T14_Nemátodos ★ Flashcards
Quais são os nemátodos intestinais que conheces?
7
- Enterobius vermicularis
- Ascaris lumbricoides
- Ancylostoma duodenalis e Necator americanus
- Strongyloides stercoralis
- Trichuris trichiura
- Trichinella spiralis
Epidemiologia dos nemátodos
Os Nemátodos tem maior prevalência na ________ e ____, ________, ________ e ____. Tendencialmente aparecem em ambientes com ________, sendo as ________ o grupo etário mais vulnerável.
- *Ásia Central
- e Oriental*,
- África sub-sahariana,
- *América do Norte
- e do Sul*
- Más condições sanitárias e de higiene
- Crianças em idade escolar
Epidemiologia dos nemátodos
As epidemias ocorrem em regiões ____ e ____, sendo que são doenças ____ ____.
- tropicais
- subtropicais
- tropicais
- negligenciadas
Epidemiologia dos nemátodos
A sua apresentação clínica mais frequente é ____ ou ____, mas podem ser ____ sobretudo nos seguintes grupos de risco:
1. ____
2. ____
3. ____
4. ____
- assintomática
- subclínica
- fatais
- indivíduos imunocomprometidos
- RN
- lactentes
- crianças pequenas
Epidemiologia dos nemátodos
Portugal a prevalência é inferior a ____% e o agente etiológico mais comum é o ____ ____.
- 6%
- Enterobius vermicularis
Os nemátodos são seres com corpos _____, não _____. Alongados, com simetria _____. Possuem _____ separados e um tubo digestivo _____.
Vivem no _____ ____ ou nos tecidos do hospedeiro (____).
O corpo é protegido por uma _____ externa, não celular.
Todos os nemátodos, à exceção do _____ _____, necessitam de um periodo fora do organismo do hospedeiro para completar o seu ciclo de vida
Os nemátodos são seres com corpos cilíndricos, não segmentados. Alongados, com simetria radial. Possuem sexos separados e um tubo digestivo completo.
Vivem no trato gastointestinal ou nos tecidos do hospedeiro (filárias).
O corpo é protegido por uma cutícula externa, não celular.
Todos os nemátodos, à exceção do Strongyloides stercoralis, necessitam de um periodo fora do organismo do hospedeiro para completar o seu ciclo de vida.
Qual é o nemátodo que não precisa de um período fora do organismo do hospedeiro para completar o seu ciclo de vida?
Todos os nemátodos, à exceção do Strongyloides stercoralis, necessitam de um periodo fora do organismo do hospedeiro para completar o seu ciclo de vida.
NEMÁTODOS: VIAS DE TRANSMISSÃO
- Ingestão de:
- ovos ______ contaminantes de ____ e _____ (ex. A. lumbricoides, ____ ____, T. trichiura)
- formas em desenvolvimento em hospedeiros ______ (ex. ____ _____)
- _____ embrionados em _______ (Trichinella spiralis)
- Ingestão de:
- ovos embrionados contaminantes de água e comida (ex. A. lumbricoides, Enterobius vermicularis, T. trichiura)
- formas em desenvolvimento em hospedeiros intermediários (ex. Dracunculus medinensis)
- quistos embrionados em carne infetada (Trichinella spiralis)
- Ingestão de:
- ovos embrionados contaminantes de água e comida (ex. ____ ____, ____ ____ e ____ ____)
- formas em desenvolvimento em hospedeiros intermediários (ex. ____ ___)
- quistos embrionados em carne infetada (___ ____)
- Ingestão de:
- ovos embrionados contaminantes de água e comida (ex. Ascaris lumbricoides, Enterobius vermicularis, Trichuris trichiura)
- formas em desenvolvimento em hospedeiros intermediários (ex. Dracunculus medinensis)
- quistos embrionados em carne infetada (Trichinella spiralis)
NEMÁTODOS: VIAS DE TRANSMISSÃO
2_ ____ _____ por larvas filariformes (ex. S. stercoralis, A. duodenale, N. americanus)
2_Penetração cutânea por larvas filariformes (ex. S. stercoralis, A. duodenale, N. americanus)
NEMÁTODOS: VIAS DE TRANSMISSÃO
2_Penetração cutânea por ____ ____ (ex. S. stercoralis, A. duodenale, N. americanus)
2_Penetração cutânea por larvas filariformes (ex. S. stercoralis, A. duodenale, N. americanus)
NEMÁTODOS: VIAS DE TRANSMISSÃO
2_Penetração cutânea por larvas filariformes (ex. ____ ____, ____ ____ e ____ ____)
2_Penetração cutânea por larvas filariformes
1. Strongyloides stercoralis
2. Ancylostoma duodenale
3. Necator americanus
NEMÁTODOS: VIAS DE TRANSMISSÃO
3Transmissão através de vetores artrópodes (___)
3_Transmissão através de vetores artrópodes (filárias)
NEMÁTODOS: VIAS DE TRANSMISSÃO
3_Transmissão através de ____ ____ (filárias)
3_Transmissão através de vetores artrópodes (filárias)
NEMÁTODOS: VIAS DE TRANSMISSÃO
4_Inalação de ____ ____ contaminado com ovos embrionados (ex. A. lumbricoides, E. vermicularis)
4_Inalação de pó contaminado com ovos embrionados (ex. A. lumbricoides, E. vermicularis)
NEMÁTODOS: VIAS DE TRANSMISSÃO
4_Inalação de pó contaminado com ____ ____ (ex. A. lumbricoides, E. vermicularis)
4_Inalação de pó contaminado com ovos embrionados (ex. A. lumbricoides, E. vermicularis)
NEMÁTODOS: VIAS DE TRANSMISSÃO
4_Inalação de pó contaminado com ovos embrionados (ex. ____ ____, ____ ____)
4_Inalação de pó contaminado com ovos embrionados (ex.
1. Ascaris lumbricoides
2. Enterobius vermicularis
Caracteriza o Ciclo de vida do Enterobius vermicularis
E. vermicularis, the pinworm, is a small, white worm that is familiar to parents who find them in the perianal folds or vagina of an infected child.
Infection is initiated by ingestion of embryonated eggs.
Larvae hatch in the small intestine and migrate to the large intestine, in which they mature into adults in 2 to 6 weeks.
Fertilization of the female by the male produces the characteristic asymmetric eggs.
These eggs are laid in the perianal folds by the migrating female.
As many as 20,000 eggs are deposited on the perianal skin.
The eggs rapidly mature and are infectious within hours
Como é a morfologia do Enterobius vermicularis?
Ovos muito leves, em forma de barril
assimétrico
Uma das faces achatada (em forma de D)
Dupla membrana
Como é o ciclo de vida do Ascaris lumbricoides?
A. lumbricoides are large (20 to 35 cm in length), pink worms (see Fig. 74.1) that have a more complex life cycle than E. vermicularis but are otherwise typical of an intestinal roundworm.
The ingested infective egg releases a larval worm that penetrates the duodenal wall, enters the bloodstream, is carried to the liver and heart, and then enters the pulmonary circulation.
The larvae break free in the alveoli of the lungs, in which they grow and molt.
In about 3 weeks, the larvae pass from the respiratory system to be coughed up, swallowed, and returned to the small intestine.
As the male and female worms mature in the small intestine (primarily jejunum), fertilization of the female by the male initiates egg production, which may amount to 200,000 eggs per day for as long as a year.
Female worms can also produce unfertilized eggs in the absence of males.
Eggs are found in the feces 60 to 75 days after the initial infection.
Fertilized eggs become infectious after approximately 2 weeks in the soil.
Helmintíase mundialmente mais comum
Endémico em regiões dos EUA, Nigéria, Sudeste da Ásia
Pode atingir 40 cm de comprimento
Caracteriza o ciclo de vida dos Ancilostomídeos
The two human hookworms are Ancilostoma duodenale (Old World hookworm) and Necator americanus (New World hookworm). Differing only in geographic distribution, structure of mouthparts, and relative size, these two species are discussed together as agents of hookworm
infection.
The human phase of the hookworm life cycle is initiated when a filariform (infective form) larva penetrates intact skin.
The larva then enters the circulation, is carried to the lungs, and similar to A. lumbricoides, is coughed up, swallowed, and develops to adulthood in the small intestine.
Adult worms lay as many as 10,000 to 20,000 eggs per day, which are released into the feces.
Egg laying is initiated 4 to 8 weeks after the initial exposure and can persist for as long as 5 years.
On contact with soil, the rhabditiform (noninfective) larvae are released from the eggs and within 2 weeks develop into filariform larvae.
The filariform larvae can then penetrate exposed skin (e.g., bare feet) and initiate a new cycle of human infection q.
Both species have mouthparts designed for sucking blood from injured intestinal tissue. A. duodenale has chitinous teeth, and N. americanus has shearing chitinous plates
Como é feito o diagnóstico laboratorial dos Ancilostomídeos?
-
Exame parasitológico das fezes com concentração (até 3 amostras, dias diferentes, em 10 dias) – **conservar a 4º C, máx. até 24h **
* ovos idênticos para ambas as espécies;
* formato oval;
* amarelo claro;
* membrana única, translúcida, transparente e brilhante - Apesar de não ser clinicamente necessário, apenas a morfologia das larvas permite a sua identificação:
- Ancylostoma duodenale: cápsula bucal com dois pares de dentes ventrais na margem interna da boca
- Necator americanus: cápsula bucal com duas lâminas cortantes semilunares na margem interna da boca
Caracteriza o ciclo de vida da Trichuris trichura
Commonly called whipworm because it resembles the handle and lash of a whip, Trichuris trichiura has a simple life cycle.
Ingested eggs hatch into a larval worm in the small intestine and then migrate to the cecum, in which they penetrate the mucosa and mature to adults.
About 3 months after the initial infection, the fertilized female worm starts laying eggs and may produce 3000 to 10,000 eggs per day.
Female worms can live for as long as 8 years.
Eggs passed into the soil mature and become infectious in 3 weeks.
T. trichiura eggs are distinctive, with dark bile staining, a barrel shape, and the presence of polar plugs in the egg shell.
Como é que efetuas o diagnóstico laboratorial de trichuríase?
Exame parasitológico das fezes com concentração (até 3 amostras, dias diferentes, em 10 dias) – conservar a 4º C, máx. até 24h
- ovos de coloração acastanhada,
- com presença de dois rolhões mucosos nos polos
Caracteriza o ciclo de vida do Strongyloides Stercoralis
Although the morphology of these worms and the epidemiology of their infections are similar to the hookworm, the life cycle of Strongyloides stercoralis differs in three aspects:
(1) eggs hatch into larvae in the intestine and before they are passed in feces;
(2) larvae can mature into filariforms in the intestine and cause autoinfection;
and (3) a free-living, nonparasitic cycle can be established outside the human host.
In direct development, such as the hookworm, a skin-penetrating S. stercoralis larva enters the circulation and follows the pulmonary course.
It is coughed up and swallowed, and adults develop in the small intestine.
Adult females burrow into the mucosa of the duodenum and reproduce parthenogenetically. Each female produces about a dozen eggs each day, which hatch within the mucosa and release rhabditiform larvae into the lumen of the bowel.
The rhabditiform larvae are distinguished from the larvae of hookworms by their short buccal capsule and large genital primordium.
The rhabditiform larvae are passed in the stool and may either continue the direct cycle by developing into infective filariform larvae or develop into free-living adult worms and initiate the indirect cycle.
In indirect development, the larvae in soil develop into free-living adults that produce eggs and larvae.
Several generations of this nonparasitic existence may occur before new larvae become skin-penetrating parasites.
Finally, in autoinfection, rhabditiform larvae in the intestine do not pass with feces but become filariform larvae.
These penetrate the intestinal mucosa or perianal skin and follow the course through the circulation and pulmonary structures, are coughed up, and then are swallowed; at this point, they become adults, producing more larvae in the intestine.
This cycle can persist for years and can lead to hyperinfection and massive or disseminated, often fatal infection.
Como é efetuado o diagnóstico laboratorial do Strongyloides Stercoralis?
-
Exame parasitológico das fezes com concentração (até 3 amostras, dias diferentes, em 10 dias) – conservar a 4ºC, máx. até 24h
OBSERVAM-SE VERMES NÃO OVOS - Serologia
- Cultura de larvas nas fezes
- PCR nas fezes
- Pesquisa do parasita no conteúdo duodenal e na expectoração
The diagnosis of strongyloidiasis may be difficult because of the intermittent passage of low numbers of first-stage larvae in stool.
Examination of concentrated stool sediment reveals the larval worms, but in contrast with hookworm infections,
in S. stercoralis infections, eggs are generally not seen.
Collecting samples from three stools, one per day for 3 days (as for G. duodenalis), is recommended because S. stercoralis larvae may occur in “showers,” with many present one day and few or none the next.
Several authors favor the Baermann funnel gauze method of concentrating living S. stercoralis larvae from fecal specimens.
This method uses a funnel with a stopcock and a gauze insert. The funnel is filled with lukewarm water to a level just covering the gauze, and a specimen of stool is placed on the gauze, partially in contact with the water.
The larvae in the stool migrate through the gauze into the water and then sediment into the neck of the funnel, in which they may be detected by low-power microscopy.
When absent from stool, larvae may be detected in duodenal aspirates or in sputum in the case of massive infection.
Finally, culture of the larvae from stool using charcoal cultures or an agar plate method may be used, although these are not routine in most laboratories.
Demonstration of anti-Strongyloides antibodies in blood may be useful as a screening test or as an adjunct for diagnosis.
Diagnosis by nucleic acid amplification tests (NAATs) has been developed for testing stool and urine and is now available in many reference laboratories.
Caracteriza o ciclo de vida da Trichinella spiralis
T. spiralis is the most important cause of human disease, but other species, such as T. pseudospiralis and T. britovi, may also cause trichinosis.
The adult form of this organism lives in the duodenal and jejunal mucosa of flesh-eating mammals worldwide.
The infectious larval form is present in the striated muscles of carnivorous and omnivorous
mammals.
Among domestic animals, swine are most frequently involved.
Fig. 74.13 illustrates the simple, direct life cycle, which terminates in the musculature of humans, in which the larvae eventually die and calcify.
The infection begins when meat that contains encysted larvae is digested.
The larvae leave the meat in the small intestine and within 2 days develop into adult worms.
A single fertilized female produces more than 1500 larvae in 1 to 3 months.
These larvae move from the intestinal mucosa into the bloodstream and are carried in the circulation to various muscle sites throughout the body, in which they coil in striated muscle fibers and become encysted.
The muscles invaded most frequently include the:
* extraocular muscles of the eye;
* the tongue;
* the deltoid, pectoral, and intercostal muscles;
* the diaphragm;
* and the gastrocnemius muscle.
The encysted larvae remain viable for many years and are infectious if ingested by a new animal host.
The muscle larvae of T. pseudospiralis do not induce the formation of a cyst and generate less inflammation than that of T. spiralis.
Como é efetuado o diagnóstico laboratorial da Trichinosíase
Serologia
Outros ECD’s: Biópsia muscular
The diagnosis is usually established with clinical observations, especially when an outbreak can be traced to consumption of improperly cooked pork or bear meat.
The laboratory may confirm the diagnosis if the encysted larvae are detected in the implicated meat or in a muscle biopsy specimen from the patient.
Marked eosinophilia is characteristically present in patients with trichinosis.
Serologic procedures also are available for confirmation of the diagnosis.
Significant antibody titers are usually absent before the third week of illness but then may persist for years.
Tabela resumo aula nemátodos
