Susceptibility and lack of evidence for a viremic state of rabies in the night owl monkey, Aotus nancymaae.

BACKGROUND: Rabies causes an acute fatal encephalomyelitis in most mammals following infection with rhabdovirus of the genus Lyssavirus. Little is known about rabies virus infection in species of New World non-human Primates (NHP). To investigate the suitability of the owl monkey Aotus nancymaae asissue sections examined were unremarkable for inflammation or other histologic signs of rabies a viable animal model for rabies virus candidate vaccine testing, we used clinical presentation, serology, viral isolation, and PCR to evaluate the incubation period, immunity, and pathogenesis of infected animals. We tested the hypothesis that no viremic state exists for rabies virus. METHODS: Eight monkeys divided into two equal groups were inoculated intramuscularly either in the neck or footpad with 105 pfu of rabies virus (Pasteur/V-13R) and observed for >130 days. Oral and blood samples were collected and analyzed. RESULTS: Two monkeys inoculated in the neck displayed classic paralytic rabies. The mean incubation period was 11.5 days. The average maximum IgG response (antibody titer >0.200 O.D.) was achieved at day 10.0 and 62.3 in the clinical rabies and non-clinical rabies cases, respectively (p = 0.0429). No difference in IgM or IgG time to seroconversion or average maximum IgM level was observed between neck versus footpad inoculation groups. No viremia or viral shedding was detected by PCR or viral isolation during the observation period, including within the two symptomatic animals three days after disease onset. Tissue sections examined were unremarkable for inflammation or other histologic signs of rabies within the asymptomatic animal. Similarly none of the brain sections exhibited immunoreactivity for rabies virus antibody. DISCUSSION: This study demonstrates there is no difference in time to immune response between inoculation sites and distance to the brain; however, immune response tends to be more rapid in cases of clinically apparent disease and prolonged in cases infected at sites further from the brain. CONCLUSIONS: Our findings support the hypothesis that a viremic state for rabies does not exist in the New World Monkey, Aotus nancymaae, and it appears that this species may be refractory to infection. The species does provide a suitable model to assess post infection immune responses. Additional studies that address the limitations of sample size, length of observation, and lack of measurable infection should be conducted.

Epidemiology of spotted fever group and typhus group rickettsial infection in the Amazon basin of Peru.

A seroprevalence study for IgG antibodies against spotted fever group (SFGR) and typhus group (TGR) Rickettsia among humans and domestic pets was conducted in the city of Iquitos, located in the Amazon basin of Peru. Of 1,195 human sera analyzed, 521 (43.6%) and 123 (10.3%) were positive for SFGR and TGR antibodies, respectively. District of residence and participant age were associated with antibody positivity for both groups, whereas rodent sightings in the home were associated with TGR antibody positivity. Of the 71 canines tested, 42 (59.2%) were positive for SFGR antibodies, and two (2.8%) were positive for TGR antibodies; one active SFGR infection was detected by polymerase chain reaction. An uncharacterized SFGR species was detected in 95.9% (71/74) of Ctenocephalides felis pools collected from domestic pets. These data suggest that rickettsial transmission is widespread in Iquitos. Rickettsia species should be further explored as potential causes of acute febrile illnesses in the region.

Rapid response to a case of mumps: implications for preventing transmission at a medical research facility / Respuesta rápida a un caso de paperas: implicaciones para la prevención del contagio en una instalación de investigación biomédica

OBJECTIVE: To prevent transmission among the staff and potentially among the non-human primate (NHP) colony at the U.S. Naval Medical Research Center Detachment in Peru, where an active case of mumps was discovered in a senior laboratory technician in Sep 03, 2007. MATERIAL AND METHODS: Subjects at the research facility were interviewed and potentially susceptible contacts were tested for mumps IgG. RESULTS: In total, 81 out of 106 staff members (76 percent) had close contact with the case. Only 6/81 (7 percent) had MMR, 33 (41 percent) reported having had mumps, and 8 of 45 (18 percent) of the potentially susceptible individuals did not have immunity (IgG > 20.0). All the susceptible, exposed individuals received MMR vaccine. There were no secondary cases and access to the NHP colony was restricted. DISCUSSION: Immediate and thorough investigation and occupational health response were imperative in preventing secondary cases of mumps among humans and NHP.

OBJETIVO: Prevenir el contagio de parotiditis al personal y potencialmente a la colonia de primates no humanos (PNH), tras detectarse un caso en el personal técnico de laboratorio en el Centro de Investigación de Enfermedades de la Marina de los EUA (NMRCD). MATERIAL Y MÉTODOS: El personal fue entrevistado y se hizo una prueba de IgG para parotiditis a los contactos potencialmente susceptibles. RESULTADOS: En total, 81 de 106 miembros del personal tuvo contacto cercano con el caso. Sólo 6/81 (7 por ciento) tenían vacuna y 33 (41 por ciento) reportaron haber tenido parotiditis, y 8 de 45 (18 por ciento) de los susceptibles potenciales no tenían inmunidad (IgG > 20.0). Todos los susceptibles expuestos fueron vacunados y no hubo casos secundarios. Se restringió el acceso a la colonia de PNH. CONCLUSIÓN: La investigación inmediata y la respuesta de salud ocupacional fue imperativa para prevenir casos secundarios de parotiditis en el personal y los NHP.

Rapid response to a case of mumps: implications for preventing transmission at a medical research facility.

OBJECTIVE: To prevent transmission among the staff and potentially among the non-human primate (NHP) colony at the U.S. Naval Medical Research Center Detachment in Peru, where an active case of mumps was discovered in a senior laboratory technician in Sep 03, 2007. MATERIAL AND METHODS: Subjects at the research facility were interviewed and potentially susceptible contacts were tested for mumps IgG. RESULTS: In total, 81 out of 106 staff members (76%) had close contact with the case. Only 6/81 (7%) had MMR, 33 (41%) reported having had mumps, and 8 of 45 (18%) of the potentially susceptible individuals did not have immunity (IgG > 20.0). All the susceptible, exposed individuals received MMR vaccine. There were no secondary cases and access to the NHP colony was restricted. DISCUSSION: Immediate and thorough investigation and occupational health response were imperative in preventing secondary cases of mumps among humans and NHP.

Susceptibility of owl monkeys (Aotus nancymaae) to experimental infection with Bartonella bacilliformis.

Bartonellosis, caused by Bartonella bacilliformis, is a clinically significant disease in parts of South America, where it is characterized by fever and hemolytic anemia during the often-fatal acute stage and warty skin eruptions during chronic disease. In this study, we evaluated owl monkeys (Aotus nancymaae) as a potential model for studying the immunogenicity and pathology of bartonellosis. Two groups of animals (n = 3 per group) received either 9.5 x 10(7) CFU B. bacilliformis by the ID route or 1.1 x 10(6) CFU by the IV route and were followed for 140 d. Animals were evaluated by physical exam, complete blood count or hematocrit (or both); infection was confirmed by Giemsa staining of blood smears, PCR amplification, and blood culture. On days 7 and 21, Giemsa-stained blood smears from both groups contained organisms (1% to 4% of erythrocytes). All blood cultures and PCR tests were negative. Complete blood counts and chemistry panels showed no difference from baseline. Serology revealed a greater than 4-fold increase in the IgM titer (compared with baseline levels) in the 3 animals from the ID group and 1 animal from the IV group. On day 35, a dermal lesion was excised from the inguinal region of 1 monkey from each group, with a second lesion excised on day 84 from the same monkey in the IV group. However the histopathology and immunostaining of these samples were not consistent with B. bacilliformis. The present study shows that owl monkeys can be infected with B. bacilliformis, but additional dosage studies are necessary to evaluate the usefulness of this species as a disease model for human bartonellosis.

Evaluation of two fecal examination techniques for detection of Trypanoxyuris spp. infection in owl monkeys (Aotus nancymae).

Infections of Trypanoxyuris spp. pinworms in Aotus nancymae and other New World primates are typically subclinical, but infection during experimental use could confound interpretation of experimental data. Further, Trypanoxyuris species are highly infective, and rapid diagnosis is important to prevent an outbreak in the animal colony. This study sought to determine whether a fecal flotation technique was sensitive enough to replace the perianal tape test for diagnosis of Trypanoxyuris spp., thereby reducing stress to the animal and sample collection time. On days 0 and 3, we collected fecal samples from 45 animals confirmed to be infected with Trypanoxyuris spp. by perianal tape testing. Fecal samples were evaluated by both a commercial analysis system and by sucrose flotation with centrifugation. For both detection methods, no significant difference in sensitivity was detected between tests conducted on day 0 versus day 3. The sensitivity of repeated commercial tests was 80%, significantly higher than the 60% for sucrose flotation. The commercial test was significantly more sensitive than sucrose flotation, indicating that the commercial system was a better method for detecting Trypanoxyuris spp. However, sensitivity of only 80% confers a considerable risk of false negatives, thereby potentially delaying treatment and further contributing to environmental contamination. In our opinion, neither method of fecal analysis was a suitable replacement for the perianal tape test to diagnose Trypanoxyuris spp. in owl monkeys.

Comparison of various anthelmintic therapies for the treatment of Trypanoxyuris microon infection in owl monkeys (Aotus nancymae).

Trypanoxyuris microon is a pinworm that infects New World nonhuman primates, including Aotus nancymae. Although it typically is clinically insignificant, infection may serve as a significant variable during experimental data analysis. In this study we sought to determine the most effective anthelmintic therapy for eradication of T. microon infection in A. nancymae. Animals confirmed to be infected with T. microon by perianal tape test were treated twice (on days 0 and 14) with pyrantel pamoate, ivermectin, or thiabendazole and evaluated for eggs by daily perianal tape test throughout the entire 28-d period. Successful clearance of eggs was defined as 5 consecutive negative perianal tape tests. Pyrantel pamoate and ivermectin were significantly more effective at egg clearance than were thiabendazole and no treatment. Overall, 100% of the pyrantel pamoate and ivermectin treatment groups were cleared of infection after 2 treatments, whereas only 60% of the thiabendazole group became negative for pinworm eggs. In addition, the time after treatment until clearance was 1 to 2 d for pyrantel pamoate, 2 to 4 d for thiabendazole, and 4 to 6.5 d for ivermectin. These results indicate that pyrantel pamoate was the most effective and rapidly acting anthelmintic for the treatment of adult T. microon infection, with ivermectin as a suitable alternative. However because of the potential for continued development of immature stages or reinfection, anthelmintic doses should be repeated after 1 to 2 wk, in combination with effective environmental sanitation.