Traveller's diarrhoea (TD) is the most common illness reported in international travellers. TD is caused by a wide range of pathogens, including bacteria, viruses and parasites. Multiplex PCR assays can be especially useful for studying the aetiology of TD. The first objective of this study was to evaluate the utility of the commercially available multiplex PCR (xTAG(®) Gastrointestinal Pathogen Panel (GPP)) for the diagnosis of TD. A total of 185 stool specimens obtained from 174 patients were processed using the GPP assay. This test detected 86 pathogens in 67 stool samples (67/185, 36.2%). Sixteen pathogens out of 86 were also detected by routine testing. The remaining pathogens (n = 70) required further confirmation by alternative techniques. Finally, 60 out of 70 pathogens were confirmed. The second objective of this study was to analyse the aetiology of TD based on the results obtained by the GPP test and routine methods. The primary pathogens causing TD were Shigella (24.2%) followed by enterotoxigenic Escherichia coli (ETEC) (23.2%), enteroaggregative E. coli (14.7%) and Giardia (13.7%). Significant regional differences were observed for ETEC with 19.4% of TD cases acquired in Africa, 11.3% in Asia and none in South Central (SC) America (p 0.01), Giardia was found in 1.5% of cases among those who had travelled to Africa, 14.1% of those who had travelled to Asia and 3% of those who had travelled to SC America (p 0.01). In conclusion, the GPP test improved the detection of enteropathogens and allowed better assessment of the aetiology of TD.

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Cytotaxonomic analysis of the polytene chromosomes from larvae of the Simulium damnosum Theobald complex from the island of Bioko in Equatorial Guinea is reported, and a new endemic cytoform is described. Chromosomally this cytoform is close to both S. squamosum (Enderlein) and S. yahense Vajime & Dunbar, but is not identical to either. However, it is morphologically and enzymatically identical to S. yahense. The Bioko form was also found to differ from other cytoforms of the S. damnosum complex in West Africa in the copy number or RFLP pattern of several different repetitive DNA sequences. It is clear that the Bioko form is genetically distinct from other populations of the S. damnosum complex, and whilst it is closest to S. yahense, it shows features that suggest a high degree of geographical and genetic isolation. Such isolation is an important consideration in the assessment of the potential for onchocerciasis vector eradication on Bioko.

Summary Bioko is the only island known in the world with endemic onchocerciasis. The island's rural communities consist of villages and cocoa plantations inhabited by Bubi and Fang ethnic groups. The aim of this study was to evaluate the impact of 8 years of vertical ivermectin distribution on the prevalence and intensity of Onchocerca volvulus infection in the rural population by means of pre‐ (1989) and post‐long term treatment (1998) epidemiological surveys. In both surveys, the entire population of 12 randomly selected communities (1723 and 1082 individuals) was examined. The mean ivermectin therapeutic coverage for the 8 years was 53.2%. Iliac crest skin snips were used for differential diagnosis between O. volvulus and Mansonella streptocerca. The crude O. volvulus infection prevalence before ivermectin intervention was 74.5% (1284/1723); after the intervention it was 38.4% (415/1082). The Community Microfilarial Load (CMFL) before and after ivermectin intervention was 28.29 microfilariae/snip vs. 2.32 microfilariae/snip. The reduction in prevalence and CMFL after eight annual rounds of ivermectin treatment corroborates the drug microfilaricidal activity and good tolerability. In the pre‐treatment survey, the prevalence was higher in the Bubi group (77.1%, 1126/1461); post‐treatment it was higher among the Fang (51.1%, 92/180). The reduction in prevalence and intensity of O. volvulus infection differed between ethnic groups and communities.