Conversion of the Kowa RC-2 camera to a digital version, instructions for use, and postprocessing of the images.

OBJECTIVE: To describe a means of converting the Kowa RC-2 camera to a digital version. PROCEDURE: The optic (OP) and the film portions (FP) of the Kowa RC-2 were separated. The lateral rails were unscrewed from the front plate of the FP. The front plate was detached from the FP. The plate was fixed to an anodized aluminum plate (AAP). The rails were screwed back onto the front plate. This system was reattached to the OP by means of the rails. A T2-E mount ring was screwed onto the AAP and fixed to a digital camera body (DCB). A flash sync extension cord was used to connect the flash cable of the Kowa to the DCB. The images obtained with the converted Kowa were inverted horizontally and vertically using image processing software. RESULTS: The images obtained with the converted Kowa RC-2 were identical in format to those using the film version with a circular image surrounded by a black rectangle. The imaged ocular structures were accurately depicted, appearing upside down and reversed on the LCD screen. The DCB was set to manual mode and focus. The shutter speed was initially set to 1/250 s, and the ISO was adjusted based on the ocular structure being photographed. An extra filter had to be placed over the light source to dim the light when imaging reflective fundi. CONCLUSION: The converted digital version of the Kowa RC-2 as described provides an affordable means of obtaining high-quality images of various ocular structures.

Detection by two enzyme-linked immunosorbent assays of antibodies to Ehrlichia ruminantium in field sera collected from sheep and cattle in Ghana.

Two serological tests for detection of antibodies to Ehrlichia (previously Cowdria) ruminantium, the causative agent of heartwater, were compared by using field sera collected from sheep and cattle as part of serosurveys in Ghana. Sera selected as either negative or positive by a new polyclonal competitive enzyme-linked immunosorbent assay (PC-ELISA) were tested by the indirect MAP1-B ELISA. Cutoff values of 14 percent positivity (14 PP) for both ruminant species were obtained for the MAP1-B ELISA by using preseroconversion Ghanaian sera and were compared with previously recommended cutoff values of 29 PP for sheep and 38 PP for cattle. With the 14-PP cutoff, of 151 sheep sera which tested negative by PC-ELISA, 89% were also negative by MAP1-B ELISA, while of 419 sheep sera positive by PC-ELISA, 98% were also positive by MAP1-B ELISA. Of 261 bovine sera negative by PC-ELISA, 82% were also negative by MAP1-B ELISA. Of 511 bovine sera positive by PC-ELISA, only 47% were positive by MAP1-B ELISA; these included 168 sera collected from cattle following first seroconversion as detected by both tests, with 125 of these sera positive by PC-ELISA but only 59 and 5 positive by MAP1-B ELISA with the 14- and 38-PP cutoff levels, respectively. These results indicate that both assays are highly sensitive and specific for detection of E. ruminantium exposure in sheep but that the MAP1-B ELISA lacks sensitivity for postseroconversion bovine sera in comparison to the PC-ELISA. Both tests confirm E. ruminantium seroprevalence of at least 70% in Ghanaian sheep; levels of exposure among Amblyomma variegatum-infested Ghanaian cattle are likely to be higher than the seroprevalence value of 66% obtained with the PC-ELISA.