Effectiveness and cost effectiveness of screening immigrants schemes for tuberculosis (TB) on arrival from high TB endemic countries to low TB prevalent countries.

BACKGROUND: Immigrants to developed countries are a major source of TB. Therefore amongst strategies adopted for TB control in developed countries include; 1) Screening immigrants at ports of entry referred to as "Port of Arrival Screening" (PoA) and 2) Passive screening (PS) for TB which means screening immigrants through general practices, hospitals, chest-clinics and emergency departments. Evidence of the effectiveness and cost effectiveness of these strategies is not consistent. OBJECTIVE: Evaluate efficiency of active PoA TB screening for immigrants from TB endemic-regions compared with Passive Screening of immigrant-populations from TB endemic-regions. METHODS: Major electronic-databases and reference lists of relevant studies were searched. Experts of immigrants' TB screening were contacted for additional studies published or unpublished. Systematic search of major databases identified only retrospective cohort-studies. Their qualities were assessed using Scottish Intercollegiate Guidelines Network (SIGN) methodological checklist for comparative cohort-studies. RESULTS: Systematic electronic searches identified 1443 citations. Of these 74 studies were retrieved for evaluation against the review's inclusion/exclusion criteria (see study inclusion/exclusion criteria). Four studies met the inclusion criteria (figure 2) which were low in the evidence hierarchy of primary effectiveness studies and had heterogeneities between them. Thus descriptive data-synthesis was performed. Proportionately PoA screening had the lowest percentage of receipt of tuberculin skin test (TST) and the highest percentage of non-attendance for TST reading (table 2). Active PoA screening reduced infectiousness by 34% compared to 30% by passive screening and new entrants screened at PoA were 80% less likely to be hospitalised Odds ratio (OR) = 0.2 (95% confidence interval (CI) 0.1 - 0.2). [Table: see text]. ECONOMIC ANALYSIS: One cost effectiveness analysis was found that compared the costs of; active PoA screening, general practice screening and homeless screening groups. The cost of detecting a case of TB were; £1.26, £13.17 and £96.36 for PS, homeless screening and active PoA screening respectively. The cost of preventing a case of TB were; £6.32, £23.00 and £10.00 for PS, homeless screening and PoA screening respectively, showing there is little difference between the different strategies. CONCLUSION: Active PoA screening is worth doing with significant benefits including early identification of risk groups with possible timely treatment/chemoprophylaxis intervention, prevention of transmission by significantly reducing infectiousness with subsequent avoidance of hospitalisation in active PoA screening group.

Morphological and anatomical studies on larval trematode of genus Brachylaima (Brachylaimidae) from the land snail, Monacha obstructa.

The metacercariae of genus Brachylaima were collected from the kidney of the land snail Monacha obstructa. About thirteen to fifteen metacercariae were collected from each snail. The metacercariae observed were elongated rather than oval. The gonads were no so developed inspite of the great similarity between this larval stage and the adults. No larval stages rather than the metacercariae were observed. The specimens were examined in fresh status and then stained with carmine and fast green as counter stain. The excretory system was developed to very great extent. This seems to be the first record of this larval stage in Egypt since 1899 when Looss collected the adult of B. aequans from Gerbillus aegyptiacus. The heavy infection of snails reflects the higher incidence of this parasite among land snails as intermediate host. Since, the life cycle of this parasite is not yet confirmed experimentally in Egypt, the species has not been identified.

The histopathological effect of metacercariae of the genus Brachylaima on the land snail, Monacha obstructa.

The histopathological changes in the kidney of the land snail Monacha obstructa and the histochemistry of the body wall of the parasite were studied. The histological pictures of the infected kidney showed extensive degree of degeneration in the renal tissue with multiple necrotic foci. Due to the mechanical and feeding effects of the parasite, the renal lamellae were disintegrated. Also, suckers increased the renal damage. In some levels of the kidney, the renal tissue was completely disappeared except the connective tissue of kidney capsule. Also, it was observed that there was a clear space between the parasites and renal tissue probably as a trial of evasion from the Host's reaction. The histochemical study on the metacercarial body wall revealed that it is consisting of three layers arranged as outer, middle and inner layers. Staining with Periodic Acid Schiff proved that the body wall is rich in mucopolysaccharide content. The idea that this parasite can be used as a biocontrol agent is also discussed.