Epidemiology of hydatidosis/echinococcosis in Ouarzazate, the pre-Saharian region of Morocco

[Hydatid cyst sampling by FTA Card method for characterizing Echinococcus granulosus sensu lato in Algeria. Preliminary results]

Introduction and objectives

Cystic echinococcosis is highly endemic in Algeria and constitutes a major socio-economic problem. Typing the species of the Echinococcus granulosus sensu lato complex circulating in cattle requires the use of a hydatid cyst sampling method adapted to difficult field conditions (high heat and humidity, long transport time). The FTA Card method currently constitutes an effective means of preserving biological samples before their molecular analysis. In the present study, the FTA Card method was used in the collection of hydatid cysts to identify the species of E. granulosus sensu lato circulating in ruminants (intermediate hosts) in eastern Algeria.

Material and methods

A PCR was carried out for 41 samples of hydatid cysts taken from six slaughterhouses in eastern Algeria, targeting the cox1 mitochondrial gene. PCR products were visualized by electrophoresis in a 1% agarose gel.

Results and conclusion

The results of the molecular analysis of all hydatid cyst samples confirmed the presence of E. granulosus sensu stricto in sheep, cattle and camels. The ubiquitous nature of the G1 genotype has been demonstrated. The use of FTA Card sampling is an efficient and simple method to obtain a biological sample in order to characterize the species of E. granulosus sensu lato in Algeria. The good preservation of the DNA in this matrix will make it easier to obtain new molecular data from difficult regions. The identification of the species of the E. granulosus sensu lato complex involved in the biological cycle is an essential prerequisite for the implementation of control measures, since different host species participate in their evolutionary cycle. The characterization of E. granulosus genotypes is essential to define an appropriate control strategy against cystic echinococcosis.

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, risk factors and zoonotic potential of intestinal parasites in dogs from four locations in Morocco

Dogs can harbor various intestinal parasites that have serious clinical, economic, and zoonotic impact. In Morocco, the epidemiological status of those parasites is largely unknown. This study aimed to obtain data on the prevalence of intestinal parasites in various Moroccan dog populations, to identify associated risk factors, to evaluate people's knowledge regarding zoonotic parasites and to estimate the risk of human infection. A total of 291 fecal samples were analyzed using a 33% Zinc Sulphate (ZnSO4) centrifugal flotation and a sheather's sugar simple flotation techniques. In addition, 100 dog owners were asked to fill out a questionnaire about their knowledge regarding canine zoonotic intestinal parasites. Overall, 58% of sampled dogs were positive for at least one parasite species. Ancylostoma/Uncinaria spp. (31.9%), Toxascaris leonina (27.4%), Toxocara canis (27.1%), Cystoisospora spp. (13.4%) and Giardia spp. (7.2%) were the most frequently isolated parasites. The overall prevalence was associated with the dogs' activity, and feces consistency. More specifically, the prevalence of Ancylostoma/Uncinaria spp., Toxascaris leonina and Cystoisospora spp. was associated with dogs' activity and feces consistency and, additionally with age for Cystoisosporaspp.Toxocara canis prevalence was associated with age and feces consistency, while Giardia spp. prevalence was associated with dogs' activity. A weak awareness among dog owners regarding the zoonotic potential of canine intestinal parasites was noticed (33%) especially when their knowledge was compared to another endemic zoonotic disease, i.e. rabies (85%). Furthermore, the rate of respecting the vaccination protocol (82%) was significantly higher than the rate of respecting the deworming protocol (47%). We conclude that intestinal parasites, including the zoonotic ones, were highly prevalent in the dogs sampled in this study whereas people's knowledge about those parasites was very limited. These findings suggest that the risk of human infection is very likely, which highlights the need for effective control programs and health education.

Prevalence of echinococcosis and Taenia hydatigena cysticercosis in slaughtered small ruminants at the livestock-wildlife interface areas of Ngorongoro, Tanzania

Aim:

Echinococcosis or hydatidosis (due to the larval stage of Echinococcus spp.) and cysticercosis (due to the larval stage of Taenia hydatigena) pose a significant economic losses due to slaughter condemnation and risk to public health in developing countries such as Tanzania where sanitation is poor and people live in close proximity with each other and with animals. This study was conducted to determine the prevalence of and to identify the predisposing factors for echinococcosis and cysticercosis in sheep and goats at three slaughter slabs located in the livestock-wildlife interface areas of Ngorongoro, Tanzania.

Materials and Methods:

A cross-sectional based survey was conducted, from January 2013 to April 2013, whereby a total of 180 animals comprising 90 goats and 90 sheep of both sexes were examined at postmortem for the evidence of larval stages of Echinococcus spp. (hydatid cyst) and T. hydatigena (Cysticercus tenuicollis) through visual inspection, incision and palpation of organs and viscera.

Results:

The prevalence of echinococcosis was 22.2% and 16.6%, in goats and sheep, respectively, while the overall infection rates for cysticercosis were 61.1% in goats and 42.2% in sheep. The result of this study revealed that goats and sheep in Malambo slaughter slab had significantly higher prevalence of T. hydatigena (C. tenuicollis) and hydatid cysts (p<0.05) compared to other slab points. T. hydatigena (C. tenuicollis) cysts were more frequently detected in the omentum than other visceral organs among the animals examined.

Conclusion:

In conclusion, the observed high prevalence of the two metacestodes larval stages leads to high condemnation rates of edible offals and raises significant public health concerns. This underscores for the need to undertake more extensive epidemiological investigations to better determine the causal factors, economic impact, and public health importance of the disease in this livestock-wildlife interface setting.

Norway rat (Rattus norvegicus) as a potential reservoir for Echinococcus granulosus: A public health implication

Cystic hydatidosis is a re-emerging parasitic zoonosis with worldwide distribution. The current study was carried out to investigate the possible role of rats in the epidemiology of such disease in urban and suburban areas. For this purpose, a total of 50 feral Norway rats (Rattus norvegicus) were collected from urban and suburban settings, Cairo, Egypt. Rats were examined to be infected with cystic hydatidosis through serological examination by IHA test as well as post-mortem examination of internal organs, histopathological or molecular identification of the collected cysts. Moreover, 42 persons inhabiting suburban areas were tested for cystic hydatidosis by IHA. The overall seroprevalence rates of cystic hydatidosis in the examined rats and persons were 36% and 11.9% respectively. Cysts from 3 rats were identified as E. granulosus hydatid cysts (one via histopathological examination while the others by molecular technique and genotyped as G6 strain). The results of the current study highlight the possible role of Norway rat in the epidemiological cycle of E. granulosus especially in urban and suburban settings.

Cystic echinococcosis in Algeria: cattle act as reservoirs of a sheep strain and may contribute to human contamination

In Algeria, cystic echinococcosis (CE) is a serious economic and public health problem. The common sheep/dog cycle is usually considered as the major source of human contamination. But to date the main strain of Echinococcus granulosus involved in the human contamination and the role of other hosts are still unknown. This paper reports an original work performed in northern Algeria combining field observations and molecular analysis. In a first step, examination of 6237 carcasses in slaughterhouses showed high infection and fertility rates in cattle and dromedaries. Then, in a second step, we used a molecular biology approach to identify the E. granulosus strain(s) involved. Forty-six samples from various origins were collected. They were analysed using comparison of PCR-amplified DNA sequences with one genomic (BG 1/3) and two mitochondrial (COI and NDI) targets. Results show the presence of a "sheep" strain of E. granulosus in North Algeria circulating between cattle and ovines and infectious to humans, whereas in South Algeria, a "camel" strain and a "sheep" strain were found to circulate in camels and in sheep, respectively. This study also reports an ambiguous genotype which resembled the "sheep" strain genotype (Gl) on the basis of the partial COI gene sequence, whereas on the basis of the partial NDI gene sequence, it was similar either to the "sheep" strain (Gl) or to the "camel" strain (G6). Besides its basic interest, our study confirms the role of other hosts (mainly cattle) in leading to transmission to humans and suggests that control measures should not only target sheep.

Combined eco-epidemiological and molecular biology approaches to assess Echinococcus granulosus transmission to humans in Mauritania: occurrence of the 'camel' strain and human cystic echinococcosis

Mauritania lies between West-Central Africa where human cystic echinococcosis (CE) is considered extremely rare and West Maghreb where CE accounts for a real public health problem. Until 1992, Mauritania was considered as human CE-free even through CE seemed well known in livestock. In 1992, the introduction of ultrasonography led to the diagnosis of the first human CE cases. In 1997, a veterinary study revealed that dogs living around Nouakchott were commonly infected by Echinococcus granulosus. To assess E. granulosus transmission and to identify the most relevant animal reservoir responsible for human CE emerging in Mauritania, a simultaneous eco-epidemiological and molecular biology approach was performed. The fieldwork included sample collection and investigation of relationship between intermediate hosts, definitive hosts and humans. Typing of E. granulosus strains was performed using comparison of polymerase chain reaction (PCR)-amplified DNA sequences with one nuclear (BG 1/3) and 2 mitochondrial (COI, NDI) targets. Results show that the 'camel' strain is actually infectious to humans and circulates between intermediate hosts including camels and cattle. It is suggested that preventive measures at slaughtering places could reduce human contamination.

Epidemiology and strain characteristics of Echinococcus granulosus in the Benghazi area of eastern Libya

The incidence of surgically confirmed cystic echinococcosis in eastern Libya was estimated to be at least 4.2 cases/100,000, with significantly more female cases than male. The prevalences of infection with Echinococcus granulosus among 1087 sheep, 881 goats, 428 camels and 614 cattle from the same region, determined postmortem in abattoirs, were 20%, 3.4%, 13.6% and 11%, respectively. Infection in the livestock was age-dependent and, generally, the female animals were more often infected than the male. The measurements of rostellar hooks on protoscoleces collected from sheep and cattle were similar but significantly different from the corresponding measurements of parasites of human or camel origin. However, when a portion of the cytochrome c-oxidase subunit I (cox1) gene from each of 30 protoscolex samples from Libya (12 from cattle, three from humans, five from camels and 10 from sheep) was sequenced, the sequences were all found to be identical to that published for the common sheep strain of E. granulosus.

An epidemiological survey of Echinococcus granulosus and other helminths in animal populations in northern Israel

In a survey carried out during the period May 1995 to November 1996, in communities of various ethnic groups in northern Israel, 206 dogs were examined for Echinococcus granulosus and other intestinal helminth parasites by arecoline hydrobromide purges and the coproantigen-ELISA. The arecoline test was performed close to the owners' homes, using plastic sheets secured to the ground. From 56 dogs examined in the Muslim town of Tamra, six (10.7%) were found to be infected with E. granulosus. Four of them also had a mixed infection of Taenia hydatigena and Dipylidium caninum (two dogs), and the remaining two dogs were infected with either D. caninum or Taenia pisiformis. An additional 18 dogs were infected with either T. pisiformis (eight dogs), D. Caninum (seven dogs), or T. hydatigena (three dogs). Two of these dogs harboured mixed infections whereas the remaining 32 dogs were free of helminths. In the Jewish villages, none of the 150 dogs examined were infected with E. granulosus, although 26 (17.3%) were infected with D. caninum, four (2.7%) with Ancylostoma spp. and one (0.7%) with Toxocara canis. Only one of the 22 stray dogs and none of the 15 jackals examined were infected with E. granulosus. However, 21 (95.4%) of the dogs and 12 (80%) of the jackals harboured helminth infections, including: D. caninum (16 dogs and seven jackals), Ancylostoma spp. (five jackals), T. hydatigena (three dogs), and T. canis (one dog). Approximately 18% of the dogs and 33% of the jackals showed mixed infections with two or more of the above helminths. In the abattoirs, 52 (5.9%) of the 874 sheep and 33 (5.3%) of the 616 goats from 17 herds slaughtered in the Muslim and Druze villages were found to be infected with E. granulosus, compared with a 0% infection rate observed in 93 sheep from two herds in Jewish villages.

Prevalence of human hydatid disease in northwestern Libya: a cross-sectional ultrasound study

A total of 4103 people were screened in an ultrasound survey of the prevalence of hydatid disease (Echinococcus granulosus) in five areas of northwestern Libya; hydatid cysts were seen in 57 (1.4%), an overall prevalence of approximately 2.0% when adjusted for the likelihood of the occurrence of cysts in other sites in the body. All ultrasound-positive cases were confirmed by dot-blot ELISA. The prevalence of hydatid cysts increased with age, and differed between the sexes except in the five to 14 age group. All diagnosed cases, even those with large cysts, were asymptomatic. This study demonstrates the value of ultrasonography for screening field populations for hydatid disease. The technique was well received locally, facilitating the rapid collection of prevalence data from all ages and both sexes. Libyan people keep guard dogs, but there is little direct human:dog contact. Many people own a single dog, invariably kept outside and often chained up. Stray dogs are common, roaming the countryside to scavenge sheep carcases etc., and such dogs could be the main reservoir of E. granulosus in Libya. Because of the minimal direct human:dog contact, transmission of hydatid disease in Libya is probably indirect by ingestion of eggs from contaminated vegetables or drinking water.