To download and print this information click here.
------------------------------------------------------------------
Clinical Features of Cysticercosis
Susan Bucher
University of Southern Indiana
Nursing 455: Community Health Nursing
Spring 2012
Clinical Features of Cysticercosis
The Centers for Disease Control and Prevention (CDC) has identified a number of "Neglected Infections of Poverty". These are infections that have received little surveillance or prevention and primarily affects impoverished people in the United States (CDC, 2012). One of the major infections targeted for further action is the parasite Taenia solium (pork tapeworm) and its' larvae (cysticerci) which is the agent that causes cysticercosis and neurocysticercosis in humans. The following is a brief summary of the clinical features of cysticercosis.
Causative agent/Mode of transmission
The causative agent of cysticercosis is cysticerci which is the larva of Taenia solium (pork tapeworm). The mode of transmission is by the human fecal oral route (Sorvillo, 2011). Humans acquire cysticerci by ingesting tapeworm eggs, gravid proglottids (worm segments which contains eggs), or cysticerci (larva). Humans can become infected through the process of autoinfection (from their own tape worm or from another human with a taeniasis infection), by ingesting contaminated water or food infected with T. solium eggs, or by eating undercooked pork infected with cysticerci. Pigs become infected with cysticerci by ingestion of water or food infected with human fecal matter containing T. solium eggs.
Reservoir
Humans are the definitive host for taeniasis (pork tapeworm) which produces the agent (cysticerci) that causes cysticercosis. Pigs/swine act as an intermediate host for cysticerci.
Incubation/Period of communicability
A host may become infectious and eggs found in the feces as early as 2 months after ingestion of taeniasis eggs or cysticerci (Enander, 2010). In pigs, cysticerci can remain viable and infectious to humans for up to 5 years. Taeniasis can survive in humans and produce eggs for several decades. In the environment eggs may remain viable for a number of months.
Only in humans can the larval attach in the intestines using their scolex and develop into a taeniasis. Only humans with a taeniasis infection (tapeworm) can spread the infection to other humans or back to pigs to continue the life cycle. A human with a cysticercosis infection but without taeniasis is not a source of infection and cannot spread the disease. Patients infected with taeniasis do not require isolation.
Symptoms of Cysticercosis infection
Taeniasis infections often present with no or minimal symptoms such as abdominal complaints while human cysticercosis infections (a parasite infection of tissue) can have a large range of symptoms which may appear weeks to years after the initial infection. How symptoms presents depends on the cysticerci (cysts) location, number, stage of development, and the hosts immune response (O’Neal, Townes & Keene, 2008).
Cysts can form subcutaneously, in muscle tissue (including the heart), in organs such as the eye, liver, lung or breast, and in brain tissue (Neurocysticercosis). Cysts can develop as painless small nodules in muscle or skin causing little or no ill effects or can have profound effects such as ocular cysts causing visual disturbance/blindness.
Neurocysticercosis is the most severe form of the disease. Neurologic symptoms of neurocysticercosis may present as balance problems, cognitive impairment, visual disturbance, paresthesias, psychiatric disturbances, headaches, nausea, vomiting, increased intracranial pressure, as epileptic seizures, or by sudden death (hydrocephalus causing a brain hernia) (Moskowitz, 2010).
Cysticerci are able to turn off its hosts immune/inflammatory defenses by secreting compounds such as prostaglandins. Symptoms of neurocysticercosis most often manifests with cyst death, degeneration and calcification causing an inflammatory response.
Population
Cysticercosis is found worldwide with endemic areas found in Mexico, Latin America, India, Africa, Spain, Portugal, and Asia. It is estimated that more than 50 million people worldwide has a cysticercosis infection. Rates are higher in rural areas with poor sanitation and where pigs are raised and allowed free range.
All humans, regardless of sex, race or age, are susceptible to infection. Because of the time span from ingestion/infection to the manifestation of symptoms, cysticercosis in children under the age of 2 is unlikely. In the USA, cysticercosis infection is mostly found in Hispanic communities with immigrants from endemic areas, but cases of infection have occurred within US in communities (CDC, 2010).
Risk Factors
Risk factors include living in or traveling to endemic areas, having a taeniasis (tapeworm) infection or living in a household with a person who has a taeniasis infection, poor hand hygiene and unsafe food handling by persons infected with taeniasis, eating raw or undercooked pork that is contaminated with cysticerci, and lack of education about parasites and the spread of disease. Environmental factors include lack of proper latrines/sewer facilities, allowing pigs to be raised where they could ingest human feces, and tainted water supplies.
Occurrence
Because cysticercosis is not nationally reportable in the US and being compounded by cysts having the potential to be misdiagnosed (VasiljeviĆ-VuČKoviĆ, 2011), national statistics are not known. One report estimates the prevalence of cysticercosis in the US to be between 41,400 to 169,000 (Hotez, 2008). One study done in Oregon reported an infection rate among Hispanics of 5.8 cases per 100,000 (O'Neal, 2011). An earlier study done in California reported 124 deaths ranging in age from 7 to 81 between the years 1989 to 2000 (Sorvillo, 2007). In all reports and studies it is stated by the authors that the belief is the numbers are understated.
Evidence-based strategies to reduce infections
Many infectious disease experts have called for better diagnosis and investigation of patients with taeniasis and cysticercosis infections, as well as national reporting. Currently reporting is required only in California and Oregon. National mandated reporting would give better data and would help educate healthcare personal about cysticercosis.
Persons found to have a taeniasis infection should be treated to eradicate the tapeworm in order to prevent cysticercosis to themselves or others. Family members or others living in close contact of persons found to be infected should be tested for infection. Experts also suggest that food handlers found to be infected with taeniasis should refrain from food duties until confirmed eradication of taeniasis is confirmed. Medications used in the treatment of taeniasis include Niclosamide, Praziquantel, Albendazole, and Nitazoxanide
At the public level, actions to reduce and halt infections include educating the public (targeting Hispanic communities first) about cysticercosis as well as the safe handling storage and cooking of pork and proper hand hygiene. Education should also include the need for medical treatment if they suspect they or someone they know could be infected.
In areas where the infection is endemic education should include avoiding fecal contamination of soil or water where pigs are raised, inspection of meat upon slaughter, and greater government assistance in implementing sustainable practices.
References
CDC. (2010). Parasites - cysticercosis. Atlanta, GA: Retrieved from http://www.cdc.gov/parasites/cysticercosis/health_professionals/index.html
CDC. (2012). Neglected parasitic infections in the united states. Atlanta, GA: DOI: (2012). Retrieved from Centers for Disease Control and Prevention website: http://www.cdc.gov/parasites/npi.html
Enander, R., Ramirez Amaya, A., Enander, R., & Gute, D. (2010). Neurocysticercosis: risk and
primary prevention strategies update. International Journal Of Environmental Health
Research, 20(5), 329-365. doi:10.1080/09603123.2010.482152
Hotez, P.J. (2008). Neglected Infections of Poverty in the United States of America. PLoS Negl Trop Dis 2(6): e256. doi:10.1371/journal.pntd.0000256
Moskowitz, J., & Mendelsohn, G. (2010). Neurocysticercosis. Archives Of Pathology & Laboratory Medicine, 134(10), 1560-1563.
O’Neal, S., Townes, J., & Keene, B. Oregon Public Health Division, (2008). T aeniasis and cysticercosi, investigative guidelines. Retrieved from website: http://public.health.oregon.gov/DiseasesConditions/CommunicableDisease/ReportingCo mmunicableDisease/ReportingGuidelines/Documents/taeniasis_cyst_guideline.pdf
O'Neal, S., Noh, J., Wilkins, P., Keene, W., Lambert, W., Anderson, J., Compton Luman, J, &
Townes, J. (2011). Taenia solium Tapeworm Infection, Oregon, 2006-2009. Emerging
Infectious Diseases, 17(6), 1030-1036.
Sorvillo, F., DeGiorgio, C., & Waterman, S. (2007). Deaths from cysticercosis, United States. Emerging Infectious Diseases, 13(2), 230-235.
Sorvillo, F., Wilkins, P., Shafir, S., & Eberhard, M. (2011). Public health implications of cysticercosis acquired in the United States. Emerging Infectious Diseases, 17(1), 1-6.
VasiljeviĆ-VuČKoviĆ, V. V., Medenica, S., & GrujiČIĆ, D. D. (2011). Neurocysticercosis Mimicking Brain Tumor. Neuroradiology Journal, 24(3), 419-423.
Please note: Diagnosis of cysticercosis or taeniasis is not made at this website or by using the survey/questionnaire. The purpose of this website and the questionnaire is to help educate the public and to be used as a tool to aid in communication between people who might be infected, people who might know others who could be infected, and medical providers. Only a medical doctor can diagnose cysticercosis and taeniasis. Cysticercosis and taeniasis are medical conditions which can be treated only by a licensed physician.
For more information please contact your doctor or local health department.