya and Morocco. Cysts were classified using the WHO classification. Patient records occurring prior to treatment, and after albendazole administration, were selected. 852 paired before/after observations of 360 cysts from 257 patients were analyzed. A McNemar-Bowker χ2 test for symmetry was significant (p<0.0001). 744 observations (87.3%) maintained the same class, and 101 (11.9%) progressed, consistent with the classification. Regression to CE3B occurred in seven of 116 CE4 cyst observations (6.0%). A McNemar-Bowker χ2 test of 1414 paired before/after observations of 288 cysts from 157 albendazole-treated patients was significant (p<0.0001). 1236 observations (87.4%) maintained the same class, and 149 (10.5%) progressed, consistent with the classification. Regression to CE3B occurred in 29 of 206 CE4 observations (14.1%). Significant asymmetry confirms the WHO classification's applicability to the natural history of CE and albendazole-induced changes. Regressions may reflect the stability of CE3B cysts.

Antibody responses against natural Taenia hydatigena infection in dogs in Kenya.

Antibody responses (IgG) against Taenia hydatigena infection in dogs in Kenya were analysed in ELISA using excretory/secretory products of T. hydatigena scoleces derived from goat cysticercus cysts. Helminth infections of individual dogs were confirmed at autopsy. T. hydatigena worms were found in 89.5% of 143 dogs, and positive anti-T. hydatigena antibody levels were detected in 58.7% of infected dogs. Positive antiscolex antibody levels were detected in 40.0% of Turkana dogs uninfected with T. hydatigena, suggesting previous infection. Antibody was not detected in 34.4% of infected dogs. There was no relationship between individual T. hydatigena worm burdens and absorbance values for sera in ELISA. It was not possible to distinguish between sera from T. hydatigena-infected and uninfected dogs.

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%.

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.

Hydatid disease: research and control in Turkana. II. The role of immunological techniques for the diagnosis of hydatid disease.

Immunological studies have been applied to the immunodiagnosis of human hydatidosis in Turkana and for the specific identification of Echinococcus eggs, particularly in regard to their potential for the assessment of a hydatid control programme in the north-west of the District. A high rate of false negatives has been obtained with sensitive antibody tests for proven hydatid patients in Turkana and presents problems for prevalence estimation in the population. A seroepidemiological study using specific antibody detection indicated a 2.17% seropositive rate, and by using a portable ultrasound 67% of antibody positives were confirmed as having liver/abdominal cysts. An enzyme immunoassay test for specific circulating antigen, often associated with circulating immune complexes, was positive in sera in 75% of hydatid patients who were antibody-negative. The formation of specific circulating immune complexes may contribute directly to the production of a state of false negativity. These studies indicate that by combining tests for antibodies and antigens together with ultrasound, the true prevalence of human hydatidosis in Turkana is at least 5%. Characterization of Echinococcus antigens recognized by human antisera from Turkana and British hydatid patients indicates that both groups recognize the same major protein antigens in cyst fluid and protoscoleces. The results of assaying anti-oncospheral antibodies in people living in the high prevalence area of north-west Turkana compared to people in areas of low prevalence indicates that most of the people in the high prevalence area are probably infected (challenged) with Echinococcus eggs. This observation suggests that there may be a high level of acquired resistance. A species-specific immunofluorescence test using an anti-Echinococcus monoclonal antibody has been developed which can specifically identify oncospheres artificially hatched from Echinococcus eggs. This test will be applied to the problem of identification of Echinococcus eggs in the environment and in dog faeces, with a view to studying the epidemiology of the disease and for use in assessment of the hydatid control programme.

Pastoralists and hydatid disease: an ultrasound scanning prevalence survey in east Africa.

An attempt was made to estimate the prevalence of hydatid disease in nomadic pastoralists living in eastern Africa and to identify environmental, cultural and behavioural factors which may influence Echinococcus transmission. 18,565 nomadic pastoralists, from 12 different groups living in the vast, semi-desert regions of Kenya, Sudan, Ethiopia and Tanzania, were screened for hydatid cysts using a portable ultrasound scanner. High prevalences of hydatidosis were recorded among the north-western (5.6%) and north-eastern (2.1%) Turkana of north-west Kenya, the Toposa (3.2%) of southern Sudan, the Nyangatom (2.2%), Hamar (0.5%) and Boran (1.8%) of south-west Ethiopia and northern Kenya and the Maasai (1.0%) of Tanzania. Lower prevalences were recorded amongst the southern (0.3%) and lake dwelling (0.3%) Turkana and the Pokot (0.1%) of Kenya. The disease was not found amongst the Turkana, Samburu, Dassanetch, Gabbra, Somali or Rendille screened on the east side of Lake Turkana. The scanning surveys were well accepted by the people and provided evidence for the need to expand the present hydatid control programme in Turkana to cover the whole hyperendemic focus. Such a programme must contain an educational component for, although most groups recognized hydatid cysts, there was complete lack of knowledge concerning the parasite and its mode of transmission.

Evaluation of a rapid dot-ELISA as a field test for the diagnosis of cystic hydatid disease.

A rapid dot enzyme-linked immunosorbent assay (dot-ELISA) was developed as a field test for the diagnosis of cystic hydatid disease caused by Echinococcus granulosus. The 30 min test was based on the detection of antibodies to antigen B of hydatid fluid and was carried out using 50 microliters of whole blood in a field assessment in the Turkana region of north-west Kenya. Initial laboratory studies showed antigen B to be preferable to crude cyst fluid, with 94% sensitivity and 90.3% specificity for Echinococcus infections. The field test was rapid, inexpensive and simple to perform and is considered to be a useful back-up to ultrasound scanning.

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.

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.