l I l infectiw stage of hoth par11si1es. I.,, iormnllr suffer from epigastric pain and arc clini"'· 11. mfoctcc palll'. '. ll. S 1 · 1 1 k,. a Y d11. 1 1 llanun-ition nt the site may resu l lo t:o 1c ·v pnins ·ind, gnoscct ""PIie u cers. n .. 'b'I" r 1-· ' mucus.,. · us,,_.. t'ons. ahow 1b11l lho. :rc 1s a puss, 1 11,, u 1eteropln-icl, u1arrh Enrlyl _m,·~th~llgl ii \1,;; the dr. :ulation which may eventually result ·,0 ncggd. " 1111d udu~ats. reac 1111& e 1cll -..Ir Iac fail I Ute. .. f hctcroplwdiasis is done tltrough stool cxaminatio11 ·'. ind. Omgnos1s o ' . ' 1 ecnvcry characteristic eggs oftbe para SJtc. or the A previous natiom,idc survey in 1967 ~evealed a _1% pre,alence for hctcroph,.. but o rccentlycom:luded survey (::woo) LO C?mpostc lu \/alley, a province in Mi. n~d1~s1s btained a prrvalencc of more than 30% m the general population. Occ anao, ~eteroplwd iasis is related to the eating habits and the level of enviro1uneniatrre. nce _ of . san11rttto facilities in the community. 11 Drugs effective against tl1e other trematodes are also effe~tive agninst the hcteroph 'd There must be a strong advoca~' ll1rough health education 011 eating only th )1 s. cooked fish. Pro,ision of sanitary toilets will definitely be useful bul it shou J;~~~h~ forgotten that there are reservoir animals th;it can continuous ly seed the environment "'ilh heterophyid eggs. WATER-BORNE PROTOZ. OA Water is a very essential compoun d for th~ snnival of. living things. It is also relalcd to proper sanitation be it for personal hygiene or en V1ronmeotal sanitation. Wntcr however, when unsafe and inadequate, may be associated with nn cnomwus number of dise.,se agents. Parasites related to unsafe water are mostly protozoan. For the parasitic infections induclcd here, clrinking water serves as a passive vehicle for transmission. Entomoeba histolytica TI1is is the only pathogenic species of amoeba that can produce lytic substances that allows the parnsite to invade tissues. The infective stage of this parasite is call eel C}'St, which can ht> ingested from con ta min3ted water nod to some c,. 1cnt from contaminated food. Upon ingestion, tl1l! cysts go down into the digestive tract and in the lower part oftl1c small intestines where the p H is slightly alkaline. Four new parusitcs called the metacysts,viii emerge. These metacysts will the move to the colon where they "ill develop into the trophozoi tc stag-e (See Illus. 1s. 10). The tropboznites may develop back into the cystic stage when U1ere is proper reabsorption al lhc descending colon or may remain astrophozo itcs if there is no proper water rcabsorption. As tmphozoite. ~. they become capable of intestinal coloni?. ation resulting eitl1cr in mucoid. al stool, with or \'lithout bloocl strc;1ks. Sometimes, tissue i Jwasion may be e:...-tcnded to the deeper layers of the inlcstincs ghing rise to u. tceration of 1he mucosu, submucosu, muscle layer. ind even the scrosa. The trophor. oites are able to rea0 extra-in_testinal organs like the liver, lungs and brain, where the parasites can ~tabhsb amoeb,_c abscess for~1ation. As a maltcr of fact, trophowiles have been fouod mother organs hkesplcen, skin, :peri-cardium 11nd even the genitals. Infected individuals harboring c:yi. 1s are asymptomatic. However, they. ire cyst passers and can, themfore, be the e Atra source of infoction In the com mu nily. This is wl1ere the problems 011 food-handlers come in. 372 Sc. :,.., ~ wilh Cam Scan:11:r 