Dr. Laetitia W. Kanja

Objectives: To establish the types of E. coli isolates that are found in river water around Nairobi and to assess the potential risk of use of this water to human health. Design: Multiple stratified sampling was carried out. Surface sampling was used in the entire study. Setting: The study was carried out on river waters surrounding Nairobi, Kenya. Subjects: Forty Escherichia coli strains isolated from river water. Main outcome measures: Serotyping, toxin gene tests and susceptibility to tetracyclines, ampicillin, chloramphenicol and kanamycin were analysed. Results: None of the isolates could be specifically serotyped using the available antisera. Toxin gene production tests using the colony hybridisation technique revealed that nine (22.5 %) of the strains were positive for heat stable (ST) toxin, seven (17.5 0/0) to the heat labile (L T) toxin and two (5 0/0) to both. Using the Agar Disk Diffusion technique, eighty per cent of the strains were susceptible to all four antibiotics, while twenty per cent of the strains showed multiple resistance. None of the strains was resistant to all four antibiotics while no strain showed resistance to kanamycin. Conclusion: None of the E. coli isolates was serotypable and it was therefore not possible to determine whether serologically identical strains of ETEC were haboured by man or animals. Toxin gene tests results showed that there is some risk of infection by diarrhoea causing ETEC to man and animals. Toxin gene tests results showed that there is some risk of infection by diarrhoea causing ETEC to man and animals if they consume this water untreated and there is evidence to show resistance of bacteria to antibiotics, hence appropriate health measures should be adhered to.

Subsequent to the discovery of DDT in the early 40's, other organochlorine pesticides have been introduced. These compounds generally resist microbial and chemical degradation and therefore persist in the environment. Despite the fact that the use of organochlorine pesticides has been banned or restricted, environmental contamination remains the main source of organochlorine pesticides in food animals (Raisbeck et al. 1989). Studies on organochlorine pesticide residues carried out on different tissues of various animal species in Kenya, have indicated varying levels of environmental contamination. (Kanja et al.; 1992, Mitema and Gitau 1990; Mugachia 1992 a; b). Organochlodne pesticides found in follicular fluid of infertile women have been implicated as the cause of infertility (Bauklouh et al. 1985). Due to the fact that swine are polytocous, the large number of follicles and corpora lutea available makes it a suitable animal model for the study of the possible effects of organochlorine pesticides on reproduction. In this study, swine fat, muscle, liver, corpus luteum and follicular fluid samples from abattoirs were analysed for organochlorine pesticide residues. The tissues were obtained from two groups of gilts; one group came from farms that used only commercial feed; the other originated from farms that used commercial feed and swill interchangeably. The objectives of this study were to establish the levels of organochlorine pesticide levels in various swine tissues and to compare the levels of the pesticides found in swine tissues from two slaughter houses obtaining pigs from different backgrounds.

In 367 domestic fowl (Gallus domesticus) eggs collected from 61 farms, residues of 10 pesticides were detected in various combinations and in the following order of frequency: p,p′-DDE (in 100% of the eggs), p,p′-DDT (98%), dieldrin (95%), Indiane (66%), p,p′-DDD (46%), o,p′-DDT (17%), β-HCH (9%), γ-HCH (5%), endrin (4%) and aldrin (0–5%). No residues of heptachlor, heptachlor epoxide, HCB or PCBs were found. The mean concentration (0–70 mg kg−1 eggs; range <0–01–10–25) of total DDT exceeded the extraneous residue limit (ERL) of 0–50 mg kg−1. The mean dieldrin residue level (0–35 mg kg−1; range 0–01–14–90) was 3–5 times higher than the ERL (0–10 mg kg−1). Only 3% of the eggs exceeded the ERL for Indane. The 156 eggs from free-range hens had significantly (P<0–05) higher residue concentrations of total DDT, dieldrin and Iindane than eggs collected from hens kept in enclosures. The mean ratio [p,p′-DDT]/[p,p′-DDE] in eggs from enclosed hens (0–97) was significantly higher (P<0–01) than in eggs from free-range hens (0–53), indicating that the former had a more direct exposure to p,p′-DDT, whereas the latter obtained more of it after environmental conversion to p,p′-DDE. Eggs from a rice-growing area had the highest concentrations of all pesticide residues detected. Accumulation ratios indicated that the levels of DDT and Iindane in the feed of enclosed hens could account for the levels in the corresponding eggs. The much higher accumulation ratios calculated for the free-range hens demonstrated that the feed ingested by these chickens obviously contained ingredients additional to those sampled, and revealed probable extensive environmental contamination by these persistent pesticides. The present results indicate that there is a need to identify sources of dieldrin in the eggs of domestic fowls and, where necessary to investigate local wildlife samples. The amounts of total DDT and dieldrin in eggs in this study seem to be higher than reported from any other country. Toxicological evaluation of the results indicates that, at lest in parts of KEnya there is a need for improved practices in the use of some organochlorine pesticides.