> Date: Sat, 2 Sep 2006 13:41:20 -0400 (EDT)
> From: ProMED-mail <promed@promed.isid.harvard.edu>
> Subject: PRO/AH/EDR> Paragonimus - USA (CA): ex Japan (03)
>
> PARAGONIMUS - USA (CALIFORNIA): EX JAPAN (03)
> *********************************************
> A ProMED-mail post
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> International Society for Infectious Diseases
> <http://www.isid.org>
>
> Date: Fri 1 Sep 2006
> From: Dr R Sehgal <sehgalr@satyam.net.in>
>
>
> There are a number of species of Paragonimus which can infect humans. These
> are as follows (according to geographical locales):
>
> China: _P. westermani_, _P. skrjabini_, _P. heterotremus_ and _P.
> hueitugensis_
> Japan: _P. westermani_, _P. miyazakii_
> Cameroon: _P. africanus_ and _P. uterobilateralis_
> Vietnam: _P. heterotremus_
> Ecuador and Peru: _P. mexicanus_
>
> However, these parasites may be found in other countries as well. _P.
> westermani_ is endemic in China, Korea, Japan, Taiwan, and the Philippines
> and has been detected in other countries including India. The life cycle of
> this trematode includes 2 intermediate hosts. The first are snails and the
> second are crabs and crayfishes, where the infective stage of the parasite
> (the metacercariae) are encysted. The major intermediate hosts which can
> transmit the infection to humans are crabs of the genera Eriocheir, Potamon
> and Sundathelphusa and crayfishes of the genus _Cambaroides_. If cooking of
> these is proper before eating there is no chance of infection being
> transmitted. Generally, in the endemic countries, crabs etc. are eaten
> either raw, in alcohol, or undercooked and this then can easily transmit
> the infection to humans.
>
> After the ingestion of the cysts (metacercariae), they excyst in the
> stomach and the larvae come out, penetrate the gut wall, and migrate
> through the mesentery and diaphragm to reach the lungs, where they mature
> into the adult worms and after fertilization start to lay eggs. This
> normally takes about 3 months. The worms can lead to pulmonary
> paragonimiasis or can also reach aberrant sites and can cause cerebral,
> cutaneous paragonimiasis.
>
> Diagnostic tests
> - ----------------
> - - Detection of typical ova in blood-stained sputum. These can be detected
> only after adult worms are mature -- that is, 3 months after infection.
> - - Detection of ova in stool in children.
> - - Detection of antibody: ELISA test has been developed and the one
> developed by the CDC gives almost 96 per cent sensitivity. The test uses 8
> kda antigen of the worm.
> - - Detection of antigen: This is better than antibody detection and gives
> 100 per cent sensitivity. This should also be positive earlier than
> antibody detection, which takes at least 2 weeks to become positive.
> - - Skin test: more of an epidemiological tool
>
> Therefore:
> 1. For an asymptomatic person it would be better to go for serology, as
> this would be positive well before the worms mature and lay eggs.
> 2. If initial serology is negative it can be repeated after 10-14 days.
> 3. If serology is positive in a non-endemic area, take it to be probable
> infection and it would be advisable to follow up and treat.
> 4. Regarding the moderator's previous query, I have no knowledge regarding
> cases after flash-fried crabs, but it would be possible, as temperature
> inside the muscle tissue of the crab may not reach the level necessary to
> kill the metacercariae.
> 5. Earlier treatment should prevent scarring and sequelae.
>
> I hope that this answers some of the queries raised.
>
> - --
> Dr R Sehgal
> <sehgalr@satyam.net.in>
>
> [ProMED-mail welcomes the explanations from Dr Sehgal. If there is further
> information on the cases from Orange County once the follow-up is
> completed, ProMED-mail will be happy to post such information. - Mod.EP]
>
>
-- Liz Brown Assistant Professor Alaska Sea Grant Marine Advisory Program School of Fisheries and Ocean Sciences University of Alaska Fairbanks PO Box 1549 Dillingham, Alaska 99576 907-842-1265 fax 907-842-3202 http://seagrant.uaf.edu/map
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