Development and Experience with an Algorithm to Evaluate Suspected Smallpox Cases in the United States, 2002-2004

Is fractional-order chaos theory the new tool to model chaotic pandemics as Covid-19?

The deadly outbreak of the second wave of Covid-19, especially in worst hit lower-middle-income countries like India, and the drastic rise of another growing epidemic of Mucormycosis, call for an efficient mathematical tool to model pandemics, analyse their course of outbreak and help in adopting quicker control strategies to converge to an infection-free equilibrium. This review paper on prominent pandemics reveals that their dispersion is chaotic in nature having long-range memory effects and features which the existing integer-order models fail to capture. This paper thus puts forward the use of fractional-order (FO) chaos theory that has memory capacity and hereditary properties, as a potential tool to model the pandemics with more accuracy and closeness to their real physical dynamics. We investigate eight FO models of Bombay plague, Cancer and Covid-19 pandemics through phase portraits, time series, Lyapunov exponents and bifurcation analysis. FO controllers (FOCs) on the concepts of fuzzy logic, adaptive sliding mode and active backstepping control are designed to stabilise chaos. Also, FOCs based on adaptive sliding mode and active backstepping synchronisation are designed to synchronise a chaotic epidemic with a non-chaotic one, to mitigate the unpredictability due to chaos during transmission. It is found that severity and complexity of the models increase as the memory fades, indicating that FO can be used as a crucial parameter to analyse the progression of a pandemic. To sum it up, this paper will help researchers to have an overview of using fractional calculus in modelling pandemics more precisely and also to approximate, choose, stabilise and synchronise the chaos control parameter that will eliminate the extreme sensitivity and irregularity of the models.

Human monkeypox

Human monkeypox is a zoonotic Orthopoxvirus with a presentation similar to smallpox. Clinical differentiation of the disease from smallpox and varicella is difficult. Laboratory diagnostics are principal components to identification and surveillance of disease, and new tests are needed for a more precise and rapid diagnosis. The majority of human infections occur in Central Africa, where surveillance in rural areas with poor infrastructure is difficult but can be accomplished with evidence-guided tools and educational materials to inform public health workers of important principles. Contemporary epidemiological studies are needed now that populations do not receive routine smallpox vaccination. New therapeutics and vaccines offer hope for the treatment and prevention of monkeypox; however, more research must be done before they are ready to be deployed in an endemic setting. There is a need for more research in the epidemiology, ecology, and biology of the virus in endemic areas to better understand and prevent human infections.

Optimization of peptide-based ELISA for serological diagnostics: a retrospective study of human monkeypox infection

Although smallpox has been eradicated, other diseases caused by virulent orthopoxviruses such as monkeypox virus (MPV) remain endemic in remote areas of western and central sub-Saharan Africa, and represent a potential biothreat due to international travel and/or inadvertent exposure. Unfortunately, extensive antigenic cross-reactivity among orthopoxviruses presents a challenge to serological diagnosis. We previously reported a 20mer peptide-based ELISA that identified recent MPV infection with >90% sensitivity and >90% specificity. However, the sensitivity of this approach was not determined with samples obtained at later time points after antibody titers had declined from their peak levels. To improve assay sensitivity for detecting MPV-specific antibodies at later time points, we compared diagnostic 20mer peptides to 30mer peptides. In addition, optimal 30mer peptides were tested in combination or after conjugating selected peptides to a carrier protein (bovine serum albumin) to further improve assay performance. An optimized combination of four unconjugated 30mer peptides provided 100% sensitivity for detecting MPV infection at 2-6 months post-infection, 45% sensitivity for detecting MPV infection at >2 years post-infection, and 99% specificity. However, an optimized combination of two peptide conjugates provided 100% sensitivity for detecting MPV infection at 2-6 months post-infection, 90% sensitivity for detecting MPV infection at >2 years post-infection, and 97% specificity. Peptide-based ELISA tests provide a relatively simple approach for serological detection of MPV infection. Moreover, the systematic approach used here to optimize diagnostic peptide reagents is applicable to developing improved diagnostics to a broad range of other viruses, and may be particularly useful for distinguishing between closely-related viruses within the same genus or family.

Eczema herpeticum and clinical criteria for investigating smallpox

Eczema herpeticum can clinically resemble smallpox. On the basis of the algorithm for rapid evaluation of patients with an acute generalized vesiculopustular rash illness, our patient met criteria for high risk for smallpox. The Tzanck preparation was critical for rapid diagnosis of herpetic infection and exclusion of smallpox.

Responding to suspected smallpox cases in the Los Angeles County from 2002 to 2006: identifying areas for education

INTRODUCTION

Although smallpox has been eradicated, health care providers in emergency departments (EDs) need to remain vigilant to its recognition. Smallpox can be confused with chickenpox. We describe suspected smallpox cases reported in Los Angeles County from 2002 to 2006 and highlight areas for education.

METHODS

We retrospectively reviewed suspected smallpox reports from 2002 to 2006. Laboratory testing was performed. Photographs of rashes were taken.

RESULTS

Five suspected smallpox cases were reported. Two presented first to an ED. Smallpox was suspected based on rash features. Previous history of chickenpox or varicella vaccination may have caused increased suspicion for smallpox. All 5 were determined to have a final diagnosis of chickenpox. Health care providers notified public health appropriately and responses were immediate.

CONCLUSIONS

Public health investigated 5 suspected smallpox cases in the past 5 years. Two presented initially to EDs. Education differentiating smallpox from chickenpox and collaboration between public health, EDs, and health care providers remains important. The ability to respond rapidly to a potential bioterrorism emergency was tested.

Smallpox as a Weapon for Bioterrorism

Smallpox, the only disease ever eradicated, is one of the six pathogens considered a serious threat for biological terrorism (Henderson et al., 1999; Mahy, 2003; Whitley, 2003). Smallpox has several attributes that make it a potential threat. It can be grown in large amounts. It spreads via the respiratory route. It has a 30% mortality rate. The potential for an attack using smallpox motivated President Bush to call for phased vaccination of a substantial number of American health care and public health workers (Grabenstein and Winkenwerder, 2003; Stevenson and Stolberg, 2002). Following September 11, 2001, the United States rebuilt its supplies of vaccine and Vaccinia Immune Globulin (VIG), expanded the network of laboratories capable of testing for variola virus, and engaged in a broad education campaign to help health care workers and the general public understand the disease (Centers for Disease Control and Prevention, 2003a). This chapter summarizes the scientific and theoretical bases for use of smallpox as a bioweapon and options for preparation for defense against it.

Transmission of atypical varicella-zoster virus infections involving palm and sole manifestations in an area with monkeypox endemicity

During a suspected monkeypox outbreak in the Republic of Congo, we documented transmission of varicella-zoster virus (VZV) infection with palm and sole manifestations among 5 family members. Genotyping results confirmed the VZV strain European E2, a genotype not previously reported in Africa. VZV with palm and sole involvement should be considered when differentiating a monkeypox diagnosis.

Performance of an algorithm for assessing smallpox risk among patients with rashes that may be confused with smallpox

After the 2001 anthrax bioterror attacks, the Centers for Disease Control and Prevention developed an algorithm to evaluate patients rapidly for suspected smallpox. A prospective, multicenter study examined the performance of this algorithm in assessing patients with an acute, generalized vesicular or pustular rash (AGVPR) admitted to emergency departments and inpatient units of 12 acute-care hospitals in 6 states. Of 26,747 patients (3.5% of all admissions) with rashlike conditions screened, 89 (1.2 patients per 10,000 admissions) had an AGVPR. Physicians or study staff classified none of 73 enrolled patients as being at high risk for having smallpox; 72 (99%) were classified as being at low risk, and 1 was classified as being at moderate risk. The discharge diagnosis for 55 (75%) of these 73 participants was varicella illness. Use of the algorithm did not result in misclassification of AGVPR as high risk for smallpox. The algorithm is a highly specific tool for clinical evaluation of suspected smallpox disease.

Retrospective analysis of monkeypox infection

Serologic cross-reactivity between orthopoxviruses is a substantial barrier to laboratory diagnosis of specific orthopoxvirus infections and epidemiologic characterization of disease outbreaks. Historically, time-consuming and labor-intensive strategies such as cross-adsorbed neutralization assays, immunofluorescence assays, and hemagglutination-inhibition assays have been used to identify orthopoxvirus infections. We used cross-adsorption to develop a simple and quantitative postadsorption ELISA for distinguishing between monkeypox and vaccinia infections. Despite the difficulty of diagnosing clinically inapparent monkeypox in previously vaccinated persons, this technique exhibited 100% sensitivity and 100% specificity for identifying clinically overt monkeypox infection irrespective of vaccination history. We also describe a Western blot technique in which up to 3 diagnostic bands may be used to distinguish between vaccinia and monkeypox infection. The techniques described provide independent diagnostic tests suitable for retrospective analysis of monkeypox outbreaks.

Public health surveillance for suspected smallpox in the United States, 2003-2005: results of a national survey

In 2005, a Web-based survey of chief epidemiologists of 50 states, the District of Columbia, 9 large cities, and 8 territories examined the status of US smallpox surveillance after the Council of State and Territorial Epidemiologists recommended that smallpox be reportable. Of 55 respondents, 95% reported state or territory laws or regulations governing smallpox reporting; 70% of states required laboratories to report variola virus. All respondents could investigate reported suspected patients; 70%-89% would investigate initially by telephone or fax. In 2004, 11 states reported 33 patients suspected of having smallpox. Reports were more likely in states that provided >/=2 educational and training sessions (67% vs. 21%; prevalence odds ratio, 7.60; 95% confidence interval, 1.07-60.45). The goal is a public health surveillance system in which all states, cities, and territories can detect and manage suspected smallpox cases urgently and in which overall surveillance for other infectious diseases is strengthened.

Varicella

Varicella-zoster virus, a herpesvirus, causes varicella (chickenpox) and, after endogenous reactivation, herpes zoster (shingles). Varicella, which is recognised by a characteristic vesicular rash, arises mainly in young children, although older individuals can be affected. In immunocompetent patients, symptoms are usually mild to moderate, but an uncomplicated severe case can have more than 1000 lesions and severe constitutional symptoms. Serious complications--including central nervous system involvement, pneumonia, secondary bacterial infections, and death--are sometimes seen. Varicella can be prevented by vaccination. Vaccine is about 80-85% effective against all disease and highly (more than 95%) effective in prevention of severe disease. In the USA, a routine childhood immunisation programme has reduced disease incidence, complications, hospital admissions, and deaths in children and in the general population, indicating strong herd immunity. Similar immunisation programmes have been adopted by some other countries, including Uruguay, Germany, Taiwan, Canada, and Australia, and are expected to be implemented more widely in future.

Health literacy in the field of infectious diseases: the paradigm of brucellosis

OBJECTIVES

Treatment outcome for infectious diseases, including brucellosis, may be influenced by patient awareness of the disease itself, as well as by compounding socioeconomic factors. We attempted to evaluate parameters of patient awareness and disease perception in brucellosis and the ways they influence outcome.

METHODS

We used a specifically developed questionnaire assessing various parameters of patient literacy on brucellosis in 70 patients with a new diagnosis of brucellosis. Patients were assessed by interviewing at the time of diagnosis and during follow-up. Awareness and perception of the disease, willingness for epidemiologic surveillance, mode of referral, treatment preferences, and adherence were evaluated.

RESULTS

Although basic disease awareness is high, willingness to collaborate in epidemiologic surveillance is limited. Patient education may improve adherence to treatment and willingness to undergo surveillance, but may also result in many false referrals for relapse. Level of academic education does not influence the results. Convenience is the major factor when determining treatment preferences.

CONCLUSION

Improving health literacy may result in improved treatment outcome and improved control of disease incidence. There is a need for constant evaluation of the quality and quantity of information distributed in order to reduce transmission of misinformation and occurrences of public anxiety.

The initial hospital response to an epidemic

The last decades have been characterized by the appearance of a substantial number of newly recognized or novel infectious agents and by the re-emergence of infectious diseases with a global impact. The objective of this article is to briefly describe the model of hospital response for early diagnosis and prompt management of patients with highly contagious infectious diseases. We reviewed the main components of hospital preparedness in response to clustering of highly contagious diseases. A model for the initial hospital response to an epidemic in our referral Institute is discussed. Prompt recognition and identification is the initial and indispensable step in facing any communicable diseases, regardless of whether it is a prevalent, a newly emerging one or deliberately released. The importance of developing and implementing nontraditional methods of public health surveillance and a system that allows a wide and immediate dissemination of information and exchange of views on risk assessment and risk management are highlighted. Case identification and laboratory capabilities and isolation procedures are the essential components for an initial hospital response. The recent bioterrorist events and the worldwide outbreaks of highly contagious infectious diseases have evidenced the need for institutional preparedness at each hospital and for identification of referral centers for patient isolation and of laboratories with adequate capabilities. Moreover, hospitals should develop a plan for coordinating all hospital components to respond to critical situations deriving from the admission of patients with highly contagious infectious diseases.

Smallpox

The WHO declared smallpox eradicated in 1980. However, concern over its potential use by terrorists or in biowarfare has led to striking growth in research related to this much-feared disease. Modern molecular techniques and new animal models are advancing our understanding of smallpox and its interaction with the host immune system. Rapid progress is likewise being made in smallpox laboratory diagnostics, smallpox vaccines, and antiviral medications. WHO and several nations are developing stockpiles of smallpox vaccine for use in the event the disease is reintroduced. National and international public-health agencies have also drawn up plans to help with early detection of and response to a smallpox outbreak. These plans hinge on physicians' ability to recognise the clinical features of smallpox and to distinguish it from other illnesses characterised by rashes.

Clinical characteristics of human monkeypox, and risk factors for severe disease

BACKGROUND

Human monkeypox is an emerging smallpox-like illness that was identified for the first time in the United States during an outbreak in 2003. Knowledge of the clinical manifestations of monkeypox in adults is limited, and clinical laboratory findings have been unknown.

METHODS

Demographic information; medical history; smallpox vaccination status; signs, symptoms, and duration of illness, and laboratory results (hematologic and serum chemistry findings) were extracted from medical records of patients with a confirmed case of monkeypox in the United States. Two-way comparisons were conducted between pediatric and adult patients and between patients with and patients without previous smallpox vaccination. Bivariate and multivariate analyses of risk factors for severe disease (fever [temperature, > or =38.3 degrees C] and the presence of rash [> or =100 lesions]), activity and duration of hospitalization, and abnormal clinical laboratory findings were performed.

RESULTS

Of 34 patients with a confirmed case of monkeypox, 5 (15%) were defined as severely ill, and 9 (26%) were hospitalized for >48 h; no patients died. Previous smallpox vaccination was not associated with disease severity or hospitalization. Pediatric patients (age, < or =18 years) were more likely to be hospitalized in an intensive care unit. Nausea and/or vomiting and mouth sores were independently associated with a hospitalization duration of >48 h and with having > or =3 laboratory tests with abnormal results.

CONCLUSION

Monkeypox can cause a severe clinical illness, with systemic signs and symptoms and abnormal clinical laboratory findings. In the appropriate epidemiologic context, monkeypox should be included in the differential diagnosis for patients with unusual vesiculopustular exanthems, mucosal lesions, gastrointestinal symptoms, and abnormal hematologic or hepatic laboratory findings. Clinicians evaluating a rash illness consistent with possible orthopoxvirus infection should alert public health officials and consider further evaluation.

Multiple diagnostic techniques identify previously vaccinated individuals with protective immunity against monkeypox

Approximately 50% of the US population received smallpox vaccinations before routine immunization ceased in 1972 for civilians and in 1990 for military personnel. Several studies have shown long-term immunity after smallpox vaccination, but skepticism remains as to whether this will translate into full protection against the onset of orthopoxvirus-induced disease. The US monkeypox outbreak of 2003 provided the opportunity to examine this issue. Using independent and internally validated diagnostic approaches with >or=95% sensitivity and >or=90% specificity for detecting clinical monkeypox infection, we identified three previously unreported cases of monkeypox in preimmune individuals at 13, 29 and 48 years after smallpox vaccination. These individuals were unaware that they had been infected because they were spared any recognizable disease symptoms. Together, this shows that the US monkeypox outbreak was larger than previously realized and, more importantly, shows that cross-protective antiviral immunity against West African monkeypox can potentially be maintained for decades after smallpox vaccination.

Chickenpox or Smallpox: The Use of the Febrile Prodrome as a Distinguishing Characteristic

BACKGROUND

The ability to differentiate chickenpox from smallpox is important for early recognition of bioterrorism events and prevention of false alarms. The febrile prodrome is a clinical feature used to differentiate these conditions. However, the prevalence of prodromal manifestations in chickenpox has not been well established.

METHODS

We evaluated prodrome characteristics of all chickenpox cases identified through an active varicella surveillance program over a 21-month period. The frequencies of various prodromal manifestations among vaccinated and unvaccinated case patients were assessed, and the impact of other demographic features on these manifestations was evaluated. Data were analyzed to determine what proportion met the smallpox febrile prodrome criteria as elaborated in the Centers for Disease Control and Prevention algorithm for evaluating patients suspected of having smallpox. Finally, we compared our data with historical data on smallpox prodromes.

RESULTS

Data on prodrome characteristics were available for 932 chickenpox cases. Prodromal fever was present in 37% of unvaccinated chickenpox case patients and in 25% of vaccinated case patients. Among unvaccinated case patients, adults were 70% more likely than children to have fever in the prodrome period. We found that prodromes are less common and less severe in chickenpox than in smallpox. Nevertheless, 7%-17% of unvaccinated chickenpox case patients meet the smallpox febrile prodrome criteria.

CONCLUSIONS

Febrile prodromes occur in a significant proportion of patients with chickenpox, particularly among unvaccinated case patients and adults. Therefore, the febrile prodrome alone is not a sufficient marker of smallpox risk. All major and minor smallpox criteria should be considered together in assessing the likelihood of smallpox.