Tag Archives: achatinidae

Therrrr Backkkk

This was the heading Harry Lee gave some days ago to his post on the Conch-L site to announce the return of Lissachatina fulica in Florida. Some religious zealot had used these snails to have his disciples swallow their juices, causing that many of them had to go to hospital for treatment.

When the media started to cover this issue, the hype began. See http://n.pr/ovmPPW. Some people now even think that all land snails are banned because they are harmful to man… One cannot be careful enough in choosing the wording of your press releases.

Today, Harry posted the following re-assuring message:

Transmission of the nematode parasite,/ Angiostrongylus cantonensis/, to
man is rare, and disease (most conspicuously eosinophilic
meningoencephalitis) even rarer. Human infection typically involves*
ingestion* of one (or more) un- or under-cooked snail. The parasite
exercises very little if any selectivity as to which amphibious or
terrestrial snail in infects in the course of its somewhat unusual life
cycle. The prominence of /Achatina fulica/ in human transmission is
essentially a function of its size and human cultural preferences. It is
likely that hundreds of snail species are naturally-infected. Among them
are /Bradybaena similaris <http://www.jaxshells.org/gallery2.htm>/ and
subulinids, e.g., <http://www.jaxshells.org/octona.htm>, which have been
introduced into the SE USA like the Giant African Snail but have spread
widely.  If it were customary for people to consume these little fellows
in areas where the parasite was present, these pulmonates would be the
culprits, and they would qualify for vilification by the Fourth Estate.

Someone, somewhere, once wrote that a person touching the mucus of an
infected snail (e.g., /Achatina fulica/) and then touching his mouth or
another mucous membrane, could allow the infective larva(e) of this
roundworm to infect him. That oft-repeated anecdote is the basis for the
rubber glove caveat. While I don’t advocate slathering uncooked snail
slime on your lips, conjunctivae, etc. in geographic areas when this
parasite occurs, reason indicates that this scenario is rank hyperbole.

A discussion of the medical geography of this parasite and the evolution
of human disease in relation to another host, apple snails, is archived
Comments on the virulence of the disease and its treatment are included.

Anyway, S.O.S. Save Our Snails. Don’t let GAS indirectly threaten native snails.

It seems like a battle lost

Last week I had a little break in a country home, when I received a message from Vincent Mouret, a French birdwatcher who visited the Rio Palenque Biological Reserve in Ecuador. This reserve was created in 1970 as a biological station in the western lowlands in Prov. Los Rios, south of Quevedo.


As Derek Kverno writes on his Birding Ecuador blog (http://bit.ly/gr3000): “Rio Palenque is perhaps the worst-case scenario for the future of conservation in northwestern Ecuador. (…) The one-hundred acre [0.4 km2] reserve has gradually become an irrelevant island of forest in a thriving agricultural sea of African palm, banana, and pineapple”. For an impression of how the place looks like, see http://bit.ly/hUtdkZ and http://bit.ly/hH56ny.

Vincent Mouret sent me two pictures of snails for identification, one of which was this one:


No guessing, this is the infamous Lissachatina fulica…! While it was already known to occur on the western slopes of the Andes in Ecuador (see my posts of 22-04 and 29-04-2010; http://bit.ly/hxEOx5), it was sad news to learn that it was found inside the rain forest. So far, to my knowledge, the species has only been reported from disturbed habitats.

According to the Reserve’s manager, the problem appeared a few months ago. Now these snails have been found on the different trails that traverse the reserve. The intention is to try to treat the invasion by means of an organic compound made of aji and other local plants. Hopefully, this treatment will not affect the native malacofauna but it has not been tested with this purpose. 

According to David Robinson (USDA malacologist) “Ecuador is already a lost cause – (unofficially) all coastal provinces are infested. The move into natural habitats is indeed disturbing”. David will be conducting a workshop for South American agencies in Argentina  in June.

Lissachatina in Argentina

In my blogpost of 08-06-2010 I reported that Lissachatina fulica had been found in Puerto Iguaz??, Dept. Misiones, Argentina. This finding is now documented in a paper by Guti??rrez et al. (2011). According to this paper the introduction took place approximately three years ago, and the population seems to be well-established. Also the risks to the native snail populations are stipulated, viz. competition for food and refuge. It is suggested that the pathway for introduction was the use of snails as fish bait.

Guti??rrez, D.E., N????ez, V., Vogler, R., Rumi, A., 2011. Invasion of the Argentinian Paranense rainforest by the giant African snail. – American Malacological Bulletin 29: 135-137.

Lissachatina again

Lissachatina fulica is marching up rapidly and causing new problems.

On 12-10-2010 I reported a new finding of this pest species in Colombia, Dept. Putumayo, Puerto Asis (see old snailblog on www.ashbreure.nl). The past week saw a new report of a Colombian occurrence of this species, in Dept. Cauca, Cali. This is a major expansion as L. fulica now has reached the western part of Colombia. As Cali is a major city with many transport links, there is now a real chance for a rapid, further expansion.


At the same time I came across a paper describing the first finding of Schistosoma mansoni eggs in feces and mucous secretion of L. fulica in Venezuela (Libora et al, 2010). The implications for public health are immediately eminent, as this is a known vector of bilharzia.

Francisco Borrero, who gave me the info on the new Cali record, mentions that there are several pathways that seems to contribute to the rapid expansion of this species. One that we came across earlier in Ecuador, is the increasing popularity of baba de caracol (snail mucous) as health care product. If it wasn’t so serious it would be ridiculous. But the Venezuelan paper precisely shows why this is so alarming.

Although the authorities are well aware of the health risks and several citizens seem to be alarmed about the risks they are exposed to, one major risk seems to be highly neglected: the effects that these Giant African Snails can have on the local snail fauna. A serious threat that deserves serious attention. But as long as snail biodiversity has no monetary value, this probably will remain wishful thinking…

Libora, M., Morales, G., Carmen, S., Isbelia, S., Luz, P., 2010. Primer hallazgo en Venezuela de huevos de Schistosoma mansoni y de otros helmintos de inter??s en salud p??blica, presentes en heces y secreci??n mucosa del molusco terrestre Achatina fulica (Bowdich, 1822). – Zootecnia Tropical 28: 383-394.

Lissachatina in the Lesser Antilles

Gerard van Buurt kindly corrected my statement in my post http://ashbreure.posterous.com/a-new-species-for-curacao on the occurrence of Zachrysia provisoria on St. Maarten and Antigua. It is a lapsus and these records actually refer to Lissachatina fulica.

During a recent workshop on pest species in the Caribbean, David Robinson presented an overview of the history of distribution of Lissachatina in the Lesser Antilles. 


What started with an intentional introduction on Guadeloupe in 1984, has spread in 20 years time to a number of islands. St. Maarten was reached in 1995, Antigua was infected in 2008 (http://www.pestalert.org/viewNewsAlert.cfm?naid=58). It is also present in Trinidad (not shown on the map). On the islands the species is mainly a nuisance for the inhabitants, not so much an agricultural pest; however, it could affect tourism and thus indirectly have economic adverse effects.

Lissachatina spreading in Sao Paulo state

Lissachatina fulica (Bowdich, 1822) is a known pest in South America (see my old blogposts, tagged Achatina) and has spread over Brazil during the last decades. Ohlweiler et al. (2010) have studied this species in the State of Sao Paulo. This parasitological study explores the number of infected populations. Compared to three years ago (Thiengo et al., 2007), the number of counties within the State of Sao Paulo where L. fulica is recorded has grown from 69 to 105. Infected populations were found in six cities. The recommendation is made of putting an epidemiological monitoring system as prevention for medical and veterinary risks.

This study highlights again the potential risk of this snail as host for nematodes, in this case in a densely populated and economic important area of Brazil.

Ohlweiler, F.P., Guimaraes, M.C. de Almeida, Takahasi, F.Y. & Eduardo, J.M., 2010. Current distribution of Achatina fulica, in the State of Sao Paulo including records of Aelurostrongylus abstrusus (Nematoda) larvae infestation. – Revista do Instituto de Medicina Tropical de Sao Paulo 52 (4): 211-214.
Thiengo, S.C., Faraco, F.A., Salgado, N.C., Cowie, R.H. & Fernandez, M.A., 2007. Rapid spread of an invasive snail in South America: the giant African snail, Achatina fulica, in Brazil. – Biological Invasions 9: 693-702.