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PubMed1988

Dracunculus insignis: experimental infection in the ferret, Mustela putorius furo.

The laboratory study of dracunculiasis has suffered from the lack of a suitable, readily available animal model. We have been able to experimentally infect ferrets. Mustela putorius furo, with the North American dracunculid, Dracunculus insignis. Ferrets were inoculated with 75 to 100 infective larvae and were necropsied 90 to 240 days later. Guinea worms were recovered from 10 (56%) of 18 ferrets. A total of 44 worms were recovered, for an average of 4.4 worms per infected ferret. Gravid female worms were recovered as early as 128 days postinoculation. Thirteen (87%) of 15 gravid female worms were recovered from the extremities. Living male worms were recovered at 200 days of age, indicating that not all male worms die shortly after mating. First-stage larvae recovered from gravid females as early as 200 days of age were found to be infective to the copepod, Acanthocyclops vernalis. These observations suggest that the ferret is an excellent laboratory animal for dracunculiasis research.

Animals↗

PubMed1986

In vitro demonstration of in utero larval development in an oviparous parasitic nematode: Haemonchus contortus.

The life-cycle of Haemonchus contortus, a pathogenic stomach nematode of sheep, is typical of those of the other members of the superfamily Trichostrongyloides, all of which require a period of development outside the definitive host. Classically, gravid H. contortus, known as strictly oviparous, releases her eggs into the abomasal lumen. The eggs are passed out in the faeces in which they hatch into the 1st-stage larvae and then develop into the infective 3rd-stage larvae. We have developed a method to study the fate of eggs within gravid worms. Using this procedure, we have shown that H. contortus may also exhibit viviparity with apparently normal development from the egg to the 4th larval stage taking place within the gravid female maintained in vitro. On the basis of these observations we speculate that viviparity might occur in vivo with consequent autoinfections; if so, this might explain some puzzling clinical and epidemiological features of haemonchosis, as well as the incomplete efficacy of current control measures.

Abomasum↗

PubMed1999

Density-dependent effects on Anguillicola crassus (Nematoda) within its European eel definitive host.

Density-dependent effects on adult and larval stages of the introduced nematode parasite Anguillicola crassus in the European eel definitive host were examined in the laboratory in naturally infected fish, and in field samples. The effect of adult nematode subpopulations on larval development over time and the effect of increasing adult intensity on the gravid female subpopulations were investigated. At high adult subpopulations the movement of larvae from the swimbladder wall into the swimbladder lumen appears to be inhibited, and A. crassus larvae to be arrested in development in a density-dependent manner. The number of gravid females per host reaches a constant level, and so the proportion of gravid female nematodes per adult subpopulation decreases relative to further increasing total adult nematode numbers. Both these mechanisms have the potential to regulate infrapopulations of A. crassus within the eel definitive host and thus the parasite suprapopulation.

Anguilla↗

PubMed2003

Factors accounting for the variability in the behavioral response of the onion fly (Delia antiqua) to n-dipropyl disulfide.

The onion fly Delia antiqua is a specialist herbivore attacking only onions and closely related Allium species. n-Dipropyl disulfide (Pr2S2) has long been known to be attractive to onion flies in the laboratory and in the field. However, the insect's response is highly variable. Using behavioral bioassays we found that Pr2S2 was highly attractive to gravid, mated female onion flies,but did not stimulate oviposition. The response of female onion flies was concentration dependent. The physiological state of the flies (i.e., age, mating status, egg load/oviposition experience) also affected their responsiveness. The response of both sexes of onion flies varied with age, but females were always more strongly attracted than males. Responsiveness of females increased during the first 10 days after emergence. It stayed at a high level until 21 days after which the experiment was terminated. The responsiveness of males reached a maximum at 6-7 days after which it declined. Mated, gravid females responded more strongly to Pr2S2 than unmated, gravid females. Females deprived of the opportunity to oviposit were more attracted compared to females that had oviposited on cut onions prior to the experiment. Electroantennograms (EAG) of females revealed a higher response to stimulation compared to males. The EAG-response of females was not affected by mating status.

Allium↗

PubMed1997

Epidemiology of syphilis in pregnancy in rural South Africa: opportunities for control.

The paper describes the epidemiology, risk factors and impact on pregnancy outcome of syphilis in pregnant women in rural South Africa. Prevalence was determined from laboratory records. A case-control study of 200 women (50 cases with syphilis) was done to investigate possible risk factors. To determine the impact on pregnancy outcome, and to evaluate the effect of treatment, a retrospective cohort was constructed. Overall prevalence of syphilis was 6.5%; it was highest in the urban antenatal clinic (9%). The odds ratios for syphilis in women gravidity 3-5 compared to gravidity 6 was 3.2 and 2.3 compared to women with gravidity 2 or less. For women with a previous birth, those with a previous perinatal death were 3.2 times more likely to have syphilis after adjusting for other risk factors. Pregnancy outcome was available for 187 women. The adjusted odds ratio of an adverse pregnancy outcome in women with syphilis was 11.8. All still births occurred in women with syphilis. The prevalence of syphilis is high in this rural area and screening should be applied to all women. Although screening was comprehensive, less than half of the detected cases were fully treated and a poor perinatal outcome ensued. On-site testing for syphilis at the time of booking would allow treatment to start immediately.

Adolescent↗

PubMed1998

[Malaria transmission in the rural zone of Niakhar, Senegal].

The anopheline bioecology and the malaria transmission were studied from January to December 1995 in three villages of the sahelian rural area of Niakhar, Senegal. This area of 29000 inhabitants, has been for several decades, a regional observatory for population and health. The three methods used for collecting mosquitoes were the collection at larval stages, the all night human biting collection, and the pyrethrum spray catch in houses during afternoons. The anophelines collected were, by numerical importance: Anopheles arabiensis, An. rufipes, An. gambiae, An. pharoensis, An. funestus and An. coustani. In the An. gambiae complex, An. arabiensis represented 97% of man biting females and 98% of half gravid resting females (difference not significant); the other reminding species of this complex was always An. gambiae. These two species belonging to the An. gambiae complex were responsible for the totality of the transmission. The anthropophilic index, obtained from half gravid indoor resting An. gambiae s.l., was 83%. The annual biting rate of An. gambiae s.l. varied from 512 to 1558 bites per man per night, depending on the villages. Vectors were observed all year long but their densities were low during the dry season. Vector population presented a notable increase due to the rains, with a maximum of about 10 bites per man per night in September or at the beginning of October; during September the biting rate represented 48% of the annual biting rate. The sporozoitic index of An. gambiae s.l., obtained by ELISA revealing the circumsporozoite protein, was 1.6% for human biting females and 1.8% for half-gravid resting females (difference not significant). Plasmodium falciparum was the only plasmodial species observed among infected anophelines. The annual transmission in the vo villages representative of the Niakhar area were 9 and 12 bites of infected anophelines per man, occurring mainly from August to October. In the third village, not representative of the area regarding permanent breeding places, the transmission was 26 bites of infected anopheline per man per year. These results were discussed in the Senegambian and sahelian contexts.

Animals↗

PubMed2004

Differential diagnosis between Tunga penetrans (L., 1758) and T. trimamillata Pampiglione et al., 2002 (Insecta, Siphonaptera), the two species of the genus Tunga parasitic in man.

Of the ten currently known species of sand fleas, only two, Tunga penetrans and Tunga trimamillata, are known to be parasites of man, besides other warm blooded animals, most of which are peridomestic. The hosts of the other eight are limited to a few genera of wild mammals. T. trimamillata was only recently identified and differentiated from T. penetrans by features of the gravid female phase. In the present paper the different morphological characters of both for non-gravid females and males of the two species are described. In the non-gravid-females the distinguishing characters are: a) differences in the length of the first two segments of the maxillary palps (the first is the longest in T. trimamillata, whereas the second is the longest in T. penetrans), this feature is associated with another character i.e. the presence of short, thick spines in addition to the bristles on the surface of the segments only in T. trimamillata; b) the presence, only in T. trimamillata, of a row of spines on the antero-medial surface of the libia of the 3rd pair of legs; c) the last abdominal spiracle protrudes in T. trimamillata but not in T. penetrans; d) the hood of the hilla in spermatheca is surrounded by a papilla only in T. penetrans. The following morphological characters differentiate males of T. trimamillata and T. penetrans: a) T. trimamillata has a row of spines on the antero-medial surface of the tibia of the 3rd pair of legs; b) the diameter of the abdominal spiracles of T. trimamillata is smaller than that of T. penetrans and the edges of the spiracles are more regular; c) the claspers and aedeagus of T. trimamillata are shorter than those of T. penetrans; d) the profile of the oedeagal apodeme differs between the two species.

Animals↗

PubMed2006

Primary dysmenorrhea and risk of preterm delivery.

Little is known about the mechanism and biochemical pathway of preterm delivery. Some drugs used to treat preterm labor are also useful for the treatment of primary dysmenorrhea. This study attempted to evaluate the association between primary dysmenorrhea and preterm delivery from an epidemiological perspective. A nested case-control study was conducted; 329 singleton preterm delivery cases were investigated, in aggregate and in subgroups (spontaneous preterm labor and preterm premature rupture of membranes). Concurrently, 329 singleton gravid women with term delivery served as controls. Medical charts and records provided information about the maternal history of dysmenorrhea, index pregnancy outcome, and demographic characteristics. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using the multiple logistic regression method. Gravid women with a history of primary dysmenorrhea had no more risk of preterm delivery than those without a history of primary dysmenorrhea (adjusted OR, 1.16; 95% CI, 0.95 to 2.19; p=0.37). However, for subgroup analysis, gravid women with severe primary dysmenorrhea were associated with an adjusted 2.73-fold risk of spontaneous preterm delivery (95% CI, 1.49 to 4.95; p=0.02), and with an adjusted 1.51-fold risk of preterm premature rupture of membranes (95% CI, 0.68 to 3.22; p=0.31). Severe primary dysmenorrhea is associated with an increased risk of spontaneous preterm delivery. A common pathophysiologic pathway may exist between these two disorders. Further in-depth biochemical and molecular studies are necessary to explore this phenomenon.

Adult↗

PubMed1989

Maternal, amniotic fluid and cord blood metabolic profile in normal pregnant and gestational diabetics during recurrent withholding of food.

In order to advise regarding the religious practice of withholding food, we studied the metabolic changes after successive 15 days of recurrent fasting of 13 hours every day in maternal plasma and liquor amnii of obese normal gravids and gestational diabetics in their third trimester. There were no significant differences between those who fasted that period for one day prior to elective cesarean section (CS) and those who fasted the same period repeatedly for 15 days. The fasted gravids had significant rises in glycerol, beta-hydroxybutyrate (BOHB) and nonesterified fatty acids (NEFA) (P less than 0.0001, P less than 0.005 and P less than 0.01, respectively) in maternal plasma, compared to unfasted gravid groups and ungravid fasted group. No significant metabolic difference was found in the liquor amnii withdrawn from fasted and unfasted groups. The influence of such short term of starvation on the fetal metabolic profile was studied in the cord blood during cesarean section (CS). Glucose, glycerol and NEFA were significantly lower in arterial than in venous cord plasma (P less than 0.05, P less than 0.01 and P less than 0.01, respectively) indicating that the fetus could utilize these substrates. Positive correlation was found between the levels of BOHB in the mother and venous cord plasma on the one hand and their levels in the arterial cord plasma and liquor amnii on the other hand implying that this substrate passes unutilized through the fetus to the liquor amnii. A pregnant woman in the third trimester should not withhold food for long periods.

Adult↗

PubMed2000

The prevalence of thromboembolic events among women with extended bed rest prescribed as part of the treatment for premature labor or preterm premature rupture of membranes.

OBJECTIVE: This study was undertaken to determine the prevalence of thromboembolic events among women with extended bed rest prescribed as part of the treatment of premature labor or preterm premature rupture of membranes. STUDY DESIGN: A retrospective chart review was undertaken of all women who had bed rest of >/=3 days' duration prescribed as part of the treatment of premature labor or preterm premature rupture of membranes in the Akron General Medical Center Perinatal Unit during the period January 1, 1997-December 31, 1998. The prevalence of thromboembolic events in this population was determined. The charts of all additional gravid women with antepartum or postpartum deep vein thrombosis or pulmonary embolism diagnosed during the study period were also reviewed. The prevalence of these disorders among the pregnant population for whom extended bed rest was not prescribed as part of the treatment of premature labor or preterm premature rupture of membranes was also calculated. Statistical comparison of the prevalences in the 2 populations was undertaken by means of the chi(2) analysis with the Fisher exact test. RESULTS: There were 192 patients admitted during the study period who had extended bed rest prescribed as part of the treatment of premature labor or preterm premature rupture of membranes. Three of these women had thromboembolic events, for a prevalence of 15.6 cases per 1000 women. Five additional gravid women were admitted for the treatment of deep vein thrombosis or pulmonary embolism. There were 6164 deliveries among women not treated with extended bed rest for premature labor or preterm premature rupture of membranes during this period. Thus the prevalence of these phenomena among the remaining pregnant women was 0.8 cases per 1000 women. The prevalences of these disorders in the 2 populations were highly significantly different. CONCLUSION: The prevalence of thromboembolic events among women for whom extended bed rest is prescribed as part of the treatment of premature labor or preterm premature rupture of membranes is significantly increased with respect to that among gravid women who do not receive this therapy and is substantially higher than previously reported. If this finding is confirmed in other populations, it may be prudent to undertake further studies to determine whether this prevalence can be reduced.

Bed Rest↗

PubMed2001

Fetal control of parturition in marsupials.

Among marsupials, the control of birth is best understood in the tammar wallaby. The young is tiny relative to the mother and is highly altricial. Adult female tammar wallabies weigh 5 kg, whereas the neonate weighs about 400 mg. However, despite this small size, there is clear evidence that the fetus provides the signal that sets the timing of birth through several mechanisms. A fetal signal activates a nitric oxide-guanylate cyclase system in the myometrium that may maintain myometrial inactivity, and this is down-regulated at term. There is also up-regulation of prostaglandin (PG) production in the gravid endometrium during the last two days of gestation that parallels increased placental PG synthesis, and a pregnancy-specific up-regulation of oxytocin receptors in the gravid myometrium that increases the responsiveness of the gravid uterus to mesotocin. These changes facilitate parturition, but an acute fetus-derived signal appears to trigger parturition. The fetal signal is probably related to glucocorticoid production. The fetal adrenal matures and is able to synthesize cortisol by Day 22 of the 26-day gestation. The fetal adrenals double in size between Day 24 and term, and their cortisol content increases over 10-fold. The pituitary of the neonate contains presumptive corticotrophs, and the adrenals increase cortisol production in response to adrenocorticotrophin. Prostaglandin E2, which is produced by the placenta, is also a potent stimulant of fetal adrenal cortisol synthesis. Treatment of tammars in late gestation with the cortisol agonist, dexamethasone, triggers birth around 23 h later. There is thus a strong case that fetal adrenal cortisol plays a key role in the preparation for birth and the timing of it. Further studies are in progress to more clearly define the mechanisms behind these actions of cortisol.

Adrenal Glands↗

PubMed1992

Maternal recognition of pregnancy in the Tasmanian bettong, Bettongia gaimardi (Marsupialia: Macropodoidea).

The fetus of the marsupial Bettongia gaimardi, the Tasmanian bettong, has both morphological and cytological effects upon the gravid uterus. Development of diapausing embryos or the initiation of oestrous cycles was achieved by removal of the pouch young (RPY). Increases in the diameter of the uterine basal endometrial glands were noted 3 and 4 days later. An animal at Day 5 after RPY had glands in the gravid uterus that were significantly larger than those in the non-gravid uterus (P less than 0.01). This difference was also found in non-pregnant animals before Day 11 and was believed to be due to the local presence of the corpus luteum. Thereafter, significant differences were only found in pregnant animals until parturition at Day 17 or 18 after RPY. These differences were attributed to the local effect of the fetus and reflect a 'maternal recognition of pregnancy', as found in other macropodoid species.

Animals↗

PubMed1991

Experimental infection of Libyan sheep with Echinococcus granulosus.

The growth rate of unilocular hydatid cysts over a two-year period was studied in Libyan sheep dosed orally with gravid segments of Echinococcus granulosus taken from stray town dogs. Seven of the eight sheep dosed with 20-100 gravid segments (say 4000-20,000 eggs) had developed only infertile hydatid cysts after 107-611 days. Sheep dosed with 1000 gravid segments (say 200,000 eggs) had developed only sterile cysts when examined 358 days after dosing. Fertile cysts were recovered from the lungs after 428 days, and after 584 days from the liver. Only sterile cysts were seen in the heart, spleen and kidneys.

Animals↗

PubMed1981

[Effect of the copper status on the reproduction performance and the milk yield of cows in 2 copper-deficient locations. 2. Effect of copper deficiency on the reproduction performance and the milk yield of cows].

The influence of copper deficiency on the reproduction performance of cows has not often been investigated. In two habitats feeding cows with mineral mixtures rich in copper resulted in a significant reduction of the aperiodically extended sexual cycles. The beginning of the first visible symptoms of heat, the period between gravidities, the duration of gravidity, the birth weight of the calves and the Cu-content of the colostrum remained uninfluenced by Cu-supply. The liver weight increase of the calves from cows without Cu-supplement during gravidity was by 5% lower during the first 90 days of life than that of the offspring of cows with additional intrauterine Cu-supply (p greater than 0.05). The mineral mixture increased the milk yield by 0.4 resp. 0.5 kg and the milk fat content by 0.10 resp. 0.13%. This resulted in an excess production of 32 resp. 62 g milk fat per cow and day of the experiment (p greater than 0,05).

Animals↗

PubMed2001

HIV and other predictors of serum beta-carotene and retinol in pregnancy: a cross-sectional study in Zimbabwe.

BACKGROUND: Vitamin A status during pregnancy is important to maternal and infant health. OBJECTIVE: Our goal was to identify predictors of serum beta-carotene and retinol. DESIGN: This was a cross-sectional study of 1669 women (22-35 wk of gestation) in Harare, Zimbabwe, who were receiving prenatal care. The statistical effects of age, season, gestational age, gravidity, HIV-1 infection, malaria parasitemia, and serum alpha1-antichymotrypsin (ACT) on serum beta-carotene (log10 transformed) and retinol were estimated by using multiple linear regression analyses. RESULTS: HIV infection was found in 31.5% of the women; 0.4% had malaria. Serum beta-carotene concentrations (geometric x: 0.19 micromol/L) were lower in HIV-infected women than in uninfected women (10beta = 0.78; 95% CI: 0.72, 0.84) and increased with age (10beta = 1.05; 1.02, 1.07) in gravida 1 but not in gravida > or =2 (P for interaction = 0.00002). Serum retinol (x: 0.92 micromol/L) increased with age (beta = 0.004; 0.0001, 0.008) in uninfected women but not in HIV-infected women (P for interaction = 0.02) and was 0.05-micromol/L (0.02, 0.09) lower in HIV-infected women than in uninfected women at 24 y of age. Furthermore, gestational age, season, use of prenatal supplements, and malaria were predictors of serum beta-carotene. Serum retinol was lower in women carrying male (beta = -0.04; -0.08, -0.00005) and multiple (beta = -0.21; -0.35, -0.08) fetuses. Serum ACT concentrations of 0.3-0.4, 0.4-0.5, and >0.5 g/L were associated with 3%, 11%, and 44% lower serum beta-carotene and 0.04-, 0.15-, and 0.41-micromol/L lower serum retinol. Serum ACT (g/L) was higher in women with malaria than in those without (beta = 0.10; 0.03, 0.16) and in gravida 1 than in gravida > or =2 (beta = 0.012; 0.003, 0.021), but was not higher in HIV-infected women than in uninfected women (beta = 0.001; -0.008, 0.011). CONCLUSIONS: HIV infection, malaria, gravidity, and gestational age were predictors of serum beta-carotene and retinol. Serum ACT was an important predictor of both and was associated with gravidity and gestational age.

Acute-Phase Reaction↗

PubMed1993

Fecundity and oviposition in laboratory colonies of the screwworm fly (Diptera: Calliphoridae).

The screwworm fly is mass-produced using an artificial larval diet and an artificial oviposition substrate. On the artificial diet, mean fecundity was 185 eggs per female, whereas host-reared flies averaged 280 eggs per female. Host-reared flies were generally larger (head capsule width [HCW] > 3.6 mm) than laboratory-reared flies (HCW < 3.6 mm). Larger flies are generally more fecund, and size is related to larval nutrition. Only 75-89% of females reared on artificial diet and maintained at 30 degrees C were gravid at 6 d of age compared with 100% of host-reared females tested at 5-6 d. When gravid females were offered artificial substrate for oviposition, approximately 28% failed to oviposit and another 11% laid only partial clutches. Among all females tested for oviposition, 25% of the total egg production was withheld. Fecundity influenced oviposition, because the more mature eggs a female had, the more likely she was to oviposit. Supplementing the adult diet of honey and water with raw meat increased fecundity by 14% under normal laboratory conditions, but by as much as 350% in flies in which larval feeding was curtailed by removal of the larvae from the media 1 d before the normal completion of development. Many females became gravid in 4-5 d at 30 degrees C versus 8-9 d at 22 degrees C. But fecundity and oviposition rate were more variable (less synchronous) in colonies maintained at the higher temperature. This suggests that there may be greater selection for laboratory adaptation at the higher maintenance temperatures.

Animals↗

PubMed1992

Effect of the repellent deet on the antennal chemoreceptors for oviposition in Aedes aegypti (Diptera: Culicidae).

The insect repellent, N,N-diethyl-m-toluamide (deet), interferes with detection of the host attractant, lactic acid (LA), by LA-excited neurons on the antennae of female Aedes aegypti (L.) mosquitoes. In the current laboratory behavioral experiment, the attraction of gravid female mosquitoes to a source of ethyl propionate, an oviposition attractant, was reduced by a factor of two when deet was present. Similarly, when deet was presented together with ethyl propionate in electrophysiological experiments, sensitivity of the neural response to ethyl propionate was depressed in a transient, dose-dependent manner that could account for the reduction in behavioral attraction of gravid females to ethyl propionate. Electrophysiologically, the sensitivity of oviposition attractant receptors to ethyl propionate on gravid females was not different from that on nongravid host-seeking females. The similarity between the depression of sensitivity of the oviposition attractant-sensitive neurons induced by deet and that observed in the host attractant-sensitive neurons suggest a common mode of action of deet on peripheral chemoreceptor neurons that mediate these behaviors.

Aedes↗

PubMed1998

Ovarian development and parity determination in Culiseta melanura (Diptera: Culicidae).

A laboratory colony of Culiseta melanura (Coquillett) was used to follow ovarian development from emergence to oviposition and to validate the accuracy of using follicular dilatations to age grade females. We observed no change in the size of the primary follicles in unfed females from emergence to 3 d of age. Sugar feeding stimulated follicular growth and produced the following 3 types of ovarioles: (1) large primary follicles that eventually developed into functional ovarioles; (2) lesser numbers of small primary follicles that developed small amounts of yolk after blood feeding but degenerated in the latter stages of development; and (3) small primary follicles that did not develop yolk after blood feeding, exhibited accelerated growth, and became rogue ovarioles with multiple false dilatations. The yolk of the small primary follicles that degenerated after blood feeding was resorbed during stage IV of egg development, and the degenerating follicles resembled gonotrophic dilatations in the latter stages of the cycle. This process produced gravid females with some secondary follicles that appeared to possess a gonotrophic dilatation. Other authors have termed these artifacts false or agonotrophic dilatations. Degenerating ovarioles bearing these artifacts were used to determine physiological age in blood fed and gravid Cs. melanura. Nulliparous females in the latter stages of gonotrophic development have single false dilatations on degenerating ovarioles, 1-parous females have 2 false dilatations on degenerating ovarioles. In unfed, nulliparous females, false dilatations can be distinguished from true dilatations because they are attached to secondary follicles that are much smaller than the primary functional follicles that fill most of the ovary. In blood fed and gravid females, follicles that support false dilatations always lack yolk. Rogue ovarioles are unreliable indicators of physiological age and should not be used for diagnostic purposes.

Animals↗