Infectious Disease Surveillance (III)

I have added some more observations from the book below.

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“Zoonotic diseases are infections transmitted between animals and humans […]. A recent survey identified more than 1,400 species of human disease–causing agents, over half (58%) of which were zoonotic [2]. Moreover, nearly three-quarters (73%) of infectious diseases considered to be emerging or reemerging were zoonotic [2]. […] In many countries there is minimal surveillance for live animal imports or imported wildlife products. Minimal surveillance prevents the identification of wildlife trade–related health risks to the public, agricultural industry, and native wildlife [36] and has led to outbreaks of zoonotic diseases […] Southeast Asia [is] a hotspot for emerging zoonotic diseases because of rapid population growth, high population density, and high biodiversity […] influenza virus in particular is of zoonotic importance as multiple human infections have resulted from animal exposure [77–79].”

“[R]abies is an important cause of death in many countries, particularly in Africa and Asia [85]. Rabies is still underreported throughout the developing world, and 100-fold underreporting of human rabies is estimated for most of Africa [44]. Reasons for underreporting include lack of public health personnel, difficulties in identifying suspect animals, and limited laboratory capacity for rabies testing. […] Brucellosis […] is transmissible to humans primarily through consumption of unpasteurized milk or dairy products […] Brucella is classified as a category B bioterrorism agent [90] because of its potential for aerosolization [I should perhaps here mention that the book coverage does overlaps a bit with that of Fong & Alibek’s book – which I covered here – but that I decided against covering those topics in much detail here – US] […] The key to preventing brucellosis in humans is to control or eliminate infections in animals [91–93]; therefore, veterinarians are crucial to the identification, prevention, and control of brucellosis [89]. […] Since 1954 [there has been] an ongoing eradication program involving surveillance testing of cattle at slaughter, testing at livestock markets, and whole-herd testing on the farm [in the US] […] Except for endemic brucellosis in wildlife in the Greater Yellowstone Area, all 50 states and territories in the United States are free of bovine brucellosis [94].”

“Because of its high mortality rate in humans in the absence of early treatment, Y. pestis is viewed as one of the most pathogenic human bacteria [101]. In the United States, plague is most often found in the Southwest where it is transmitted by fleas and maintained in rodent populations [102]. Deer mice and voles typically serve as maintenance hosts [and] these animals are often resistant to plague [102]. In contrast, in amplifying host species such as prairie dogs, ground squirrels, chipmunks, and wood rats, plague spreads rapidly and results in high mortality [103]. […] Human infections with Y. pestis can result in bubonic, pneumonic, or septicemic plague, depending on the route of exposure. Bubonic plague is most common; however, pneumonic plague poses a more serious public health risk since it can be easily transmitted person-to-person through inhalation of aerosolized bacteria […] Septicemic plague is characterized by bloodstream infection with Y. pestis and can occur secondary to pneumonic or bubonic forms of infection or as a primary infection [6,60].
Plague outbreaks are often correlated with animal die-offs in the area [104], and rodent control near human residences is important to prevent disease [103]. […] household pets can be an important route of plague transmission and flea control in dogs and cats is an important prevention measure [105]. Plague surveillance involves monitoring three populations for infection: vectors (e.g., fleas), humans, and rodents [106]. In the past 20 years, the numbers of human cases of plague reported in the United States have varied from 1 to 17 cases per year [90]. […] Since rodent species are the main reservoirs of the bacteria, these animals can be used for sentinel surveillance to provide an early warning of the public health risk to humans [106]. […] Rodent die-offs can often be an early indicator of a plague outbreak”.

“Zoonotic disease surveillance is crucial for protection of human and animal health. An integrated, sustainable system that collects data on incidence of disease in both animals and humans is necessary to ensure prompt detection of zoonotic disease outbreaks and a timely and focused response [34]. Currently, surveillance systems for animals and humans [operate] largely independently [34]. This results in an inability to rapidly detect zoonotic diseases, particularly novel emerging diseases, that are detected in the human population only after an outbreak occurs [109]. While most industrialized countries have robust disease surveillance systems, many developing countries currently lack the resources to conduct both ongoing and real-time surveillance [34,43].”

“Acute hepatitis of any cause has similar, usually indistinguishable, signs and symptoms. Acute illness is associated with fever, fatigue, nausea, abdominal pain, followed by signs of liver dysfunction, including jaundice, light to clay-colored stool, dark urine, and easy bruising. The jaundice, dark urine, and abnormal stool are because of the diminished capacity of the inflamed liver to handle the metabolism of bilirubin, which is a breakdown product of hemoglobin released as red blood cells are normally replaced. In severe hepatitis that is associated with fulminant liver disease, the liver’s capacity to produce clotting factors and to clear potential toxic metabolic products is severely impaired, with resultant bleeding and hepatic encephalopathy. […] An effective vaccine to prevent hepatitis A has been available for more than 15 years, and incidence rates of hepatitis A are dropping wherever it is used in routine childhood immunization programs. […] Currently, hepatitis A vaccine is part of the U.S. childhood immunization schedule recommended by the Advisory Committee on Immunization Practices (ACIP) [31].”

“Chronic hepatitis — persistent and ongoing inflammation that can result from chronic infection — usually has minimal to no signs or symptoms […] Hepatitis B and C viruses cause acute hepatitis as well as chronic hepatitis. The acute component is often not recognized as an episode of acute hepatitis, and the chronic infection may have little or no symptoms for many years. With hepatitis B, clearance of infection is age related, as is presentation with symptoms. Over 90% of infants exposed to HBV develop chronic infection, while <1% have symptoms; 5–10% of adults develop chronic infection, but 50% or more have symptoms associated with acute infection. Among those who acquire hepatitis C, 15–45% clear the infection; the remainder have lifelong infection unless treated specifically for hepatitis C.”

“[D]ata are only received on individuals accessing care. Asymptomatic acute infection and poor or unavailable measurements for high risk populations […] have resulted in questionable estimates of the prevalence and incidence of hepatitis B and C. Further, a lack of understanding of the different types of viral hepatitis by many medical providers [18] has led to many undiagnosed individuals living with chronic infection, who are not captured in disease surveillance systems. […] Evaluation of acute HBV and HCV surveillance has demonstrated a lack of sensitivity for identifying acute infection in injection drug users; it is likely that most cases in this population go undetected, even if they receive medical care [36]. […] Best practices for conducting surveillance for chronic hepatitis B and C are not well established. […] The role of health departments in responding to infectious diseases is typically responding to acute disease. Response to chronic HBV infection is targeted to prevention of transmission to contacts of those infected, especially in high risk situations. Because of the high risk of vertical transmission and likely development of chronic disease in exposed newborns, identification and case management of HBV-infected pregnant women and their infants is a high priority. […] For a number of reasons, states do not conduct uniform surveillance for chronic hepatitis C. There is not agreement as to the utility of surveillance for chronic HCV infection, as it is a measurement of prevalent rather than incident cases.”

“Among all nationally notifiable diseases, three STDs (chlamydia, gonorrhea, and syphilis) are consistently in the top five most commonly reported diseases annually. These three STDs made up more than 86% of all reported diseases in the United States in 2010 [2]. […] The true burden of STDs is likely to be higher, as most infections are asymptomatic [4] and are never diagnosed or reported. A synthesis of a variety of data sources estimated that in 2008 there were over 100 million prevalent STDs and nearly 20 million incident STDs in the United States [5]. […] Nationally, 72% of all reported STDs are among persons aged 15–24 years [3], and it is estimated that 1 in 4 females aged 14–19 has an STD [7]. […] In 2011, the rates of chlamydia, gonorrhea, and primary and secondary syphilis among African-­Americans were, respectively, 7.5, 16.9, and 6.7 times the rates among whites [3]. Additionally, men who have sex with men (MSM) are disproportionately infected with STDs. […] several analyses have shown risk ratios above 100 for the associations between being an MSM and having syphilis or HIV [9,10]. […] Many STDs can be transmitted congenitally during pregnancy or birth. In 2008, over 400,000 neonatal deaths and stillbirths were associated with syphilis worldwide […] untreated chlamydia and gonorrhea can cause ophthalmia neonatorum in newborns, which can result in blindness [13]. The medical and societal costs for STDs are high. […] One estimate in 2008 put national costs at $15.6 billion [15].”

“A significant challenge in STD surveillance is that the term “STD” encompasses a variety of infections. Currently, there are over 35 pathogens that can be transmitted sexually, including bacteria […] protozoa […] and ectoparasites […]. Some infections can cause clinical syndromes shortly after exposure, whereas others result in no symptoms or have a long latency period. Some STDs can be easily diagnosed using self-collected swabs, while others require a sample of blood or a physical examination by a clinician. Consequently, no one particular surveillance strategy works for all STDs. […] The asymptomatic nature of most STDs limits inferences from case­-based surveillance, since in order to be counted in this system an infection must be diagnosed and reported. Additionally, many infections never result in disease. For example, an estimated 90% of human papillomavirus (HPV) infections resolve on their own without sequelae [24]. As such, simply counting infections may not be appropriate, and sequelae must also be monitored. […] Strategies for STD surveillance include case reporting; sentinel surveillance; opportunistic surveillance, including use of administrative data and positivity in screened populations; and population-­based studies […] the choice of strategy depends on the type of STD and the population of interest.”

“Determining which diseases and conditions should be included in mandatory case reporting requires balancing the benefits to the public health system (e.g., utility of the data) with the costs and burdens of case reporting. While many epidemiologists and public health practitioners follow the mantra “the more data, the better,” the costs (in both dollars and human resources) of developing and maintaining a robust case­-based reporting system can be large. Case­-based surveillance has been mandated for chlamydia, gonorrhea, syphilis, and chancroid nationally; but expansion of state­-initiated mandatory reporting for other STDs is controversial.”