Parasitic zoonoses in Sri Lanka : an update Both predicted and unexpected infections are being reported

Cestodes Since 1993 (1) several cases of sparganosis caused probably by Spirometra sp. have been observed. (5,6 and Samarasinghe S, personal communication). Bertiella studeri, an anoplocephalid tapeworm, is now recognised as a parasite acquired in areas where monkey reservoir hosts abound (7). As summarised by the present author (8) this cestode (Weerasooriya MV, Edirisinghe JS, personal communications), Taenia solium, Hymenolepis diminuta (Weerasooriya MV, personal communication) and hydatid cysts of Echinococcus granulosus are seen by clinicians and parasitologists, but not reported. An unusual infection, probably a spurious one, of Taenia taeniaeformis of the cat has recently been reported in a child (9).


Protozoa
Several cases of locally transmitted cutaneous leishmaniasis have been recorded (2,3) and recently reviewed (4).No other new infections have been reported but a case of infection with the coccidian Cyclospora was seen in a foreign visitor about two years back.It is possible that cases of Cyclospora are missed as measurements of oocysts and sporulation are not routinely done.

Cestodes
Since 1993 (1) several cases of sparganosis caused probably by Spirometra sp. have been observed.(5,6 and Samarasinghe S, personal communication).Bertiella studeri, an anoplocephalid tapeworm, is now recognised as a parasite acquired in areas where monkey reservoir hosts abound (7).As summarised by the present author (8) this cestode (Weerasooriya MV, Edirisinghe JS, personal communications), Taenia solium, Hymenolepis diminuta (Weerasooriya MV, personal communication) and hydatid cysts of Echinococcus granulosus are seen by clinicians and parasitologists, but not reported.An unusual infection, probably a spurious one, of Taenia taeniaeformis of the cat has recently been reported in a child (9).

Nematodes
Although a few cases of infection have been reported they are based only on serological tests and parasite larvae have not been seen in visceral larva migrans cases in Sri Lanka.A recent case of a child with hepatomegaly, high eosinophilia, raised ESR, and serologically positive for T canis was most probably an example of this infection; but serial sections of liver biopsies failed to reveal any parasite (Weerasooriya MV, personal communication).In a field study of children in Hindagala, Kandy, a high infection rate has been observed, using a T canis specific ELISA technique (D Iddawela, personal communication).
A case of human infection of the vitreous of the eye caused by the cat hookworm, probably Ancylostoma tubaeforme, leading to loss of vision was also reported (10).The dog filarial worm Dirofilaria repens in now frequently seen in Sri Lanka and over 170 cases are on record (11,12,13,14,15,16).It is interesting to note that corresponding to population and surface area Sri Lanka has more cases than Italy which has a record of many more cases (16).A filarial worm of animal origin that has been identified as Brugia ceylonensis of cats has been added to this list of zoonoses (17).
Parastrongylus (Angiostrongylus), a rodent lungworm found mostly in bandicoots in Sri Lanka, was predicted to be a possible zoonotic parasite (1).It has now been reported on three occasions (18,19,20).These have all been ocular infections, and it is of interest that of a total of 16 authentic ocular infections worldwide three have been from Sri Lanka.
Quite unexpectedly, two cases of a nematode infection with Gnathostoma sp, probably G. spinigerum, have been recorded (S Samarasinghe, BJC Perera and Ratnasena BGN, personal communication).This is surprising in a country like Sri Lanka where uncooked or undercooked invertebrate or vertebrate intermediate hosts or paretenic hosts are rarely, if ever, eaten.However, in both cases there was a suggestion that undercooked freshwater fish have been consumed.
It is necessary to emphasise that some of these infections may not necessarily be acquired by eating raw or undercooked intermediate or paratenic hosts but rather by contamination of food with the infective larval stages of these parasites in uncooked vegetables eg.lettuce and Centella ("Gotukola") as suggested for Parastrongylus infections (18,19,20).In the case of Gnathostoma, ingestion of the infective larva in the crustacean Cyclops is also a possible cause of infection.