''Trichostrongylus'' species are
nematodes (round worms), which are ubiquitous among herbivores worldwide, including cattle, sheep, donkeys, goats, deer, and rabbits.
[Garcia LS, editor. Diagnostic Medical Parasitology. 5 ed. Washington, DC: ASM Press; 2007.][Strickland GT, editor. Hunter's Tropical Medicine and ]Emerging Infectious Diseases
''Emerging Infectious Diseases'' (EID) is an open-access, peer-reviewed journal published by the Centers for Disease Control and Prevention (CDC). EID is a public domain journal and covers global instances of new and reemerging infectious diseas ...
. 8 ed. Philadelphia, PA: WB Saunders Company; 2000.
At least 10 ''Trichostrongylus'' species have been associated with human infections.
Infections occur via ingestion of infective larvae from contaminated vegetables or water.
Epidemiological studies indicate a worldwide distribution of ''Trichostrongylus'' infections in humans, with the highest prevalence rates observed in individuals from regions with poor sanitary conditions, in rural areas, or who are farmers / herders. Human infections are most prevalent in the Middle East and Asia,
with a worldwide estimated prevalence of 5.5 million people.
Life cycle
Eggs are passed through the feces of an infected definitive host, usually a mammalian herbivore including rabbits, sheep, cattle, and rodents. Under certain environmental conditions, which include optimal temperature and humidity, larvae hatch from eggs after several days. Hatched rhabditiform larvae grow on vegetation or within soil. After 5 to 10 days, two molts (L1 & L2) have occurred and the parasite becomes a filariform (L3) larvae that is infectious. Infection in mammals occurs upon ingestion of infective filariform (L3) larvae. The larvae reaches the small intestine to reside and mature into adult worms within their definitive hosts. Infections in humans may occur as incidental infections. Trichostrongylus consists of multiple species that relate to each of its host, when it comes to parasitic survival and infection. For example, ''Trichostrongylus affinis'' primarily infects cottontail rats, ''Trichostrongylus sigmodontis'' affects hispid cotton rat, and marsh rice rat, and ''Trichostrongylus retortaeformis'' primarily affects European rabbits (''Oryctolagus cuniculus'').
Clinical presentation
The majority of human infections are asymptomatic or associated with mild symptoms. Symptomatic individuals may experience abdominal pain, nausea, diarrhea, flatulence, dizziness, generalized fatigue, and malaise.
Eosinophilia is frequently observed.
Infections with a heavy worm burden can lead to
anemia
Anemia or anaemia (British English) is a blood disorder in which the blood has a reduced ability to carry oxygen due to a lower than normal number of red blood cells, or a reduction in the amount of hemoglobin. When anemia comes on slowly, t ...
,
cholecystitis
Cholecystitis is inflammation of the gallbladder. Symptoms include right upper abdominal pain, pain in the right shoulder, nausea, vomiting, and occasionally fever. Often gallbladder attacks (biliary colic) precede acute cholecystitis. The pai ...
, and emaciation.
Regarding ''Trichostrongylus retortaeformis'', worm burden is affected parallel to host immune system and climate change. Although immunity prevents any significant long-term net accumulation of T. retortaeformis in the rabbit population, its seasonal effect is to increase heterogeneity in infection and transmission between individuals by worsening the parasite burden in the juveniles exposed to climate warming.
Diagnosis
The adult worms live in the
small intestine. The diagnosis is based on the observation of eggs in the stool. The eggs are 85–115 um, oval, elongated, and pointed at one or both ends.
''Trichostrongylus'' eggs must be differentiated from hookworm eggs, which are smaller and do not have pointed ends.
Prevention and treatment
Since the use of herbivore manure as fertilizer is a common practice preceding infection, thorough cleaning and cooking of vegetables is required for prevention of infection.
Treatment with
pyrantel pamoate
Pyrantel is a medication used to treat a number of parasitic worm infections. This includes ascariasis, hookworm infections, enterobiasis (pinworm infection), trichostrongyliasis, and trichinellosis. It is taken by mouth.
Side effects inclu ...
is recommended as the first line drug.
Alternative agents include
mebendazole
Mebendazole (MBZ), sold under the brand name Vermox among others, is a medication used to treat a number of parasitic worm infestations. This includes ascariasis, pinworm infection, hookworm infections, guinea worm infections, hydatid disea ...
and
albendazole
Albendazole (also known as albendazolum) is a broad-spectrum anthelmintic and antiprotozoal agent of the benzimidazole type. It is used for the treatment of a variety of intestinal parasite infections, including ascariasis, pinworm infection, ho ...
.
Successful treatment with
ivermectin
Ivermectin (, '' EYE-vər-MEK-tin'') is an antiparasitic drug. After its discovery in 1975, its first uses were in veterinary medicine to prevent and treat heartworm and acariasis. Approved for human use in 1987, today it is used to treat i ...
has also been reported.
Another way of avoiding these free-swimming stages of infective larvae, is to wear protective footwear when walking in areas of parasite prominence, and maintain general sanitary practices throughout the day.
Species
Species:
*''
Trichostrongylus affinis
''Trichostrongylus affinis'' is a species of parasitic nematode in the genus ''Trichostrongylus''. It primarily infects cottontails (''Sylvilagus''), but has also been found in the hispid cotton rat (''Sigmodon hispidus'') and the marsh rice rat ...
''
*''
Trichostrongylus andreevi''
*''
Trichostrongylus askivali''
*''
Trichostrongylus axei''
*''
Trichostrongylus brevis
''Trichostrongylus'' species are nematodes (round worms), which are ubiquitous among herbivores worldwide, including cattle, sheep, donkeys, goats, deer, and rabbits.Garcia LS, editor. Diagnostic Medical Parasitology. 5 ed. Washington, DC: ASM P ...
''
*''
Trichostrongylus calcaratus''
*''
Trichostrongylus capricola
''Trichostrongylus'' species are nematodes (round worms), which are ubiquitous among herbivores worldwide, including cattle, sheep, donkeys, goats, deer, and rabbits.Garcia LS, editor. Diagnostic Medical Parasitology. 5 ed. Washington, DC: ASM P ...
''
*''
Trichostrongylus colubriformis''
*''
Trichostrongylus duretteae
''Trichostrongylus'' species are nematodes (round worms), which are ubiquitous among herbivores worldwide, including cattle, sheep, donkeys, goats, deer, and rabbits.Garcia LS, editor. Diagnostic Medical Parasitology. 5 ed. Washington, DC: ASM P ...
''
*''
Trichostrongylus lerouxi
''Trichostrongylus'' species are nematodes (round worms), which are ubiquitous among herbivores worldwide, including cattle, sheep, donkeys, goats, deer, and rabbits.Garcia LS, editor. Diagnostic Medical Parasitology. 5 ed. Washington, DC: ASM P ...
''
*''
Trichostrongylus longispicularis
''Trichostrongylus'' species are nematodes (round worms), which are ubiquitous among herbivores worldwide, including cattle, sheep, donkeys, goats, deer, and rabbits.Garcia LS, editor. Diagnostic Medical Parasitology. 5 ed. Washington, DC: ASM P ...
''
*''
Trichostrongylus medius
''Trichostrongylus'' species are nematodes (round worms), which are ubiquitous among herbivores worldwide, including cattle, sheep, donkeys, goats, deer, and rabbits.Garcia LS, editor. Diagnostic Medical Parasitology. 5 ed. Washington, DC: ASM P ...
''
*''
Trichostrongylus ostertagiaeformis
''Trichostrongylus'' species are nematodes (round worms), which are ubiquitous among herbivores worldwide, including cattle, sheep, donkeys, goats, deer, and rabbits.Garcia LS, editor. Diagnostic Medical Parasitology. 5 ed. Washington, DC: ASM P ...
''
*''
Trichostrongylus pietersei
''Trichostrongylus'' species are nematodes (round worms), which are ubiquitous among herbivores worldwide, including cattle, sheep, donkeys, goats, deer, and rabbits.Garcia LS, editor. Diagnostic Medical Parasitology. 5 ed. Washington, DC: ASM P ...
''
*''
Trichostrongylus probolurus
''Trichostrongylus'' species are nematodes (round worms), which are ubiquitous among herbivores worldwide, including cattle, sheep, donkeys, goats, deer, and rabbits.Garcia LS, editor. Diagnostic Medical Parasitology. 5 ed. Washington, DC: ASM P ...
''
*''
Trichostrongylus retortaeformis''
*''
Trichostrongylus sigmodontis''
*''
Trichostrongylus skrjabini
''Trichostrongylus'' species are nematodes (round worms), which are ubiquitous among herbivores worldwide, including cattle, sheep, donkeys, goats, deer, and rabbits.Garcia LS, editor. Diagnostic Medical Parasitology. 5 ed. Washington, DC: ASM P ...
''
*''
Trichostrongylus suis
''Trichostrongylus'' species are nematodes (round worms), which are ubiquitous among herbivores worldwide, including cattle, sheep, donkeys, goats, deer, and rabbits.Garcia LS, editor. Diagnostic Medical Parasitology. 5 ed. Washington, DC: ASM P ...
''
*''
Trichostrongylus tenuis
''Trichostrongylus tenuis'', also known as the strongyle worm, is a gut nematode found in the United Kingdom, sensitive to Pyrantel pamoate. Larvae have a short migration inside the mucosa of the intestine and return quickly to the digestive tra ...
''
*''
Trichostrongylus ventricosus
''Trichostrongylus'' species are nematodes (round worms), which are ubiquitous among herbivores worldwide, including cattle, sheep, donkeys, goats, deer, and rabbits.Garcia LS, editor. Diagnostic Medical Parasitology. 5 ed. Washington, DC: ASM P ...
''
*''
Trichostrongylus vitrinus
''Trichostrongylus'' species are nematodes (round worms), which are ubiquitous among herbivores worldwide, including cattle, sheep, donkeys, goats, deer, and rabbits.Garcia LS, editor. Diagnostic Medical Parasitology. 5 ed. Washington, DC: ASM Pr ...
''
References
{{Taxonbar, from=Q2066824
Trichostrongylidae
Rhabditida genera