Pediatric Trichinosis Workup
- Author: Germaine L Defendi, MD, MS, FAAP; Chief Editor: Russell W Steele, MD more...
The following studies are indicated in trichinosis:
CBC (complete blood count) with indices
Peripheral eosinophilia is almost universal and is an early laboratory finding. Eosinophilia begins approximately 10 days after ingestion and may reach a peak of 5000/µL by 3-4 weeks after ingestion (range of about 50-70% of the white cell indices).
Eosinophil counts remain elevated during the acute parenteral stage of infection, regress slowly, and may remain elevated (although at lower levels) for 3 months post-infection.
Of grave concern is the absence of eosinophilia, eosinopenia or gradual disappearance of eosinophils during the parenteral phase of the illness. This serologic finding indicates an overwhelming infection, a sign of immunosuppression and carries a very poor prognosis. 
Leukocytosis (elevated white cell count) is typical and appears in the early phase of infection. The elevated white cell count subsides before eosinophil counts return to the normal reference range.
Creatine kinase (CK), and lactate dehydrogenase (LDH) levels are elevated in 75-90% of cases. CK levels may increase as much as 10-fold, whereas the rise in LDH levels is less. Neither serum levels correlate with clinical disease severity.
Hypoalbuminemia is a marker of severe clinical disease.
Serologic studies 
In the US, immunodiagnostic tests currently available are enzyme immunoassays (EIAs). EIAs detect Trichinella -specific antibodies and use antigen preparations that may be either crude extracts prepared from homogenates of T. spiralis muscle larvae or excretory-secretory (ES) products produced by cultured larvae. The key antigenic product is secreted from stichocytes located on the anterior side of the larva. The T. spiralis larva-1 group, also named as TSL-1 group of larval secretory antigens, are conserved in all species/isolates of Trichinella and thus can be used to detect infection in animals or people infected with any of Trichinella species currently recognized.[19, 20]
Trichinella -specific antibody levels are usually not detected until 3 to 5 weeks post-infection, well after the onset of acute-stage illness. Antibody development is also affected by the infecting dose of larvae. The higher infecting dose induces a faster patient's antibody response. Repeat serum specimens should be drawn several weeks apart to demonstrate sero-conversion in patients whose initial EIA specimen was negative.
EIAs with ES antigens detect antibodies earlier than bentonite flocculation (BF) test in 25% of serum specimens from patients with acute infection. The BF test typically becomes positive 3 weeks post-infection. EIAs also remain positive for longer period of time after infection than the BF, and are reactive in a larger proportion of persons with no clinical evidence of trichinosis.[19, 3]
EIA is used for routine screening. Present recommendations are to test all EIA-positive specimens using the BF test, for confirmation. Positive results by both tests indicate Trichinella infection within the last several years.
IgG, IgM, and IgE antibodies are detectable in many patients; however, tests based on IgG antibodies are most sensitive. Typically these antibody levels peak in 2 or 3 months post-infection and then decline slowly over several years.
Tests based on immunoglobulin G (IgG)–ELISA specific antibodies are most sensitive (100% positive on the 50th day of infection). However, IgG antibodies can persist for years after infection, even if the disease process itself was benign or asymptomatic. Morakote et al. reported that 31 months after T. spiralis infection, the diagnostic sensitivity of IgG-ELISA was 88%. 
Morakote et al. further reported that IgM-ELISA’s peak sensitivity was 93% at 57th day post-infection. IgE-ELISA was 100% positive on the 85th day of infection. At 31 months post-infection, IgE-ELISA was positive 47%, while IgM-ELISA was sensitive only to 12%. Data from the IgM-ELISA appears to be a helpful indicator of infection within a 3-year (36 month) time frame.
Of the three antibodies, immunoglobulin E (IgE)–class antibodies appear first and are typical positive at the parenteral phase of trichinosis; however IgE antibodies are seldom detected during this time because their serum half-life is relatively short. An IgG antibody is detectable early in patients with high-titers, cited at 23 days post infection. 
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Plain radiography may show calcified densities in soft tissues, indicating old infection, but is not useful in diagnosing acute infection.
In patients with CNS involvement, brain CT scanning using ring enhancement following intravenous contrast reveals multiple small hypodense lesions in the hemispheric white matter.
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Stool examination: Charcot-Leyden crystals from eosinophils may be found in stools. Ova are not found in stools; larvae are rarely found in stools.
Antigen detection: Circulating antigens can be detected by EIA or immunoradiometric assay and by monoclonal antibodies specific for antigens obtained from T spiralis muscle larvae, although these tests are not typically used for diagnosis.
Polymerase chain reaction (PCR): In cases in which the diagnosis is questioned (eg, atypical presentations or patients who are immunosuppressed) or in early stages of infection when other test results are negative (eg, serologic studies), PCR testing used to detect Trichinella- specific DNA in muscle biopsy and blood specimens can be helpful.
See the list below:
Definitive diagnosis can be made via biopsy of a tender skeletal muscle. The muscle tissue (0.2 to 0.5 grams) is best examined unfixed under low microscope power to detect whole larvae. In cases in which the diagnosis is unclear, this biopsy sample may confirm the suspected diagnosis using parasitologic or histologic studies.
Electromyography (EMG) reveals changes of the myopathic type during the acute stage, but these changes are not pathognomonic for trichinosis. In most patients, bioelectric disturbances correspond in severity to the clinical course.
See the list below:
Basophilic transformation of muscle fibers occurs within 4-5 days after larvae penetration (about 2 weeks post-ingestion) and is a valuable diagnostic criterion, even in cases, in which no larvae can be demonstrated. Only a portion of the affected muscle fiber undergoes basophilic transformation; the area that becomes the so-called larval nurse-cell.
- Myofibrils disappear, the sarcoplasm becomes basophilic, and the cell nucleus is displaced to the center of the cell.
- The larva can be observed within the affected nurse cell-larva complex.
- Infiltration by eosinophils and mononuclear cells also occurs.
Attempting diagnosis before larvae begin to coil (ie, < 2 wk after larvae enter the muscle cell) creates a risk of confusing the worm appearance with fragments of muscle tissue.
Absence of a capsule and presence of a straight larva in the nurse-cell complex indicate an ongoing infection.
Markell EK, Voge M, John DT. Medical Parasitology, 6th ed. Philadelphia, PA: WB Saunders Company; 1986. 270-74.
Knopp S, Steinmann P, Keiser J, Utzinger J. Nematode infections: soil-transmitted helminths and trichinella. Infect Dis Clin North Am. 2012 Jun. 26(2):341-58. [Medline].
Oski FA, et al. Tissue nematodes Trichinella spiralis. In Principles and Practices of Pediatrics 2nd edition. Philadelphia, PA: JB Lippincott; 1994. 1413-14.
Kennedy ED, Hall RL, Montgomery SP, Pyburn DG, Jones JL. Trichinellosis surveillance - United States, 2002-2007. MMWR Surveill Summ. 2009 Dec 4. 58(9):1-7. [Medline].
American Academy of Pediatrics. Trichinellosis (Trichinella spiralis). Red Book: 2009 Report of the Committee on Infectious Diseases. 28th. Elk Grove Village, IL: American Academy of Pediatrics; 2009. 673-4.
Hall RL, Lindsay A, Hammond C, Montgomery SP, Wilkins PP, da Silva AJ, et al. Outbreak of human trichinellosis in Northern California caused by Trichinella murrelli. Am J Trop Med Hyg. 2012 Aug. 87(2):297-302. [Medline]. [Full Text].
Murrell KD, Pozio E. Worldwide occurrence and impact of human trichinellosis, 1986-2009. Emerg Infect Dis. 2011 Dec. 17(12):2194-202. [Medline].
Cui J, Wang ZQ, Xu BL. The epidemiology of human trichinellosis in China during 2004-2009. Acta Trop. 2011 Apr. 118(1):1-5. [Medline].
Pannwitz G, Mayer-Scholl A, Balicka-Ramisz A, Nockler K. Increased Prevalence of Trichinella spp., Northeastern Germany, 2008. Emerg Infect Dis. 2010 Jun. 16(6):936-42. [Medline].
Neghina R, Neghina AM, Marincu I, Iacobiciu I. Trichinellosis in children and adults: a 10-year comparative study in Western Romania. Pediatr Infect Dis J. 2011 May. 30(5):392-5. [Medline].
Moller LN, Koch A, Petersen E, et al. Trichinella infection in a hunting community in East Greenland. Epidemiol Infect. 2010 Sep. 138(9):1252-6. [Medline].
Cabie A, Bouchaud O, Houze S, et al. Albendazole versus thiabendazole as therapy for trichinosis: a retrospective study. Clin Infect Dis. 1996 Jun. 22(6):1033-5. [Medline].
Lo YC, Hung CC, Lai CS, Wu Z, Nagano I, Maeda T. Human trichinosis after consumption of soft-shelled turtles, taiwan. Emerg Infect Dis. 2009 Dec. 15(12):2056-8. [Medline].
Kusolsuk T, Kamonrattanakun S, Wesanonthawech A, et al. The second outbreak of trichinellosis caused by Trichinella papuae in Thailand. Trans R Soc Trop Med Hyg. 2010 Jun. 104(6):433-7. [Medline].
Intapan PM, Chotmongkol V, Tantrawatpan C, Sanpool O, Morakote N, Maleewong W. Molecular identification of Trichinella papuae from a Thai patient with imported trichinellosis. Am J Trop Med Hyg. 2011 Jun. 84(6):994-7. [Medline]. [Full Text].
Rosenblatt JE. Laboratory diagnosis of infections due to blood and tissue parasites. Clin Infect Dis. 2009 Oct 1. 49(7):1103-8. [Medline].
Centers for Disease Control and Prevention. Laboratory Identification of Parasitic Diseases of Public Health Concern. CDC. Available at http://www.cdc.gov/dpdx/trichinellosis/dx.html. Accessed: November 29, 2013.
Escalante M, Romaris F, Rodriguez M, et al. Evaluation of Trichinella spiralis larva group 1 antigens for serodiagnosis of human trichinellosis. J Clin Microbiol. 2004 Sep. 42(9):4060-6. [Medline]. [Full Text].
Morakote N, Sukhavat K, Khamboonruang C, Siriprasert V, Suphawitayanukul S, Thamasonthi W. Persistence of IgG, IgM, and IgE antibodies in human trichinosis. Trop Med Parasitol. 1992 Sep. 43(3):167-9. [Medline].
Watt G, Saisorn S, Jongsakul K, et al. Blinded, placebo-controlled trial of antiparasitic drugs for trichinosis myositis. J Infect Dis. 2000 Jul. 182(1):371-4. [Medline].
Centers for Disease Control and Prevention. Parasites – Trichinellosis (also known as Trichinosis), Prevention and Control. CDC. Available at http://www.cdc.gov/parasites/trichinellosis/prevent.html. Accessed: December 13, 2013.
Neghina R, Iacobiciu I, Neghina AM, Marincu I. Trichinellosis, another helminthiasis affecting the central nervous system. Parasitol Int. 2011 Jun. 60(2):230. [Medline].
Aronson SM. A tale of an inconsequential worm. Med Health R I. 1999 Oct. 82(10):347. [Medline].
Astudillo LM, Arlet PM. Images in clinical medicine. The chemosis of trichinosis. N Engl J Med. 2004 Jul 29. 351(5):487. [Medline].
Barennes H, Sayasone S, Odermatt P, De Bruyne A, Hongsakhone S, Newton PN, et al. A major trichinellosis outbreak suggesting a high endemicity of Trichinella infection in northern Laos. Am J Trop Med Hyg. 2008 Jan. 78(1):40-4. [Medline].
Bruschi F. Trichinellosis in developing countries: is it neglected?. J Infect Dev Ctries. 2012 Mar 12. 6(3):216-22. [Medline].
Bruschi F, Korenaga M, Watanabe N. Eosinophils and Trichinella infection: toxic for the parasite and the host?. Trends Parasitol. 2008 Oct. 24(10):462-7. [Medline].
CDC. Trichinellosis associated with bear meat--New York and Tennessee, 2003. MMWR Morb Mortal Wkly Rep. 2004 Jul 16. 53(27):606-10. [Medline].
De Bruyne A, Ancelle T, Vallee I, Boireau P, Dupouy-Camet J. Human trichinellosis acquired from wild boar meat: a continuing parasitic risk in France. Euro Surveill. 2006. 11(9):E060914.5. [Medline].
Dubey ML, Khurana S, Singhal L, Dogra S, Singh S. Atypical trichinellosis without eosinophilia associated with osteomyelitis. Trop Doct. 2011 Oct. 41(4):244-6. [Medline].
Dupouy-Camet J, Lecam S, Talabani H, Ancelle T. Trichinellosis acquired in Senegal from warthog ham, March 2009. Euro Surveill. 2009 May 28. 14(21):[Medline].
Feigin RD, Cherry JD. Parasitic myocarditis. Textbook of Pediatric Infectious Diseases. Philadelphia, Pa: WB Saunders Co; 2004. 407-9.
Gamble HR, Pozio E, Bruschi F, et al. International Commission on Trichinellosis: recommendations on the use of serological tests for the detection of Trichinella infection in animals and man. Parasite. 2004 Mar. 11(1):3-13. [Medline].
Golab E, Szulc M, Wnukowska N, Rozej W, Fell G, Sadkowska-Todys M. Outbreak of trichinellosis in North-Western Poland--update and exported cases, June-July 2007. Euro Surveill. 2007 Jul. 12(7):E070719.2. [Medline].
Gomez-Morales MA, Ludovisi A, Amati M, Cherchi S, Pezzotti P, Pozio E. Validation of an enzyme-linked immunosorbent assay for diagnosis of human trichinellosis. Clin Vaccine Immunol. 2008 Nov. 15(11):1723-9. [Medline].
Gotistein B, Piarroux R. Current trends in tissue-affecting helminths. Parasite. 2008 Sep. 15(3):291-8. [Medline].
Hall RL, Lindsay A, Hammond C, Montgomery SP, Wilkins PP, da Silva AJ. Outbreak of human trichinellosis in Northern California caused by Trichinella murrelli. Am J Trop Med Hyg. 2012 Aug. 87(2):297-302. [Medline].
Hidron A, Vogenthaler N, Santos-Preciado JI, Rodriguez-Morales AJ, Franco-Paredes C, Rassi A Jr. Cardiac involvement with parasitic infections. Clin Microbiol Rev. 2010 Apr. 23(2):324-49. [Medline].
Ilic N, Gruden-Movsesijan A, Sofronic-Milosavljevic L. Trichinella spiralis: shaping the immune response. Immunol Res. 2012 Apr. 52(1-2):111-9. [Medline].
Jansen A, Schoneberg I, Stark K, Nockler K. Epidemiology of trichinellosis in Germany, 1996-2006. Vector Borne Zoonotic Dis. 2008 Apr. 8(2):189-96. [Medline].
Kaewpitoon N, Kaewpitoon SJ, Philasri C, et al. Trichinosis: epidemiology in Thailand. World J Gastroenterol. 2006 Oct 28. 12(40):6440-5. [Medline].
Kociecka W. Trichinellosis: human disease, diagnosis and treatment. Vet Parasitol. 2000 Dec 1. 93(3-4):365-83. [Medline].
Lazarevic AM, Neskovic AN, Goronja M, et al. Low incidence of cardiac abnormalities in treated trichinosis: a prospective study of 62 patients from a single-source outbreak. Am J Med. 1999 Jul. 107(1):18-23. [Medline].
Lindh J, Ljungstrom I. Trichinella spp. Akuffo H, Linder E, Ljungstrom I, Wahlgren M. Parasites of the Colder Climates. London and New York: Taylor & Francis; 2003. 195-204.
Long SS, Pickering LK, Prober CG. Trichinella spiralis. Pediatric Infectious Diseases. 2003. 1344-46.
Madariaga MG, Cachay ER, Zarlenga DS. A probable case of human neurotrichinellosis in the United States. Am J Trop Med Hyg. 2007 Aug. 77(2):347-9. [Medline].
Mandell GL, Bennett JE, Dolin RD. Tissue nematodes, including trichinosis, dracunculiasis, and the filariases. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. Philadelphia, Pa: Churchill Livingstone; 2005. 3267-76.
Marva E, Markovics A, Gdalevich M, et al. Trichinellosis outbreak. Emerg Infect Dis. 2005 Dec. 11(12):1979-81. [Medline].
McIntyre L, Pollock SL, Fyfe M, Gajadhar A, Isaac-Renton J, Fung J. Trichinellosis from consumption of wild game meat. CMAJ. 2007 Feb 13. 176(4):449-51. [Medline].
Mitreva M, Jasmer DP. Biology and genome of Trichinella spiralis. WormBook. 2006 Nov 23. 1-21. [Medline].
Murrell KD, Bruschi F. Clinical trichinellosis. Prog Clin Parasitol. 1994. 4:117-50. [Medline].
Neghina R, Moldovan R, Marincu I, Calma CL, Neghina AM. The roots of evil: the amazing history of trichinellosis and Trichinella parasites. Parasitol Res. 2011 Oct 8. [Medline].
Neghina R, Neghina AM. Reviews on trichinellosis (IV): hepatic involvement. Foodborne Pathog Dis. 2011 Sep. 8(9):943-8. [Medline].
Outbreak of trichinellosis in French hunters who ate Canadian black bear meat. Can Commun Dis Rep. 2006 May 1. 32(9):109-12. [Medline].
Ozdemir D, Ozkan H, Akkoc N, et al. Acute trichinellosis in children compared with adults. Pediatr Infect Dis J. 2005 Oct. 24(10):897-900. [Medline].
Papatsiros VG, Boutsini S, Ntousi D, Stougiou D, Mintza D, Bisias A. Detection and zoonotic potential of Trichinella spp. from free-range pig farming in Greece. Foodborne Pathog Dis. 2012 Jun. 9(6):536-40. [Medline].
PDR. Physician's Desk Reference. Montvale, NJ: Thomson Healthcare; 2000.
Pozio E, Darwin Murrell K. Systematics and epidemiology of trichinella. Adv Parasitol. 2006. 63:367-439. [Medline].
Pozio E, Gomez Morales MA, Dupouy-Camet J. Clinical aspects, diagnosis and treatment of trichinellosis. Expert Rev Anti Infect Ther. 2003 Oct. 1(3):471-82. [Medline].
Pozio E, Hoberg E, La Rosa G, Zarlenga DS. Molecular taxonomy, phylogeny and biogeography of nematodes belonging to the Trichinella genus. Infect Genet Evol. 2009 Jul. 9(4):606-16. [Medline].
Taratuto AL, Venturiello SM. Trichinosis. Brain Pathol. 1997 Jan. 7(1):663-72. [Medline].
Taylor WR, Tran GV, Nguyen TQ, Dang DV, Nguyen VK, Nguyen CT, et al. Acute Febrile Myalgia in Vietnam due to Trichinellosis following the Consumption of Raw Pork. Clin Infect Dis. 2009 Aug 27. [Medline].
Tint D, Cocuz ME, Ortan OF, Niculescu MD, Radoi M. Cardiac involvement in trichinellosis: a case of left ventricular thrombosis. Am J Trop Med Hyg. 2009 Aug. 81(2):313-6. [Medline].
Turk M, Kaptan F, Turker N, et al. Clinical and laboratory aspects of a trichinellosis outbreak in Izmir, Turkey. Parasite. 2006 Mar. 13(1):65-70. [Medline].
Watt G, Silachamroon U. Areas of uncertainty in the management of human trichinellosis: a clinical perspective. Expert Rev Anti Infect Ther. 2004 Aug. 2(4):649-52. [Medline].