Isolation of a new flavivirus related to cell fusing agent virus (CFAV) from field-collected flood-water Aedes mosquitoes sampled from a dambo in central Kenya.

Cell fusing agent virus (CFAV) is an RNA insect virus that was isolated from a line of Aedes aegypti mosquito cells and has been assigned to the family Flaviviridae, genus Flavivirus. We report here the first isolation of a CFA-like virus from field-collected mosquitoes. Mosquito larvae and pupae were sampled from flooded dambos in Central Province, Kenya during the short rain season of 1999. Specimens were reared to adults, identified and pooled by species and were tested for the presence of virus. Two virus isolates were obtained from two pools of Aedes macintoshi mosquitoes. The virus isolates replicated only in invertebrate cells in culture and not in vertebrate cells or in mice. The virus isolates did not antigenically cross-react with known arboviruses but were identified to family by reverse-transcriptase polymerase chain reaction (RT-PCR) performed using primers specific to alphaviruses, bunyaviruses and flaviviruses; only the flavivirus-specific primers produced a DNA fragment of the expected size. Nucleic acid sequencing of this fragment showed the two isolates to be nearly identical. Comparison of sequences to the GenBank database using BLAST identified the virus as most closely related to CFAV. Results from cross-neutralization tests suggested that, although the BLAST search indicated homology to CFAV, the virus isolated represented a new insect flavivirus. Detailed characterization of this new virus, described in Crabtree et al. [7], further supports this finding. We propose this new flavivirus be designated Kamiti River virus (KRV). This is the first isolation of a CFA-like virus from field-collected mosquitoes and indicates the presence of this group of viruses in nature.

Longitudinal study of young children in Kenya: intestinal parasitic infection with special reference to Giardia lamblia, its prevalence, incidence and duration, and its association with diarrhoea and with other parasites.

84 young children from a rural community, Nderu, in Kenya, were each followed for up to 10 months, from January to November 1987. Their ages ranged from 10 to 28 months over the period of study. Stools were obtained once a week, as were reports from the mothers about presence of abdominal complaints, including diarrhoea. A total of 2258 stools and 1873 reports were collected. 9 parasites were commonly encountered of which Giardia lamblia was the most frequent at 44.7%. The overall estimated number of new Giardia episodes per year per child was 2.77 +/- 2.22 SD and the mean estimated duration of infection was 75.25 +/- 73.84 SD days per child. The mean proportion of positive visits per child was 0.42 +/- 0.25 SD. Giardia trophozoites, Trichomonas hominis, Chilomastix mesnili, Entamoeba histolytica, Blastocystis hominis and Hymenolepis nana were all significantly associated with unformed stools and reports of diarrhoea. There was a significant probability of finding Giardia in stool within +/- 2 weeks of a report of diarrhoea. Poly-parasitism was common and several paired associations were significantly positive, particularly between species of amoebae. Quantity of Giardia in stool (expressed as a 0 to 5+ score) was suppressed both by type and number of other parasites present.