Biological species in Praomys (Mastomys) natalensis (Smith), a rodent carrier of Lassa virus and bubonic plague in Africa.

Plague has been known from countries surrounding Rhodesia from as early as 1935, but was first reported from Rhodesia in 1974. Part of our investigation of the complex ecosystem involving Yersinia pestis is critical assessment of the evolutionary status of natural populations belonging to formal, taxonomic species of implicated rodents. We present data on chromosomal and hemoglobin variation in sympatric populations and laboratory produced hybrids that give unequivocal evidence for at least two biologicql species in the taxon Praomys (Mastomys) natalensis. We argue for the usefulness of the biological species concept as a basis for any ecological investigation into pathogen biology.

Serological diagnosis of neurocysticercosis: evaluation of ELISA tests using cyst fluid and other components of Taenia solium cysticerci as antigens.

An ELISA system was developed to assist with the diagnosis of neurocysticercosis. Antigens were prepared from the fluid, the protoscolex and the cyst wall of cysticerci dissected from infected pigs. The fluid antigen was tested both fresh and after freeze-drying and one year's storage. Sera from patients with proven neurocysticercosis were most reactive using the fluid and least reactive using the cyst wall antigens. Freeze-drying and prolonged storage of fluid antigen did not reduce its reactivity and repeated testing of sera with this antigen gave optical density values within 15% of the original value. Using this ELISA system positive results were obtained from all patients with active neurocysticercosis. Sera from patients with calcified cysts were usually non-reactive or marginally reactive to the fluid antigen.

Microbial pathogens associated with diarrhoea in children admitted to Harare Hospital for rehydration therapy.

PIP: Stool speciment from 236 children admitted to Harare Hospital with acute diarrhea were examined for bacterial, viral and parasitic pathogens. Results were compared with specimens from 192 control patients admitted to the same hospital for other reasons. C. jejuni (13,6% diarrhea, 2,1% controls) and E. coli (10,3% diarrhea, 2,6% controls) were the most common pathogens isolated, and were isolated only from children under 2 years of age. Other bacterial pathogens were isolated from older children as well as infants, while parasites were isolated mainly from children 2 years of age. Virus particles were detected by electron microscopy in only 2 patients, both with diarrhea. Of the E. coli strains isolated from children with diarrhea, the majority belonged to 5 serotypes and these serotypes were uncommon in controls. The significance of C. jejuni as a major cause of summer diarrhea in infants in Zimbabwe is demonstrated, but further studies are recommended to investigate microbial pathogens in older children and in winter months.^ieng

Influence of environmental mycobacteria on the prevalence of leprosy clinical type.

A comparison was made of antibody levels to 16 environmental mycobacteria in leprosy patients and healthy controls. Significant differences in response were found between patients and controls from an area of Zimbabwe with predominantly lepromatous leprosy when compared to an area where more tuberculoid cases were found. The results obtained suggest that exposure to some environmental mycobacteria may influence the type of leprosy developed by susceptible individuals.

A virilizing hilus-cell tumour in an African patient with Turner's syndrome.

A 26-year-old African female presented with primary amenorrhoea and genital abnormalities. She had the physical stigmata of Turner's syndrome and a 45, X karyotype. Severe masculinization of the external genitalia, apparently present from birth, was present and a laparotomy revealed a hilus-cell tumour of the right streak gonad. Clitoridectomy and vaginoplasty were performed but subsequent oestrogen therapy failed to produce breast development.