Studies on the sero-epidemiology of endemic diseases in Libya. I. Echinococcosis in Libya

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.

The global status and genetic characterization of hydatidosis in camels (Camelus dromedarius): a systematic literature review with meta-analysis based on published papers

Hydatidosis is a potential zoonotic helminthic disease affecting a broad spectrum of mammals, including humans, worldwide. The current review was conducted to investigate the genotypic status and prevalence of hydatid disease in camels across the world. For the purpose of the study, the articles addressing the worldwide prevalence of hydatidosis in camels were searched in several English language databases. The search process resulted in the inclusion of 122 papers. Based on the data presented in the reviewed articles, the pooled prevalence of hydatid disease in camels across the world was measured at 23.75% (95% CI 20.15-27.55). Moreover, the subgroup analysis demonstrated significant differences in the overall prevalence of hydatidosis among camels based on year, geographic area, climate parameters, camel population, gender, infected organ, fertility rate of the cyst and laboratory diagnostic technique. Furthermore, the Echinococcus granulosus genotypes identified in camels with hydatidosis included G1, G2, G3, G1-G3, G5, G6, G7, G6-G7 and G6-G10, with G6 being the most common genotype throughout the world. The data obtained from the current study are central to the better conceptualization of the biological and epidemiological characteristics of E. granulosus s.l. genotypes around the world, which can be helpful in the planning and adoption of more comprehensive control strategies.

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.

Human Cystic Echinococcosis in the Nalut District of Western Libya: A Clinico-epidemiological Study

Human cystic echinococcosis (CE) is an endemic disease in the Mediterranean area that has not yet been fully documented in western Libya. The present study describes the clinico-epidemiologic profile of CE in western Libya’s Nalut district. From April 2008 to July 2011, 36 cases of CE were confirmed following surgical removal of cysts. The cysts were most frequently found in the liver (61.1%), followed by the lungs (19.4%), kidneys (11.1%), peritoneal cavity (11.1%), and spleen (5.6%). Among the 36 patients, 6 possessed plural cysts and 3 had cysts in 2 organs. Blood samples from this group were examined for the presence of serum anti-hydatid IgG antibodies, which revealed positivity in 25 patients (69.4%). An additional 300 blood samples were collected randomly from the inpatient and outpatient clinics at Nalut Hospital. Twenty-seven samples (9%) were found to be positive for the anti-hydatid IgG antibody among which the prevalence of infection tended to be higher in men (12%) than in women (6%). This study demonstrates that CE is a major parasitic infectious disease of public health significance in Libya, notably in the western part of the country, and that disease awareness needs to be raised nationwide.

The monetary burden of cystic echinococcosis in Iran

Cystic echinococcosis (CE) is a globally distributed parasitic infection of humans and livestock. The disease is of significant medical and economic importance in many developing countries, including Iran. However, the socioeconomic impact of the disease, in most endemic countries, is not fully understood. The purpose of the present study was to determine the monetary burden of CE in Iran. Epidemiological data, including prevalence and incidence of CE in humans and animals, were obtained from regional hospitals, the scientific literature, and official government reports. Economic data relating to human and animal disease, including cost of treatment, productivity losses, and livestock production losses were obtained from official national and international datasets. Monte Carlo simulation methods were used to represent uncertainty in input parameters. Mean number of surgical CE cases per year for 2000-2009 was estimated at 1,295. The number of asymptomatic individuals living in the country was estimated at 635,232 (95% Credible Interval, CI 149,466-1,120,998). The overall annual cost of CE in Iran was estimated at US$232.3 million (95% CI US$103.1-397.8 million), including both direct and indirect costs. The cost associated with human CE was estimated at US$93.39 million (95% CI US$6.1-222.7 million) and the annual cost associated with CE in livestock was estimated at US$132 million (95% CI US$61.8-246.5 million). The cost per surgical human case was estimated at US$1,539. CE has a considerable economic impact on Iran, with the cost of the disease approximated at 0.03% of the country's gross domestic product. Establishment of a CE surveillance system and implementation of a control program are necessary to reduce the economic burden of CE on the country. Cost-benefit analysis of different control programs is recommended, incorporating present knowledge of the economic losses due to CE in Iran.

The seroprevalences of cystic echinococcosis, and the associated risk factors, in rural-agricultural, bedouin and semi-bedouin communities in Jordan

An ELISA was used to determine the seroprevalence of cystic echinococcosis (CE), caused by Echinococcus granulosus, in representatives of the rural-agricultural, semi-bedouin and bedouin communities of Jordan. The knowledge, attitudes and practices (KAP) pertaining to the transmission of CE in such communities were also investigated. In the ELISA, serum samples from 2388 subjects were tested for IgG antibodies reacting with antigens in crude sheep hydatid fluid (CSHF). The rural-agricultural subjects were significantly more likely to be seropositive (11.4%) than the semi-bedouin (5.0%) or bedouin (3.7%), but male and female subjects were equally likely to be seropositive. Among the rural-agricultural and semi-bedouin subjects, those aged 11-20 years were most likely to be seropositive. Among the bedouin subjects, however, seroprevalence was highest for those aged 31-40 years. When the distribution of 59 seropositive subjects detected within 36 rural-agricultural households was investigated, 12 (33.3%) of the households were each found to have at least two seropositive members. Immunoblotting indicated that 27.1% of the seropositive rural-agricultural subjects showed immunoreactivity to at least one of the CSHF antigen-B components (of 8-12, 16 and 24 kDa). The living conditions, practices and lifestyles of the rural-agricultural, semi-bedouin and bedouin communities favour the spread of CE in Jordan and warrant an effective programme for the control of the disease.

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.

Biochemical profiles of hydatid cyst fluids of Echinococcus granulosus of human and animal origin in Libya

A comparative study on the biochemical parameters in hydatid cyst fluids of sheep, goats, camels, cattle and human cystic forms of Echinococcus granulosus has been made in Libya. Quantitative variations in the levels of sodium, potassium, calcium, cholesterol, glucose, urea, creatinine and gamma glutamyl transpeptidase (gamma GT) were found in the cystic fluids of different host origins although these differences were statistically insignificant compared with the hydatid fluids of sheep. However, the concentration of triglycerides and proteins were significantly elevated in the cyst fluids of sheep compared with the other fluids studied. Similarities in the biochemical composition of different hydatid cyst fluids suggest the existence of sheep strains of E. granulosus in human and other domestic animal intermediate hosts in Libya.

Omentoplasty in the prevention of deep abdominal complications after surgery for hydatid disease of the liver: a multicenter, prospective, randomized trial. French Associations for Surgical Research

BACKGROUND

Omentoplasty (OP) is thought to fill residual cavity, to assist healing of raw surfaces, and to promote resorption of serosal fluid and macrophagic migration in septic foci. Results published to date, whether retrospective or prospective, are not controlled and are discordant.

STUDY DESIGN

The authors investigated whether OP, either filling the residual cavity after unroofing, or covering the hepatic raw surface after pericystectomy, could reduce the rate or severity of deep abdominal complications (DAC) after surgical treatment of hydatid disease of the liver. Between January 1993 and December 1996, 115 consecutive patients (51 males and 64 females, mean age 42+/-16 years [range 10 to 80 years]) with previously unoperated uni- or multilocular hydatid disease of the liver, complicated or not, without other abdominal hydatid disease, were randomly allotted to OP (n = 58) or not (NO) (n = 57) after unroofing, total, or partial pericystectomy. Patients were divided into 2 strata according to the site of the cyst with respect to the diaphragm: a) posterosuperior segments II, VII, and VIII or b) anterior segments III, IV, V, and VI. Main outcomes measures included deep bleeding, hematoma, infection, or bile leakage. Subsidiary measures included wound complications, extraabdominal complications, duration of operation, and length of hospital stay.

RESULTS

Both groups were comparable regarding patient demographics, cyst characteristics, intraoperative procedures, search for bile leaks, and intraoperative transfusion requirements. On the other hand, more patients (86%) in NO had associated drainage of the abdominal cavity than in OP (64%) and the duration of operation was 9 minutes longer in OP, but neither of these differences was statistically significant. Less DAC occurred in OP (10%) than in NO (23%) (a posteriori gamma risk < 0.05) and fewer deep abdominal abscesses (0 versus 11%) (p < 0.03). Median duration of hospital stay, however, was similar.

CONCLUSIONS

OP decreases the rate of DAC and especially deep abdominal abscess after surgical treatment (unroofing or pericystectomy) for hydatid disease of the liver and should be recommended in this setting.

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.

Public health aspects of cystic echinococcosis in the Arab countries

Human cystic echinococcosis (CE) caused by larval Echinococcus granulosus is a zoonosis of major public health importance throughout the region comprising Arab North Africa and the Middle East. Prevalence rates are determined by epizootiological factors related to the size of stray dog population and its worm burden and to the infection rates in the intermediate host reservoir livestock population. Socio-economic development and socio-cultural practices are considered important determinants in the continued transmission of the disease. The reasons why CE remains a significant public health problem in the region are summarized.

Serodiagnosis and seroepidemiology of human unilocular hydatidosis in Jordan

A total of 2182 serum samples from 38 patients with surgically confirmed unilocular hydatidosis, 19 clinically assessed patients, 15 patients with parasitic infections other than hydatidosis, 104 hospital outpatients, and 2006 normal Jordanians were serodiagnosed for the presence of IgG antibodies against hydatid fluid, circulating immune complexes (CIC), and/or hydatid circulating antigen (CA). Anti-hydatid IgG antibodies were detected in the sera of 77.4% of patients with hydatid disease and persist for very long periods postsurgery. As many as 54.1% of patients with hydatidosis had positive levels of CIC, and 16.1% had circulating antigen in their sera. The search for circulating antigen and CIC decreased the number of false-negative hydatid cases from seven to three, and the combined sensitivity of the assays thus increased from 77.4% to 90.3%. Using the immunoblot technique, 16- and < 14.4-kDa Echinococcus granulosus-specific bands were detected in sera from 54.1% and 61.5% of patients with hydatid disease who were tested before and after surgery, respectively. The seropositivity rate for anti-hydatid IgG antibodies was 2.4% for the general Jordanian population and 5.8% for hospital outpatients.

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.

Echinococcosis in Libya. III. Further studies on the prevalence of Echinococcus granulosus in dogs

Of 92 dogs examined for Echinococcus granulosus at five sites in Libya from April 1985 to September 1988 33 (35.9%) were infected, the prevalences ranging from 60% (Zawiyah) and 52.0% (Tripoli) in the north-west, to 28.6% (Benghazi) and 28.5% (Darna) in the north-east. None of eight dogs at Al-Kufra, in the south-eastern desert, were infected. Twenty dogs each had two to 200 worms, nine had 201-1000 worms and four each had over 1000 worms (one dog in Tripoli had 17,120 worms). Most infections were seen in dogs aged three to four years; 45.4% of bitches and 35.4% of males were infected.

Echinococcosis in Libya. IV. Prevalence of hydatidosis (Echinococcus granulosus) in goats, cattle and camels

During a survey of 14 Libyan abattoirs in 1985-1987 the carcasses of 4316 locally-bred goats, cattle and camels were inspected for cysts of Echinococcus granulosus. Of 2295 goats, 35 adults (1.5%) had cysts; no kids were infected. Thirty-one adult goats had infected livers, 28 had lung infections, and four each had cysts in their kidneys and spleens. Most (59.7%) of the infections were light, with medium infections in 31.3% and heavy infections in 8.9%; 85.7% of the cysts in the lungs and 38.7% of those in the livers were fertile; three of the four kidney infections and two of the four spleen infections were fertile. Of the 1023 cattle carcasses, mild infections with E. granulosus were seen in 55 (5.4%); all the cysts were sterile and confined to the liver. Of 998 camels, 358 (35.9%) had hydatid cysts. These involved the lungs in 96.9%, either as the sole site (74.3%) or jointly with the liver (22.6%). Lung cysts (57.6%) and liver cysts (41.2%) were fertile.

Serodiagnosis of human hydatid disease in Riyadh, Saudi Arabia

The Indirect Haemagglutination (IHA) test was used routinely for the diagnosis of hydatid disease in patients at the King Abdul Aziz and King Khalid University Hospitals, Riyadh, Saudi Arabia. Among 52 patients with suspected human hydatid disease, 30 positive cases were detected by means of serodiagnosis. As a control group, the level of hydatid IHA antibodies were determined in blood donors and in patients with no history of human hydatid disease. The serological results obtained in this control group showed that 70% had no hydatid IHA antibodies whereas 25% had antibody titres of 1:4 to 1:8, which are of no clinical significance.