Risk factors associated with first symptomatic infection of {\it Cryptosporidium parvum\/} in an infant population in Bilbeis, Egypt

Diarrhea disease is a leading cause of morbidity and mortality, especially in children in developing countries. An estimate of the global mortality caused by diarrhea among children under five years of age was 3.3 million deaths per year. Cryptosporidium parvum was first identified in 1907, but it was not until 1970 that this organism was recognized as a cause of diarrhea in calves. Then it was as late as 1976 that the first reported case of human Cryptosporidiosis occurred. This study was conducted to ascertain the risk factors of first symptomatic infection with Cryptosporidium parvum in a cohort of infants in a rural area of Egypt. The cohort was followed from birth through the first year of life. Univariate and multivariate analyses of data demonstrated that infants greater than six months of age had a two-fold risk of infection compared with infants less than six months of age (RR = 2.17; 95% C.I. = 1.01-4.82). When stratified, male infants greater than six months of age were four times more likely to become infected than male infants less than six months of age. Among female infants, there was no difference in risk between infants greater than six months of age and infants less than six months of age. Female infants less than six months of age were twice more likely to become infected than male infants less than six months of age. The reverse occurred for infants greater than six months of age, i.e., male infants greater than six months of age had twice the risk of infection compared to females of the same age group. Further analysis of the data revealed an increased risk of Cryptosporidiosis infection in infants who were attended in childbirth by traditional childbirth attendants compared to infants who were attended by modern childbirth attendants (nurses, trained midwives, physicians) (RR = 4. 18; 95% C.I. = 1.05-36.06). The final risk factor of significance was the number of people residing in the household. Infants in households which housed more than seven persons had an almost two-fold risk of infection compared with infants in homes with fewer than seven persons. Other risk factors which suggested increased risk were lack of education among the mothers, absence of latrines and faucets in the homes, and mud used as building material for walls and floors in the homes. ^

Fate and effects of drilling wastes in a shallow estuarine mesocosm

To address concerns expressed about the possible effect of drilling mud discharges on shallow, low-energy estuarine ecosystems, a 12 month study was designed to detect alterations in water quality and sediment geochemistry. Each drilling mud used in the study and sediments from the study site were analyzed in the laboratory for chemical and physical characteristics. Potential water quality impacts were simulated by the EPA-COE elutriation test procedure. Mud toxicity was measured by acute and chronic bioassays with Mysidopsis bahia, Mercenaria mercenaria, and Nereis virens.^ For the field study, a relatively pristine, shallow (1.2 m) estuary (Christmas Bay, TX) without any drilling activity for the last 30 years was chosen for the study site. After a three month baseline study, three stations were selected. Station 1 was an external control. At each treatment station (2, 3), mesocosms were constructed to enclose a 3.5 m$\sp3$ water column. Each treatment station included an internal control site also. Each in situ mesocosm, except the controls, was successively dosed at a mesocosm-specific dose (1:100; 1:1,000; or 1:10,000 v/v) with 4 field collected drilling muds (spud, nondispersed, lightly-treated, and heavily-treated lignosulfonate) in sequential order over 1.5 months. Twenty-four hours after each dose, water exchange was allowed until the next treatment. Station 3 was destroyed by a winter storm. After the last treatment, the enclosures were removed and the remaining sites monitored for 6 months. One additional site was similarly dosed (1:100 v/v) with clean dredged sediment from Christmas Bay for comparison between dredged sediments and drilling muds.^ Results of the analysis of the water samples and field measurements showed that water quality was impacted during the discharges, primarily at the highest dose (1:100 v/v), but that elevated levels of C, Cr (T,F), Cr$\sp{+3}$ (T, F), N, Pb, and Zn returned to ambient levels before the end of the 24 hour exposure period or immediately after water exchange was allowed (Al, Ba(T), Chlorophyll ABC, SS, %T). Barium, from the barite, was used as a geochemical tracer in the sediments to confirm estimated doses by mass balance calculations. Barium reached a maximum of 166x background levels at the high dose mesocosm. Barium levels returned to ambient or only slightly elevated levels at the end of the 6 month monitoring period due to sediment deposition, resuspension, and bioturbation. QA/QC results using blind samples consisting of lab standards and spiked samples for both water and sediment matrices were within acceptable coefficients of variation.^ In order to avoid impacts on water quality and sediment geochemistry in a shallow estuarine ecosystem, this study concluded that a minimal dilution of 1:1,000 (v/v) would be required in addition to existing regulatory constraints. ^