Prevalence Of Natural Infection Research Articles

A Saliva-Based Serological and Behavioral Analysis of SARS-CoV-2 Antibody Prevalence in Howard County, Maryland.

The objective of the study was to estimate severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) seroprevalence in the Howard County, Maryland, general population and demographic subpopulations attributable to natural infection or coronavirus disease 2019 (COVID-19) vaccination and to identify self-reported social behaviors that may affect the likelihood of recent or past SARS-CoV-2 infection. A cross-sectional, saliva-based serological study of 2,880 residents of Howard County, Maryland, was carried out from July through September 2021. Natural SARS-CoV-2 infection prevalence was estimated by inferring infections among individuals according to anti-nucleocapsid immunoglobin G levels and calculating averages weighted by sample proportions of various demographics. Antibody levels between BNT162b2 (Pfizer-BioNTech) and mRNA-1273 (Moderna) recipients were compared. Antibody decay rate was calculated by fitting exponential decay curves to cross-sectional indirect immunoassay data. Regression analysis was carried out to identify demographic factors, social behaviors, and attitudes that may be linked to an increased likelihood of natural infection. The estimated overall prevalence of natural infection in Howard County, Maryland, was 11.9% (95% confidence interval, 9.2% to 15.1%), compared with 7% reported COVID-19 cases. Antibody prevalence indicating natural infection was highest among Hispanic and non-Hispanic Black participants and lowest among non-Hispanic White and non-Hispanic Asian participants. Participants from census tracts with lower average household income also had higher natural infection rates. After accounting for multiple comparisons and correlations between participants, none of the behavior or attitude factors had significant effects on natural infection. At the same time, recipients of the mRNA-1273 vaccine had higher antibody levels than those of BNT162b2 vaccine recipients. Older study participants had overall lower antibody levels compared with younger study participants. The true prevalence of SARS-CoV-2 infection is higher than the number of reported COVID-19 cases in Howard County, Maryland. A disproportionate impact of infection-induced SARS-CoV-2 positivity was observed across different ethnic/racial subpopulations and incomes, and differences in antibody levels across different demographics were identified. Taken together, this information may inform public health policy to protect vulnerable populations. IMPORTANCE We employed a highly innovative noninvasive multiplex oral fluid SARS-CoV-2 IgG assay to ascertain our seroprevalence estimates. This laboratory-developed test has been applied in NCI's SeroNet consortium, possesses high sensitivity and specificity according to FDA Emergency Use Authorization guidelines, correlates strongly with SARS-CoV-2 neutralizing antibody responses, and is Clinical Laboratory Improvement Amendments-approved by the Johns Hopkins Hospital Department of Pathology. It represents a broadly scalable public health tool to improve understanding of recent and past SARS-CoV-2 exposure and infection without drawing any blood. To our knowledge, this is the first application of a high-performance salivary SARS-CoV-2 IgG assay to estimate population-level seroprevalence, including identifying COVID-19 disparities. We also are the first to report differences in SARS-CoV-2 IgG responses by COVID-19 vaccine manufacturers (BNT162b2 [Pfizer-BioNTech] and mRNA-1273 [Moderna]). Our findings demonstrate remarkable consistency with those of blood-based SARS-CoV-2 IgG assays in terms of differences in the magnitude of SARS-CoV-2 IgG responses between COVID-19 vaccines.

Prevalence of natural infection by Trypanosoma evansi in Crioula LAGEANA cattle

Cattle trypanosomiasis negatively impacts animal husbandry due to high morbidity, productivity losses, and mortality rates. Knowledge regarding Trypanosoma evansi infections in locally adapted breeds remains limited. Some cattle breeds exhibit trypanotolerance, requiring the determination of prevalence, as well as related tolerance and resistance characteristics, for disease control programs. This study aimed to determine T. evansi prevalence in Crioula Lageana cattle and associate clinical, hematological, and biochemical aspects with the infection to further research on tolerance in this population. Blood samples from 310 Crioula Lageana cattle were tested using Polymerase Chain Reaction (PCR) and Indirect Immunofluorescence Reaction (IIFR). T. evansi prevalence was 8% (24/310) using PCR and 4% (11/310) using IIFR. Positive animals showed increased ruminal movements, elevated eosinophil counts, and reduced monocyte numbers, but both latter within the reference range for the species. Albumin concentrations were low in positive cases and remained below the reference range limit for both groups. However, triglycerides exceeded the physiological range for the species in both positive and negative groups. Increased gamma-glutamyltransferase (GGT) activity was observed in positive animals. In conclusion, Crioula Lageana cattle exhibited enzootic instability with a low T. evansi infection prevalence when assessed using PCR and IIFR techniques. Furthermore, the animals did not display clinical, hematological, or biochemical alterations attributable to the presence of hemoparasites.

Feline Foamy Virus Infection: Characterization of Experimental Infection and Prevalence of Natural Infection in Domestic Cats with and without Chronic Kidney Disease.

Foamy viruses (FVs) are globally prevalent retroviruses that establish apparently apathogenic lifelong infections. Feline FV (FFV) has been isolated from domestic cats with concurrent diseases, including urinary syndromes. We experimentally infected five cats with FFV to study viral kinetics and tropism, peripheral blood mononuclear cell (PBMC) phenotype, urinary parameters, and histopathology. A persistent infection of primarily lymphoid tropism was detected with no evidence of immunological or hematologic perturbations. One cat with a significant negative correlation between lymphocytes and PBMC proviral load displayed an expanded FFV tissue tropism. Significantly increased blood urea nitrogen and ultrastructural kidney changes were noted in all experimentally infected cats, though chemistry parameters were not outside of normal ranges. Histopathological changes were observed in the brain, large intestine, and other tissues. In order to determine if there is an association of FFV with Chronic Kidney Disease, we additionally screened 125 Australian pet cats with and without CKD for FFV infection and found that FFV is highly prevalent in older cats, particularly in males with CKD, though this difference was not statistically significant compared to controls. Acute FFV infection was clinically silent, and while some measures indicated mild changes, there was no overt association of FFV infection with renal disease.

Toxoplasma gondii: Prevalence of natural infection in pigeons and ducks from middle and upper Egypt using serological, histopathological, and immunohistochemical diagnostic methods.

Toxoplasma gondii is one of the most serious coccidian parasites, which infect human and nearly all warm-blooded animals. Domestic farm birds, which represent a good source of animal protein for humans, are subjected to such infection. Because pigeons and ducks get their feed from the soil, they are susceptible to being infected orally with Toxoplasma oocysts. Consequently, these birds may represent a public health problem for humans. Lack of information on T. gondii infection in pigeons and the insufficient data on its epidemiology in ducks were the main reasons to perform the present study. In the current study, four hundred and fifty-two blood and tissue samples were collected from 310 pigeons and 142 ducks from Asyut, Fayoum, Beni Suef, Minya, and Giza provinces, Egypt. Specific antibodies for Toxoplasma gondii were determined using recombinant TgSAG2t specific surface antigen based ELISA. Histopathological and immunohistochemical (IHC) examinations were also performed. Overall Toxoplasma positivity was 13.55%, 1.61%, and 1.61% in pigeons and 10.56%, 2.11%, and 2.11% in ducks using ELISA, histopathology, and IHC, respectively. Statistically significant difference in the T. gondii prevalence was observed in relation to period of the year. No significant changes were recorded regarding the gender or age. The current study indicated soil contamination and observable Toxoplasma infection in pigeons and ducks, which could represent a major danger for human infection.

Host-pathogen interactions and immune evasion strategies in Francisella tularensis pathogenicity.

Francisella tularensis is an intracellular Gram-negative bacterium that causes life-threatening tularemia. Although the prevalence of natural infection is low, F. tularensis remains a tier I priority pathogen due to its extreme virulence and ease of aerosol dissemination. F. tularensis can infect a host through multiple routes, including the intradermal and respiratory routes. Respiratory infection can result from a very small inoculum (ten organisms or fewer) and is the most lethal form of infection. Following infection, F. tularensis employs strategies for immune evasion that delay the immune response, permitting systemic distribution and induction of sepsis. In this review we summarize the current knowledge of F. tularensis in an immunological context, with emphasis on the host response and bacterial evasion of that response.

First report of Lymnaea cousini Jousseaume, 1887 naturally infected with Fasciola hepatica (Linnaeus, 1758) (Trematoda: Digenea) in Machachi, Ecuador

We report the first finding of Lymnaea cousini naturally infected with Fasciola hepatica in Ecuador. A sample of 70 snails was collected in April 2005 from a wetland located in a valley at approximately 3000 m a.s.l., near the locality of Machachi, Pichincha Province. The prevalence of natural infection in L. cousini was 31.43%, which is the highest value ever recorded for naturally infected lymnaeid species.

Cell culture propagation and biochemical analysis of the Ljungan virus prototype strain

Ljungan virus (LV) is proposed as a potentially important rodent harbored viral human pathogen. Little is known about the biophysical nature of the virus and despite being molecularly characterized, progress in epidemiological and basic biological studies of LV has been hampered by the lack of a robust and reliable cell culture propagation system. Here we report the first description of an efficient lytic multi-cycle cell culture propagation of the LV prototype strain (87-012). Biophysical analysis of gradient purified LV virions generated by this system identified mature infectious virions to possess a sedimentation coefficient of 160S and in agreement with previous molecular prediction, polyprotein analysis suggests that the native virion is composed of only three major structural proteins. The nucleotide composition of the complete genome of the LV cell culture adapted virus was determined and compared to that of the parental prototype LV. Numerous mutations were observed scattered throughout the viral genome and particularly in VP1. The development of this cell culture system for LV should open new avenues in the study of LV biology, structure, pathogenesis, and prevalence of natural infection in the wider community.

Prevalence of blood-borne viral hepatitis in different communities in Yemen.

It is generally believed that hepatitis B (HBV) and C (HCV) viruses are highly prevalent in the Republic of Yemen. This study investigated the prevalence of HBV and HCV markers in 494 blood donors from Aden, 493 blood donors from Sana'a, 97 residents from an African ethnic minority in Sana'a and 99 residents of Soqotra Island. There were significant differences in the prevalence of HBV carriage (HBsAg: 6.7, 15, 19.6 and 26.3% respectively; P < 0.001); past HBV infection (anti-HBc: 17.4, 18.5, 30.9 and 59.6% respectively; P < 0.001); susceptibility to HBV (absence of HBV markers: 73.3, 61.9, 38.1 and 9.1% respectively; P < 0.001), infectivity of HBV carriers (HBV DNA: 51.5, 33.8, 52.6 and 65.4% respectively; P = 0.028) and HCV antibodies (RIBA confirmed or indeterminate: 0.6, 0.2, 5.2 and 5.1% respectively; P < 0.001). A significant difference in HBV carrier rate and a borderline significant difference in the prevalence of natural infection was observed between males and females in the African community (P = 0.02 and 0.06 respectively). In contrast, in Soqotra Island, there was no significant sex difference in HBV carrier rate but susceptibility was significantly more prevalent in males (P = 0.03). This study illustrates that significant difference in prevalence and epidemiology exists among different communities within the same country, reflecting political, geographical and social differences. Control strategies should take these differences into account.

Prevalence of infection by the protozoan Hemolivia mariae in ticks.

This paper considers the prevalence of natural infections of the protozoan Hemolivia mariae, in its hosts the Australian sleepy lizard, Tiliqua rugosa, and the ixodid tick species, Amblyomma limbatum. We investigate whether the protozoan may be influencing the tick population in the field, by comparing the observed prevalence of infection in ticks with the prevalence expected from known transmission dynamics. The prevalence of infection in nymphs was similar to the expected prevalence, but the observed prevalence in adults was higher than expected. These results provide no evidence for infection-induced mortality in ticks. We also found that tick loads on infected and uninfected lizards were not significantly different and, overall, infected lizards were as likely to be tick-infested as uninfected lizards. However, infected lizards were less likely to be found carrying female ticks. On balance, the evidence did not strongly support the hypothesis that ticks avoid feeding on infected lizards. We use known parameters of H. mariae transmission to estimate the rate of tick ingestion that may be required to sustain the observed prevalences in the field.

Paramphistomum daubneyi and Fasciola hepatica: the prevalence of natural or experimental infections in four species of freshwater snails in eastern France

Parasitological investigations were performed in July and September–October 1997 in six farms located in the department of Saône et Loire (eastern France) to determine the prevalence of natural infections with Paramphistomum daubneyi and Fasciola hepatica in four species of freshwater snails. Cercaria-containing rediae of P. daubneyi and/or F. hepatica were found in Lymnaea palustris (one snail only) and Lymnaea truncatula. Some living sporocysts and immature rediae were noted in Lymnaea ovata (P. daubneyi or F. hepatica) and in Physa acuta (P. daubneyi only). The prevalence of each trematode infection was often less than 10%. Experimental infections of juvenile and preadult snails (1 and 4 mm in height, respectively) were also performed to test the susceptibility of these four snail species to P. daubneyi, either singly or in combination with F. hepatica. Both 1 and 4 mm high L. truncatula could sustain the full development of P. daubneyi, whether in single or double infections. In L. palustris dually exposed to both trematodes, cercaria-containing rediae of P. daubneyi were found in one juvenile and one preadult snails, while immature infections were noted in ten juvenile and two preadult snails. The overall prevalence of P. daubneyi infection in L. palustris was 11.1% in juvenile snails and 2.1% in preadults. Larval forms of P. daubneyi and F. hepatica were only noted in dually-exposed juvenile L. ovata and P. acuta. In L. ovata, mature and immature rediae of F. hepatica were detected in 17.6% of snails, while immature rediae of P. daubneyi were noted in 4.4% of snails. In P. acuta, only immature infections were detected (5.1% of snails with P. daubneyi, and 1.2% with F. hepatica). These results demonstrated that Lymnaea species other than L. truncatula could sustain the full development of P. daubneyi and that immature larvae of this trematode might be found in naturally- or experimentally-infected L. ovata and P. acuta.

Prevalence of natural infection with simian immunodeficiency virus and simian T-cell leukemia virus type I in a breeding colony of sooty mangabey monkeys

The seroprevalence of antibodies to simian immunodeficiency virus (SIVsmm) and simian T-cell leukemia virus type I (STLV-I) in a captive breeding colony of sooty mangabey monkeys was determined, and infection by SIVsmm was confirmed in all cases by virus isolation. Among 138 animals tested, 57 and 33% were infected with SIVsmm and STLV-I, respectively. While the proportion of female mangabeys (66%) differed significantly (P less than 0.01) from the proportion of male mangabeys (42%) infected with SIVsmm, the proportions of males and females infected with STLV-I were similar, suggesting independent transmission of the two viruses. Among mangabeys less than 1 year old, none were infected with STLV-I and only five of 27 mangabeys, all of which were at least 6 months old when first tested, were infected with SIVsmm. The data document that natural infection of sooty mangabey monkeys with SIVsmm or in association with STLV-I infection does not result in increased disease or mortality, and that transmission of both SIVsmm and STLV-I appears to occur primarily through sexual activity.

Papio doguera (dog face baboon), a primate reservoir host of Schistosoma mansoni in East Africa

1. 1) A prevalence of natural infection with Schistosoma mansoni of 23.9 per cent. was found in 134 Papio doguera (dog face baboons) classified as children or older. These findings were based upon the examination of tissue removed at autopsy from the liver and intestine. 2. 2) The demonstration of natural infection in baboons indicates that P. doguera is a reservoir host for S. mansoni in East Africa.