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The effect of ultra-violet irradiation on cercariae of Schistosoma mansoni
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LABORATORY MEETING
When fresh serum from baboons or humans infected with S. haematobium was substituted for normal serum in the culture flasks, many schistosomula died during the initial 4-day period. The same anti-S. haematobium sera had only a slight lethal effect on schistosomula of S. mansoni. A converse effect was observed with serum from a rhesus monkey hyperimmunized against S. mansoni. This serum had a very marked lethal effect on schistosomula of S. mansoni and no detectable activity against schistosomula of S. haematobium. These results suggest that there may be no cross-immunity between S. haematobium and S. mansoni.
The effect o f ultra-violet irradiation on cercariae o f Schistosoma mansoni A. M. G H A N D O U R AND G. WEBBE Winches Farm Field Station (London School of Hygiene and Tropical Medicine) STANDEN and FULLER (1959) have shown that ultra-violet irradiation of cercariae of S. mansoni inhibits their development to the adult stage. T h e present work was carried out in an attempt to explain this phenomenon. A Hanovia ultra-violet lamp was used to irradiate freshly shed cercariae (maintained in a 10 ml. suspension) at a distance of 16.5 cm. from the lamp for 5-20 seconds i.e. exposures that had no visible effect on the motility and behaviour of the cercariae. The demonstration showed that irradiation of the cercariae for intervals as short as 5-20 seconds markedly increased their mortality during penetration of mouse skin. When normal non-irradiated cercariae were used to infect mice only 30% of them died during penetration. However, when carcariae irradiated for 20 seconds were used as many as 68% died. Migration of schistosomula to the lungs of mice was unaffected by irradiation of cercariae. T h e recovery of living fully mature schistosomula was relatively high on day 3 postinfection (2.26%) increasing steadily to a peak of 16.9% on day 7. This contrasts sharply with irradiated cercariae the migration of which was drastically affected: very few (0.5-1.0%) dead immature schistosomula were recovered on day 3 postinfection, and none at all from day 4-10. T h e percentage recovery of mature adult worms from their usual locations in the liver and mesenteric veins was quite normal in mice following infection with normal non-irradiated cercariae, as high as 33% recovery being observed. However, no mature worms were recovered from mice infected with irradiated cercariae. T h e demonstration clearly showed the inimical effects of ultra-violet irradiation on cercariae of S. mansoni. REFERENCE STANDEN, O. D. & FULLER, K. A. (1959). Trans. R. Soc. trop. Med. Hyg., 53, 372.
M o r p h o l o g y and ecology o f L y m n a e i d m a i l s o f Iraq w i t h special reference to fascioHasis H U S S E I N M. A L - M A S H H A D A N I Ross Institute of Tropical Hygiene, London School of Hygiene and Tropical Medicine L. auricularia L. T h e snail is the largest species of Lymnaeidae in Iraq. Its morphology and detailed anatomy concerning digestive and reproductive systems have been described. Shell measurements show that there is a slight increase in aperture-length/shell-length and width-length/shell-length percentages ratios with an increase in shell-length of various populations of L. auricularia investigated. All the snail populations are susceptible to infection with F. gigantica and viable metacercariae are produced by all of them. T h e rate of infection varies with the age of the snails and with the localities ranging from 16.0 to 90-9%. The prepatent period of F. gigantica within the snail host is determined as 36-62 days 14-15 mature cercarlae of F. gigantica are usually seen inside a mature redia. Experimentally infected rabbits with F. gigantica either succumbed or showed serious liver cirrhosis; 6-7 immature worms were recovered from each rabbit. Infection rate of fascioliasis at Sheikh Omar abattoir, Baghdad, varied from 0-4-42.6% among sheep, goat, cow and waterbuffalo. Infection rates of paramphistomiasis varied from 0.4--6.9% among goat, cow and water-buffalo. Infection rates of hydatidosis varied from 0.6--4.0% among sheep, goat, cow and waterbuffalo. Infection with liver fluke seriously affects the animals, moreover, their livers are no longer suitable for h u m a n consumption. T h e larval trematodes encountered in L. auricularia are distome cercariae, xiphi diocercariae, echinostome cercariae and furcocercariae. It has been found that rates of infection with different trematodes depends on the month of infection, size and locality of the snails. Oviposition is a continuous process throughout the year under laboratory conditions and even in field in sheltered habitats, eggs within the egg-masses ranging from 4-160. Growth of young snails is moderate under laboratory conditions 24 °27°C., reaching maturity in about 8-9 weeks. The ecology and distribution of the snail in Lower Mesopotamia are described and the habitats investigated are plotted and numbered on the map. The snail is widely distributed. It is truly aquatic, found in permanent, still or slow flowing and temporary collections of water. T h e slightly alkaline environment which is found to be more common in the Iraqi habitats of the snail should be taken into consideration when selecting the most suitable chemicals for, snail control. There is no
LABORATORY MEETING
When fresh serum from baboons or humans infected with S. haematobium was substituted for normal serum in the culture flasks, many schistosomula died during the initial 4-day period. The same anti-S. haematobium sera had only a slight lethal effect on schistosomula of S. mansoni. A converse effect was observed with serum from a rhesus monkey hyperimmunized against S. mansoni. This serum had a very marked lethal effect on schistosomula of S. mansoni and no detectable activity against schistosomula of S. haematobium. These results suggest that there may be no cross-immunity between S. haematobium and S. mansoni.
The effect o f ultra-violet irradiation on cercariae o f Schistosoma mansoni A. M. G H A N D O U R AND G. WEBBE Winches Farm Field Station (London School of Hygiene and Tropical Medicine) STANDEN and FULLER (1959) have shown that ultra-violet irradiation of cercariae of S. mansoni inhibits their development to the adult stage. T h e present work was carried out in an attempt to explain this phenomenon. A Hanovia ultra-violet lamp was used to irradiate freshly shed cercariae (maintained in a 10 ml. suspension) at a distance of 16.5 cm. from the lamp for 5-20 seconds i.e. exposures that had no visible effect on the motility and behaviour of the cercariae. The demonstration showed that irradiation of the cercariae for intervals as short as 5-20 seconds markedly increased their mortality during penetration of mouse skin. When normal non-irradiated cercariae were used to infect mice only 30% of them died during penetration. However, when carcariae irradiated for 20 seconds were used as many as 68% died. Migration of schistosomula to the lungs of mice was unaffected by irradiation of cercariae. T h e recovery of living fully mature schistosomula was relatively high on day 3 postinfection (2.26%) increasing steadily to a peak of 16.9% on day 7. This contrasts sharply with irradiated cercariae the migration of which was drastically affected: very few (0.5-1.0%) dead immature schistosomula were recovered on day 3 postinfection, and none at all from day 4-10. T h e percentage recovery of mature adult worms from their usual locations in the liver and mesenteric veins was quite normal in mice following infection with normal non-irradiated cercariae, as high as 33% recovery being observed. However, no mature worms were recovered from mice infected with irradiated cercariae. T h e demonstration clearly showed the inimical effects of ultra-violet irradiation on cercariae of S. mansoni. REFERENCE STANDEN, O. D. & FULLER, K. A. (1959). Trans. R. Soc. trop. Med. Hyg., 53, 372.
M o r p h o l o g y and ecology o f L y m n a e i d m a i l s o f Iraq w i t h special reference to fascioHasis H U S S E I N M. A L - M A S H H A D A N I Ross Institute of Tropical Hygiene, London School of Hygiene and Tropical Medicine L. auricularia L. T h e snail is the largest species of Lymnaeidae in Iraq. Its morphology and detailed anatomy concerning digestive and reproductive systems have been described. Shell measurements show that there is a slight increase in aperture-length/shell-length and width-length/shell-length percentages ratios with an increase in shell-length of various populations of L. auricularia investigated. All the snail populations are susceptible to infection with F. gigantica and viable metacercariae are produced by all of them. T h e rate of infection varies with the age of the snails and with the localities ranging from 16.0 to 90-9%. The prepatent period of F. gigantica within the snail host is determined as 36-62 days 14-15 mature cercarlae of F. gigantica are usually seen inside a mature redia. Experimentally infected rabbits with F. gigantica either succumbed or showed serious liver cirrhosis; 6-7 immature worms were recovered from each rabbit. Infection rate of fascioliasis at Sheikh Omar abattoir, Baghdad, varied from 0-4-42.6% among sheep, goat, cow and waterbuffalo. Infection rates of paramphistomiasis varied from 0.4--6.9% among goat, cow and water-buffalo. Infection rates of hydatidosis varied from 0.6--4.0% among sheep, goat, cow and waterbuffalo. Infection with liver fluke seriously affects the animals, moreover, their livers are no longer suitable for h u m a n consumption. T h e larval trematodes encountered in L. auricularia are distome cercariae, xiphi diocercariae, echinostome cercariae and furcocercariae. It has been found that rates of infection with different trematodes depends on the month of infection, size and locality of the snails. Oviposition is a continuous process throughout the year under laboratory conditions and even in field in sheltered habitats, eggs within the egg-masses ranging from 4-160. Growth of young snails is moderate under laboratory conditions 24 °27°C., reaching maturity in about 8-9 weeks. The ecology and distribution of the snail in Lower Mesopotamia are described and the habitats investigated are plotted and numbered on the map. The snail is widely distributed. It is truly aquatic, found in permanent, still or slow flowing and temporary collections of water. T h e slightly alkaline environment which is found to be more common in the Iraqi habitats of the snail should be taken into consideration when selecting the most suitable chemicals for, snail control. There is no