CAMALI.ANINA 



Tlio iiii'inlicrs of Imlli sii|»"rfiiiiiilics iif tliis siiIkikIit. I'mih.iI 

 liinoiilc;! ami Orin'iiiu'iiloidoa, so far as known utilize coin'iioiis 

 as intorniodiato hosts. Tlu'io can ho no doutit, from a oonsid 

 oration of tlio habitat ami life cycU-, that tho Caniallanoidoa, 

 ihvi'llinK as adnlts in the alimentary canal of aquatii' liosts, arc 

 the more primitive, and that the tissue dwcllinR Draciincnloidca, 

 sometimes occurring in land animals, are a later evolutionary 

 development. The relation of these two groups is conip;iratilc, 

 in a broad way, with the relation of the Si)irnroidea and the 

 Kilarioidea. In the case of the Filarioidca a habitat in the 

 tissues is accompanied by evolution of a new method of exit and 

 rtiitrance of embryos via the skin, whereas in the Dracuuculoidea 

 it is accompanied by a new — but difTerent — method of exit via 

 the skin, suitable for an aquatic animal, but with retention of 

 the primitive oral path of entry. 



C.\M.VT,I..\NUS SWEETI 



The life cycle of this worm was worked out by Moorthy 

 (1038). The adult worms live in the intestine of a freshwater 

 fish (Ophiciplialus flachiin) and produce free larvae which es- 

 cape with the feces of the host. The embryos have a tinely 

 striated cuticle, a single dorsal denticle or boring cuticular 

 tooth, and fairly well differentiated internal organs. On reach- 

 ing water the larvae are swallowed by suitable species of 

 Cjirlops and reach the body cavity 2 or .S hours after infection. 

 These larvae undergo the first molt '2i to 36 hours later, and 

 the second one after -■) to 7 days, in hot weather. The third- 

 stage larvae are provided with ridged jaws suggestive of those 

 of the adult, and have three unequal mucrones at the tip of 

 the tail. No mention is made of these larvae becoming en- 

 cysted in Cyclops. When infected Cyclops are eaten by small 

 fish the larvae are activated by fish bile, escape from their 

 copcpod hosts and undergo further development, including pos- 

 sibly the third molt, in the intestines of these fish. The infec- 

 tion of the final host is thought to result from feeding on the 

 second intermediate host, and the larvae undergo their fourth 

 and final molt in the intestines of this host, acquiring the adult 

 type of mouth. Whether the intervention of a second inter- 

 mediate host is optional or obligatory was not determined, but 

 in nature it would probabl.v be the usual thing, since the final 

 liost does not ordinarily feed on Cyclops directly. 





A-B — CamaUanuB gtreeti (A — Head, fourth stage; B — Tail, same). 

 C — Procamailanus fulvidraconin, mature embryo. D — Uninfected Cy- 

 clops. K — Cyclops infected with Dra4'uncutu« medinfnsU. F-G — Dra- 

 cuneulus medinensis (F — Cephalic region undergoing second molt; G — 

 Tail, same. A-B, after Moorthy, 19:i8, J. Parasit. v. 24 (4). C. after 

 Li, 1935. J. Parasit.. v. 21 (2). D. F,, after Fuelleborn. 1913. Filario- 

 •en des Mensch. F. G. after Moorthy. 1938, Am. J. Hyg. v. 27 (2). 



.No encysted forms of ('. siicti were fouiul in fish hosts, nor 

 was any evidence found of their penetrating the walla of the 

 intestine, but caniallaniil larvae of another type were found 

 encysted in the body cavity, loosely attached to the intestines. 

 These were observed to exeyst when eaten by Opliiciphaliis 

 (jachua, but failed to undeugo further develoimient in that host. 



An essentially .similar develoi)nu'nt in Cyclops has been dem- 

 on.strated for I'rocamallanus fill roil raconis by Li (l!t3.">), except 

 that only one molt was observed. It seems i)robal>le that the 

 first one was overlooked, since Li's figure of a (i-day old larva 

 corresponds with Moorthy 's second stage larva of Camallaniix, 

 and his second stage larva with Moorthy 's third stage. How- 

 ever, Fereira vl al (Ifi.Sfi) state that P. cearetisis develops only 

 to the second stage in Ditiptomiis, the third and fourth stages 

 being |)a.sscd in the intestines of the fiy of a fish other than 

 the definitive host. Although they speak of this host as a 

 "waiting host" (i.e., transport host) it would appear to be a 

 true second intermediate host if their observation is correct 

 that development to the third stage does not occur in Cyclops, 



It will be seen that the canuillanid life cycle is e-ssentially 

 the same as that of Hpiroxys or of Gnatlwstoma except for the 

 l)roducti"n of free embryos instead of eggs by the parent 

 worms. 



DrACUNCULUS ilEDlNEXSIS 



The adult female guinea worm, nraciinculiis medinensis, 

 when preparing for parturition, appears in the subcutaneous 

 tissues of her host and jiroduces a small ulcer on the surface of 

 the skin. Upon stimulation by chilling of the skin, which hap- 

 pens in nature when the skin is plunged into water, she con- 

 tracts violently in such a manner that a portion of the larva- 

 filled uterus is prolai)sed through a rupture in the cuticle, and 

 the prolapsed portion of the uterus, bursting, liberates a small 

 cloud of larvae. These larvae are unusually large (about OOO 

 /;» long), have a striated cuticle, a cuticular boring tooth or 

 denticle, well-developed esophagus and intestine with dilated 

 lumen, and a long filiform tail. 



These larvae swim about in water and undergo further devel- 

 opment only after being swallowed by certain species of cope- 

 pods. The details of their development was worked out by 

 Moorthy (1938). They reach the body cavity a few hours 

 after being swallowed. They undergo two molts in the body 

 cavity, the first one on the .5th to 7th day after infection, the 

 second on the 8th to 12th day in hot weather. They start under- 

 going the second molt before casting off the exuviae of the 

 first. The larvae grow very little in size, and actually de- 

 crease in length due to the loss of most of the filamentous tail. 

 The third stage larvae increase slightly in size for about a 

 week after the second molt, but after that undergo no further 

 development; they are infective for the definitive host 4 to 8 

 days after the exuviae of the second molt are shed. They have 

 a long esophagus of the adult type, and four mucrones at the 

 tip of the tail. They remain active in the body cavity of the 

 Cyclops for 4 or o weeks, but subsequently coil up and become 

 quiet, but are not encysted. In addition to the usual type of 

 larvae Moorthy also found a small proportion (1: 900) of 

 "abnormal" larvae in which the tail is malformed. Moorthy 

 suggested timt these may have been males, but it is more likely 

 that they should be regarded as abnormal individuals. 



The early development of the larvae in the definitive host has 

 not been followed. Sexually mature females 12 to 24 mm in 

 length were found by Moorthy and Sweet (1938) in deep con- 

 nective tissues of experimentally infected dogs 67 days after 

 infection, and Moorthy believed that at this time fertilization 

 had already taken place. Migration of the worms to the 

 subcutaneous tissue and the formation of an ulcer for the 

 egress of larvae occurs about a year after Infection in man. 



An essentially similar life cycle occurs in the case of D. 

 ophithnsis of garter snakes (Brackett, 1938). Cyclops infected 

 with this species may be eaten by tadpoles and possibly other 

 transijort hosts; in tadpoles the larvae were found to remain 

 free and viable in the body cavity for at least 2 weeks, but no 

 further growth or development was observed. 



The Philometridae, which have been found in a great variety 

 of parenteral locations in aquatic hosts, have a life cycle es- 

 sentially similar to that of Dracunculits. Thomas (1929) found 

 that the first-stage larvae of Fhilometra nodtilosa are devoured 

 by Cyclops and invade its body cavity. Attempts at infection 



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