Tilapia are able to withstand long-term exposure to low environmental pH, judged by their energy status, ionic balance and plasma cortisol

Tilapia Oreochromis mossambicus were exposed to water at pH 4·0 for 37 days. The water was acidified slowly over 6 h enabling the animals to acclimate and preventing damage of the gill epithelium. Additional stressors, e.g. aluminium ions and handling stress, were avoided. No mortality or decreased food consumption was observed during the exposure period. No significant changes were observed between the control and acid exposed groups for the energy rich compounds and related parameters, i.e. the adenylate energy charge, the pool of total adenine nucleotides, and the IMP load of white muscle and liver, indicating maintenance of homeostasis. Moreover, there were no significant differences between control groups and acidified groups at 3, 17 and 37 days for plasma sodium, chloride, cortisol and glucose, implying that ionic balance was maintained and that there was no activation of the pituitary-interrenal axis. It is concluded that tilapia can acclimate to water at pH 4·0 when the acidification rate is slow and additional stressors are avoided.     

Mortality by cause of death in a rural area of Machakos District, Kenya in 1975-78

This paper examines mortality by cause of death in a rural area of Machakos district in Kenya. The cause-of-death data collected between 1975 and 1978 were likely to be of fairly good quality. The number of deaths was higher among infants and children. Infectious diseases and diseases of the respiratory system were the leading causes of death among children below 5 years of age. Next in prominence were the causes ascribed to congenital anomalies and perinatal conditions. Among adolescents and young adults, injury and poisoning, together with tuberculosis and other infectious and parasitic diseases, were the leading causes of death. Degenerative diseases, especially diseases of the circulatory system and neoplasms and respiratory illness, were responsible for the majority of deaths among the older population.