Echinococcosis is a cosmopolitan zoonosis caused by adult or larval stages of cestodes belonging to the genus Echinococcus (family Taeniidae). The two major species of medical and public health importance are Echinococcus granulosus and E. multilocularis, which cause cystic echinococcosis (CE) and alveolar echinococcosis (AE), respectively. Both CE and AE are both serious diseases, the latter especially so, with a high fatality rate and poor prognosis if managed inappropriately. This review discusses new concepts and approaches in the immunology and diagnosis of CE, but comparative reference has also been made to AE infection and to earlier pivotal studies of both diseases. The review considers immunity to infection in the intermediate and definitive hosts, innate resistance, evasion of the immune system, and vaccination of intermediate and definitive hosts, and it particularly emphasizes procedures for diagnosis of CE and AE, including the value of immunodiagnostic approaches. There is also discussion of the new advances in recombinant and related DNA technologies, especially application of PCR, that are providing powerful tools in the fields of vaccinology and molecular diagnosis of echinococcosis.

Concepts in Immunology and Diagnosis of Hydatid Disease

Present situation of echinococcosis in the Middle East and Arabic North Africa

The larvae of Megaselia scalaris (Diptera: Phoridae) exploit a broad spectrum of larval pabula. Consequently, the species features in a range of situations that affect the resources or well-being of humans. Furthermore, M. scalaris is readily cultured in the laboratory and is therefore favored as an experimental species for genetic, developmental, and bioassay studies. However, the extensive but widely scattered literature, reviewed herein, is frequently ignored by specialists, which gives rise to the unwitting repetition of previous work as well as insupportable proposals.

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Natural History of the Scuttle Fly, Megaselia scalaris

Molecular epidemiology of Cryptosporidium in livestock animals and humans in the Ismailia province of Egypt.

Bone hydatid disease lacks a typical clinical appearance and image characteristics on x ray or CT are similar to those of tuberculosis, metastases and giant cell tumour or bone cysts. However, MRI does show distinctive diagnostic features of bone hydatid disease, especially in the spine. Until recently, treatment of osseous hydatid disease has been entirely surgical. Effective chemotherapy using benzimidazoles, particularly mebendazole, albendazole and combination treatments, has now been achieved in experimental studies and clinical practice. However, most of these drugs are still in the experimental stage or are in the early stages of clinical use.

Bone hydatid disease

Human cystic hydatidosis (cystic echinococcosis) is a chronic zoonotic disease that results from infection with the dog tapeworm Echinococcus granulosus. In Egypt, cystic echinococcosis (CE) is recognized in slaughtered livestock by veterinarians, however, there is little information about human CE infection rates. We describe an immunological assay useful for the diagnosis of human cystic hydatidosis. Sera were collected from surgically confirmed hydatid cases (34), nonendemic subjects free from parasitic infection (20) and from subjects (109) infected with other helminths (Hymenolepis nana, Schistosoma mansoni, Fasciola hepatica and Ancylostoma duodenale). Hydatid cyst fluid (HCF) of camel origin was used as antigen in an ELISA format to measure total E. granulosus specific IgG antibodies and IgG subclasses. Sensitivity measurements of total IgG, and IgG1-4 were 100, 100, 79.4, 61.8 and 55.9%, respectively, whereas respective specificity reached 65.1, 97.7, 98.4, 96.1 and 83. 7%. The diagnostic value of measuring IgG1 (97.7%), as assessed by a rating index (J) for combined sensitivity and specificity, was superior to total IgG (65.1%) and IgG2-4 (77.8, 57.9 and 39.6%, respectively). These findings set the stage for field evaluation of the IgG1 assay in areas endemic with human cystic hydatidosis.

An enzyme‐linked immunosorbent assay for detection of IgG1 antibodies specific to human cystic echinococcosis in Egypt

The role of adhesion molecules; the intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) as mediators in development of skin allergy caused by giardiasis and the controlling role of the cytokine interleukin (IL)-6 over these adhesion molecules were studied. The work included 25 symptomatic giardiasis patients with skin allergy manifested by diffuse urticaria, pruritus, wheal and erythema, and had positive serum anti-Giardia immunoglobulin (Ig) E measured as mean optical density (OD) value by enzyme linked immunosorbent assay (ELISA), employed as an evidence of allergic sensitization (G.I). They were compared with 30 symptomatic giardiasis patients (G.II) and 20 apparently healthy control subjects (G.III), both latter groups had negative serum anti-Giardia IgE. The mean OD value of anti-Giardia IgE was significantly increased in G.I (P 0.05) compared with G.III. Serum levels of soluble forms of adhesion molecules; sICAM-1 & sVCAM-1, and IL-6 were determined by ELISA. sICAM-1 & sVCAM-1 serum levels were significantly increased (P 0.05) between Gs. II & III. Serum IL-6 significantly increased in G.I (P < 0.001) & G.II (P < 0.05) compared with G.III, and was significantly higher (P < 0.001) in G.I than G.II. Serum IL-6 correlated positively with serum sICAM-1 (P < 0.01) and sVCAM-1 (P < 0.001) in G.I. The results are discussed.

Human giardiasis as an etiology of skin allergy: the role of adhesion molecules and interleukin-6.

Megaselia scalaris is a worldwide distributed insect of medical importance. In a laboratory-based study, stool samples with undefined maggot infestation were examined and the presence of M. scalaris maggots was confirmed. Binocular stereo-microscopy was used for identification of the maggots. Larvae were allowed to develop into adults onto a human stool culture. The larvae and the emerged flies were identified using standard keys. This may be the first report of M. scalaris as a causative agent of human myiasis in Egypt. Details of the third instar larva, pupa and adults were given.

Megaselia scalaris causing human intestinal myiasis in Egypt.

A crude water extract of Solanum nigrum leaves was used as a chemical attenuate to Schistosoma mansoni cercariae prior to infection of Swiss female mice. Cercariae were exposed to 2.5, 5, 7.5 and 10 mg/l concentrations of the extract for 30 min. The effect on the ability of cercariae to penetrate mice skin, as well as, effect on schistosome worm burden after 8 weeks of infection were measured. The observed reduction of cercarial penetration was significant at 7.5 and 10 mg/l concentrations (p < 0.001). The mean number of worm burden declined from 28.5 worms/ mouse in untreated group to 4.4 worms/mouse with 7.5 mg/l treatment (p < 0.01). At a concentration of 10 mg/l, mice had no adult worm. The cercarial infectivity, as measured by the proportion of worms recovered in relation to the number of cercariae administrated, decreased with the increase in the extract concentration and was significant at a concentration of 7.5 mg/l (p < 0.01). The number of schistosome eggs in hepatic tissue decreased in treated mice. The reduction in egg count (per gram liver) was significant at 5 mg/l (p < 0.05) and 7.5 mg/I (p < 0.001). The treatment with Solanum water extract had no effect on female fecundity. These data point to Solanum as a promising agent for the control of schistosomiasis.

Effects of Solanum nigrum leaves water extract on the penetration and infectivity of Schistosoma mansoni cercariae.

Cryptosporidium parvum has a world wide distribution. Numerous nosocomial outbreaks of cryptosporidiosis have occurred, also numerous well documented water born outbreaks have occurred. The present study included 104 patients and 27 contacts, both were subjected to stool examination by MZN stain. ELISA for detection of Cryptosporidium Ag in stool was further carried out for the patients developing diarrhea after admission (12), patients admitted with diarrhea (17), and for contacts. Twenty four water samples collected from Pediatric Hospital, and examined by MZN and ELISA. The results showed that 11.5% of examined cases developed diarrhea after admission. 8% of them were positive for cryptosporidiosis by both MZN and ELISA. 17% (3/27) of the contacts were negative by MZN stain. ELISA was found to be 100% sensitive, 94.1% specific. Water samples were found to be negative for C. parvum.

Manal M A Rifaat

Papers

An enzyme‐linked immunosorbent assay for detection of IgG1 antibodies specific to human cystic echinococcosis in Egypt

Human giardiasis as an etiology of skin allergy: the role of adhesion molecules and interleukin-6.

Megaselia scalaris causing human intestinal myiasis in Egypt.

Effects of Solanum nigrum leaves water extract on the penetration and infectivity of Schistosoma mansoni cercariae.

Nosocomial sources of cryptosporidial infection in newly admitted patients in Ain Shams University Pediatric Hospital.