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This study was designed to test the effects of two message features (source and level of autonomy support) that are commonly found in short-form social media (e.g. TikTok) videos about Pap tests. The source is defined as who is communicating the message, and autonomy support refers to providing an individual with the independence, respect, and choice to make their own decision. In an online experiment, 636 females aged 21-29 viewed TikTok videos about Pap tests varying in source (doctor vs. peer) and level of autonomy support (either using controlling language to demand getting a Pap test or being supportive of one's choice of whether they receive a Pap test) and then responded to outcomes measures including perceived source credibility, perceived message effectiveness, attitude toward the message, attitude toward Pap tests, intention to engage with the videos, and intention to get a Pap test. Doctors were perceived as more credible than peers, and doctor videos were perceived to be more effective than peer videos. Autonomy support interacted with source, such that autonomy-supportive videos delivered by a doctor improved attitude toward the messaging and attitude toward Pap tests. Regardless of the source, autonomy-supportive videos increased intention to engage with the content on social media. As Pap test rates have recently declined among young women in the United States and viewing of Pap test-related videos has skyrocketed on the TikTok platform, short-form social media sites like TikTok may be an effective health communication tool for health professionals.

Background: Recruiting participants for clinical trials poses challenges. Major barriers to participation include psychological factors (eg, fear and mistrust) and logistical constraints (eg, transportation, cost, and scheduling). The strategic design of clinical trial messaging can help overcome these barriers. While strategic communication can be done through various channels (eg, recruitment advertisements), health care providers on the internet have been found to be key sources for communicating clinical trial information to US adults in the social media era., Objective: This study aims to examine how communication source (ie, medical doctors and peers) and message framing of TikTok videos (ie, psychological and logistical framing) influence clinical trial-related attitudes, perceptions, and sign-up behaviors under the guidance of the integrated behavioral model., Methods: This study used a 2 (source: doctor vs peer) × 2 (framing: psychological vs logistical) between-participant factorial design web-based experiment targeting adults in the United States who had never participated in clinical trials (ie, newcomers). A Qualtrics panel was used to recruit and compensate the study respondents (n=561). Participants viewed short-form videos with doctors or peers, using psychological or logistical framing. The main outcome measures included perceived source credibility, self-efficacy, attitude toward clinical trial participation, behavioral intention, and sign-up behavior. Structural equation modeling was used to analyze the direct and indirect effects of message factors on the outcome variables. Source (doctor=1; peer=0) and framing (psychological=1; logistical=0) were dummy-coded., Results: Doctor-featured messages led to greater perceived source credibility (β=.31, P<.001), leading to greater self-efficacy (95% CI 0.13-0.30), which in turn enhanced behavioral intention (95% CI 0.12-0.29) and clinical trial sign-up behavior (95% CI 0.02-0.04). Logistical barrier-framed messages led to greater self-efficacy (β=-.09, P=.02), resulting in higher intention to participate in clinical trials (95% CI -0.38 to -0.03) and improved sign-up behavior (95% CI -0.06 to -0.004). Logistical barrier-framed messages were also directly associated with an increased likelihood of signing up for a clinical trial (β=-.08, P=.03). The model accounted for 21% of the variance in clinical trial sign-up behavior. Attitude did not significantly affect behavioral intention in this study (β=.08, P=.14), and psychological and logistical barrier-framed messages did not significantly differ in attitudes toward clinical trial participation (β=-.04, P=.09)., Conclusions: These findings advance our understanding of how people process popular message characteristics in short-form videos and lend practical guidance for communicators. We encourage medical professionals to consider short-form video sites (eg, TikTok and Instagram Reels) as effective tools for discussing clinical trials and participation opportunities. Specifically, featuring doctors discussing efforts to reduce logistical barriers is recommended. Our measuring of actual behavior as an outcome is a rare and noteworthy contribution to this research., (©Sisi Hu, Ciera E Kirkpatrick, Namyeon Lee, Yoorim Hong, Sungkyoung Lee, Amanda Hinnant. Originally published in the Journal of Medical Internet Research (https://www.jmir.org), 15.08.2024.)

Using 100 videos posted to TikTok by harm reduction creators with the hashtags #narcansaveslives and #naloxonesaveslives, this study examines who is posting, what they are saying, and how they are explaining Narcan/naloxone to their followers. Incorporating the concept of reverse agenda setting, we examine how, through hashtags, TikTok creators can set the agenda for what is important to discuss in the harm reduction space. Findings demonstrate that harm reduction creators have developed a collective voice and created an affective public, attempting to educate others, shed stigma, and normalize the conversation around harm reduction. These creators are using TikTok to educate followers about the prevalence of opioid use, the availability of Narcan/naloxone, correcting misinformation, and discussing the reality of recovery. Echoing prior studies, this research illustrates how TikTok has become an essential resource for health questions, including opioid use. Practical implications are also discussed.

Background: TikTok is one of the most-used and fastest-growing social media platforms in the world, and recent reports indicate that it has become an increasingly popular source of news and information in the United States. These trends have important implications for public health because an abundance of health information exists on the platform. Women are among the largest group of TikTok users in the United States and may be especially affected by the dissemination of health information on TikTok. Prior research has shown that women are not only more likely to look for information on the internet but are also more likely to have their health-related behaviors and perceptions affected by their involvement with social media., Objective: We conducted a survey of young women in the United States to better understand their use of TikTok for health information as well as their perceptions of TikTok's health information and health communication sources., Methods: A web-based survey of US women aged 18 to 29 years (N=1172) was conducted in April-May 2023. The sample was recruited from a Qualtrics research panel and 2 public universities in the United States., Results: The results indicate that the majority of young women in the United States who have used TikTok have obtained health information from the platform either intentionally (672/1026, 65.5%) or unintentionally (948/1026, 92.4%). Age (959/1026, 93.47%; r=0.30; P<.001), education (959/1026, 93.47%; ρ=0.10; P=.001), and TikTok intensity (ie, participants' emotional connectedness to TikTok and TikTok's integration into their daily lives; 959/1026, 93.47%; r=0.32; P<.001) were positively correlated with overall credibility perceptions of the health information. Nearly the entire sample reported that they think that misinformation is prevalent on TikTok to at least some extent (1007/1026, 98.15%), but a third-person effect was found because the young women reported that they believe that other people are more susceptible to health misinformation on TikTok than they personally are (t 1025 =21.16; P<.001). Both health professionals and general users were common sources of health information on TikTok: 93.08% (955/1026) of the participants indicated that they had obtained health information from a health professional, and 93.86% (963/1026) indicated that they had obtained health information from a general user. The respondents showed greater preference for health information from health professionals (vs general users; t 1025 =23.75; P<.001); the respondents also reported obtaining health information from health professionals more often than from general users (t 1025 =8.13; P<.001), and they were more likely to act on health information from health professionals (vs general users; t 1025 =12.74; P<.001)., Conclusions: The findings suggest that health professionals and health communication scholars need to proactively consider using TikTok as a platform for disseminating health information to young women because young women are obtaining health information from TikTok and prefer information from health professionals., (©Ciera E Kirkpatrick, LaRissa L Lawrie. Originally published in JMIR Infodemiology (https://infodemiology.jmir.org), 21.05.2024.)

Background: The importance of vaccination in combating the COVID-19 pandemic is widely acknowledged. The aim of this study was (1) to understand how one's vaccine conspiracy beliefs would influence their public health news processing, (2) to examine how specific public health news features (i.e., news frame) would influence message processing, and (3) to examine if there were any differences between Black and White participants in their message processing., Methods: A nationwide online experiment (N = 821) with a 3 (vaccine conspiracy beliefs: high vs. moderate vs. low) × 2 (participants' race: Black vs. White) × 2 (news frames: gain vs. loss) mixed-factorial design was conducted in the United States., Results: Participants' level of vaccine conspiracy beliefs was predictive of their responses to outcome measures. Additionally, Black participants reported higher perceived message effectiveness, more favorable attitudes toward the message, and higher vaccination intentions than White participants. Furthermore, health news that emphasized vaccination benefits produced more favorable attitudes than those emphasizing losses associated with non-vaccination, especially for White participants. Lastly, participants reported more favorable attitudes toward gain-framed health news regardless of their vaccine conspiracy beliefs., Conclusion: It is crucial for health officials to work to find effective media message strategies to combat COVID-19 vaccine conspiracy theories and misinformation. Furthermore, this study supports the significance of health organizations' ongoing efforts to tailor public health messaging to specific racial groups, as evidenced by considerable variations in perceptions among Black and White Americans., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier India Pvt Ltd.)

This study experiments with TikTok videos to promote clinical trial participation. More specifically, it examines how short-form video sources (doctors vs. prior volunteers for clinical trials) influence perceived source credibility, self-efficacy, and behavioral intention to participate in clinical trials. Findings from this online experiment ( N  = 396) showed that doctor sources led to greater behavioral intention through enhancing source credibility compared to prior volunteer sources. Alternatively, prior volunteer sources increased behavioral intention via enhanced self-efficacy for participants with low trust in doctors. These findings contribute to the understanding of how short-form video sources act as heuristic cues, leading to persuasion outcomes. Overall, we recommend featuring doctors when using video-based messages to promote clinical trial participation. Also, this study emphasizes the need for health communication practitioners to consider prior volunteers as spokespersons when targeting populations with low baseline trust in doctors.

Guided by the elaboration likelihood model and framing theory, this study explores the potential of short-form video platforms (e.g. TikTok), for targeted clinical trial recruitment. An online experiment compared doctor vs. peer-led videos addressing logistical or psychological barriers to participation, mimicking common TikTok communication tactics. Results indicate that high (vs. low) TikTok users are more persuaded by recruitment messages, and they exhibit stronger intentions to participate in clinical trials. Although doctor-sourced messages generate greater credibility and a more favorable message attitude, peer-sourced messages may be more effective in increasing participation intention. Lastly, doctor-sourced videos that address logistical barriers and peer-sourced videos that discuss psychological barriers result in higher self-efficacy for clinical trial participation. This study contributes to the growing body of research on new media's role in health communication and provides insights into how to strategically utilize TikTok and other short-form video platforms for clinical trial recruitment.

This study examines how news features (framing and the use of exemplars) can help overcome two common barriers (psychological and cognitive) impeding Black American participation in clinical trials. In an online experiment, Black participants ( N  = 390) viewed social media news posts varying in framing (focus on psychological vs. cognitive barriers) and use of an exemplar (present vs. absent and White vs. Black) and then responded to outcome measures including perceived message effectiveness, message attitudes, and intention to participate in clinical trials. The findings illustrate that including a racially matched (i.e. Black) exemplar improves attitudes toward clinical trial messages. Most notably, featuring a race-matched exemplar increases intention to participate in a trial when the messages discuss psychological barriers. These findings enhance our understanding of how messages can be better designed to increase Black American participation in clinical trials, thereby contributing to reducing health inequities and improving health outcomes.

Research has suggested that Instagram is detrimental to one's body image and health, as a result of its image-driven nature and the social comparisons that are commonly made between users' bodies and the bodies they see portrayed. This study was designed to provide a better understanding of the effects of thin and fat body types portrayed in Instagram posts. This was done by examining how such body type portrayals influence attention to the posts, in addition to influencing outcomes such as body dissatisfaction and appearance management behavioral intentions. A total of 309 college students viewed 30 Instagram posts in an online experiment with a 2 (portrayed body type: thin vs. fat) X 15 (message repetition) within-subjects design. The findings indicate that thin-body portrayals increase audience self-reported attention to the posts and state body dissatisfaction, but female users who self-perceive themselves as fat report a similar level of attention to the posts regardless of portrayed body types. Additionally, Instagram use (defined as the number of photos users personally post) is found to moderate the effects of the body portrayals.

The current study was designed to examine effective message strategies that can be employed in designing mediated communication messages to improve clinical trial research participation. In the study, a total of 300 participants completed an online experiment in which they responded to five different clinical trial recruitment advertisements whose information sources varied in their credentials and race. Overall, peer-featured ads in which previous clinical trial participants communicated their prior experience in clinical trial participation, compared to expert-featured ads in which medical doctors communicated information about clinical trials, led to higher message and topic relevance, higher message credibility, more favorable attitudes toward clinical trials, and higher intentions to participate in future clinical trials. Further, there was a statistically significant interaction among source credentials, racial match (between source and participant), and participant's race on message and topic relevance such that both White and Black participants rated ads from racially mismatched peers highly effective (greater message and topic relevance); however, for doctor featured ads, White participants reported higher message and topic relevance for racially matched (White doctor) ads, and Black participants reported higher message and topic relevance for racially mismatched (White doctor) ads. We discuss theoretical and practical implications.

This study examined whether framing, exemplar presence and exemplar race in social media news posts influence rural White men's perceptions, attitudes and behavioral intentions toward clinical trial participation, and if so, how individual trust in doctors moderates the effects of these three factors. An experiment with a 2 within (framing: cognitive versus psychological barriers) × 2 within (exemplar: present versus absent) × 2 between (exemplar race: White versus Black) subjects mixed factorial design was conducted among rural White men (N = 208). Twelve social media news posts about clinical trial participation were created for the experiment. Results revealed that respondents had greater behavioral intentions to participate in clinical trials after seeing posts with exemplars present (versus absent). When news posts addressed cognitive barriers (e.g. lacking knowledge about the value of clinical trials), the presence of exemplars enhanced perceived self-efficacy to participate in clinical trials. Participants with lower trust in doctors reported more favorable attitudes to posts with exemplars, and the posts with Black exemplars were perceived as more effective (approaching statistical significance). When communicating about clinical trials to rural White men, health professionals should consider including exemplars and addressing cognitive barriers to participation., (© The Author(s) 2022. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Ixodes dammini Spielman, Clifford, Piesman & Corwin was found for the first time in Illinois in November 1987, when two adult females were collected from two deer in Jo Daviess County in the northwestern corner of the state. In 1988, in a study of six state parks in northern Illinois, questing adults and nymphs were encountered in one park in Ogle County. During the firearm deer hunt in November 1988, adult female and male ticks were found in several counties, with a high rate of infestation (greater than 25%) in two counties (Ogle and Rock Island) along the Rock River, which flows from Wisconsin into the Mississippi River. Several cases in humans with no history of travel outside of the state have been reported, primarily from northern Illinois. We suspect that infiltration of infected ticks and wildlife from Wisconsin is resulting in the emergence of Lyme disease in Illinois. Because all the components necessary for the completion of the tick life cycle and for the transmission of Borrelia burgdorferi are available throughout much of the state, I. dammini and Lyme disease can spread and become established in large portions of Illinois.

In southwestern New Jersey during 1986 and 1987, common barn-owls and pigeons were captured on farmsteads and tested for Toxoplasma gondii antibodies by a modified direct agglutination test. In 1986, 3/28 (10.7%) adult and 0/124 nestling owls tested positive at titers of greater than or equal to 1:40. Additionally, 2/34 (5.9%) pigeons tested had T. gondii antibodies at titer of 1:320. In 1987, 9/38 (27.3%) adult and 18/80 (22.5%) nestling owls tested positive at titers of greater than or equal to 1:25; this includes 3/38 (7.9%) adult and 1/80 (1.3%) nestling owls that tested positive at a titer of 1:50.

The object of this study was to determine the importance of domestic cats in the epidemiology of human giardiasis. Of six laboratory-reared cats inoculated with cultured Giardia lamblia trophozoites from humans, only one showed the presence of cysts in the feces, and cysts were found on only 1 of the 80 days of observation. In a second experiment, eight cats were inoculated with G. lamblia cysts isolated from a human being. Over an 8-week period of observation, two of eight cats were found to have passed cysts in their feces, one on only one day and the other on 2 days. Postmortem examination of all of the cats found to be passing G. lamblia cysts at some time during the experiments did not reveal any small-intestinal trophozoites. These results suggest that domestic cats are relatively insusceptible to G. lamblia from humans and, consequently, that cats probably are not significant reservoir hosts of Giardia spp. infective for human beings. Moreover, it appears that the Giardia spp. which parasitize cats are distinct from those of human beings.

Giardia sp infection was believed responsible for chronic, intermittent diarrhea in a group of 14 Persian cats. Seven of the cats were shedding Giardia sp cysts, and 6 of these cats had diarrhea at the time of fecal examination. Conversely, only 1 of 6 clinically normal cats in the group was shedding Giardia sp cysts. Cysts were not detected in feces of 2 cats with diarrhea. Cats less than or equal to 3 years old were more likely to be found shedding cysts. The parasite apparently was eradicated from the cattery by a combination of cage disinfection (1% sodium hypochlorite solution) and oral furazolidone treatment (4 mg/kg of body weight, BID for 5 consecutive days). During treatment, clinical signs resolved, and all cats remained clinically normal 2 months after treatment.

Giardia spp. are common, yet frequently overlooked, parasites of small animals. These parasites may cause chronic diarrhea in dogs and cats. This article discusses the clinical signs of giardiasis, and its diagnosis, treatment, and control.

Several strains of inbred mice were infected with the protozoan parasite Leishmania donovani, and, at several points during the infection, spleens of groups of these mice were tested for natural killer (NK)-cell activity vs lymphoma target cells in vitro and were evaluated for parasite burdens. Generally, elevated followed by normal (compared to uninfected control mice) or subnormal NK responses occurred as the result of infection. Elevated NK responses were not accompanied by high circulating levels of interferon, yet infected mice responded to an injection of an interferon inducer with interferon production as great as control mice. No consistent correlations among susceptibility phenotype to L. donovani infection, spontaneous NK activity phenotype, and infection-induced NK activation/depression patterns were detected among the various strains of mice.

The susceptibility of domestic cats to visceral leishmaniasis was examined by inoculating cats with amastigotes of Leishmania donovani and L. chagasi by the intravenous route, and with promastigotes of L. chagasi by the intradermal route. Parasites were recovered from intravenously inoculated cats as long as 16 weeks after inoculation, but parasites apparently did not locate in the viscera in cats inoculated intradermally. Parasites were not detected in intravenously inoculated cats killed at 24 weeks of infection. All cats developed significantly elevated serum antibody titers to Leishmania spp., but none developed the symptoms usually associated with visceral leishmaniasis in humans.

Prevalences of, and risk factors associated with, protozoan and helminth parasite infections were determined for pet dogs and cats presented to the teaching hospital of the University of Pennsylvania School of Veterinary Medicine. Of 2294 canine fecal specimens, 34.8% were found to contain one or more kinds of parasite, consisting of: hookworms (14.4%); Trichuris vulpis (12.3%); Giardia (7.2%); ascarids (5.5%); coccidia (2.7%); cestodes (1.6%). The following risk factors were identified with infection in dogs: age less than 2 years; urban locality; male sex. Gonadectomy was associated with decreased parasite prevalences in both male and female dogs. Significant seasonal variations in prevalences of hookworm, ascarid and Giardia infections were found in dogs. Of 452 feline fecal specimens tested, 24.6% were positive for parasites, including: ascarids (16.4%); Giardia (3.5%); coccidia (2.9%); cestodes (2.4%); hookworm (1.1%). Host age of less than 2 years was a significant risk factor associated with parasitism in cats. Of 1571 dogs tested for Dirofilaria immitis microfilaremia, 3.7% were positive. Non-urban locality was a significant risk factor for D. immitis infection in dogs.

Lymph node biopsy specimens from several previously reported cases of unusual feline peripheral lymphadenopathies were re-examined by a modified Dieterlé silver-impregnation staining technique. In a proportion of these specimens, the Dieterlé stain revealed tiny pleomorphic, intensely argyrophilic coccobacilli. These organisms were predominantly located within macrophages. The infected cells were focally distributed, particularly in the interfollicular regions of the nodes. They were inconspicuous in sections stained by other, more conventional staining methods. It is possible that these coccobacilli represent yet another, previously unidentified, cause of chronic lymph node hyperplasia in the cat.

Of 220 muskrat fecal specimens collected from 12 sites in southwestern New Jersey, 154 (70%) were found to contain cysts of the protozoan parasite Giardia spp. Cysts from selected muskrat fecal specimens infected Mongolian gerbils, but attempts to cultivate trophozoites removed from these gerbils were unsuccessful. Salmonella spp. were not detected in any of the muskrat fecal specimens.

Leishmania major infection in genetically susceptible BALB/c mice is associated with the development of chronic primary lesions as well as multiple metastatic lesions. Spleen cells from these mice were shown to have depressed in vitro responses to concanavalin A (Con A) that coincided with the development of indomethacin-sensitive suppressor cells. Depressed responses to Con A were noted as early as 1 wk after parasite inoculation and correlated with the increased production of prostaglandin E2 (PGE2) by spleen cells from infected mice. Mice induced by prior irradiation (550 rad) to heal infection did not develop indomethacin-reversible depression in responsiveness to Con A. Although macrophages appear to be the major source of PGE2 production, in vitro studies indicate that infection per se is not a sufficient stimulus to initiate prostaglandin (PG) synthesis, suggesting the involvement of other cell types. Mice treated in vivo with indomethacin exhibited significantly fewer metastatic lesions than control mice, suggesting that PG may play a role in the exacerbation of cutaneous disease in these animals.

After infection with the protozoan parasite Leishmania donovani, C57BL/6J bg/bg (beige) mice, which are deficient in natural killer (NK) activity, were unable to control splenic parasite loads relative to phenotypically normal C57BL/6J bg/+ and +/+ mice, particularly beyond 21 days of infection. When beige mice were injected intravenously with 2 or 3 X 10(6) syngeneic, cloned NK cells (NKB61B10 cell line), they displayed splenic parasite burdens which did not differ significantly from those of normal controls. In C57BL/6 +/+ mice rendered NK deficient by split-dose irradiation (four weekly, 200-rad doses of gamma irradiation beginning at 4 weeks of age) splenic and hepatic parasite levels were significantly higher than those in nonirradiated controls at 15 days of infection and beyond. In both sets of experiments, relative degrees of hepato- and splenomegaly were not sufficient to account for differences in parasite burdens among NK-deficient and normal mice. Taken together, the results of these experiments suggest that NK cells may contribute to parasite elimination during the acquired-resistance phase of L. donovani infection in mice.

Giardia infection was believed responsible for chronic diarrhea, weight loss, lethargy, inappetence, and dermatitis in a 4-year-old Thoroughbred horse. Fecal cysts were detected by the zinc sulfate centrifugal flotation method. All clinical signs resolved upon treatment with metronidazole suspension (5 mg/kg body weight per os, TID for 10 days).

A population of American kestrels breeding in southeastern Pennsylvania was examined for hematozoa. Haemoproteus tinnunculi infected 17 of 23 (74%) of the adults. Parasitemia ranged from two to 252, with a median of 32 infected erythrocytes per 10,000. Parasitemia and body weight of female kestrels were negatively correlated. This parasite was not observed in the six juvenile or 38 nestling kestrels examined. Trypanosoma sp. was detected by culture in three of seven (43%) adults, but not in the six juveniles and eight nestlings examined.

A mass found in the stomach of a 10-year old cat contained a female worm of the genus Gnathostoma. The mass was described as a muscular pseudogranuloma induced by the worm. Although the worm species could not be ascertained, it was concluded that the cat served as an aberrant host for a Gnathostoma sp that usually infects wild mammals in the area.

Cryptosporidiosis is a self-limiting protozoal disease of the intestinal tract. Although identified as possible agents of calf diarrhea less than 15 years ago, Cryptosporidium spp. are now believed to be common in calves and in many other host animal species worldwide. Recent literature on all aspects of cryptosporidiosis in calves is reviewed, predicaments in diagnosis and management are discussed, and public health concerns are raised.

The prevalence of Salmonella spp. in nestling common barn-owls was investigated in southwestern New Jersey during the summer of 1985. Of 94 owls sampled by swabbing the cloaca, eight (8.5%) were found to harbor Salmonella spp. Three serotypes--S. thompson, S. tuindorp, and S. typhimurium--were identified. Five (20%) of the 25 nest sites examined (all of them in or near farm buildings or dwellings) contained Salmonella-positive owls.

The authors consider coccidial infections of the genera Isospora, Sarcocystis, Cryptosporidium, Besnoitia, and Hammondia.

Eggs of a tapeworm, Diphyllobothrium sp (probably D dendriticum), were detected in feces of a healthy, 5-month-old, Siberian Husky. The dog acquired its infection in northern Canada while consuming a diet that included raw salmonid fish. Such fish serve as intermediate hosts for Diphyllobothrium spp. The infection was successfully eliminated by oral administration of a single dose of praziquantel (7.5 mg/kg of body weight.

The courses of two protozoal diseases, cutaneous and visceral leishmaniasis, were examined in three groups of C57BL/6J mice. One group of mice was homozygous recessive for the beige gene (bg/bg). Beige mice are the genetic homologue of the human Chédiak-Higashi syndrome and, among other defects, are profoundly deficient in natural killer cell activity. Wild-type (+/+) mice, which respond to experimental cutaneous or visceral leishmaniasis by eventually eliminating their parasites, and heterozygous beige (bg/+) mice served as controls; both are phenotypically normal in natural killer cell activity, which is particularly high in the spleen. In bg/bg mice, the course of Leishmania tropica, a causative agent of cutaneous leishmaniasis, was similar to that in control mice after both primary and challenge inoculations. All groups of mice expressed similar humoral and cellular immune responses to L. tropica antigen. However, bg/bg mice failed to eliminate amastigotes of Leishmania donovani, a causative agent of visceral leishmaniasis, from their spleens over an observation period of 56 days, in contrast to bg/+ and +/+ controls. Similar levels of anti-leishmanial antibody were produced by all groups of mice, and all mice responded comparably to footpad injections of L. donovani antigen. The results of this study suggest a possible role for natural killer cells in recovery from L. donovani but not from L. tropica infection.

Regional differences in the response of mice to infection with three strains of dermotropic Leishmania spp. were shown for skin covering the trunk. Lesions tended to appear earlier and to grow more rapidly on sites over the caudal half of the body than the cranial half, and caudal lesions were more likely than cranial ones to result in metastatic disease in susceptible strains of mice. Site-related variations in lesion development were observed in different strains of mice as well as in golden hamsters. The effect of these regional differences on the development of some parasite-specific, immunological reactions was examined, as were parasite thermosensitivity and location-related variations in host skin temperature as possible explanations.

C57BL/6 mice chronically infected with the protozoan parasite Leishmania donovani exhibit profoundly depressed splenic natural killer (NK) cell activity as measured by in vitro cytolysis of lymphoma target cells. Injection of infected mice with an interferon (IFN) inducer or in vitro treatment of infected splenocytes with IFN, a phorbol ester, or indomethacin failed to restore their NK activity to the degree shown by age-matched, uninfected mice. Fractionation of infected splenocytes by nylon wool, Sephadex G-10, or carbonyl iron and magnetism treatments was also unable to effect an increase in NK activity. Addition of infected splenocytes to uninfected ones in in vitro NK assays suppressed the NK activity of the latter, and the suppression could be partially or wholly abrogated by prior fractionation of infected splenocytes by the methods noted above. In vitro treatment of infected splenocytes with concanavalin A revealed the presence of NK activity in these cell populations. The results indicate that splenocytes in L. donovani-infected mice become insensitive to IFN stimulation; and the impairment of another, possibly IFN-independent pathway of NK-cell activation may also contribute to the observed L. donovani-induced depression in splenic NK activity in C57BL/6 mice.

Blood smears from 259 birds of 12 species, representing four families of raptors, from New Jersey, Pennsylvania, Delaware, and Virginia were examined for blood parasites. Infected birds constituted 59.1% of the total. Birds were infected with one or more of the following genera of protozoa: Leucocytozoon (43.2%); Haemoproteus (21.6%); Plasmodium (1.2%); and Trypanosoma (1.2%). Blood culture of 142 raptors of 11 species for Trypanosoma revealed a prevalence of 41.5%. Plasmodium circumflexum is reported for the first time in Accipiter striatus, and Trypanosoma sp. in Buteo jamaicensis.

Giardia cysts were detected in feces of a domestic llama (Lama glama) and in feces of lambs (Ovis aries) from Wisconsin, U.S.A. All of the animals examined were immature, and they had recent histories of poor condition and passing unformed or semiformed, pale stools. Giardia cysts from both host species were excysted in vitro, and the trophozoites were cultivated axenically. Furthermore, Giardia cysts from both sources were shown to produce infection in Mongolian gerbils (Meriones unquiculatus). The finding of Giardia in the llama represents a new host recorded for this parasite. Also, this is the first report of Giardia-infected sheep from the Western Hemisphere.

Sarcocysts of Sarcocystis sp. were found in 26 (50%) of 52 raccoons (Procyon lotor) from Ohio, Pennsylvania, Florida, and Maryland. Although only 4 (7.7%) of 52 cardiac muscles specimens were found to contain sarcocysts, 25% to 36.5% of tongue, diaphragm, masseter muscle, and esophagus specimens were found infected. By light microscopy, sarcocyst walls were less than 3 micron thick and had no conspicuous projections; interior septa were indistinct. By transmission electron microscopy, sarcocyst walls had short (mean = 2.7 micron), villus-like protrusions; thin septa were seen within the sarcocysts. The raccoon may be an intermediate host for a Sarcocystis sp. that completes its life cycle in an unidentified, wild carnivore.

The excretion of Giardia sp cysts in the feces of naturally and artificially infected cats fluctuated sporadically, and cysts were undetectable several times during 7 weeks of observation. The mean prepatent period for Giardia infection in 7 cats was 9.6 days (range, 5 to 16 days). The amount of the cyst inoculum did not appear to affect the length of the prepatent period. Six of 11 cats had clinical signs consistent with those of giardiasis. Clinical signs and cyst excretion were eliminated after treatment with metronidazole or furazolidone. Moderate oral or parenteral doses of corticosteroids produced little, if any, alteration in the infection. Postmortem examination of 1 inoculated cat revealed Giardia trophozoites in the jejunum and upper portion of the ileum but not in the duodenum, lower portion of the ileum, cecum, or colon. Giardia cysts isolated from cat feces produced infection in Mongolian gerbils but not in C57BL/6J mice.

In August 1986, 133 dogs at the Veterinary Service of the Netherlands Antilles and the SPCA of Curaçao were examined for microfilaremia and for evidence of gastrointestinal parasitism. Microfilariae of Dipetalonema reconditum were present in 27.8% of the dogs examined with no significant difference in the infection rate between domestic and feral dogs. Microfilariae of the canine heartworm Dirofilaria immitis were found in 9% of the dogs with a significantly higher rate of infection in domestic (pet) dogs (13.5%) than in feral dogs (3.4%). Of the intestinal parasites observed Ancylostoma sp. was present in the highest percentage of dogs (68.4%) followed by Toxocara sp. (7.5%). Other parasites were present in less than 5% of the dogs examined and included, in decreasing order of prevalence, Spirocerca sp., Giardia sp., coccidia, Taenia sp. and Trichuris sp. The present paper presents the first evidence of Di. reconditum on Curaçao and suggests the introduction of D. immitis to the island within the 10 years preceeding this report. The persistently high rate of infection with Ancylostoma underscores the continuing risk of cutaneous larva migrans to human beings in the region.

Of 105 migrating falconiform birds of 7 species examined for Salmonella shedding in New Jersey, 2 (1.9%) were positive for Salmonella spp. Both positive birds were immature red-tailed hawks (Buteo jamaicensis). Salmonella enteritidis and S newport were the serotypes isolated. Neither serotype expressed multiple resistance when tested against a panel of 12 antimicrobial drugs.