Anthrax is the transmittable disease arising from infection with the Gram-positive, spore-forming bacterium Bacillus anthracis. Humans acquire naturally occurring disease from contact with infected animals or contaminated animal products. The disease more commonly infects herbivores, which ingest the spores from the soil. Animal vaccination is a common practice and has decreased animal mortality from the disease (5). There are three main illnesses in humans depending on the route of contact—cutaneous, inhalational, and gastrointestinal. The cutaneous form is the most common natural disease, although outbreaks of gastrointestinal anthrax are occasionally reported due to the consumption of undercooked, contaminated meat. Inhalational anthrax is rare but has raised the most concern as a bioterrorist threat because of its high mortality rate and ease of dissemination (5).

The spores of B. anthracis are stable for many years; are resistant to sunlight, heat, and disinfectants; and can be dispersed as a dry or moist aerosol cloud. It is reported that weaponized spores may be disseminated throughout an entire building even after delivery by a contained letter (6). As an example of the deadly nature of the spores, it was reported from the former Soviet Union that an outbreak near one of its weapons facilities in 1979 resulted in 77 cases of inhalational anthrax with 66 deaths (85% mortality) (4,6). In the fall of 2001, 22 cases of anthrax infection occurred following delivery of spores through the US Postal Service. Eleven of the cases were inhalational with five deaths occurring in that group, while the rest of the cases were cutaneous (4,5,6). The knowledge that strains of B. anthracis have been modified and may potentially be released creates a whole new outlook in public health policies. It is estimated that more than 30,000 potentially exposed persons were placed on postexposure prophylaxis during the US outbreak of 2001 (6). The direct and indirect costs of handling a limited contamination such as the 2001 mailed attacks are undoubtedly high.

The spores germinate in an environment rich in amino acids, nucleic acids, and glucose, such as in mammalian tissues or blood. The bacteria multiply rapidly and will only form spores again when the nutrients are depleted, such as when contaminated body fluids are discharged and encounter ambient air. The vegetative bacteria do not survive long in ambient conditions unlike their spore form which may remain stable for many years.

Inhalational anthrax begins when inhaled spore particles sized 1 to 5 µm enter alveolar spaces and are subsequently ingested by macrophages. Spores that survive and are not lysed may travel to the mediastinal lymphatic tissue where they germinate and multiply. The incubation period varies. Most often, incubation occurs within 1 to 7 days but can be delayed as much as 43 days (2,4,5,6). The replicating B. anthracis produces toxins that carry on cellular damage even if all living bacteria are eradicated with antibiotics (4,5). This ongoing damage results in hemorrhagic lymphadenitis, hemorrhagic mediastinitis, necrosis, and pleural effusions. The patient may present initially with fever, cough, dyspnea, and malaise. An initial chest radiograph may be abnormal with widened mediastinum, infiltrates, and effusion. The more fulminant case progresses rapidly with a continued rise in fever, worsening dyspnea, chest pain, and respiratory failure. Blood culture will usually show the characteristic colony formation, but direct communication with the lab is important when B. anthracis is suspected as such colonies may be mistaken for contaminant normal flora (2,5). Neurological complications, such as hemorrhagic meningitis, cerebral edema, parenchymal brain hemorrhages, vasculitis, and subarachnoid hemorrhage, can be associated with the three different forms of anthrax exposure. The aforementioned should be considered a fourth type of presentation that prompts investigation for bioterrorism (7). The organism may be identified readily in the cerebrospinal fluid in the presence of absence of CNS symptomatology.

Cutaneous anthrax occurs following the deposition of the spores in cuts or abrasions of the skin. Subsequently, germination occurs in the skin, and toxin production proceeds to local tissue edema and necrosis. A skin vesicle typically forms which then dries to form a black eschar. Antibiotic therapy will not alter the course of skin destruction and eschar resolution, but it will decrease the localized edema and the risk of systemic spread. Systemic spread may be possible, and untreated mortality is reported to be as high as 20% (4,5,6,7). Gastrointestinal anthrax may be contracted from ingestion of contaminated meat. Spores may germinate in either the upper or the lower intestinal tract. Ulcer formation in the mouth or esophagus may lead to regional lymphadenitis. In the lower tract, intestinal anthrax may lead to nausea, vomiting, acute abdomen, ascites, mesenteric lymphadenopathy, bowel edema, and bloody diarrhea. In both cases, death may occur due to systemic illness, and mortality as high as 25% to 60% has been reported (2,5,6,7). Unfortunately, there is limited information available on anthrax infection during pregnancy, but in general, usual nonpregnant therapeutic guidelines are employed given the high morbidity and mortality to the untreated patient let alone the treated individual (8).

It is important to remember that casual contact or respiratory droplets from coughing or sneezing do not spread anthrax. While person-to-person respiratory transmission does not occur, caution should be used when caring for patients with nonintact skin from cutaneous anthrax (2). Treatment consists of a combination therapy that usually includes ciprofloxacin and doxycycline and may also include clindamycin, rifampin, vancomycin, or chloramphenicol (5). The recommendations for appropriate antibiotic therapy are the same for pregnant women or children as for nonpregnant adults. One should check with an infectious disease consultant or the CDC website for the latest recommended drug combination. Supportive end organ therapy such as ventilator assistance is usually required for severe cases.

Prophylactic antimicrobial therapy is not needed unless law enforcement and public health officials document an actual exposure. It is recommended that the primary care women’s health provider not initiate the therapy unless directed to do so by the appropriate public health officials (9). Screening may be performed
by way of nasal swab, but due to potential error, postexposure prophylaxis is recommended only after a confirmed exposure or high-risk encounter (9).

The current CDC guidelines were based on susceptibilities determined from anthrax isolates from the intentional exposures in 2001 (7). These isolates were found to be sensitive to penicillin, amoxicillin, ciprofloxacin, doxycycline, chloramphenicol, clindamycin, tetracycline, rifampin, clarithromycin, and vancomycin. Adult exposure prophylaxis is typically given with ciprofloxacin 500 mg orally every 12 hours for 60 days or doxycycline 100 mg orally every 12 hours for 60 days (2). The recommendation is the same for pregnant and lactating women. The potential morbidity and mortality from anthrax are felt to outweigh the historical and theoretical concerns regarding these medications (9). If the anthrax isolate in a current case is found to be sensitive to penicillin, the pregnant or lactating patient should be switched to amoxicillin 500 mg orally three times a day for the remainder of the prophylaxis period (9).

Vaccination against anthrax may be performed. The vaccine, called anthrax vaccine adsorbed (AVA), is a cell-free product given in a six-dose series over 18 months (5). While there has been significant media coverage of concerns over side effects of the vaccine following the US military’s mandated vaccination of active-duty and reserve-duty personnel, AVA is thought to be acceptably safe (5). Due to the potential for spores to remain dormant in tissues for prolonged periods despite antibiotic prophylaxis, there has been interest in the use of AVA for postexposure prophylaxis in conjunction with antibiotics (5,8). The vaccine should theoretically be safe for use during pregnancy due to a lack of an active organism. No published experience is available on the use of the vaccine during pregnancy, but the potential benefits may outweigh the risk associated with systemic diseases in the event of a large-scale exposure. Experience from the military vaccination program suggests no adverse effect on pregnancy outcomes for women vaccinated prior to becoming pregnant (10).

Smallpox is caused by the DNA virus known as variola. It is easily transmitted from person to person by respiratory droplets. In addition, the virus may remain stable on fomites for up to 1 week (6). The virus replicates in respiratory epithelia and then migrates to regional lymph nodes. An initial viremia, accompanied by mild fever and malaise, will lead to introduction of the virions to a variety of tissues, resulting in localized infections in the kidneys, lungs, intestines, skin, and lymphoid tissues. After an incubation of 7 to 17 days, a second viremia occurs with high fevers, headache, backache, rigors, and vomiting. A rash is usually apparent within 48 hours of this new phase. The rash is initially maculopapular but changes soon to a vesicular eruption. The characteristic smallpox appearance is reached when the vesicles become pustules. Viral shedding may occur from the time of the rash until the lesions have crusted and separated. Death may occur in this phase due to overwhelming viremia and multiple organ failure (6).

Historical series of pregnant women affected by smallpox describe very high rates of prematurity and fetal loss (11). In addition, pregnant women appear more susceptible to the disease, with case-fatality rates as high as 61% among unvaccinated individuals and mortality rates of 27% even among vaccinated pregnant women. This compares with commonly reported mortality rates in nonpregnant adults of 3% when vaccinated and 30% among unvaccinated patients (2,11). Pregnant women develop the hemorrhagic form of the disease with increased frequency compared with nonpregnant women and men (8,11). This hemorrhagic form of smallpox is characterized by fever, backache, abdominal pain, and a diffuse red rash. Historically, spontaneous epistaxis, ecchymoses, and bleeding into
various organs led to rapid patient deterioration. The case-fatality rate among women with hemorrhagic smallpox was 100% in one series. Congenital smallpox among live born infants has been reported to occur in as many as 9% to 60% cases, with a very high mortality rate (8,11).

Infected patients should be isolated in negative-pressure rooms. Anyone who has had direct contact with and infected person should undergo strict quarantine with respiratory isolation for 17 days (4). Especially in the setting of large numbers of infected individuals, quarantine and separate physical facilities may be required to minimize further disease spread. Airborne and body fluid contact precautions must be utilized. All discarded laundry or waste should be placed in biohazard bags and autoclaved prior to disposal (6). A certain number of hospital personnel may need to be vaccinated in advance in order to provide care in the event of a deliberate infection. Hospitals with maternity services should anticipate the need to designate obstetrical and neonatal physicians and nurses for a team response.

Cidofovir has been tried with success against other pox viruses and has been reported to show in vitro activity against variola, but it cannot yet be recommended as treatment (2,4). The principles of managing an outbreak of smallpox will be isolation and supportive care of infected patients and postexposure vaccination for contacts. Vaccination against smallpox is by inoculation of the related Orthopoxvirus, vaccinia. Vaccination is moderately effective at aborting or attenuating the disease if given within 4 days of an exposure (2,4). Complications from widespread vaccination with vaccinia in the past included localized dermal reactions, vaccinia gangrenosa (with local extensive skin necrosis at the site of inoculation), eczema vaccinatum (a super infection of eczema with the vaccinia virus), progressive vaccinia, and postvaccinial encephalitis (11). While pregnant mothers may be vaccinated, there is a low risk of a potentially fatal fetal infection from the vaccinia virus. Therefore, routine vaccination of pregnant women in nonemergent settings is not recommended. In the event of an actual bioterrorism event, a pregnant woman at risk for exposure must weigh the risks of adverse effect from the vaccine against the devastating outcomes associated with smallpox infection in pregnancy (11).

Tularemia is a bacterial zoonosis first isolated by McCoy and Chapin in Tulare County, CA, in 1912 while searching for the causative agent of a disease affecting ground squirrels in the region. Documentation of this disease dates back to the 16th century in Norway and has been described throughout the northern hemisphere. Shortly after its isolation, Tularemia was recognized as a potential agent of severe and possibly fatal disease. A number of countries have done extensive research on its possible application as a biological weapon including Japan, Russia, and the United States. In the 1950s and 1960s, the US military developed weapons that could deliver aerosolized Francisella tularensis (12). Along with stock piling of weaponized F. tularensis, a live attenuated vaccine was developed that could partially protect against the virulent SCHU S4 strain and research was performed with various antibiotic regimens including streptomycin, tetracyclines, and chloramphenicol. With the termination of its biological weapons development program by executive order in 1970, all supplies were subsequently destroyed by 1973. Parallel efforts by the former Soviet Union continued into the 1990s with strains engineered that are resistant to vaccines and antibiotics (12). The impact of a weaponized release of Tularemia was estimated by the WHO in 1969 that aerosol dispersal of 50 kg of virulent F. tularensis over a metropolitan area with 5 million inhabitants would result in 250,000 incapacitation casualties including 19,000 fatalities (12).

The epidemiology of Tularemia is extremely complex. The organism has been isolated from over 200 animal species, including warm- and cold-blooded vertebrates, invertebrates, and numerous arthropods (13

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