Endemic Paragonimus kellicotti infections in animals and humans in USA and Canada: Review and personal perspective

Infections with the lung fluke, Paragonimus kellicotti, have been diagnosed in a variety of domestic and wild animals and humans in USA and Canada. Although there are many species of Paragonimus in other parts of the world; P. kellicotti is the only species definitively diagnosed in USA and Canada. Fresh water snails (several species) and crayfish (mainly Orconectes spp.) are its intermediate hosts. Humans and animals become infected with P. kellicotti only by ingesting metacercariae encysted in the heart of crayfish. After ingestion, the fluke penetrates intestinal wall, enters peritoneal cavity, and reaches pleural cavity by direct penetration of diaphragm, 2-3 weeks post inoculation (p.i.). Young flukes penetrate lungs and become encysted in pulmonary tissue, often in pairs. Time to maturity is around 4-7 weeks p.i. Eggs are coughed up, swallowed, and are excreted in feces. Although the parasite has been known for more than a century, there has been an upsurge of human infections in the USA. Here, I review P. kellicotti infections in naturally infected hosts. Pathogenesis, diagnosis, and treatment in parasite-free cats and dogs experimentally infected P. kellicotti are reviewed to shed light on the pathogenesis of human paragonimiasis. Problems and challenges facing diagnosis of paragonimiasis, especially non-pulmonary infections, are discussed. Fluke stages are deposited in Smithsonian Museum.

THU0286 THE SYSTEMIC LUPUS INTERNATIONAL COLLABORATING CLINICS (SLICC) FRAILTY INDEX (SLICC-FI) PREDICTS DAMAGE ACCRUAL IN SYSTEMIC LUPUS ERYTHEMATOSUS (SLE) PATIENTS. DATA FROM A MULTI-ETHNIC, MULTI-CENTER US LUPUS COHORT

Background:

The Systemic Lupus International Collaborating Clinics (SLICC) Frailty Index (SLICC-FI) has been developed as a predictor of outcomes in SLE patients1-3. It combines disease activity, damage, comorbidities and health-related quality of life measures.

Objectives:

To evaluate the SLICC-FI as a predictor of damage accrual in systemic lupus erythematosus (SLE) patients.

Methods:

Patients from a multi-ethnic, multi-center US lupus cohort were included. Damage was ascertained with the SLICC/American College of Rheumatology (ACR) damage index (SDI) at last visit. The first visit in which the SLICC-FI could be derived was considered as the baseline visit. Univariable and multivariable Poisson regression models were performed to determine the association between the baseline SLICC-FI and last SDI, adjusted for sex, age at diagnosis, ethnicity, insurance, prednisone daily dose, antimalarial and immunosuppressive drug use at baseline. Age and gender were included a priori in the multivariable model, the other variables were included if they had a p<0.10 in the univariable models.

Results:

Of the 503 patients included, 454 (90.3%) were female with mean (SD) age 37.1 (12.5) years at diagnosis; 174 (34.6%) were African-American, 144 (28.6%) were Caucasians, 86 (17.1%) Hispanics (Texas), and 99 (19.7%) were Hispanics (Puerto Rico). The mean (SD) baseline SLICC-FI was 0.26 (0.06). The final mean (SD) SDI score was 1.9 (2.2). Higher SLICC-FI scores at baseline predicted greater damage accrual in the univariable analysis [Estimate=5.058, (SE=0.498); p<0.0001]. The SLICC-FI remained associated with damage accrual in the multivariable model, after adjustment for possible confounders [Estimate= 3.561 (SE=0.538); p<0.0001].

Conclusion:

The SLICC-FI predicts damage accrual in SLE patients from a multi-ethnic cohort, supporting the importance of this index in the evaluation of SLE patients, combining several aspects of the disease.

References:

[1]Legge A, Kirkland S, Rockwood K, et al. Construction of a Frailty Index as a Novel Health Measure in Systemic Lupus Erythematosus. J Rheumatol. 2020; 47: 72-81

[2]Legge A, Kirkland S, Rockwood K, et al. Evaluating the Properties of a Frailty Index and Its Association With Mortality Risk Among Patients With Systemic Lupus Erythematosus. Arthritis Rheumatol. 2019; 71: 1297-107

[3]Legge A, Kirkland S, Rockwood K, et al. Prediction of Damage Accrual in Systemic Lupus Erythematosus Using the Systemic Lupus International Collaborating Clinics Frailty Index (SLICC-FI). Arthitis Rheumatol. Epub ahead of print 2019 Oct 21.

Disclosure of Interests:

Manuel F. Ugarte-Gil Grant/research support from: Jannsen, Pfizer, Jyoti Dubey: None declared, Gerald McGwin: None declared, Luis Vila: None declared, Graciela S Alarcon: None declared

Are molecular tools clarifying or confusing our understanding of the public health threat from zoonotic enteric protozoa in wildlife?

Emerging infectious diseases are frequently zoonotic, often originating in wildlife, but enteric protozoa are considered relatively minor contributors. Opinions regarding whether pathogenic enteric protozoa may be transmitted between wildlife and humans have been shaped by our investigation tools, and have led to oscillations regarding whether particular species are zoonotic or have host-adapted life cycles. When the only approach for identifying enteric protozoa was morphology, it was assumed that many enteric protozoa colonized multiple hosts and were probably zoonotic. When molecular tools revealed genetic differences in morphologically identical species colonizing humans and other animals, host specificity seemed more likely. Parasites from animals found to be genetically identical - at the few genes investigated - to morphologically indistinguishable parasites from human hosts, were described as having zoonotic potential. More discriminatory molecular tools have now sub-divided some protozoa again. Meanwhile, some infection events indicate that, circumstances permitting, some "host-specific" protozoa, can actually infect various hosts. These repeated changes in our understanding are linked intrinsically to the investigative tools available. Here we review how molecular tools have assisted, or sometimes confused, our understanding of the public health threat from nine enteric protozoa and example wildlife hosts (Balantoides coli - wild boar; Blastocystis sp. - wild rodents; Cryptosporidium spp. - wild fish; Encephalitozoon spp. - wild birds; Entamoeba spp. - non-human primates; Enterocytozoon bieneusi - wild cervids; Giardia duodenalis - red foxes; Sarcocystis nesbitti - snakes; Toxoplasma gondii - bobcats). Molecular tools have provided evidence that some enteric protozoa in wildlife may infect humans, but due to limited discriminatory power, often only the zoonotic potential of the parasite is indicated. Molecular analyses, which should be as discriminatory as possible, are one, but not the only, component of the toolbox for investigating potential public health impacts from pathogenic enteric protozoa in wildlife.

Low salt exposure results in inactivation of Toxoplasma gondii bradyzoites during formulation of dry cured ready-to-eat pork sausage

The production of safe and healthy food products represents one of the main objectives of the food industry. The presence of microorganisms in meat and products containing meat can result in a range of human health problems, as well as economic losses to producers of these products. However, contaminated meat products continue to initiate serious and large-scale outbreaks of disease in consumers. In addition to outbreaks of diseases caused by bacteria and viruses, parasitic organisms, such as Toxoplasma gondii, are responsible for foodborne infections worldwide, and in the case of T. gondii, is considered the 2nd leading cause of death from foodborne illness in the U.S. Transmission of Toxoplasma gondii has historically been linked to the consumption of raw or undercooked meat products, including pork. Specific concerns with respect to pork products are ready-to-eat (RTE) pork meals. These are pork or products containing pork that are prepared by curing or drying, and are not intended to be cooked before being consumed. Previous studies have demonstrated that T. gondii is inactivated during dry cured sausage preparation, apparently in the batter during fermentation. In this study, we have analyzed timing of inactivation of T. gondii in freshly prepared pepperoni batter to confirm our previous findings, to determine how quickly inactivation occurs during fermentation, and to confirm what parameters of the sausage preparation are involved in inactivation of the parasite. Results from the current and previous study indicate that rapid inactivation of T. gondii bradyzoites occurs in low salt batter for dry cured sausage within 4 h of initiation of fermentation.

Rapid inactivation of Toxoplasma gondii bradyzoites during formulation of dry cured ready-to-eat pork sausage

Curing processes for pork meat in the U.S. currently require individual validation of methods to demonstrate inactivation of Trichinella spiralis, a nematode parasite historically associated with pork. However, for protozoan parasites, no such strictures exist. It has been assumed, with little evidence, that curing processes required to inactivate Trichinella also inactivate Toxoplasma gondii. Currently no model of meat chemistry exists that can be correlated with inactivation of T. gondii. Given the possibility of the presence of T. gondii in pork meat, and the frequent use of pork for ready-to-eat (RTE) products not intended to be cooked, curing methods which inactivate T. gondii early in the curing process would be of great value to producers. In this study, we tested the effect of five variables - salt/brine concentration, water activity (aw), pH, temperature, and time on inactivation of T. gondii bradyzoites in tissue cysts using low and high endpoints for common curing treatments during preparation of dry cured pork sausage. Survival of T. gondii bradyzoites at each stage of preparation was assessed using a mouse bioassay. Results indicated that encysted T. gondii bradyzoites do not survive the early stages of the dry curing process within the endpoint parameters tested here, even at levels of NaCl that are lower than typically used for dry curing (1.3%). Exposure of T. gondii encysted bradyzoites to curing components in the formulated batter resulted in rapid inactivation of bradyzoites. These data suggest that the use of dry curing components may be effective for controlling T. gondii potentially transmitted through RTE meats, rendering them safe from risk with respect to T. gondii transmission to human consumers.

Variability in theophylline volume of distribution and clearance in patients with acute respiratory failure requiring mechanical ventilation

This study examines the intrasubject variability in theophylline volume of distribution (V) and clearance (CL) in critically ill, mechanically ventilated adults. Fifteen patients received two intravenous doses of theophylline approximately ten hours apart. Although there was no statistical difference between the mean VI (first dose, 0.51 L/kg) and V2 (second dose, 0.47 L/kg), the absolute difference between measurements of 0.15 L/kg was statistically significant (p less than .05). Range of differences follows: between VI and V2, 3.8 to 72.4 percent (mean, 33.5 percent); between CL1 and CL2, 6.1 to 100 percent (mean, 32.2 percent). Absolute difference between clearances was 0.019 L/kg/hr. A comparative error analysis revealed an absolute difference for V of 27.9 percent and for CL of 37 percent. Considerable intra-subject variability was shown for theophylline V and CL in these critically ill adults. Variability in V was not significantly different than variability in CL, and may result in severe underdosing or overdosing.

Evaluation of premixed intravenous theophylline loading doses

We evaluated the use of a standard protocol utilizing premixed theophylline containers in comparison to traditional intravenous aminophylline loading doses in 19 critically ill adults. Blood samples were obtained immediately before and after 30-minute infusions of aminophylline and theophylline bags. Aminophylline loading doses were calculated to the exact mg/kg and were delivered as such. Calculation of the theophylline loading dose used a simplified protocol that uses doses rounded to the nearest 100 mg. Comparison of the relative performance of the two loading dose methods was evaluated by computing mean squared prediction errors and root mean squared errors. The two methods were not statistically different when evaluated by a matched pair t-test. We conclude that use of a standard protocol that rounds theophylline doses to the nearest 100mg results in peak theophylline concentrations not significantly different from those predicted.