Influenza: the next pandemic?: A review.

OBJECTIVES: To examine existing information on the recent influenza outbreaks in order to create awareness of a possible influenza pandemic and to suggest future research areas in developing control strategies in Kenya. DATA SOURCES: Review of literature via Internet, articles, journals and un-refereed features from the media and personal communications. DATA SELECTION: Most published data from 1979 to March 2005 found to reveal cases of influenza outbreaks were included in the review. Also, selected articles on the recent outbreaks and professional guidance on influenza infections were critically examined and analyzed. DATA EXTRACTION: Abstracts and articles identified were accessed, read to establish relevance to this review. DATA SYNTHESIS: Important points were prioritised and then included as subtitles; below each subtitle, published works were included. Finally, a table of influenza outbreaks and the strains of the viruses involved were drawn as summary. CONCLUSION: Influenza is a highly contagious, acute respiratory disease that may spread rapidly and pervasively through a population. Due to the diversity of susceptible reservoirs of influenza viruses and the interspecies transmission recently reported, a mutated strain of the virus to which people have no immunity could cause an influenza pandemic once the virus gains efficient and sustained human-to-human transmission. The fear that avian influenza could be a precursor to the next pandemic is real and inevitable, given the extremely high case-fatality ratio among confirmed cases and that genetic sequencing of influenza A (H5N1) viruses from human cases in Thailand and Vietnam show resistance to the antiviral medication amantadine and rimantadine. This calls for a high level of preparedness to avoid a public health emergency. Nowhere is this paradigm more real than in Africa.

Intestinal parasitoses and other infections in a college community.

In order to assess the health status of students doing their teaching diploma course at the Siriba Teachers College, Maseno, a study of their blood slides, their stools for ova and cysts and their urine samples for urinary tract infection was carried out. A total of 298 students were investigated: 27 (6%) had intestinal parasites, 96 (32.2%) had urinary tract infection, i.e., pyuria, bacteria and epithelial cells in their urines, most of them being females (55/96 or 57.3%). The peak occurrence of urinary tract infections was in the 22-23 year age group. There were four female students who were found to have Trichomonas vaginalis giving a prevalence rate of 1.3%.

Knowledge and attitudes to malaria control and acceptability of permethrin impregnated sisal curtains.

OBJECTIVES: The objectives of this study were to conduct a survey on the knowledge and practices relating to malaria prevention and treatment in two rural communities in Western Kenya, and to determine the acceptability of specially designed permethrin impregnated sisal strands curtains previously introduced into one of the study communities as barriers to mosquito biting. DESIGN: A knowledge, attitudes and practices (KAP) survey was conducted by pre-trained interviewers using a pre-tested questionnaire. SETTING: The study was conducted in two communities located 15 km northwest of Kisumu town, and next to the swamps bordering Lake Victoria in Kisumu District, Western Kenya. PARTICIPANTS: Adult individuals from 50 houses selected from the intervention, and 50 houses from the control sites were included in the study. RESULTS: Both communities had a clear conception of malaria and its symptoms, and of the mosquito as its vector. Malaria was recognised as a potential cause of death by 44% and 72% of the participants in the intervention and control sites respectively. Sixty two per cent to 74% of the people interviewed in both sites named mosquitoes as the causative agents of malaria. Chloroquine was still the drug of choice for malaria treatment, with over 70% usage among the study population. Mention of pyrimethamine/sulfadoxine and pyrimethamine/sulfalene as alternative therapy was below five per cent. Despite a high level (86%) of awareness of bednets as effective barriers to mosquito biting, they were reported in use by less than 35% in both communities. Sisal strand curtains were considered effective and acceptable to more than 80% of the community. CONCLUSIONS: The results of this study underscore the existing need for affordable means of mosquito control, such as sisal strand curtains, for such rural communities which may be acutely aware of the problems associated with malaria, but are constrained from taking any action by lack of resources.

The effect of permethrin impregnated sisal curtains on vector density and malaria incidence: a pilot study.

Impregnation of bednets and curtains with suitable pyrethroids may reduce entomological inoculation rates (EIR) and malaria incidence. We conducted a quasi-experimental pilot study over 3 months in Western Kenya on 20 houses with 54 children. Ten houses in the experimental site received sisal curtains treated with permethrin at either 0.5g/m2 or 0.1g/m2. Control houses had untreated curtains or none. Mosquito vector density (MVD), man biting rates (MBR), and residual insecticidal effects (RIE) of permethrin were determined every two weeks. MVD was reduced by 97.7% and 98.7% in houses from the 2 experimental groups with a 60% reduction with unimpregnated curtains. MBR varied from 6.4 (no curtains), 1.7 (unimpregnated), 0.7 (0.5g/m2 curtains) to 0.4 (1.0g/m2 curtains). RIE begun to decline after the fourth month. Malaria incidence remained similar at the two sites. We conclude that covering of eaves and windows with permethrin impregnated sisal curtains can reduce MVD and the number of mosquito bites to individuals sleeping in protected houses.

Maternal immune responses and risk of infant infection with HIV-1 after a short course Zidovudine in a cohort of HIV-1 infected pregnant women in rural Kenya.

OBJECTIVE: To investigate the effects of short-course nucleoside reverse transcriptase inhibitor (Zidovudine, ZDW/AZT) on maternal immune responses and risk of infant infection with HIV-1 among rural-based mothers in western Kenya. DESIGN: A prospective cohort study involving HIV-1 seropositive pregnant mothers and their infants. SUBJECTS: One hundred and seven HIV-1 seropositive asymptomatic pregnant women and their infants. METHODS: After informed consent, the women were enrolled at gestation age between 16-24 weeks. For cultural and economic reasons, all mothers were allowed to breast feed their infants. Short-course antepartum regime of AZT was administered to all mothers starting at 36 weeks gestation until start of labour. Maternal absolute CD4+ T cell subset assays were performed before 3rd trimester (about 36 weeks gestation) and after a 4-week therapy of AZT (at least one month post-nuptially). Infant HIV-1 status was determined by HIV-1 DNA polymerase chain reaction (PCR) on samples sequentially taken at 1, 2, 3, 4, 6 and 9 months and confirmed by serology at 18 months of age. INTERVENTIONS: Antepartum short-course orally administered AZT: 300mg twice-daily starting at 36 weeks gestation until start of labour, 300mg at labour onset and 300mg every three hours during labour until delivery. MAIN OUTCOME MEASURES: Maternal CD4+ T cell counts before and after AZT treatment. Determination of infant HIV-1 infection status. RESULTS: Among 107 women sampled, only 59 received full dose of AZT and thus qualified for present analysis. Of these, 12 infected their children with HIV, while 47 did not. Comparison of CD4+ T cells before and after AZT treatment scored a significant rise in all mothers (P = 0.01). This increase in CD4+ T cells was not significant among mothers who infected their infants with HIV-1 (P = 0.474). However, a significant rise in CD4+ T cells following AZT therapy was observed only in mothers who did not transmit HIV-1 to their infants (P=0.014). CONCLUSION: These data suggest that a rise in the CD4+ T cell counts following short AZT regimen, now widely in use in resource-weak countries, may be evidence of the active suppression of the replication of HIV. However, further studies to examine the multi-factorial effect of CD4+ lymphocytes and pregnancy on MTCT of HIV need to be carried out to help fully explain the effect of AZT on immune response and whether the CD4+T cell count can be used as a true test of immunological normalisation during antiretroviral therapy.

Comparative determination of Plasmodium falciparum sporozoite rates in Afrotropical Anopheles from Kenya by dissection and ELISA.

The Plasmodium falciparum rate was determined by microscopical examination of one salivary gland (three lobes) and by enzyme-linked immunosorbent assay (ELISA) of the other salivary gland in each of 1580 Anopheles mosquitoes collected from western Kenya during both the wet and dry seasons. The sporozoite rate in the wet season was much higher than that in the dry season, and the sporozoite rate determined by ELISA was generally lower than that determined by microscopy. The ELISA gave a positive reaction to circumsporozoite protein in some glands whose counterparts did not show the presence of sporozoites by microscopy, thus giving an 'overestimation' of the sporozoite rate. This overestimation was greater in the dry season than in the wet season, and greater in Anopheles gambiae than in An. funestus, but overall it was only 1.2% (19/1580). These results are at variance with reports of other workers, who have shown ELISA overestimation of the sporozoite rate as high as 30%. Our tests indicated that the ELISA sensitivity was 80.6%, its specificity was 98.7%, and its accuracy was 97.5%.

Some observations on the biting behavior of Anopheles gambiae s.s., Anopheles arabiensis, and Anopheles funestus and their implications for malaria control.

Studies were carried out in three villages in western Kenya on the biting behavior of Anopheles gambiae s.s., Anopheles arabiensis, and Anopheles funestus. Blood feeding behavior and departure from houses were studied under the impact of permethrin-impregnated eaves-sisal curtains. Only 2-13% of the female vector population was collected biting before 2200 hr. Over 90% of the villagers went to bed by 2100 hr. An. funestus was 6.6-8.2 times more likely to bite people indoors than outdoors, while An. gambiae s.l. females were only 2 times as likely. Under the influence of permethrin-impregnated sisal curtains placed under the eaves of village houses, there was a marked egress of blood-fed An. funestus and An. gambiae s.s. Permethrin seems to have induced exophily of half-gravid female An. gambiae s.s. While An. gambiae s.s. remained highly anthropophagic under the impact of permethrin, An. funestus shifted to feeding more on cattle. An arabiensis were largely zoophilic. Our results underline the difficulties of controlling An. gambiae s.s., the principal African malaria vector. New strategies must be found to control this vector.