A longitudinal study of Middle East respiratory syndrome coronavirus (MERS-CoV) in dromedary camels

BACKGROUND

Middle East respiratory syndrome coronavirus (MERS-CoV) was identified in humans in 2012. Since then, 2605 cases and 937 associated deaths have been reported globally. Camels are the natural host for MERS-CoV and camel to human transmission has been documented. The relationship between MERS-CoV shedding and presence of neutralizing antibodies in camels is critical to inform surveillance and control, including future deployment of camel vaccines. However, it remains poorly understood. The longitudinal study conducted in a closed camel herd in Egypt between December 2019 and March 2020 helped to characterize the kinetics of MERS-CoV neutralizing antibodies and its relation with viral shedding.

RESULTS

During the 100-day longitudinal study, 27 out of 54 camels (50%) consistently tested negative for presence of antibodies against MERS-CoV, 19 (35.2%) tested positive and 8 (14.8%) had both, positive and negative test results. Fourteen events that could be interpreted as serological indication of probable infection (two seroconversions and twelve instances of positive camels more than doubling their optical density ratio (OD ratio) in consecutive samples) were identified. Observed times between the identified events provided strong evidence (p = 0.002) against the null hypothesis that they occurred with constant rate during the study, as opposed to clustering at certain points in time. A generalized additive model showed that optical density ratio (OD ratio) is positively associated with being an adult and varies across individual camels and days, peaking at around days 20 and 90 of the study. Despite serological indication of probable virus circulation and intense repeated sampling, none of the tested nasal swab samples were positive for MERS-CoV RNA, suggesting that, if the identified serological responses are the result of virus circulation, the virus may be present in nasal tissue of infected camels during a very narrow time window.

CONCLUSIONS

Longitudinal testing of a closed camel herd with past history of MERS-CoV infection is compatible with the virus continuing to circulate in the herd despite lack of contact with other camels. It is likely that episodes of MERS-CoV infection in camels can take place with minimal presence of the virus in their nasal tissues, which has important implications for future surveillance and control of MERS-CoV in camel herds and prevention of its zoonotic transmission.

Computational modelling of mobile bearing TKA anterior-posterior dislocation

Anterior-posterior stability in an unconstrained mobile-bearing total knee arthroplasty (TKA) and one with rotational constraints is compared in a computational model based on an ASTM test. Both TKA designs dislocate at loads greater than reported maximum in vivo forces. The posterior drawer forces (mean: 3027 N vs. 1817 N) needed to induce subluxation increase with a greater anterior jump distance (12 mm vs. 7 mm; refers to the vertical height of the anterior or posterior border of the tibial insert's articulating surface). The posterior jump distance for both tested TKA differed by 1.5 mm and had minimal effect on the magnitude of the anterior drawer forces at dislocation in mid-flexion (unconstrained vs. constrained: 445 N vs. 412 N). The unconstrained insert dislocated by means of spin-out whereas in the constrained TKA the femur dislocated from the bearing during posterior drawer and the bearing from the baseplate during anterior drawer. MCL function is an important consideration during ligament balancing since a ± 10% variation in MCL tension affects dislocation forces by ± 20%. The simulation platform provided the means to investigate TKA designs in terms of anterior-posterior stability as a function of knee flexion, collateral ligament function and mechanical morphology.

Scalp and intracranial EEG in medically intractable extratemporal epilepsy with normal MRI

Purpose. To investigate EEG and SPECT in the surgical outcome of patients with normal MRI (nonlesional) and extratemporal lobe epilepsy. Methods. We retrospectively identified 41 consecutive patients with nonlesional extratemporal epilepsy who underwent epilepsy surgery between 1997 and 2007. The history, noninvasive diagnostic studies (scalp EEG, MRI, and SPECT) and intracranial EEG (iEEG) monitoring was reviewed. Scalp and iEEG ictal onset patterns were defined. The association of preoperative studies and postoperative seizure freedom was analyzed using Kaplan-Meier analysis, log-rank test, and Cox proportional hazard. Results. Thirty-six of 41 patients had adequate information with a minimum of 1-year followup. Favorable surgical outcome was identified in 49% of patients at 1 year, and 35% at 4-year. On scalp EEG, an ictal onset pattern consisting of focal beta-frequency discharge (>13–125 Hz) was associated with favorable surgical outcome (P = 0.02). Similarly, a focal fast-frequency oscillation (>13–125 Hz) on iEEG at ictal onset was associated with favorable outcome (P = 0.03). Discussion. A focal fast-frequency discharge at ictal onset identifies nonlesional MRI, extratemporal epilepsy patients likely to have a favorable outcome after resective epilepsy surgery.

Which stroke symptoms prompt a 911 call? A population-based study

INTRODUCTION

Many studies show that a major barrier to short-term treatment of stroke is patient or bystander delay in responding to stroke symptoms. Most studies have found that less than half of stroke/transient ischemic attack (TIA) events result in a 911 call. We sought to determine which symptoms prompt the public to call 911.

METHODS

A population of 1.3 million within a 5-county region was screened for TIA and all strokes in 1999 using all local hospital International Classification of Diseases, Ninth Edition, codes for stroke (430-436) during 1999. Documented stroke symptoms were abstracted from the medical record. Symptoms were grouped as weakness, numbness, speech/language, confusion/decreased level of consciousness, headache, visual changes, and dizziness/vertigo/coordination. Cases included in this analysis had their strokes at home or work and presented to an emergency department. Logistic regression assessed which symptoms predicted a 911 call, adjusting for age, race, sex, prior stroke, baseline disability, overall stroke severity, home vs work, and stroke subtype.

RESULTS

Two thousand nine hundred seventy-five stroke/TIA patients met inclusion criteria, of whom 40% used emergency medical services. After adjustment, symptoms that increased odds of a 911 call were weakness, confusion/decreased level of consciousness, speech/language, and dizziness/coordination/vertigo. Numbness was less likely to result in a 911 call as were visual changes. The presence of headache was not associated with the decision to call 911.

DISCUSSION

The public appears to respond differently based on the type of stroke symptom, independent of overall severity. Public awareness messages regarding stroke warning signs should be designed with this in mind.

Seizure control in patients with idiopathic generalized epilepsies: EEG determinants of medication response

In a minority of patients with idiopathic generalized epilepsies (IGEs), seizures continue despite appropriate treatment. We sought to determine the clinical and EEG factors associated with medication response in these patients. All patients with IGEs evaluated by epilepsy specialists between 17 November 2008 and 16 November 2009 were included. We collected information on seizure freedom (dependent variable), EEG asymmetries, response to valproic acid (VPA), MRI characteristics, medication use, demographics, and seizure history (predictors). We identified 322 patients with IGEs; 45 (14%) were excluded from analyses because they had always had a normal EEG (N=26), there were no EEG data (N=3), or they were non-compliant with medication (N=26). Patients with juvenile myoclonic epilepsy were more likely to respond to VPA than were patients with other IGEs, and VPA response was associated with seizure freedom. When EEG characteristics were considered, presence of any focal EEG abnormalities (focal slowing, focal epileptiform discharges, or both) was associated with decreased odds of seizure freedom. These findings suggest that patients with IGEs with poor seizure control may have atypical IGEs with possibly focal, for example, frontal, rather than thalamic onset.

Designing a Message for Public Education Regarding Stroke

Background and Purpose— Previous studies have shown poor public knowledge of stroke warning signs. The current public education message adopted by the American Heart Association lists 5 stroke warning signs (“suddens”). Another message called FAST (face, arm, speech, time) could be easier to remember, but it does not contain as many stroke symptoms. We sought to assess the percentage of stroke/transient ischemic attack (TIA) patients identified by both public awareness messages by examining presenting symptoms of all stroke/TIA patients from a large, biracial population in 1999.

Methods— Cases of stroke who presented to an emergency department or were directly admitted were ascertained at all local hospitals by screening of ICD-9 codes 430 to 436, and prospective screening of emergency department admission logs, in 1999. Study nurses abstracted initial presenting symptoms from the medical record. All-cause 30-day case-fatality was calculated.

Results— During 1999, 3498 stroke/TIA patients (17% black, 56% female) presented to an emergency department. Of these events, 11.1% had presenting symptoms not included in FAST, whereas 0.1% had presenting symptoms not included in the suddens. The FAST message performed much better for ischemic stroke and TIA than for hemorrhage, missing 8.9% of the ischemic strokes and 8.2% of the TIAs, versus 30.6% of intracerebral hemorrhage/subarachnoid hemorrhage cases. Case-fatality in patients missed by FAST was similar to patients with FAST symptoms (9.0% versus 11.6%, P =0.15).

Conclusions— Within our population, we found that the FAST message identified 88.9% of stroke/TIA patients. The FAST message performed better for ischemic stroke and TIA than for hemorrhagic stroke. Whether the FAST message is easier to recall for the public than the “suddens” message has yet to be determined.

Hypovitaminosis E induced neuropathy in exocrine pancreatic failure

A 4 year old girl with congenital nerve deafness and pancreatic insufficiency had incapacitating ataxia. Electrophysiological studies of the median nerve and the brain stem evoked response were abnormal. Serum vitamin E concentration was low. After intramuscular injections of vitamin E the ataxia disappeared and electrophysiological variables reverted to normal.