Clinical Presentation

Epidemiology

References and Primary Source

Introduction:
Lagochilascariasis is an uncommon parasitic nematode (helmintiasis) found in Latin American countries. It is an intestinal parasite of felines like the cloudy leopard, Felis nebulosa. As a zoonosis, lagochilascariasis is transmitted to humans where it is found subcutaneously in unusual locations like tissues of the neck, eye, lungs, mastoid (hard, bony structure behind the ear), and oropharynx (throat at the back of the mouth),. In addition to humans, it has been found to parasitize humans, domestic cats, dogs, and silvatic, or forest dwelling, carnivores (Lanfredi et al. 1998).

Agent: (Nematoda) lagochilascariasis minor (L.minor)

Synonym: lagochilascaris

History of Discovery:
Lagochilascariasis was first described by Leiper in 1909. Five species have been recognized in this genus: L. minor Leiper, 1909; L. major Leiper, 1910; L. turgida Travassos, 1924; L. sprenti, 1983; and L. buckleyi Sprent, 1971

Since 1998, 68 human cases have been reported in Amazon region of Central and South America. Because many patients with lagochilascariasis come from the lowest social-economic class (notably from rural areas), it is suspected that the parasite has a wild origin.

Image courtesy of Paco et al. 1999. pg 448.

Typical residence of patient with lagochilascariasis living in a woody area in

Araguaina, Tocantins, Brazil

Clinical Presentation:
Symptoms vary from mild subcutaneous lesions to more severe manifestations involving the central nervous system. Most commonly, abscesses form on the side of the neck with fistulae out of which eggs, larvae and adult worms are sometimes expelled. Abscesses can be drained, and eggs and adult stages of L.minor can be found in the secretion.  

Transmission:
Humans and domestic animals are considered accidental hosts due to the rarity of cases and the exceptional location of lesions. Infected patients tend to live close to woody areas and maintain a diet of hunted meat, such as guinea pigs, copybara, and agoutis, which places them at risk of contracting L. minor by inadvertently ingesting infective eggs.

Image courtesy of www.ernstmaissen.ch. Agoutis

Image courtesy of www.wikimedia.org. Copybara

Reservoir: Wild felines like the cloudy leopard (Felis nebulosa) act as definitive hosts.

Vector: Studies have shown that wild rodents act as intermediate hosts because they are both susceptible to the parasitic infection and they are ingested as food. It is possible that agrarian animals could act as potential paratenic or intermediate hosts in the life cycle.

Incubation Period: Not known

Morphology:

Both male and female worms are small, but females are longer and reach up to 15 mm in length while males reach up to 9 mm. Adult worms are stout with tapered ends, and the anterior end is similar in its dome shaped both sexes. Eggs appear similar in shape and size to those of Toxocara cati. T.cati eggs resemble ascaris but are larger, less elongate, and have a thinner shell and aluminoid outer covering. T. canis eggs measure about 85 by 75 micrometer and have a diameter of 65 to 70 micrometers.

Using a scanning electron miscroscopy (SEM), Lanfredi, Neto and Gomes (1998) observed L. minor collected from twenty-five worms from the State of Para, Brazil, and detailed its morphology with the images below:

Image and text courtesy of Lanfredi et al. 1998. pg 328-329

Life Cycle:

Wild rodents act as intermediate hosts, characteristic of an ascarid heteroxenic cycle where reproduction occurs in distinctive patterns. Meanwhile felines act as definitive host for the worm, but the cycle is only completed when intermediate hosts are provided (Paco et al. 1999) Rodents infected with the worms are eaten by felines, domestic animals, and humans through ingestion of either uncooked or lightly cooked meat containing encysted larvae.

Personal Interpretation of Life Cycle of Lagochilascaris

Image courtesy of Paco et al. 1999. pg 443. Cross section of a lung of vesper mice (Calomys callosus) showing 3rd-stage larvae in the center of a granulomatous lesion

Image courtesy of Paco et al. 1999. pg 444. Carcass of agouti showing nodule dissemination

Image courtesy of Paco et al. 1999. pg 444. Individual nodules, indicated by the black arrow, contain a 3rd-stage larva which are encysted in tissues of agouti

Image courtesy of Paco et al. 1999. pg 445. A cat, an accidental host, with cervical lesion after being inoculated with 55 larva of L. minor, which were encysted in tissues of vesper mice

Image courtesy of Paco et al. 1999. pg 445. A cat with tonsil lesion examined after being inoculated with 70 larva of L. minor 57 days later

Image courtesy of Paco et al. 1999. pg 446. A cat with bilateral tonsil lesion

Diagnosis:
Physical examination of subcutaneous lesions.

Management and Therapy:

Primary treatment is surgery, but levamisole is reported to assist in treatment of the infection.  Levamisole is approved in the United States and Canada only for treatment of colorectal carcinoma and melanoma (Markell and Voge 2006, pg 317). Treatment with albendazole at a dosage of 400 mg/day for 30 days, in addition to antibiotics, promoted regression of the lesion.

Epidemiology:

Since 2001, 109 cases have been reported exclusively in the Amazon region. The state of Pará accounts for 49.5% of the world’s casuistry. Human infections with L. minor have a neotropical distribution.

Country Info: Lagochilascariasis has been reported in Central and South America, including Mexico, Costa Rica, Colombia, Venezuela, Suriname, Boliva, Brazil, Trinidad, and Tobago. The Brazilian Amazon has become an important focus, particularly in the areas between the Tocantins and Araguaia rivers (Paco et al. 1999 pg 441)

Public Health and Prevention Strategies:

The rarity of human cases does not warrant large public health initiatives, but education about the dangers of eating rodent meat which serves as an intermediate host is needed. Rats, guinea pigs, and agoutis are often used as food in regions with incidences of human lagochilascariasis.

References:

Barbosa, Carlos Augusto Lopes, Dulcinea Maria barbosa Campos, and Jayrson Arujo de Oliveira. 1998. "Assessement of Ivermectin Therapeutic Efficacy on Third-Stage Larvae of Lagochilascaris minor in Mice Experimentally Infected." Revista do Instituto de Medicina Tropical de Sao Paulo. Vol. 40(3).

Campos, D. et al. 1992. "Experimental Life Cycle of Lagochilascaris minor Leiper, 1909." Rev Inst. Med. Trop. S. Paulo 34 (4): 277-287.

Lanfredi, Reinalda Marisa, Habib Fraiha Neto, and Delir Correa Gomes. 1998. "Scanning Electron Miscroscopy of Lagochilascaris minor Leiper, 1909 (Nematoda: Ascarididae)." Mem Inst Oswaldo Cruz, Rio de Janeiro, Vol. 93(3): 327-330.

Markell and Voge's Medical Parasitology. 2006. David T. John and William A. Petri, Jr. 9th ed. Saunders Elsevier: pg 317.

Moncada, Ligia I., Alvarez, Carlos A., Castellanos, Carlos et al. 1998. Lagochilascaris minor in a Patient from the Colombian Amazon: A Case Report. Rev. Inst. Med. trop. S. Paulo. 40 (6) [cited 15 May 2006]

Paco, Julieta Machado, Dulcinea Maria Barbosa Campos, and Jayrson Araujo de Oliveira. 1999. "Wild Rodents as Experimental Intermediate Hosts of Lagoschilascaris minor Leiper." Memorias do Instituto Oswaldo Cruz. Vol. 94(4): 441-449.

Primary Source:

Initiated correspondence with Dr. Dulcinéa Maria Barbosa Campos at the Instituto de Patologia Tropical e Saúde Pública via e-mail at dmcampos@ufg.br .

Images from Life Cycle:

http://members.tripod.com/~CloveApple/rodent401.gif

http://www.kidsplanet.org/factsheets/graphics/snow_leopard.gif

http://projects.edtech.sandi.net/brooklyn/humanbody/images/body.gif

http://earthsoils.calpoly.edu/LOESS/MicroJPEG/NEMATODE.jpeg

http://www.eslkidstuff.com/Worksheets/My%20neighbors%20cat.gif

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