Cystic echinococcosis of livestock and humans in central Sudan

Epidemiology of Echinococcus granulosus sensu lato in the Greater Horn of Africa: A systematic review

BACKGROUND

Cystic echinococcosis (CE) is a neglected zoonotic disease that is caused by Echinococcus granulosus sensu lato (s.l.), the life cycle of which involves multiple hosts. We conducted a systematic review (SR) on E. granulosus s.l. in the Greater Horn of Africa (GHA), to provide a picture of its recent epidemiology across all hosts.

METHODS

For this SR, conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement, five electronic databases, as well experts in the region were consulted to retrieve records published between 2000 and 2022, reporting the presence of E. granulosus s.l. infections in any natural host in the GHA (Djibouti, Eritrea, Ethiopia, Kenya, Sudan, Somalia, South Sudan, Tanzania and Uganda).

PRINCIPAL FINDINGS

A total of 247 records were retained, describing the presence of E. granulosus s.l. throughout the GHA, except for Djibouti. Only few population surveys on human CE were conducted in the area, with the prevalence ranging between 0.3 and 11.3%. In animals, the reported prevalence ranged up to 61.6% in camels, 88.4% in cattle; 65.2% in goats, 9.9% in pigs, 67.8% in sheep and 94.5% in dogs. In addition, E. granulosus s.l. was also reported in wildlife. A total of five species were reported in the different hosts, namely E. granulosus sensu stricto (G1, G3, GOmo), E. canadensis (G6/7), E. ortleppi (G5), E. felidis, and E. equinus (G4).

CONCLUSIONS

We confirm that E. granulosus s.l. is prevalent throughout the GHA. Nevertheless, despite our efforts to screen grey literature, an accurate assessment of the epidemiology in GHA remains challenging, due to the lack of combined host, in-depth risk factor and behavioural studies, as well as the wide diversity in subpopulations studied and diagnostic tools used. Interdisciplinary and transboundary partnerships would be essential for the design of effective control strategies, tuned to the GHA setting.

Occurrence and Phylogenetic Description of Cystic Echinococcosis Isolate from Egyptian Camel (Camelus Dromedarius)

Cystic echinococcosis is one of the most significant cyclo-zoonotic diseases of major economic and public health significance worldwide. The current study was carried out to determine the epidemiological profile of cystic echinococcosis as well as to investigate its molecular and phylogenic status from one-humped camel (Camelus dromedarius) in the southern region of Egypt. In the present work, 110 camels freshly slaughtered at Daraw abattoirs, Aswan governorate were inspected for the presence of Hydatid cysts (HCs) visually and manually by palpation and incision, over a period of one year (June, 2018 - May, 2019). Furthermore, fourteen fertile hydatid cyst samples were collected from lungs of slaughtered camels. DNA extraction from two fertile samples was successfully achieved followed by phylogenetic analysis on two mitochondrial genes (cox1and nad1). Out of 110 camels slaughtered 11 (10 %) were found harboring hydatid cysts. The infection was found to prevail throughout the year, with the highest peak encountered in winter (45.5 %). The lungs were the most frequently infected organs (72.7 %) with liver cysts occurring at a significantly lower rate (27.3 %). The mean value of total protein, glucose, urea, cholesterol, magnesium, potassium, copper and creatinine was higher in cystic fluid from camels as compared to cattle. Blast and phylogenetic analysis on sequenced genes showed the presence of Echinococcus intermedius, originally the pig genotype (G7) in camels for the first time in Egypt. To the best of our knowledge, the current research provides a description of the current epidemiological and molecular situation of camel hydatidosis in the southern region of Egypt. Furthermore, the current results may have significant implications for hydatid disease control in the studied region.

Co-infection of fasciolosis and hydatidosis and their financial loss in cattle slaughtered at Wolaita Sodo municipal abattoir, southern Ethiopia

Fasciolosis and hydatidosis are the world’s most common zoonotic major parasitic ailments of domesticated animals with financial and public health implications. A cross-sectional study was conducted on 384 randomly selected cattle slaughtered at Wolaita Sodo municipal abattoir to estimate the prevalence and associated risk factors for co-infection of hydatidosis and fasciolosis using the ante- and postmortem examination techniques. Of the 384 examined cattle, 4.17% were found to harbor co-infections of hydatidosis and fasciolosis. Similarly, the prevalence of concurrent fasciolosis and hydatidosis infections was 76.56% and 23.44% in local and crossbred animals, respectively. The current study took into account risk factors such as age, breed, origin, and body condition score; however, there is a statistically insignificant association between the risk factors and the prevalence of concurrent fasciolosis and hydatidosis infection. In this study, overall fasciolosis was recorded at a rate of 9.38%, with the highest prevalence of F. hepatica at 8.59%, followed by unidentified flukes at 4.17% and F. gigantica at 0.78%. Likewise, the single prevalence of hydatidosis was recorded at 10.94%. Of the 142 examined cysts, the liver alone harbors 54 cysts, and the lung alone harbors 88 cysts, with a total of 43 calcified, 21 sterile, 56 viable, 9 nonviable, and 13 mixed cysts. The predicted yearly financial loss from organ condemnation was 15,436,142.00 ETB Birr. This study demonstrated that hydatidosis and fasciolosis are two relatively widespread parasite diseases of cattle in Ethiopia, causing significant economic loss attributable to organ rejection and indirect weight loss. Thus, awareness of the impact of the disease on the community could disrupt the parasite’s life cycle, and its economic significance was forwarded to other points.

Africa-wide meta-analysis on the prevalence and distribution of human cystic echinococcosis and canine Echinococcus granulosus infections

BACKGROUND

Echinococcosis is a neglected zoonosis of increasing public health concern worldwide. According to the World Health Organization, 19,300 lives and 871,000 disability-adjusted life-years are lost globally each year because of cystic echinococcosis. Annual costs associated with cystic echinococcosis were estimated at US$ 3 billion because of treatment of cases and losses in the livestock industry.

METHODS

We performed the random-effects model of meta-analysis using 51-year (1970-2021) data available from AJOL, Google Scholar, PubMed, Science Direct, Scopus and Web of Science. We also applied the Joanna Briggs Institute critical appraisal instrument for studies reporting prevalence data, the Cochran's Q-test, Egger's regression test and the single study deletion technique to respectively examine within-study bias, heterogeneity, across-study bias and sensitivity.

RESULTS

Thirty-nine eligible studies on human cystic echinococcosis (HCE) from 13 countries across the five African sub-regions showed an overall prevalence of 1.7% (95% CI 1.1, 2.6) with a statistically significant (P < 0.001) sub-group range of 0.0% (95% CI 0.0, 14.1) to 11.0% (95% CI 7.6, 15.7). Highest prevalences were observed in Eastern Africa (2.7%; 95% CI 1.4, 5.4) by sub-region and Sudan (49.6%; 95% 41.2, 58.1) by country. Another set of 42 studies on Echinococcus granulosus infections (EGI) in dogs from 14 countries across the five African sub-regions revealed an overall prevalence of 16.9% (95% CI 12.7, 22.3) with a significant (P < 0.001) variation of 0.4 (95% CI 0.0, 5.9) to 35.8% (95% CI 25.4, 47.8) across sub-groups. Highest prevalences of E. granulosus were observed in North Africa (25.6%; 95% CI 20.4, 31.6) by sub-region and Libya (9.2%; 95% CI 5.7, 13.9) by country.

CONCLUSION

Human cystic echinococcosis and EGI are respectively prevalent among Africans and African dogs. We recommend a holistic control approach that targets humans, livestock, dogs and the environment, which all play roles in disease transmission. This approach should involve strategic use of anthelminthics in animals, standardized veterinary meat inspection in abattoirs, control of stray dogs to reduce environmental contamination and proper environmental sanitation. Mass screening of humans in hyper-endemic regions will also encourage early detection and treatment.

Prevalence of cystic echinococcosis and associated risk factors among humans in Khartoum State, Central Sudan

Background

Hydatid disease or cystic echinococcosis (CE) is caused by the larval stages of the cestode parasite Echinococcus granulosus. The objectives of this study were to estimate the prevalence of seropositivity and to identify the risk factors associated with the disease among humans in Khartoum State, Central Sudan.

Methods

A cross-sectional study was conducted between November 2017 and April 2018. A total of 305 randomly selected consenting participants from three localities were included in the current investigation using a multistage probability sampling method. An in-house enzyme-linked immunosorbent assay was used to detect immunoglobulin G antibodies to E. granulosus. The χ² test and logistic regression analysis were used to determine the risk factors associated with CE seropositivity.

Results

A seroprevalence of 6.5% (20/305) was recorded among humans in Khartoum State, Central Sudan. Age (odds ratio [OR] 16.61 [confidence interval {CI} 2.21 to 117.92], p=0.006), locality (OR 3.08 [CI 1.42 to 22.54], p=0.011) and contact with dogs (OR 2.34 [CI 0.026 to 0.646], p=0.013) were recorded as potential risk factors for seropositivity to CE in the study area.

Conclusions

The seroprevalence of CE (6.5%) is high among humans in Khartoum State, Central Sudan. Improved surveillance is necessary to optimize control and prevention strategies for CE as an important neglected zoonotic disease among the human population in the study area of Central Sudan.

A study on causes of cattle liver condemnation at an abattoir in Omdurman area, Khartoum State, Sudan

BACKGROUND

Information obtained from abattoirs on the causes of liver condemnation is important in preventing the spread of diseases and for promoting food security. The current study reviews three years (2009 to 2011) postmortem inspection records of cattle slaughtered at an abattoir in Omdurman, Khartoum State, Sudan. The aim was to determine the prevalence of diseases and conditions that lead to liver condemnation.

RESULTS

From a total of 234,175 cattle slaughtered, 8,910 (3.8%) livers were condemned due to several diseases/conditions mainly fasciolosis, cysticercosis, necrosis, abscess, calcification, hemorrhages, liver cirrhosis, hydatidosis, and other miscellaneous causes. Collectively, fasciolosis was the leading cause of liver condemnation and was responsible for 51.6 % of total liver condemnations followed by necrosis (18.6%), and cysticercosis (13.5%).

CONCLUSIONS

Because of their zoonotic nature, the observed high frequency of some detected diseases/conditions is thought to pose a public health risk among consumers. This survey could be used as a regional baseline for future monitoring of control programmers against these liver diseases.

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.

Zoonotic Pathogens of Dromedary Camels in Kenya: A Systematised Review

Kenya is home to Africa’s third largest population of dromedary camels, and production at commercial and local levels are increasingly important. In pastoral and nomadic communities in the arid and semi-arid lands (ASALs), camels play a vital role in food security, while commercial milk production and formalized export markets are rapidly emerging as camel populations expand into non-traditional areas. Until recently, little focus was placed on camels as hosts of zoonotic disease, but the emergence of Middle Eastern respiratory coronavirus (MERS-CoV) in 2012, and the discovery of exposure to the virus in Kenyan camels, highlighted the need for further understanding of this area. This systematised review utilised a robust search strategy to assess the occurrence of camel-associated zoonoses in Kenya and to evaluate the quality of the published literature. Seventy-four studies were identified, covering sixteen pathogens, with an increasing number of good quality studies in recent years. Despite this, the area remains under-researched and there is a lack of robust, high-quality research. Trypanosome spp., Echinococcus granulosus and Brucella spp. appeared most frequently in the literature. Pathogens with the highest reported prevalence were MERS-CoV (0–100%), Echinococcus granulosa (7–60%) and Rift Valley fever virus (7–57%). Exposure to Brucella spp., Coxiella burnetii and Crimean-Congo haemorrhagic fever virus showed higher levels in camel or camel-associated vectors than other livestock species, although brucellosis was the only disease for which there was robust evidence linking camel and human exposure. Zoonotic agents with less severe human health outcomes, such as Dermatophilosus congolensis and contagious ecthyma, were also represented in the literature. This review provides an important summary of the scope and quality of current knowledge. It demonstrates that further research, and improved adherence to robust study design and reporting are essential if the zoonotic risk from camels in Kenya, and elsewhere, is to be better understood.

The current prevalence and diversity of cystic echinococcosis in slaughtered animals in Egypt

Cystic echinococcosis is a potential zoonotic helminthic disease affect a broad spectrum of mammals including humans worldwide. The economic impact of the disease interestingly requires updated gathering information on the prevalence in slaughtered animals. Accordingly, in the current study, 573 camels, 4300 sheep, and 1235 pigs were surveyed in four Egyptian municipal abattoirs. Among those, 62 (10.82%) camels, 33 (0.77%) sheep and 3 (0.24%) pigs had cystic echinococcosis in lungs, livers and spleen. The diversity of cysts revealed that positive-cystic echinococcosis animals from all species were detected in El-Basatin abattoir. In El-Monieb abattoir, sheep only were infected. In El-Waraa and Beni-Suef abattoirs, cysts were seen in camels only. Infected animals included both sexes. In camels, lungs were the most affected organs, while in sheep, livers were the most abundant. In pigs, hydatid cysts were detected only in lungs. Moreover, camel cysts were mostly large-sized (diameter > 10 cm) with smaller cysts are also recorded. In sheep, small-, moderately- and large-sized cysts were equally present. Cysts in pigs were large-sized. Camels showed a higher percentage of fertile cysts (46.77%; 29/62) followed by sheep (21.21%; 7/33). Calcified/degenerated cysts were less in camels (38.71%; 24/62) than in sheep (75.76%). Non-viable cysts were the less frequent in both species (14.52% in camels and 3.03% in sheep). All cysts recovered from pigs were fertile. In Egypt, governmental agencies and veterinary authorities are asked to potentially eradicate stray dogs (the main definitive host) and towards the proper hygienic disposal of infected offal in abattoirs to minimize the prevalence of cystic echinococcosis.

Validation of the methylene blue test for assessment of viability of protoscolices from hydatid cysts

Background:

Methylene blue was used as a vital stain for the assessment of viability of protoscolices from hydatid cysts taking advantage of the chemical nature of the dye as a redox indicator and the kinetically distinct molecular transfer systems of Echinococcus protoscolex for uptake of materials across the tegument.

Aim:

The present study attempts to validate the application of methylene blue staining for assessment of viability of protoscolices.

Methods:

To validate the criteria by which viability is assessed, control tests were performed using normal protoscolices and protoscolices previously treated with distilled water at 60°C for 5 minutes. Performance of methylene blue was further studied at intervals over a period of 50 minutes after protoscolex exposure using 1% dye concentration.

Results:

Normal protoscolices were able to adsorb and reduce the dye and have, therefore, lost the blue color. Protoscolices previously treated with warm water on the other hand, being functionally dead, failed to reduce the adsorbed dye and permanently retained the blue color. Results also indicated that a clear distinction between dead and alive protoscolices can be made within 1 minute. Reading of the test after 10 minutes would be misleading giving a false result.

Conclusion:

These findings suggest that viability of protoscolices can be assessed on the basis of acquisition and loss/retaining of the dye blue color. Increasing the concentration of methylene blue to 1% was noticed to be associated with remarkable enhancement of contractility, sucker movement, and evagination. Such an excitatory action of the dye may be exploited in viability tests which adopt these criteria.

A Review of Zoonotic Pathogens of Dromedary Camels

Dromedary, or one-humped, camels Camelus dromedarius are an almost exclusively domesticated species that are common in arid areas as both beasts of burden and production animals for meat and milk. Currently, there are approximately 30 million dromedary camels, with highest numbers in Africa and the Middle East. The hardiness of camels in arid regions has made humans more dependent on them, especially as a stable protein source. Camels also carry and may transmit disease-causing agents to humans and other animals. The ability for camels to act as a point source or vector for disease is a concern due to increasing human demands for meat, lack of biosafety and biosecurity protocols in many regions, and a growth in the interface with wildlife as camel herds become sympatric with non-domestic species. We conducted a literature review of camel-borne zoonotic diseases and found that the majority of publications (65%) focused on Middle East respiratory syndrome (MERS), brucellosis, Echinococcus granulosus, and Rift Valley fever. The high fatality from MERS outbreaks during 2012-2016 elicited an immediate response from the research community as demonstrated by a surge of MERS-related publications. However, we contend that other camel-borne diseases such as Yersinia pestis, Coxiella burnetii, and Crimean-Congo hemorrhagic fever are just as important to include in surveillance efforts. Camel populations, particularly in sub-Saharan Africa, are increasing exponentially in response to prolonged droughts, and thus, the risk of zoonoses increases as well. In this review, we provide an overview of the major zoonotic diseases present in dromedary camels, their risk to humans, and recommendations to minimize spillover events.

Echinococcosis in Tambool, Central Sudan: a knowledge, attitude and practice (KAP) study

Introduction

In Sudan, echinococcosis (EC) is a chronic neglected zoonotic parasitic disease caused by Echinococcus granulosus. Studies have shown high prevalence rates in dogs (50-70%), camels (35%) and sheep, goats and cattle (10-11%). In total, 0.3-1.0% of humans in Central and South Sudan are infected with the G6 camel strain. This strain is almost exclusively the cause of human infections. The objective of this study was to explore knowledge, attitudes and practices (KAP) regarding the disease among people living around Tambool city, Central Sudan.

Methods

A cross-sectional survey was conducted in three villages around the city of Tambool in Central Sudan. Three-hundred-and-twelve households were selected from the administrative unit of the area for participation in the study, of which 300 agreed to partake. A standardized questionnaire was designed to collect data on EC in animals, humans and the environment. The questionnaire domains were socio-demographic characteristics, KAP regarding echinococcosis.

Results

The population surveyed showed that 68.7% (206/300) had never heard of the disease, while 31.3% (94/300) had heard about it. The level of knowledge among the 31.3% of those that had heard about the disease was excellent (69/94; 73.4%); so were their attitudes (76/94; 80.9%). However, the majority of the participants (64/94; 68%) showed poor practice regarding this disease, enhancing the odds for further propagation of parasite circulation in the animal and human populations at risk. Knowledge was found to be significantly associated with marital status. Practice was found to be significantly associated with occupation.

Conclusions

There is a need for the implementation of a multidisciplinary program using the One Health approach to effectively control and prevent EC.

Hydatidosis of Camels and Sheep Slaughtered in Aswan Governorate, Southern Egypt

Background: Hydatidosis is an infection caused by the cystic larval stage of Echinococcus granulosus. This disease is a zoonotic disease has a worldwide distribution and common in developing and undeveloped countries. Objectives: The objective of the present study is to studying the infection rate and predilection seats of hydatid cyst affections among slaughtered food animals in Aswan Governorate, southern Egypt and study the effect of age and sex of infected slaughtered animals on the infection with hydatid cyst. Also, study the effect of seasonal variations in the infection with hydatid cyst among slaughtered animals. In addition, the macroscopic examination, microscopic examination, scanning electron microscopy and histopathological studies for the collected hydatid cyst are examined. Methods: This investigation was carried out from August 2015 to July 2016 in two main slaughterhouses in Aswan Governorate to study the hydatidosis in camels and sheep. By routine meat inspection, hydatid cyst count and characterization was conducted. Findings: A total of 2080 camels and 674 sheep were examined. Of these, 173 (8.32%) camels and 3 (0.45%) sheep were found to harbour one or more hydatid cysts. Female and older age slaughtered animals were more susceptible to infection with these metacestode than males and younger animals. Hydatid cyst infection in slaughtered animals is most commonly found in lung followed by liver while mixed infection in both lung and liver was found only in camel. Hydatid cyst in slaughtered camels was higher in autumn followed by winter, while hydatid cyst in slaughtered sheep was found only in autumn season. Fertile cysts in lung and liver of slaughtered camels was 83.4% and 30% respectively. While the fertility of hydatid cyst in infected lung and liver of sheep was 100%. Main conclusions: This study reported that slaughtered animals were infected with relatively high infection rate of hydatid cyst may be due to the presence of socio-economic conditions favourable for the disease and maintenance of high level of infection. So must design governmental control programs against hydatidosis to minimize the infection rate in Aswan Governorate and ensure effective protection not only for animal population but also for humans at risk of contracting the infection.

First detection of Echinococcus granulosus sensu stricto (G1) in dogs in central Sudan

Eighty-four stray dogs shot as a part of a governmental rabies control program in two neighboring towns of central Sudan were examined for the presence of Echinococcus spp. and other intestinal helminths. Echinococcus worms were identified to species level by PCR and gene sequencing. For comparative reasons, rectal content of the necropsied dogs was examined for helminth eggs and subjected to copro-PCR for Echinococcus. At necropsy, 51.2% (43/84) of the dogs harbored Echinococcus canadensis (G6/7) worms with worm burdens ranging from 22,000 to 80,000. Dipylidiun caninum was found in 53.6% of the dogs. At coproscopy, taeniid eggs were found in 37 of the 43 dogs which were positive for Echinococcus at necropsy, but none in the 41 necropsy-negative dogs. In addition, 58% of the rectal samples contained eggs of Toxocara spp., 34.5% eggs of Trichuris spp. (34.5%), and 26% eggs of Ancylostoma caninum. Copro-PCR gave positive results for E. canadensis with 97.5% (39/40) of nonhibiting samples from the necropsy positive dogs; the one remaining dog tested positive for E. granulosus sensu stricto (G1), whose partial cox1 and nad1 sequences showed a 100% identity with various reference sequences of the G1 genotype. 100% of 38 non-inhibited samples taken from the necropsy-negative dogs were also negative in copro-PCR. This is the first study which combines prevalence and genetic identification of Echinococcus spp. in dogs of Sudan. Together with a recent report from cattle, it confirms the autochthonous presence, at low level, of E. granulosus sensu stricto in Central Sudan.

First molecular characterization of Echinococcus granulosus (sensu stricto) genotype 1 among cattle in Sudan

Background

Echinococcus granulosus sensu lato (s.l.) is the causative agent of cystic echinococcosis (CE), which is a cosmopolitan zoonotic parasitic disease infecting humans and a wide range of mammalian species including cattle. Currently, little information is available on the genetic diversity of Echinococcus species among livestock in Sudan. In the present study, fifty (n = 50) hydatid cysts were collected from cattle carcasses (one cyst sample per animal) at Al-kadarou slaughterhouse, Khartoum North, Sudan. DNA was extracted from protoscolices and the germinal layer of each cyst and subsequently amplified by PCR targeting the mitochondrial NADH dehydrogenase subunit 1 (NADH-1) gene. The amplified PCR products were purified and subjected to direct sequencing for subsequent construction of phylogenetic tree and net work analysis.

Results

The phylogenetic tree revealed the presence of Echinococcus canadenesis genotype 6 (G6) in 44 cysts (88.0%), Echinococcus ortleppi genotype 5 (G5) in 4 cysts (8.0%) and Echinococcus granulosus sensu stricto (s.s) genotype 1 (G1) in 2 cysts (4.0%). The phylogenetic network analysis revealed genetic variation among the different haplotypes/genotypes. This report has provided, for the first time, an insight of the role of cattle in the transmission of the zoonotic G1 echinococosis.

Conclusions

The results of the study illustrate that Sudanese breeds of cattle may play an important role in the transmission dynamics and the epidemiology of cystic echinococcosis in Sudan. This study reports the first molecular identification of E. granulosus s.s. in cattle in Central Sudan.

Global Distribution of Alveolar and Cystic Echinococcosis

Alveolar echinococcosis (AE) and cystic echinococcosis (CE) are severe helminthic zoonoses. Echinococcus multilocularis (causative agent of AE) is widely distributed in the northern hemisphere where it is typically maintained in a wild animal cycle including canids as definitive hosts and rodents as intermediate hosts. The species Echinococcus granulosus, Echinococcus ortleppi, Echinococcus canadensis and Echinococcus intermedius are the causative agents of CE with a worldwide distribution and a highly variable human disease burden in the different endemic areas depending upon human behavioural risk factors, the diversity and ecology of animal host assemblages and the genetic diversity within Echinococcus species which differ in their zoonotic potential and pathogenicity. Both AE and CE are regarded as neglected zoonoses, with a higher overall burden of disease for CE due to its global distribution and high regional prevalence, but a higher pathogenicity and case fatality rate for AE, especially in Asia. Over the past two decades, numerous studies have addressed the epidemiology and distribution of these Echinococcus species worldwide, resulting in better-defined boundaries of the endemic areas. This chapter presents the global distribution of Echinococcus species and human AE and CE in maps and summarizes the global data on host assemblages, transmission, prevalence in animal definitive hosts, incidence in people and molecular epidemiology.

Ecology and Life Cycle Patterns of Echinococcus Species

The genus Echinococcus is composed of eight generally recognized species and one genotypic cluster (Echinococcus canadensis cluster) that may in future be resolved into one to three species. For each species, we review existing information on transmission routes and life cycles in different geographical contexts and - where available - include basic biological information of parasites and hosts (e.g., susceptibility of host species). While some Echinococcus spp. are transmitted in life cycles that involve predominantly domestic animals (e.g., dog - livestock cycles), others are wildlife parasites that do or do not interact with domestic transmission. In many cases, life cycle patterns of the same parasite species differ according to geography. Simple life cycles contrast with transmission patterns that are highly complex, involving multihost systems that may include both domestic and wild mammals. Wildlife transmission may be primary or secondary, i.e., resulting from spillovers from domestic animals. For most of the species and regions, existing information does not yet permit a conclusive description of transmission systems. Such data, however, would be highly relevant, e.g., for anticipation of geographical changes of the presence and frequency of these parasites in a warming world, or for initiating evidence-based control strategies.

Development and evaluation of real-time loop-mediated isothermal amplification assay for rapid detection of cystic echinococcosis

BACKGROUND

Cystic echinococcosis (CE) or hydatidosis, caused by the larval stage of Echinococcus granulosus (EG)-complex, is a neglected parasitic disease of public health importance. The disease is endemic in many African and Mediterranean countries including the Sudan. The objective of the present study was to develop and evaluate a real-time loop-mediated isothermal amplification (LAMP) assay for simple and rapid detection of CE in humans and domestic live stock in Sudan.

METHODS

A set of six LAMP primers, designed from the mitochondrial NADH-1 gene of EG cattle strain of genotype 5 (G5), was used as a target for LAMP assay. The assay was performed at a constant temperature (63 °C), with a real-time follow-up using a LightCycler and fluorochrome dye. Following amplification cycles in a simple water bath, LAMP products were observed for color change by naked eye and were visualized under UV light source using agarose gel electrophoresis.

RESULTS

The real-time LAMP assay identified a variety of hydatid cysts strains recovered in the Sudan, including Echinococcus canadenses (G6) and Echinococcus ortleppi (G5). Real-time LAMP positive results were detected by the presence of an amplification curve, whereas negative results were indicated by absence of fluorescence detection. Positive LAMP results appeared as a bluish-colored reaction as observed by naked eye, whereas negative LAMP results were observed as purple-colored reaction. The sensitivity studies indicated that the LAMP assay detected as little as a 10 fg of parasite DNA. There was 100 % agreement between results of the LAMP assay and our previously described nested PCR when testing 10-fold serial dilution of DNA extracted from EG-complex hydatid cyst. However, there was no cross-reactivity with other parasites including cysticercus bovis, Fasciola gigantica, and Schistosoma bovis and nucleic acid free samples.

CONCLUSION

The developed LAMP assay would be expected to prove highly significant in epidemiological surveys of CE in developing countries or areas of resource-poor settings for both ease of use and cost.

Point-of-Care Ultrasound Assessment of Tropical Infectious Diseases--A Review of Applications and Perspectives

The development of good quality and affordable ultrasound machines has led to the establishment and implementation of numerous point-of-care ultrasound (POCUS) protocols in various medical disciplines. POCUS for major infectious diseases endemic in tropical regions has received less attention, despite its likely even more pronounced benefit for populations with limited access to imaging infrastructure. Focused assessment with sonography for HIV-associated TB (FASH) and echinococcosis (FASE) are the only two POCUS protocols for tropical infectious diseases, which have been formally investigated and which have been implemented in routine patient care today. This review collates the available evidence for FASH and FASE, and discusses sonographic experiences reported for urinary and intestinal schistosomiasis, lymphatic filariasis, viral hemorrhagic fevers, amebic liver abscess, and visceral leishmaniasis. Potential POCUS protocols are suggested and technical as well as training aspects in the context of resource-limited settings are reviewed. Using the focused approach for tropical infectious diseases will make ultrasound diagnosis available to patients who would otherwise have very limited or no access to medical imaging.

High seroprevalence of echinococossis, schistosomiasis and toxoplasmosis among the populations in Babati and Monduli districts, Tanzania

BACKGROUND

The neglected tropical diseases, echinococcosis, schistosomiasis and toxoplasmosis are all globally widespread zoonotic diseases with potentially harmful consequences. There is very limited data available on the prevalence of these infections, except for schistosmiasis, in underdeveloped countries. This study aimed to determine the seroprevalence of Echinococcus multilocularis, Schistosoma mansoni, and Toxoplasma gondii antibodies in populations from the Monduli and Babati districts in Tanzania.

METHODS

A total of 345 blood samples were collected from 160 and 185 randomly selected households from Babati and Monduli districts, Tanzania between February and May of 2012 and analyzed them using the enzyme linked immunosorbent assay. The antibodies were determined using the NovaLisa® Toxoplasma gondii IgG, NovaLisa® Schistosoma Mansoni IgG, NovaLisa® Echinococcus IgG and NovaLisa® Toxoplasma gondii IgM kits (Novatec, Germany).

RESULTS

The seropositivity estimated for E. multilocularis, S. mansoni, and T. gondii IgG was 11.3% (95% confidence interval (CI): 7.96-14.6), 51.3% (95% CI: 46.0-56.5), and 57.68% (95% CI: 52.5-62.9), respectively. The seropositivity for T. gondii IgM was 11.3% (95% CI: 7.96-14.6). Living in the Monduli district was found to be the main risk factor for IgG seropositivity for both schistosomiasis (OR =1.94; 95% CI: 1.23-3.08; p =0.005) and toxoplasmosis (OR =2.09; 95% CI: 1.31-3.33; p =0.002).

CONCLUSIONS

These results suggest that restricting disease transmission, implementing control measures, and introducing training projects to increase public awareness are imperative, particularly for the Monduli district.

First report on circulation of Echinococcus ortleppi in the one humped camel (Camelus dromedaries), Sudan

Background

Echinococcus granulosus (EG) complex, the cause of cystic echinococcosis (CE), infects humans and several other animal species worldwide and hence the disease is of public health importance. Ten genetic variants, or genotypes designated as (G1-G10), are distributed worldwide based on genetic diversity. The objective of this study was to provide some sequence data and phylogeny of EG isolates recovered from the Sudanese one-humped camel (Camelus dromedaries). Fifty samples of hydatid cysts were collected from the one- humped camels (Camelus dromedaries) at Taboul slaughter house, central Sudan. DNAs were extracted from protoscolices and/or associated germinal layers of hydatid cysts using a commercial kit. The mitochondrial NADH dehydrogenase subunit 1 (NADH1) gene and the cytochrome C oxidase subunit 1 (cox1) gene were used as targets for polymerase chain reaction (PCR) amplification. The PCR products were purified and partial sequences were generated. Sequences were further examined by sequence analysis and subsequent phylogeny to compare these sequences to those from known strains of EG circulating globally.

Results

The identity of the PCR products were confirmed as NADH1 and cox1 nucleotide sequences using the Basic Local Alignment Search Tool (BLAST) of NCBI (National Center for Biotechnology Information, Bethesda, MD). The phylogenetic analysis showed that 98% (n = 49) of the isolates clustered with Echinococcus canadensis genotype 6 (G6), whereas only one isolate (2%) clustered with Echinococcus ortleppi (G5).

Conclusions

This investigation expands on the existing sequence data generated from EG isolates recovered from camel in the Sudan. The circulation of the cattle genotype (G5) in the one-humped camel is reported here for the first time.

A systematic review of the literature on cystic echinococcosis frequency worldwide and its associated clinical manifestations

A systematic literature review of cystic echinoccocosis (CE) frequency and symptoms was conducted. Studies without denominators, original data, or using one serological test were excluded. Random-effect log-binomial models were run for CE frequency and proportion of reported symptoms where appropriate. A total of 45 and 25 articles on CE frequency and symptoms met all inclusion criteria. Prevalence of CE ranged from 1% to 7% in community-based studies and incidence rates ranged from 0 to 32 cases per 100,000 in hospital-based studies. The CE prevalence was higher in females (Prevalence Proportion Ratio: 1.35 [95% Bayesian Credible Interval: 1.16-1.53]) and increased with age. The most common manifestations of hepatic and pulmonary CE were abdominal pain (57.3% [95% confidence interval [CI]: 37.3-76.1%]) and cough (51.3% [95% CI: 35.7-66.7%]), respectively. The results are limited by the small number of unbiased studies. Nonetheless, the age/gender prevalence differences could be used to inform future models of CE burden.

Cystic echinococcosis in sub-Saharan Africa

Cystic echinococcosis is regarded as endemic in sub-Saharan Africa; however, for most countries only scarce data, if any, exist. For most of the continent, information about burden of disease is not available; neither are data for the animal hosts involved in the lifecycle of the parasite, thus making introduction of preventive measures difficult. Available evidence suggests that several species or strains within the Echinococcus granulosus complex are prevalent in sub-Saharan Africa and that these strains might be associated with varying virulence and host preference. Treatment strategies (chemotherapy, percutaneous radiological techniques, but mainly surgery) predominantly target active disease. Prevention strategies encompass anthelmintic treatment of dogs, slaughter hygiene, surveillance, and health-educational measures. Existing data are suggestive of unusual clinical presentations of cystic echinococcosis in some parts of the continent, for which the causes are speculative.

A Cross-Sectional Study Investigating Cystic Hydatidosis in Slaughtered Cattle of Western Province in Zambia

A cross-sectional study was conducted from October 2007 to November 2008 to estimate the prevalence of hydatidosis in slaughtered cattle from two abattoirs in Mongu, Western Province, Zambia, using prospective and retrospective data. Out of the 4061 cattle examined during postmortem inspection, 84 (2.1%) were positive for hydatidosis. No cases were detected from Kaoma and Shangombo districts; however, prevalence ranged from 0.6% to 2.5% in districts where it was present. Sex was found to be positively associated with hydatidosis (P = 0.035) with female cattle being more likely to have hydatidosis (OR = 1.62). In the retrospective study (1994 to 2007), annual prevalence of hydatidosis ranged from 1.56% (n = 12,641) in 2006 to 4.7% (n = 2633) in 2001 with an overall prevalence of 3% (4689/158,456). This value is comparable to that observed in cattle slaughtered between October 2007 and November 2008 (2.1%). Hydatidosis was observed in the lungs (51.2%), liver (47.6%), and kidneys (1.2%). The percentage of viable cysts was 43.7%. This study confirms the presence of hydatidosis in cattle in Western Province of Zambia and estimates economic losses due to organ condemnations. Data presented herein provides a useful baseline for developing policy and intervention measures.

Worldwide epidemiology of liver hydatidosis including the Mediterranean area

The worldwide incidence and prevalence of cystic echinococcosis have fallen dramatically over the past several decades. Nonetheless, infection with Echinococcus granulosus (E. granulosus) remains a major public health issue in several countries and regions, even in places where it was previously at low levels, as a result of a reduction of control programmes due to economic problems and lack of resources. Geographic distribution differs by country and region depending on the presence in that country of large numbers of nomadic or semi-nomadic sheep and goat flocks that represent the intermediate host of the parasite, and their close contact with the final host, the dog, which mostly provides the transmission of infection to humans. The greatest prevalence of cystic echinococcosis in human and animal hosts is found in countries of the temperate zones, including several parts of Eurasia (the Mediterranean regions, southern and central parts of Russia, central Asia, China), Australia, some parts of America (especially South America) and north and east Africa. Echinococcosis is currently considered an endemic zoonotic disease in the Mediterranean region. The most frequent strain associated with human cystic echinococcosis appears to be the common sheep strain (G1). This strain appears to be widely distributed in all continents. The purpose of this review is to examine the distribution of E. granulosus and the epidemiology of a re-emerging disease such as cystic echinococcosis.

Slaughter stock abattoir survey of carcasses and organ/offal condemnations in Arusha region, northern Tanzania

The current study reviews a 3-year record of slaughtered animals in Arusha abattoir to determine the causes of carcasses and organ/offal condemnations. A total of 115,186 cattle, 61,551 sheep, 37,850 goats and 13,310 pigs were slaughtered. Out of the slaughtered cattle, 8.6% were pregnant. Up to 125 (0.108%), 39 (0.063%), 40 (0.106%) and 132 (0.992%) of all cattle, sheep, goats and pig carcasses, respectively, were totally condemned. Cysticercosis was the leading cause of total carcass condemnations in cattle (0.051%) and in pig (1.397%), while emaciation accounted for 0.045% and 0.074% of carcass condemnations in sheep and goats, respectively. Livers and lungs were the most condemned organs in all four animal species. The main cause of condemnations of cattle livers was fasciolosis (8.6%), while stilesiosis in sheep and goats accounted for 8.1% and 7.3%, respectively. Ascariasis (4.03%) was the only cause of liver condemnation in pigs. Pneumonia was the leading cause of lung condemnations at the rates of 3.99%, 2.43% and 2.83% in cattle, sheep and goats, respectively. Because of their zoonotic nature, occurrences of hydatidosis, cysticercosis, fasciolosis and tuberculosis may pose a public health risk. Thus, there is a need to introduce appropriate control measures of livestock diseases to minimise the rate of infection and reduce economic losses.

Epidemiology and control of human gastrointestinal parasites in children

Parasites found in the human gastrointestinal tract can be largely categorized into two groups, protozoa and helminths. The soil-transmitted helminths (Ascaris lumbricoides, hookworm and Trichuris trichiura) are the most prevalent, infecting an estimated one-sixth of the global population. Infection rates are highest in children living in sub-Saharan Africa, followed by Asia and then Latin America and the Caribbean. The current momentum towards global drug delivery for their control is at a historical high through the efforts of numerous initiatives increasingly acting in coordination with donors, governments and local communities. Together, they have delivered enormous quantities of drugs, especially anthelmintics to children through nationwide annual or biannual mass drug administration largely coordinated through schools. However, a much larger and rapidly growing childhood population in these regions remains untreated and suffering from more than one parasite. Mass drug administration has profound potential for control but is not without considerable challenges and concerns. A principal barrier is funding. Stimulating a research and development pipeline, supporting the necessary clinical trials to refine treatment, in addition to procuring and deploying drugs (and sustaining these supply chains), requires substantial funding and resources that do not presently exist. Limited options for chemotherapy raise concerns about drug resistance developing through overuse, however, satisfactory pharmaco-epidemiology and monitoring for drug resistance requires more developed health infrastructures than are generally available. Further, the limited pharmacopeia does not include any effective second-line options if resistance emerges, and the research and development pipeline is severely depressed. Herein, we discuss the major gastrointestinal protozoa and helminths reviewing their impact on child health, changing epidemiology and how this relates to their control.

Neglected tropical diseases in sub-saharan Africa: review of their prevalence, distribution, and disease burden

The neglected tropical diseases (NTDs) are the most common conditions affecting the poorest 500 million people living in sub-Saharan Africa (SSA), and together produce a burden of disease that may be equivalent to up to one-half of SSA's malaria disease burden and more than double that caused by tuberculosis. Approximately 85% of the NTD disease burden results from helminth infections. Hookworm infection occurs in almost half of SSA's poorest people, including 40-50 million school-aged children and 7 million pregnant women in whom it is a leading cause of anemia. Schistosomiasis is the second most prevalent NTD after hookworm (192 million cases), accounting for 93% of the world's number of cases and possibly associated with increased horizontal transmission of HIV/AIDS. Lymphatic filariasis (46-51 million cases) and onchocerciasis (37 million cases) are also widespread in SSA, each disease representing a significant cause of disability and reduction in the region's agricultural productivity. There is a dearth of information on Africa's non-helminth NTDs. The protozoan infections, human African trypanosomiasis and visceral leishmaniasis, affect almost 100,000 people, primarily in areas of conflict in SSA where they cause high mortality, and where trachoma is the most prevalent bacterial NTD (30 million cases). However, there are little or no data on some very important protozoan infections, e.g., amebiasis and toxoplasmosis; bacterial infections, e.g., typhoid fever and non-typhoidal salmonellosis, the tick-borne bacterial zoonoses, and non-tuberculosis mycobaterial infections; and arboviral infections. Thus, the overall burden of Africa's NTDs may be severely underestimated. A full assessment is an important step for disease control priorities, particularly in Nigeria and the Democratic Republic of Congo, where the greatest number of NTDs may occur.

A retrospective survey of hydatidosis in livestock in Arusha, Tanzania, based on abattoir data during 2005-2007

A 3-year (2005-2007) retrospective study was carried out to investigate the occurrence of cystic echinococcosis (CE) in cattle and shoats (sheep and goats) slaughtered at Arusha municipal abattoir, Tanzania. A total of 115,186 cattle and 99,401 shoats were slaughtered. Cattle liver, lungs, spleen and heart condemnation rate was 16.35%, 13.04%, 2.09% and 3.06% respectively while 17.63%, 7.63%, 0.38% and 0.04% of shoats' liver, lungs, spleen and heart respectively were condemned. A highly significant (p < 0.001) cystic echinococcosis (CE) infection rate was recorded in shoats (6.02%) than in cattle (4.2%) probably because of differences in grazing patterns. Cattle lungs were more affected by CE (22.5%) than liver (19.7%) while shoats liver were found to be more affected (21%) than the lungs (19.3). A significant (p < 0.001) higher CE infection rate was observed in cattle spleen (15.5%) than shoats (9.7%). There was no significant (p > 0.05) difference between condemnation rates due to hydatidosis during rain and dry seasons probably because of chronicity of the disease. The study have established that CE is prevalent in animals slaughtered at Arusha abattoir and causes higher condemnation rates of edible offals. This merit for more extensive epidemiological investigations to better determine the prevalence, economic impact and public health importance of the disease in the region.

Hydatidosis of slaughtered animals in Ngorongoro district of Arusha region, Tanzania

A study on the prevalence of hydatidosis in cattle, goats and sheep was carried out in Ngorongoro district of Arusha region, Tanzania. A 4-years data records from four slaughter slabs were retrieved and analysed. In addition, meat inspection was done in the same slaughter slabs for nine months and 64 households were interviewed to assess the community awareness on hydatidosis. Results showed the overall prevalence of hydatidosis to be 47.9%. Species prevalence of 48.7%, 34.7% and 63.8% in cattle, goats and sheep respectively was recorded. Of 174 cysts examined in cattle, 37 (21.3%) were fertile, 126 (72.4%) were sterile and 11 (6.3%) were calcified. Out of 215 goats and 67 sheep cysts examined, 52 (24.7%) and 26 (38.8%) were fertile, 138 (64.2%) and 38 (56.7%) were sterile, 24 (11.2%) and 3 (4.5%) were calcified respectively. The higher percentage of fertile hydatid cysts in sheep and goats coupled with the practice of backyard slaughter of sheep and goats suggests that, these animals could be important intermediate hosts for the maintenance of the domestic life cycle of E. granulosus in the locality. Questionnaire survey revealed that 17.2% of the respondents were aware of hydatidosis but non of them were knowledgeable on its transmission. Up to 84.4% of the respondents had domestic ruminants and donkeys, while 89.1% had dogs. Of the households with dogs, only 19.3% had their dogs dewormed at least once in life time. Most of the households (87.7%) had their dogs managed freely and 77.2% of the respondents reported school children to be the closest friends of dogs in the family. The prevalence of E. granulosus infection in wildlife and the possible relationship of the domestic cycle to the sylvatic cycle operating in the same area are unknown and need to be studied.

Hydatidosis of slaughtered animals in Bahir Dar Abattoir, Northwestern Ethiopia

The study was conducted from May 2005 to December 2006 in Bahir Dar Abattoir to assess the current status of hydatidosis in cattle and sheep. Hydatid cyst count and characterization were conducted based on routine meat inspection. Of the total 420 cattle and 340 sheep slaughtered in Bahir Dar Abattoir 143 (34.05%) and 36 (10.6%) animals were found harboring hydatid cysts respectively. Thorough meat inspection in the abattoir revealed that 202 and 54 visceral organs were found harboring one or more hydatid cysts in cattle and sheep respectively. Differences in prevalence rates between the two species of animals were highly significant (P < 0.001). The infection of the lung, liver, kidney, spleen and heart were found to be 57.9% , 36.6% , 3% , 1.5% , 1% in cattle and 50%, 48.1% and 1.9% in sheep respectively. From the total of 864 in cattle and 138 in sheep hydatid cysts counted 315 (36.4%), 268 (31.0%), 65 (7.5%), 216 (25.0%) in cattle and 92 (66.7%), 20 (14.5%), 1 (0.7%), 25 (18.1%) in sheep were found to be small, medium, large and calcified cysts respectively and 484 (56.0%), 164 (18.9%), 216 (25%) in cattle and 35 (25.4%), 78 (56.5%), 25 (18.1%) in sheep were sterile, fertile and calcified cysts respectively. Viability rates of 62.2% in cattle and 78.2% in sheep were observed. The rate of cyst calcification was higher in the liver than in the lung while fertility rate was higher among the cysts of the lung for both cattle and sheep.

Emergence/re-emergence of Echinococcus spp.--a global update

This review provides an update of the biological aspects of the genus Echinococcus and focuses on newly recognized endemic areas. Infection with the intermediate cystic stage of all species of Echinococcus causes disease and incapacity in animals and humans, and in the most serious cases, death of the host. Transmission of Echinococcus to new continents has occurred during European colonisation and the parasite has often taken advantage of Echinococcus-naive wildlife populations in these new environments, incorporating them into its transmission pattern. Echinococcus granulosus consists of a complex of 10 strains. Host specificities of these strains have important implications for transmission and control. As a result of human behaviour and/or political instability in a number of countries Echinococcus is re-emerging as an important public health issue. The importance of wildlife reservoirs in perpetuating transmission and as a source of infection for domestic animals and humans is addressed. The review also refers to the transmission pattern of a recently described new species, Echinococcus shiquicus, from China.

Epidemiology and control of echinococcosis in sub-Saharan Africa

Cystic echinococcosis (CE) is highly endemic among the nomadic pastoral tribes of East Africa, but is rare amongst the agriculturally based communities. Echinococcus granulosus infections are common in dogs from all countries in sub-Saharan Africa where they have been examined. Transmission of E. granulosus to humans is affected by such factors as prevalence of the parasite in domestic dogs, behaviors of humans towards dogs, and heterogenicity of the parasite and susceptibility of humans to infection. Sheep and goats appear to be the most common domestic intermediate hosts, but recent studies suggest that camels are equally important intermediate host, especially in Sudan and Turkana. At least five of ten E. granulosus genotypes are infective to humans in sub-Saharan African. Most human cases of CE are caused by the sheep strain (GI) and camel strain (G6) of E. granulosus. Other strains occurring in the area may include a lion strain, the horse strain (G4 or Echinococcus equinus) and the cattle strain (G5 or Echinococcus ortleppi).