Susceptibility of healthcare workers in Kenya to hepatitis B: new strategies for facilitating vaccination uptake.

Hepatitis B virus (HBV) infection is preventable, yet many healthcare workers (HCWs) in resource-poor countries remain at risk. The aims of this study were to evaluate the susceptibility of HCWs in a Kenyan district to HBV infection, and the feasibility of expanding the Extended Programme of Immunization (EPI) for infants to incorporate hepatitis B vaccination of HCWs. HCWs in Thika district, Kenya were invited to complete an interviewer-administered questionnaire about their immunization status and exposure to blood or body fluids. Participants were asked to provide a blood sample to assess natural or vaccine-induced protection against HBV. All non-immune HCWs were offered hepatitis B vaccination. Thirty percent (168/554) of HCWs reported one or more needlestick injuries (NSIs) in the previous year, with an annual incidence of 0.97 NSIs/HCW/year. Only 12.8% (71/554) of HCWs had received vaccination previously and none had been screened for immunity or for hepatitis B surface antigen. In total, 407 staff provided blood samples; 41% were HBV core antibody, 4% expressed hepatitis B surface antibody from previous vaccination, and 55% were unprotected. Two hundred and twenty-two staff were eligible for vaccine delivered through the EPI infrastructure. Self-motivated uptake of a full course of vaccine was 92% in the smaller health centres and 44% in the district hospital. This study demonstrates the importance of hepatitis B vaccination of HCWs in parts of Africa where high exposure rates are combined with low levels of vaccine coverage. High rates of vaccination can be achieved using childhood immunization systems for the distribution of vaccine to HCWs.

CD4T lymphocyte subsets and disease manifestation in children with and without HIV born to HIV-1 infected mothers.

OBJECTIVE: To understand the natural history of HIV-1 infection in children in terms of evolution of childhood clinical manifestations versus the immune status, we prospectively studied children with and without maternally transmitted HIV-1 infection born to mothers infected with HIV-1 for two years between March 1998 and March 2000. DESIGN: A prospective cohort study. SETTING: An institutional children's home. SUBJECTS: Fifty nine children (26 males and 33 females) with and without maternally transmitted HIV-1 infection born to mothers infected with HIV-1 and adopted in institutional children home. METHODS: HIV-1 status of children under nine months was confirmed by polymerase chain reaction(PCR). ELISA for HIV-1 antibody in serum/plasma was used to confirm HIV-infection status for children aged < or = 18 months. Children were visited every three months between March and June 2000. At every visit blood was collected for total white cell count, haemoglobin and CD4+ and CD8+ T cell counts. The institutional doctor routinely examined children and treated all ailments. Clinical data were recorded. MEASURES: HIV-DNA, anti-HIV antibodies, total white blood count, total T cell counts, CD4 and CD8 T cell subset counts, frequency of childhood manifestations of infection. RESULTS: The children were aged between 4.5 and 13 years. The baseline haematological and immunological profiles (mean, mode) were: HIV-1 sero-converters (WBC 7151,7150; HB 11.6, 12.0; CD4+ 686, 795; CD8+ 2168, 1507) and HIV-1 de-seroconverters (mean, mode) were: (WBC 8386, 7150; HB 11.7, 12.8; CD4+ 735, 795; CD8+ 2168, 1507). The commonest causes of illnesses among the HIV-1 children were URTI (85.3%), TB(56.1 %), pneumonia (56.2%), tonsillitis (34.1%), parotiditis (28%) and acute otitis media (25%). The distribution of clinical manifestations was similar between the two categories of children, except URTI, whose prevalence was significantly increased among HIV-1 infected children (p-value=0.006). Among the HIV-1 infected children, only TB, parotiditis, and acute otitis media (AOM) were significantly associated with decreased CD4+ T cell count (p<0.05) resulting from HIV infection. CONCLUSIONS: HIV infection in children predisposes them to common childhood infections that can be used as markers of immune decline. TB, AOM, URTI may be early indicators of suspicion that would enable selective screening for HIV infection in children.

Measles trends and vaccine effectiveness in Nairobi, Kenya.

OBJECTIVES: To determine morbidity and mortality from measles and to estimate measles vaccine effectiveness among children hospitalised with measles in two hospitals in Nairobi. DESIGN: A review of hospital records (index cards). SETTING: Kenyatta National Hospital and Mbagathi District Hospitals covering the years 1996-2000. METHOD: A review of index cards for measles morbility and mortality was undertaken in the two hospitals. Measles data at the Kenya Expanded Programme on Immunisation covering both hospitals was analysed for vaccine effectiveness. RESULTS: The incidence of measles was unusually high in 1998 between July and November (monthly range 130-305), reflecting on the occurrence of an outbreak at that time. There was no definite monthly incidence trend of measles in 1996,1997, 1999 and 2000. The median age of cases was 13 months (range 0-420 months) for Kenyatta hospital and 18 months (range 1-336 months) for Mbagathi Hospital. Significantly, 29.8% of all cases were aged below nine months when routine immunisation for measles had not begun. The median number of days spent in hospital were five days (range 0-87 days) for Kenyatta and four days (range 1-13 days) for Mbagathi. The overall case fatality rate was 5.6% and was similar for both males and females. The overall measles vaccine effectiveness among measles cases admitted to Kenyatta and Mbagathi Hospitals was 84.1%. CONCLUSION: The case admissions in Kenyatta and Mbagathi Hospitals suggest measles was prevalent in Nairobi over the latter half decade of the 1990's. Apart from 1998 when there was an outbreak, the seasonality of measles was dampened. The 1998 outbreak suggests a build up of susceptible children the majority of whom were born in the last quarter of 1996. The high mortality may have had to do with the majority of cases presenting late when symptoms were already complicated and severe.

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.

An in vitro evaluation of extracts from some medicinal plants in Kenya against herpes simplex virus.

The extracts from 21 medicinal plants commonly used in traditional remedies in Kenya were screened for antiviral activity against wild type 7401H strain herpes simplex virus type 1. The plant extracts exhibited antiviral activity against the virus in the plaque and yield reduction assays. The results reveal that twelve plants may contain constituents that could be exploited for the management of HSV infections. Although the extracts used in these experiments contain a complex matrix of a large number of compounds the results indicate that useful compounds can be isolated for further exploitation.

Epidemiological study of the G serotype distribution of group A rotaviruses in Kenya from 1991 to 1994.

An epidemiological study on the G serotype distribution of group A rotaviruses (GARV) isolated in Kenya was carried out in one urban hospital in Nairobi and in two rural hospitals in Nanyuki and Kitui to clarify the prevalent G serotypes before future introduction of the ready licensed rotavirus vaccine in Kenya. A total of 1,431 stool specimens were collected from children, who were mainly outpatients, aged from 0 to 6 years old with acute gastroenteritis from August 1991 to July 1994. Samples positive for GARV by conventional ELISA were then analyzed by subgrouping and serotyping ELISA and by PAGE. To ascertain the G serotypes of viruses in samples that were unable to be typed by serotyping ELISA, polymerase chain reaction was also attempted. The prevalence of GARV was 28.4% in the urban hospital, 22.5% in Nanyuki, and 13.7% in Kitui. Among rotavirus-positive samples, subgroup II rotaviruses were detected in 63.1%, and subgroup I rotaviruses were 25.9%. Serotype G4 was most prevalent, accounting for 41.6% followed by 23.3% of serotype G1, 17.0% of serotype G2, and serotype G3 was rarely isolated. Seven strains of serotype G8/P1B rotavirus was detected for the first time in Kenya by RT-PCR. Eleven specimens with an unusual composition of subgroup, serotype, and electropherotype were atypical GARV in which the P-serotype was P1A, P1B, or P2. Although uncommon GARV serotype G8/P1B and atypical GARV were detected, the four major GARV serotypes, G1 through G4, should be targeted at this moment for vaccination to control this diarrheal disease in Kenya. Continuous monitoring of the G- and P-serotype distribution of GARV should provide important information about the impact of rotavirus vaccination in Kenya.

KEMRI Hep-cell II hepatitis B surface antigen screening kit.

BACKGROUND: Kenya is a high hepatitis B virus (HBV) endemic zone. Prevention of HBV transmission by transfusing safe blood is necessary. Kits for screening hepatitis B surface antigen (HBsAg) are usually imported and are expensive. Hence it has been difficult to screen donated and patient blood samples all over Kenya. OBJECTIVE: To produce a HBsAg screening kit locally in order to be able to screen donated and patient blood samples all over Kenya. DESIGN: A laboratory based study. SETTING: Centre for Virus Research (CVR), Kenya Medical Research Institute (KEMRI), Nairobi. METHOD: Purified HBsAg from plasma of carriers obtained from National Public Health Laboratories Services (NPHLS) was used to minimise guinea pigs to produce antihepatitis B (anti HBs) antibody. The anti HBs was then used to sensitise sheep red blood cells (SRBC). The final product was freeze dried (lyophilised) and its sensitivity and specificity was compared with other commercial kits. RESULTS: The sensitivity and specificity of KEMRI Hep-cell II was found to be 98% and 99%, respectively. The kit was found to be stable and potent for one year whether kept 4 degrees C, 37 degrees C or room temperature. CONCLUSION: KEMRI Hep-cell II was successfully produced locally. The sensitivity and specificity were comparable to other commercial kits. The kit was stable and potent for one year between temperature of 4 degrees C and 37 degrees C. The kit required only simple apparatus to carry out the test hence it can be used anywhere in Kenya. It was also cheap and affordable.

PIP: Kenya is a high hepatitis B virus endemic zone, and prevention of viral transmission by transfusing safe blood is necessary. However, kits for screening hepatitis B surface antigen (HBsAg) are usually imported and are expensive; hence, it has been difficult to screen donated and patient blood samples all over the country. This laboratory-based study, conducted at the Kenya Medical Research Institute (KEMRI), produced a HBsAg screening kit locally in order to be able to screen donated and patient blood samples throughout Kenya. Purified HBsAg from plasma carriers obtained from the National Public Health Laboratories Services was used to induce guinea pigs to produce anti-hepatitis B antibody (anti-HBs). The anti-HBs was then used to sensitize sheep red blood cells. The final product was freeze dried (lyophilized) and its sensitivity and specificity was compared with other commercial kits. The KEMRI Hep-cell II had 98% and 99% sensitivity and specificity, respectively, in comparison with other commercial kits. The kit was found to be stable and potent for 1 year at temperatures of 4 degrees Celsius, 37 degrees Celsius, or at room temperature. The KEMRI Hep-cell II kit is cheap and affordable and requires a simple apparatus to carry out the test; hence, it can be used anywhere in Kenya.

First recorded outbreak of yellow fever in Kenya, 1992-1993. I. Epidemiologic investigations.

Outbreaks of yellow fever (YF) have never been recorded in Kenya. However, in September 1992, cases of hemorrhagic fever (HF) were reported in the Kerio Valley to the Kenya Ministry of Health. Early in 1993, the disease was confirmed as YF and a mass vaccination campaign was initiated. Cases of suspected YF were identified through medical record review and hospital-based disease surveillance by using a clinical case definition. Case-patients were confirmed serologically and virologically. We documented 55 persons with HF from three districts of the Rift Valley Province in the period of September 10, 1992 through March 11, 1993 (attack rate = 27.4/100,000 population). Twenty-six (47%) of the 55 persons had serologic evidence of recent YF infection, and three of these persons were also confirmed by YF virus isolation. No serum was available from the other 29 HF cases. In addition, YF virus was isolated from a person from the epidemic area who had a nonspecific febrile illness but did not meet the case definition. Five patients with confirmed cases of YF died, a case-fatality rate of 19%. Women with confirmed cases of YF were 10.9 times more likely to die than men (P = 0.010, by Fisher's exact test). Of the 26 patients with serologic or virologic evidence of YF, and for whom definite age was known, 21 (81%) were between 10 and 39 years of age, and 19 (73%) were males. All patients with confirmed YF infection lived in rural areas. There was only one instance of multiple cases within a single family, and this was associated with bush-clearing activity. This was the first documented outbreak of YF in Kenya, a classic example of a sylvatic transmission cycle. Surveillance in rural and urban areas outside the vaccination area should be intensified.

First recorded outbreak of yellow fever in Kenya, 1992-1993. II. Entomologic investigations.

The first recorded outbreak of yellow fever in Kenya occurred from mid-1992 through March 1993 in the south Kerio Valley, Rift Valley Province. We conducted entomologic studies in February-March 1993 to identify the likely vectors and determine the potential for transmission in the surrounding rural and urban areas. Mosquitoes were collected by landing capture and processed for virus isolation. Container surveys were conducted around human habitation. Transmission was mainly in woodland of varying density, at altitudes of 1,300-1,800 m. The abundance of Aedes africanus in this biotope, and two isolations of virus from pools of this species, suggest that it was the principal vector in the main period of the outbreak. A third isolate was made from a pool of Ae. keniensis, a little-known species that was collected in the same biotope. Other known yellow fever vectors that were collected in the arid parts of the valley may have been involved at an earlier stage of the epidemic. Vervet monkeys and baboons were present in the outbreak area. Peridomestic mosquito species were absent but abundant at urban sites outside the outbreak area. The entomologic and epidemiologic evidence indicate that this was a sylvatic outbreak in which human cases were directly linked to the epizootic and were independent of other human cases. The region of the Kerio Valley is probably subject to recurrent wandering epizootics of yellow fever, although previous episodes of scattered human infection have gone unrecorded. The risk that the disease could emerge as an urban problem in Kenya should not be ignored.

Prevalence of human calicivirus infections in Kenya as determined by enzyme immunoassays for three genogroups of the virus.

An epidemiological survey on human calicivirus (HuCV) infections and associated gastroenteritis in infants was conducted to clarify the prevalence of HuCV infections in infants and adults in Kenya. Enzyme immunoassays (EIAs) for three genogroups of HuCVs, Norwalk virus (NV), Mexico virus (MXV), and Sapporo virus (SV), were used to detect antigen or antibody. We tested 1,431 stool samples obtained from children younger than 6 years old with acute gastroenteritis who visited outpatient clinics in three districts in Kenya from August 1991 to July 1994. Thirty-two (2.2%) of these stool samples were positive for SV antigen. Only one (0.1%) of 1,186 samples was positive for NV antigen and none of 246 samples was positive for MXV antigen. One hundred ninety-three serum samples were tested for antibodies to NV and MXV, and 64 of them were examined for antibody to SV. The pattern of the age-related prevalence of serum antibody to NV was different from that of antibodies to MXV and SV. The acquisition of serum antibodies to HuCVs in the three genogroups appeared in early childhood, at about 1 to 2 years of age. The prevalence of serum antibody to NV was low (about 60%) throughout adulthood compared with a high prevalence of antibody (approximately 80 to 90%) to MXV and SV. These data indicate that infections with viruses in the three genogroups of HuCVs are common in Kenya, and immunological responses to NV may be different from those to MXV and SV. The EIAs for the detection of NV and MXV antigens appear to be quite specific for prototype NV and MXV strains, respectively, so that they can detect only a few strains of HuCVs related to them. Alternatively, NV and MXV caused less severe infections that did not bring children to the outpatient clinics for gastroenteritis in Kenya.

Human plasma derived hepatitis B vaccine: Kenyan experience.

OBJECTIVE: To determine the efficacy and safety of hepaccine B. DESIGN: Vaccination on first-come-first-served basis. SETTING: Kenya Medical Research Institute (KEMRI) staff and families at Nairobi, Kenya. PARTICIPANTS: A total of 107 vaccinees aged 0-10 years and 10 years and above. MAIN OUTCOME: Antibody to hepatitis B surface antigen (anti HBs) checked one month after the third dose of the vaccine. RESULTS: Ninety seven per cent of the vaccinees developed antiHBs. Side effects were few in the form of soreness at site of injection and headache. CONCLUSION: Hepaccine B produced good immune response in vaccinees with minimal side effects.

Study of hepatoma from all provincial hospitals in Kenya

Hepatocellular carcinoma is common in Kenya occurring at an earlier age than in Europe. It is the third commonest solid tumour among males at the Kenyatta National Hospital. Hepatitis B virus seems to be playing a very important role in the causation of HCC. A study done at the KNH in 1985 showed that hepatitis B surface antigen (HBsAg) was positive in 85of HCC patients. Some of these cases had integrated HBV-DNA in the liver; whereas others had free HBV-DNA. We undertook to screen patients with possible HCC clinically and ultrasonographically in all teh provincial hospitals in Kenya and taat KHN. These patients had blodded samples taken for HBV markers; hepatitis C virus (HCV)) antibodies and allllphafetopreotein (AFP). A few of teh patients had histological confirmation of the HCC. A total of 137 cases of HCC were screened; with a mean age of 45.7 years (range 7-86 years). The prevalence of HBsAg in HCC was found to be 39.4 per cent and the prevalence of anti-HCV Ab was found to be 2.9 per cent. AFP was positive in 51.8 per cent of HCC cases with 38 per cent of cases having levels greater than 200 ng/ml. Most of the HCC cases were diffuse (48 per cent) or multiple (32.7 per cent) and only solitary in 9.2 per cent of the cases. Even the solitary tumours were large with an average size of 41.3 pmm. HBV plays an important role in the causation of HCC in our setup whereas HCV does not seem to be as important. AFP is an important indicator of HCC and combined with ultrasound; it can be used for early diagnosis of HCC in high risk groups; that is; HBsAg positive individuals

Yellow fever in Kenya: the need for a country-wide surveillance programme.

Since the emergence of yellow fever (YF) as a public health threat in Kenya in 1992-1993, low level transmission of the virus to humans has continued to occur. A programme of YF surveillance has been instrumental in the monitoring of YF activity and has clearly demonstrated an expansion of the zone of virus activity into regions that were not affected in the 1992-1993 epidemic. This is of major concern for the approximately 29 million Kenyans who are unvaccinated and therefore at risk of infection. A revision of the surveillance programme is underway to create a more efficient system of recognition of suspect YF cases, laboratory diagnosis and reporting to the appropriate authorities for action. In addition, a research programme to study YF ecology in Kenya will benefit the surveillance programme, enabling it to target potential 'hotspots' of YF activity. As it may not be possible, for financial reasons, to incorporate YF vaccination into the Kenya Expanded Programme of immunization in the immediate future, the need for continued surveillance to monitor the emergence of YF in Kenya is vital.

Hemorrhagic fevers: few clues after 25 years.

There is a high prevalence of Ebola antibodies found in the Kenya population, related to geographical area and season, although the clinical disease was never found and the virus was not isolated. A field study was carried out in 7 hospitals in western Kenya, 1986 -1987 (including surveillance studies in suspect areas), to intensify collection and transport of samples, testing facilities, patient observation with record keeping and follow-up. This study involved 1109 admitted patients with fever and/or bleeding, 155 contacts of haemorrahagic fever antibody (Hfab) patients, and 916 people in suspect areas. Respectively 160,44 and 80 persons were found Hfab positive mainly to Ebola, using an indirect immunofluorescent assay. From 676 viral cultures no virus was isolated. A relationship between antibody titres and ecological factors, social habitat, age, sex or season was not found. The non-specificity of IF testing was demonstrated by: 1) the disagreement between the results of two reference laboratories; 2) the unpredictability of the titre conversation course; and 3) by proving a significant cross-reactivity with Borrelia burgdorferii antibodies, Plasmodium falcparum antibodies and Salmonella typhi antibodies. Renewed testing in 1995 of 90 positive sera (with low titres) showed 19 sera to be positive by Elisa (2 in Zaire, 1 in Sudan, 9 in Reston and 7 in Cote d'Ivoire) from which 4 were confirmed by IFI 2 in Reston and 2 in Cote d'Ivoire. These findings are more proof that non-human virulent strains of Filoviridae, especially Ebola virus, are around in Kenya.

Polio Eradication by the year 2000.

In May l988, the Annual Meeting of the World Health Assembly (WHA) committed WHO to the exciting challenge of Global Eradication of Poliomyelitis by the year 2000. The World accepted this challenge based on a number of scientific factors that had already been witnessed and certain other basic epidemiological factors concerning the transmission of the wild polio virus: 1. Smallpox had been eradicated and the global machinery and commitment for repeating such a feat could still be mobilised on She same lines to tackle another global menace; 2. The Pan American Health Organisation (PAHO) had already by May 1985 committed the American region to polio eradication by the year 1990. Although many people were initially sceptical of this initiative, it was quickly realised and recorded that the programme mounted by PAHO was achieving a high level of success and the goal of eradication was achievable; 3. Epidemiological! transmission factors that are persuasive to science for mounting eradication initiatives include: a) The wild polio virus moves from man to man only and has no wild animal reservoir to maintain it. b) An infected individual either dies, is crippled or fully recovers and remains immune without retaining or carrying the virus for many years (no carrier state) c) Available vaccine, particularly the oral (OPV) is not only capable of inducing long standing immunity in an individual but can, by multiplying in the gut, exclude or interrupt the circulation of the wild strain. The basic concepts and strategies for polio eradication recommended by WHO and now adapted globally are quite simple: 1. For each national expanded programme on immunisation (EPI) to raise the primary polio coverage rate with OPV to beyond 80% as a routine in children under one year. Under such conditions of immunisation in every locality in every district and province, the incidence of paralytic polio is quickly reduced to very low levels. Most countries in the world have already achieved and exceeded this level of coverage. 2. For each country to conduct National Immunisation Days (NIDs) daring which 2 doses of OPV, one month apart, are administered to ALL children under 5 years of age irrespective of their previous vaccination status. This strategy boosts the immunity in (he children already vaccinated and catches those missed by routine services. The wild polio virus cannot live for long periods outside the human body, hence the NIDs effectively remove the wild polio virus from circulation. China was able to vaccinate over SO million children under 5ysars with OPV within two days. Currently the practice is for many neighbouring countries (even upto 15 at a time) to simultaneously operationalise their NIDs on 2 to 3 days. 3. For each country to establish and operate an extremely sensitive surveillance system capable of detecting any new case of acute flaccid paralysis (AFP), Since paralysis can be produced by other conditions, it is necessary to back up the field surveillance with a reliable laboratory service capable of isolating poliovirus from the stool samples of paralytic cases. An isolated poliovirus would then have to be typed as wild or vaccine type strain. The strategies described above have all beers activated in all countries of the world and the world is already1 witnessing a dramatic disappearance of new cases of AFF. The International Certification Commission on Polio Eradication has established formal criteria by which countries can be certified polio-free. A polio-free status has to be maintained for at least 3 years in the countries of a region for that region to be certified as having eradicated the wild poliovirus. Global eradication will have been achieved if and when all regions in the world have been certified. The world is, no doubt, most grateful to all those international organisations, such as the Rotary International, WHO, UNICEF, national governments of the developed world through! donor agencies such as J1CA, US AID, D ANID A, etc., for the enormous resources that have been mobilised to operationalise EPI programmes for polio eradication. This gratitude is also a tribute in the late Dr. Albert Sabin, the discoverer of the oral poliomyelitis vaccine, which has been the major biological tool making it possible to eradicate the wild type poliovirus.

Emerging and re-emerging Infectious diseases: a global health threat.

The HIV/AIDS pandemic can truly be described as an infectious disease that has recently emerged and judging from its rapid global spread, it leaves no doubt that it is one of the greatest health threats mankind has to contend with. This pandemic has alerted and stimulated the international scientific community to seriously reflect oa other recent episodes of emerging and re-emerging infections. The examples that have recently been observed and addressed include new emerging infectious diseases, unusual manifestations of previously known diseases and unusual eruption of known diseases in unusual geographic foci or unusual altitudes. The scientific community has considered the following as plausible explanations for the epidemics: 1. It is known that micro-organisms mutate and selection pressures for appearance of resistant strains are encouraged by the widespread misuse of drugs; 2. Human population pressures, particularly ih the developing world, is leading migration to urban slums. Other populations are venturing into virgin jungles to open up new agricultural land. In the same category are economic pursuits in the forest or alteration of the environment by economic activities such as new dams and roads. All these activities put new susceptible populations at risk of interacting with new disease ecological systems. It is also tempting to include in this category civil disruptions which have led to acute displacement of large populations within a country or across international borders as refugees; 3. The re-emergence of some of the old familiar diseases, hitherto considered well controlled, can be attributed directly to the deterioration of health services as a result of global economic depression which has affected some countries more severely than others; 4. There is sound and growing scientific evidence implicating global warming as contributing to some of the new disease manifestations. The threat to health by emerging and re-emerging infectious diseases is a reality and the scientific basis for this occurrence, though complex, is slowly being understood. The response of the international scientific community to this situation has been acknowledged as appropriate. It is gratifying to recognise the leading role that CDC/US A in collaboration with WHO are playing in globalising the responses to these threats. WHO has rightly assumed its leadership role in matters of this nature in coordinating global efforts to address this subject. A new division of Emerging Infectious Diseases (EMC) became operational in WHO headquarters in October 1995. The scientific world looks to it for timely, accurate global information, coordination and resource mobilisation. Some of the activities that are deemed central in globalising the surveillance for emerging and re-emerging diseases are: 1. Setting up of a global network for laboratories capable of rapidly identifying emerging and re-emerging organisms; 2. Setting up of a global network for surveillance and monitoring the development of antibiotic resistant organisms. The WHONET computer programme is already operational in some countries and extension of its use to other countries will lead to a very powerful and comprehensive global monitoring system for antibiotic resistant organisms. The participation of Kenya Medical Research Institute in this programme has been elicited as one of the pilots for Africa; 3. Setting up rapid reaction forces to respond to specific outbreak situations in order to control the spread of an emerging infectious disease. In this area of rapid trans not continental travel, the world is viewed as a "global village" and the relevance of the current International Sanitary Regulations requires a re-appraisal. Global sensitisation of the international community to the importance of this programme will ease and facilitate efforts at mobilisation resources needed and the training of the manpower required to make the above activities operational on a global scale.

Detection of HBV-DNA and HCV-RNA viral sequences by polymerase chain reaction in selected Kenyan samples and the relationship to HBV seromarkers.

We undertook a study on selected samples from patients who had presented with viral hepatitis and conditions of the liver (liver cirrhosis, chronic hepatitis and hepatocellular carcinoma). Diagnosis, screening and confirmation for viral hepatitis was done using a battery of techniques: ultrasound, conventional serological methods (Hepatitis B surface Antigen [HBsAg] - Reverse Passive Haemagglutination [RPHA], Hepatitis B core Antibody [HBcAb] - Passive Haemagglutination [PHA], Alpha-feto Protein - RPHA), Hepatitis B e Antigen/Antibody [HBeAg/Ab] - Radioimmunoassay [RIA], Hepatitis C antibody [HCV-Ab] - Enzyme Immunosorbent Assay [EIA]. Due to the high specificity and sensitivity of the Polymerase Chain Reaction technique [PCR] in detecting the viral genomes, it was used to establish the presence of the HBV-DNA and HCV-RNA to correlate the serological diagnosis of their respective seromarkers. A total of 39 serum samples were tested comprising 11 blood donors, 8 chronic liver disease patients and 20 hepatocellular carcinoma cases. 4/19 (21%) HCV-antibody (C-l) reactive samples were found to be positive for HCV-RNA by PCR. 14 of the 19 (73.7%) including the 4 HCV-RNA positive cases tested positive for HBcAb. 6 of 11 (55%) HBsAg positive cases also tested positive for HBV-DNA by PCR, In 8 of 20 (40%) hepatocellular carcinoma cases, no aetiological role could be assigned to hepatitis B or C as only HBcAb was demonstrated in those cases.