Abstract The utilization of oral lesions as a screening tool for HIV is not well documented. Attendees at two primary health care facilities (Khutsong and Heidelberg) were assessed to determine the predictive value of group I oral lesions for HIV infection. The objectives were to investigate the: 1) HIV prevalence amongst attendees at PHC facilities, 2) Prevalence of HIV-related oral lesions and 3) Correlation between the oral lesions and the HIV status using the Likelihood Ratio test. Methods: All patients over 12 months of age presenting at the two facilities for a curative care consultation over a one-week period (in April 2005) were included. Consent was obtained by trained counselors who also conducted a brief interview and offered pre-test counseling to patients wishing to know their HIV status. Two calibrated dentists conducted a head, neck and oral examination and administered a rapid saliva HIV test (OraQuick HIV-1/2-Rapid HIV-1/2 Antibody Test). Results: A total of 654 attendees were surveyed in the 2 facilities. There was a 100% response. The mean age of the participants was 34 years (range: 1-94), and the majority (73%) were female. HIV prevalence rates were 34% at Khutsong and 36% at Heidelberg. The HIV prevalence peaked at 46% in the 16-45 age groups. Of the 228 who tested positive for HIV, 121 (53%) patients were diagnosed with 1 or more Group I oral lesion. Oral candidiasis (46%) and oral hairy leukoplakia (19%) were the two most common oral lesions diagnosed in the HIV positive cohort. The positive predictive values and specificity values for multiple lesions ranged between 96% and 100%. Most of the likelihood ratios for multiple lesions were greater than 10 which implied that the patients who presented with these lesions were extremely likely to test positive for HIV. The sensitivity values (1% to 37%) and negative predictive values (66% to 70%) remained relatively low. Conclusion: The HIV prevalence of patients attending PHC facilities was high (34%). Oral lesions are useful markers of HIV-infection and should alert clinicians to the presence of HIV infection. Multiple group I lesions were more predictive of HIV infection compared to single lesions.

The present thesis examines questions related to the temporal origin of the Flavivirus genus and the ecology of tick-borne pathogens. In the first study, we date the origin and divergence time of the Flavivirus genus. It has been argued that the first flaviviruses originated after the last glacial maximum. This has been contradicted by recent analyses estimating that the tick-borne flaviviruses emerged at least before 16,000 years ago. It has also been argued that the Powassan virus was introduced into North America at the time between the opening and splitting of the Beringian land bridge. Supported by tip date and biogeographical calibration, our results suggest that this genus originated circa 120,000 (156,100–322,700) years ago if the Tamana bat virus is included in the genus, or circa 85,000 (63,700–109,600) years ago excluding the Tamana bat virus. In the second study we estimate the prevalence of tick-borne encephalitis virus (TBEV) in host-seeking Ixodes ricinus from 29 localities in Sweden and compare our data with those of neighbouring countries. Nymphs and adult ticks were screened for TBEV using a real-time PCR assay. The mean TBEV prevalence for all tick stages combined was 0.26% for Sweden and 0.28% for all Scandinavian countries, excluding Iceland. The low prevalence of TBEV in nature may partly be explained by the fact that TBEV occurs in spatially small foci and that the inclusion of ticks from non-infected foci will reduce the prevalence estimate. In the third and fourth study, we conducted the first large-scale investigations to estimate the prevalence and geographical distribution of Anaplasma spp. and Rickettsia spp. in host-seeking larvae, nymphs and adults of I. ricinus ticks in Sweden. Ticks were collected from several localities in central and southern Sweden and were subsequently screened for the presence of Anaplasma spp. and Rickettsia spp. using a real-time PCR assay. For all active tick stages combined, the mean prevalence of Anaplasma spp. and Rickettsia spp. in I. ricinus in Sweden was estimated to 1.1% and 4.8%, respectively. It was also shown that A. phagocytophilum and R. helvetica are the main Anaplasma and Rickettsia species occurring in Sweden.

The most widespread of invasive crayfish in the Czech Republic is the spiny-cheek crayfish (Orconectes limosus). It is a major disease carrier of crayfish plague, caused by the pathogen Aphanomyces astaci. The infection is lethal to European native species of crayfish. Transmission of this disease is usually associated with the spread of crayfish, which is dependent on their movement. The main aim of this work was to evaluate the differences in crayfish migratory activity in the Pšovka brook among seasons, and assess the factors that may affect it, by the use of radiotelemetry and trapping. We tested the hypothesis that crayfish use brook in the period from spring to autumn and then return back into a pond to overwinter. Furthermore, we evaluated how far from the pond crayfish migrate, and whether there is any relationship between migration and the season or water temperature. The results demonstrate that the activity varies among seasons (being strongly affected by breeding season) but in most studied periods did not significantly depend on water temperature. According to our monitoring, the spiny-cheek crayfish does not spread substantially to upstream parts of the Pšovka. Seasonal migration between the pond and the brook was monitored using two-way flow-through traps installed at the mouth of...