History

Fact Explanation
Cough and wheeze Following the ingestion of toxocara eggs, the larvae hatch in the small intestine, invade the mucosa, and enter the portal system. From there larvae proceed to the lungs where they induce a pulmonary inflammatory response in the form of an eosinophilic pneumonitis [1].
Fever Due to the migratory tracts of hatched larvae associated with necrosis and inflammation [2].
Abdominal pain Larvae can proceed from the intestine to the liver. The deposited larvae causes an inflammatory response in the liver which manifests as eosinophilic granulomas resulting in liver enlargement and necrosis [3].
History of asthma, atopic dermatitis and other allergic conditions Several immunological mechanisms have been proposed regarding helminth mediated modulation of allergy, including: enhancing or suppressing allergic inflammation directed against the parasite; immunological cross-reactivity between helminth allergens and aeroallergens; affecting allergic inflammation directed against aeroallergens through bystander effects in the same tissues such as the lungs [4].
Presence of household pets Infected dogs and cats deposit toxocara eggs in the soil via feces. Poor personal hygiene as well as consumption of raw vegetables grown in contaminated kitchen gardens may lead to ingestion of such eggs [2].
Consumption of raw meat Infective eggs that are ingested by chickens, rabbits, etc, leads to the depostion of larvae in their tissues which are potentially infective to predators on these animals [2].
Seizure. The immune reaction which is triggered in the brain due to deposited larvae may lead to generalized seizures, while granulomas may lead to focal seizures [5].
Blindness. In the eye, migrating larvae can damage the retina, inducing granulomatous reactions, resulting in blindness [3].
Malaise, psychomotor agitation, disturbance of concentration and other features of encephalitis. Encephalitis occurs due to eosinophilic granulomata and immune vasculitis in the brain as a result of deposited larvae inducing a inflammatory reaction [6].
Chest discomfort. Direct larval invasion to the myocardium and hypersensitivity reactions to the parasites result in an eosinophilic myocarditis [7].
References
  1. SHARGHI N., SCHANTZ P. M., CARAMICO L., BALLAS K., TEAGUE B. A., HOTEZ P. J.. Environmental Exposure to Toxocara as a Possible Risk Factor for Asthma: A Clinic-Based Case-Control Study. Clinical Infectious Diseases [online] 2001 April, 32(7):e111-e116 [viewed 26 June 2014] Available from: doi:10.1086/319593
  2. MAGNAVAL JEAN-FRANçOIS, GLICKMAN LAWRENCE T., DORCHIES PHILIPPE, MORASSIN BRUNO. Highlights of human toxocariasis. Korean J Parasitol [online] 2001 December [viewed 26 June 2014] Available from: doi:10.3347/kjp.2001.39.1.1
  3. DESPOMMIER D.. Toxocariasis: Clinical Aspects, Epidemiology, Medical Ecology, and Molecular Aspects. Clinical Microbiology Reviews [online] 2003 April, 16(2):265-272 [viewed 26 June 2014] Available from: doi:10.1128/CMR.16.2.265-272.2003
  4. COOPER PHILIP J. Interactions between helminth parasites and allergy. Current Opinion in Allergy and Clinical Immunology [online] 2009 February, 9(1):29-37 [viewed 26 June 2014] Available from: doi:10.1097/ACI.0b013e32831f44a6
  5. AKYOL ALI, BICEROL BANU, ERTUG SEMA, ERTABAKLAR HATICE, KIYLIOGLU NEFATI. Epilepsy and seropositivity rates of Toxocara canis and Toxoplasma gondii. Seizure [online] 2007 April, 16(3):233-237 [viewed 27 June 2014] Available from: doi:10.1016/j.seizure.2006.12.008
  6. SOMMER C, RINGELSTEIN E B, BINIEK R, GLOCKNER W M. Adult Toxocara canis encephalitis.. Journal of Neurology, Neurosurgery & Psychiatry [online] 1994 February, 57(2):229-231 [viewed 27 June 2014] Available from: doi:10.1136/jnnp.57.2.229
  7. KIM JI HEE, CHUNG WOO-BAEK, CHANG KYUNG-YOON, KO SUN-YOUNG, PARK MI-HEE, SA YOUNG-KYOUNG, CHOI YUN-SEOK, PARK CHUL-SOO, LEE MAN-YOUNG. Eosinophilic Myocarditis Associated with Visceral Larva Migrans Caused by Infection . J Cardiovasc Ultrasound [online] 2012 December [viewed 27 June 2014] Available from: doi:10.4250/jcu.2012.20.3.15

Examination

Fact Explanation
Hepatomegaly Larvae can proceed from the intestine to the liver. The deposited larvae causes an inflammatory response in the liver which manifests as eosinophilic granulomas resulting in liver enlargement and necrosis [1].
Rales heard on auscultation of the lung. Following the ingestion of toxocara eggs, the larvae hatch in the small intestine, invade the mucosa, and enter the portal system. From there larvae proceed to the lungs where they induce a pulmonary inflammatory response in the form of an eosinophilic pneumonitis [2].
Chronic urticaria Several immunological mechanisms have been proposed regarding helminth mediated modulation of allergy, including: enhancing or suppressing allergic inflammation directed against the parasite; immunological cross-reactivity between helminth allergens and aeroallergens; affecting allergic inflammation directed against aeroallergens through bystander effects in the same tissues [3].
References
  1. DESPOMMIER D.. Toxocariasis: Clinical Aspects, Epidemiology, Medical Ecology, and Molecular Aspects. Clinical Microbiology Reviews [online] 2003 April, 16(2):265-272 [viewed 26 June 2014] Available from: doi:10.1128/CMR.16.2.265-272.2003
  2. SHARGHI N., SCHANTZ P. M., CARAMICO L., BALLAS K., TEAGUE B. A., HOTEZ P. J.. Environmental Exposure to Toxocara as a Possible Risk Factor for Asthma: A Clinic-Based Case-Control Study. Clinical Infectious Diseases [online] 2001 April, 32(7):e111-e116 [viewed 26 June 2014] Available from: doi:10.1086/319593
  3. COOPER PHILIP J. Interactions between helminth parasites and allergy. Current Opinion in Allergy and Clinical Immunology [online] 2009 February, 9(1):29-37 [viewed 26 June 2014] Available from: doi:10.1097/ACI.0b013e32831f44a6

Differential Diagnoses

Fact Explanation
Pneumonia It presents with cough and fever, associated increased sputum production [1].
Hookworm infection It also presents with features of anemia due to intestinal blood loss [2].
Bronchial asthma It presents with chronic cough and wheeze, but improvement of symptoms with bronchodilators, diurnal variation in symptoms and increase in bronchial responsiveness to nonspecific or allergic or other specific stimuli can be seen [3].
Filariasis It presents with paroxysmal cough and wheezing as a part of tropical pulmonary eosinophilia but also shows features resulting from adult worms residing in the lymphatics such as Lymphadenopathy and limb and genital swelling [4].
Ascariasis. It is also transmitted via fecal contaminated soil associated with poor hygienic practices and gives rise to an eosinophilic inflammatory response during larval lung migration resulting in cough and wheeze. Additionally large numbers of adult worms in the intestine can give rise to intestinal obstruction [5].
Echinococcosis. It is also transmitted via fecal contaminated soil associated with poor hygienic practices and gives rise to cystic lesions. Pulmonary cysts produce symptoms of cough and dyspnea while liver cysts can result in cholestasis which would give rise to jaundice [6].
References
  1. MüLLER BEAT, HARBARTH STEPHAN, STOLZ DAIANA, BINGISSER ROLAND, MUELLER CHRISTIAN, LEUPPI JöRG, NUSBAUMER CHARLY, TAMM MICHAEL, CHRIST-CRAIN MIRJAM. Diagnostic and prognostic accuracy of clinical and laboratory parameters in community-acquired pneumonia. BMC Infect Dis [online] 2007 December [viewed 26 June 2014] Available from: doi:10.1186/1471-2334-7-10
  2. HOTEZ PETER J., BROOKER SIMON, BETHONY JEFFREY M., BOTTAZZI MARIA ELENA, LOUKAS ALEX, XIAO SHUHUA. Hookworm Infection. N Engl J Med [online] 2004 August, 351(8):799-807 [viewed 26 June 2014] Available from: doi:10.1056/NEJMra032492
  3. RYAN G, LATIMER K., DOLOVICH J, HARGREAVE F.. Bronchial responsiveness to histamine: relationship to diurnal variation of peak flow rate, improvement after bronchodilator, and airway calibre. Thorax [online] 1982 June, 37(6):423-429 [viewed 26 June 2014] Available from: doi:10.1136/thx.37.6.423
  4. MOORE T. A., REYNOLDS J. C., KENNEY R. T., JOHNSTON W., NUTMAN T. B.. Diethylcarbamazine-Induced Reversal of Early Lymphatic Dysfunction in a Patient with Bancroftian Filariasis: Assessment with Use of Lymphoscintigraphy. Clinical Infectious Diseases [online] 1996 November, 23(5):1007-1011 [viewed 26 June 2014] Available from: doi:10.1093/clinids/23.5.1007
  5. BETHONY JEFFREY, BROOKER SIMON, ALBONICO MARCO, GEIGER STEFAN M, LOUKAS ALEX, DIEMERT DAVID, HOTEZ PETER J. Soil-transmitted helminth infections: ascariasis, trichuriasis, and hookworm. The Lancet [online] 2006 May, 367(9521):1521-1532 [viewed 27 June 2014] Available from: doi:10.1016/S0140-6736(06)68653-4
  6. ECKERT J., DEPLAZES P.. Biological, Epidemiological, and Clinical Aspects of Echinococcosis, a Zoonosis of Increasing Concern. Clinical Microbiology Reviews [online] December, 17(1):107-135 [viewed 27 June 2014] Available from: doi:10.1128/CMR.17.1.107-135.2004

Investigations - for Diagnosis

Fact Explanation
Eosinophilia in full blood count. Larvae induce an eosinophil predominant inflammatory reaction [1].
Stool examination to rule out other parasitic infections. Larvae cannot complete their lifecycle in the human and therefore do not excrete infective stages [2].
Antigen detection via ELISA. Specific antigens are secreted by second stage larvae [2].
Elevated isohemagglutinin titres. It occurs because of the similarity between antigens of the parasites and those of human erythrocytes. [3].
Hypergammaglobulinemia. Due to polyclonal activation as a result of chronic release of different antigens of the parasite [3].
Abdominal ultrasound scan- hypoechoic areas in the liver. Abdominal CT scan- low-density areas in the liver. MRI scan of brain- hyper-intense areas on T2-weighted images These point towards granulomatous lesions which occur within organs in areas of larval deposition as a result of the inflammatory response [1].
Pulmonary infiltrates on chest radiograph. Deposited larvae in the lung induce a pulmonary inflammatory response in the form of an eosinophilic pneumonitis [4].
References
  1. MAGNAVAL JEAN-FRANçOIS, GLICKMAN LAWRENCE T., DORCHIES PHILIPPE, MORASSIN BRUNO. Highlights of human toxocariasis. Korean J Parasitol [online] 2001 December [viewed 26 June 2014] Available from: doi:10.3347/kjp.2001.39.1.1
  2. DESPOMMIER D.. Toxocariasis: Clinical Aspects, Epidemiology, Medical Ecology, and Molecular Aspects. Clinical Microbiology Reviews [online] 2003 April, 16(2):265-272 [viewed 26 June 2014] Available from: doi:10.1128/CMR.16.2.265-272.2003
  3. JACOB CRISTINA M. A., PASTORINO ANTONIO C., PERES BENEDITO A., MELLO ELIZABETE O., OKAY YASSUHIKO, OSELKA GABRIEL W.. Clinical and laboratorial features of visceral toxocariasis in infancy. Rev. Inst. Med. trop. S. Paulo [online] 1994 February [viewed 26 June 2014] Available from: doi:10.1590/S0036-46651994000100004
  4. SHARGHI N., SCHANTZ P. M., CARAMICO L., BALLAS K., TEAGUE B. A., HOTEZ P. J.. Environmental Exposure to Toxocara as a Possible Risk Factor for Asthma: A Clinic-Based Case-Control Study. Clinical Infectious Diseases [online] 2001 April, 32(7):e111-e116 [viewed 26 June 2014] Available from: doi:10.1086/319593

Management - General Measures

Fact Explanation
Treatment of infected dogs or cats in the household with appropriate antihelminthic treatment. Infected dogs and cats deposit toxocara eggs in the soil via feces. Poor personal hygiene as well as consumption of raw vegetables grown in contaminated kitchen gardens may lead to ingestion of such eggs [1].
References
  1. MAGNAVAL JEAN-FRANçOIS, GLICKMAN LAWRENCE T., DORCHIES PHILIPPE, MORASSIN BRUNO. Highlights of human toxocariasis. Korean J Parasitol [online] 2001 December [viewed 26 June 2014] Available from: doi:10.3347/kjp.2001.39.1.1

Management - Specific Treatments

Fact Explanation
Albendazole. Dose: 10 mg/kg for 5 days. It acts by binding to parasite beta tubulin, inhibiting its polymerization and impairing glucose uptake [1].
Thiabendazole. Dose: 25 mg/kg for 3 to 7 days. It acts by binding to parasite beta tubulin, inhibiting its polymerization and impairing glucose uptake [1].
Diethylcarbamazine. 3-4 mg/kg for 21 days. It acts on the parasite neuromuscular pathways and paralyses them [2].
Corticosteroids. It suppresses the intense allergic manifestations of the infection [3]. It should be noted that corticosteroids are needed only in severe infection.
References
  1. VENKATESAN P. Albendazole. [online] 1998 February, 41(2):145-147 [viewed 26 June 2014] Available from: doi:10.1093/jac/41.2.145
  2. HORTON J.. Albendazole: a review of anthelmintic efficacy and safety in humans. Parasitology [online] December [viewed 26 June 2014] Available from: doi:10.1017/S0031182000007290
  3. DESPOMMIER D.. Toxocariasis: Clinical Aspects, Epidemiology, Medical Ecology, and Molecular Aspects. Clinical Microbiology Reviews [online] 2003 April, 16(2):265-272 [viewed 26 June 2014] Available from: doi:10.1128/CMR.16.2.265-272.2003