Serologic survey for hantavirus infection in domestic animals and coyotes from New Mexico and northeastern Arizona.

OBJECTIVE: To determine whether animals had serologic evidence of infection with Sin Nombre virus (SNV). DESIGN: Prospective serosurvey. SAMPLE POPULATION: Serum samples were obtained from 145 cats, 85 dogs, 120 horses, and 24 cattle between April 1993 and August 1994 and 54 coyotes between December 1994 and February 1995. PROCEDURE: Serum samples were analyzed by western immunoblot assays for reaction with SNV nucleocapsid antigen. Samples with reactivity to SNV nucleocapsid proteins were used to probe multiple-antigen blots containing recombinant fusion proteins derived from prototypic hantaviruses. Lung tissue or blood clots were used in nested reverse-transcriptase polymerase chain reaction assays for a 320-nucleotide portion of the SNV G1 gene. RESULTS: Sera from 4 of 145 (2.8%) cats and 4 of 85 (3.5%) dogs had trace reactivity to full-length SNV-encoded nucleocapsid proteins. All samples from horses, cattle, and coyotes were nonreactive. Sera from cats and dogs that had trace IgG-antibody reactivity to nucleocapsid proteins were then tested for IgG-antibody reactivity to nucleocapsid proteins of prototypic hantaviruses. One cat had multiple cross-reactivities with these hantaviruses, consistent with exposure to a hantavirus; however, epitope mapping studies did not support this conclusion. Reverse-transcriptase polymerase chain reaction studies of blood clots or lung tissue from 2 animals that had weak reactivity to SNV failed to amplify any hantavirus sequence. CLINICAL IMPLICATIONS: Domestic animals, particularly dogs and cats, as well as coyotes do not appear to have a major role in the maintenance and transmission of SNV.

Comparison of four serotests for the detection of Dirofilaria immitis infection in dogs.

Three hundred two dogs were tested with 4 serotests for heartworm antigen (AG) or antibody (AB) and with the Knott test. The 4 serotests evaluated were an enzyme-linked immunosorbent assay (ELISA) for adult heartworm-specific AB (AB-ELISA), a quantitative, indirect immunofluorescent assay (IFA) for adult heartworm-specific AB (AB-IFA), an IFA test for microfilaria (MF)-specific AB (MF-IFA), and an ELISA for adult heartworm AG (AG-ELISA). The presence of heartworms was ascertained in all dogs by necropsy examination. Of 302 dogs, 20 (6.6%) had heartworms in the heart at necropsy. Of infected dogs, 9 (45%) had occult infections. Test sensitivities were 75%, 95%, 70%, and 75% for the AB-ELISA, AB-IFA, MF-IFA, and AG-ELISA, respectively. Test specificities were 85% (AB-ELISA), 77% (AB-IFA), 87% (MF-IFA), and 99% (AG-ELISA). The best agreement between serotest results and necropsy findings was obtained with the AG-ELISA (97%). The 4 serotests detected 86% (AB-ELISA), 100% (AB-IFA), 67% (MF-IFA), and 78% (AG-ELISA) of the dogs with occult heartworm infection. A significant (P less than 0.05) association between intestinal parasitism and positive heartworm test results was found with only AB-IFA. Seemingly, the Knott test, or some other concentration method for detecting circulating MF should be the first heartworm test performed. If the examination for MF is negative, the dog has clinical signs, and radiographic findings are suggestive of occult heartworm infection, then a serotest for adult heartworm AG is recommended.