EPIDEMIOLOGY OF HEPATITIS B VIRUS IN THE KENYAN POPULATION:

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EPIDEMIOLOGY OF HEPATITIS B VIRUS IN THE KENYAN
POPULATION

• E.O.OGUTU
• DEPARTMENT OF MEDICINE
• UNIVERSITY OF NAIROBI
• KENYA.

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HBV MARKERS

• 70-90 of kenyans have markers of HBV by early
  teens.
• (Wankya et al. E.Afri.Med. J. 1979, Greenfield
  et al. E.afri. Med. J. 1986 Bowry et al.
  E.Afri.Med.J. 1481983.)
• However a study done in an area where HBV
  infection was of low endemicity 40-60 of the
  population had HBV markers by adulthood.
• (Okoth et al E.Afr. Med.J. 67 1990.)

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TableHbsAg Carrier rate in various studies done
in Kenya
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HBsAg. CARRIER RATE

• HBsAg. Carrier state in Kenya is 3-30 ,
  depending on the area of study
• However the average carrier rate is 7-10 .

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Prevalence of HBsAg with age.(Greenfield et al)
95 confidence limits
Figure shows that infection rare in 1st year of
life
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Prevalence Of Total Anti-HBc in HBV Low Endemic
Area

• Okoth et al 1990 reported on prevalence of
  anti-core antibody from a hepatitis B low
  endemic area. He screened 3779 specimens.
• He found that the prevalence of anti HBc
  increases with age
• Family members of HBV carriers have higher
  prevalence rates.

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Prevalence of total anti HBc in a HBV low
endemic area in kenya
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Prevalence of total anti-HBc with age.(Greenfield
et al.)
From 3yrs HBV infection (anti HBc) increases
linearly with age to reach peak At the 4th
decade.
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Prevalence of HBs Anti. In the Kenyan population(
Okoth et al 1990)
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Prevalence of HBs- Anti.in the kenyan population
cont.

• The above data shows the following-
• Prevalence of anti- HBs in adults is higher than
  in children.
• The prevalence in carrier family members is much
  higher than in non carrier members.
• Note that the above study was in a low endemic
  area for HBV.
• A study done by Bowry et al (1981)in an average
  endemic area i.e. Nairobi. found 57 of 104
  volunteer blood donors to be anti- HBs ve.

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Fig Increased prevalence of anti- HBS ant. In
family members of 117HBV carriers
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Subtypes of HBsAg in Kenya
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HBeAg status in the kenyan population

• 10 of asymptomatic HBsAg carriers in the Kenyan
  population are positive for HBeAg.(Greenfield et
  al)
• Overall, 87.5 of HBeAg ve. Patients have HBV
  DNA in both symptomatic asymptomatic.(Greenfield
  et al.)
• HBeAg status has been shown to decrease with age
  .(Greenfield et al Okoth et al.)
• Ok0th et al 1990 reported that 23.6 of females
  in the child bearing age were highly infectious
  (HBeAg ve.)

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Table HBeAg status by ageGreenfield et al
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HbsAg Carrier State In Volunteer Blood Donors In
Kenya
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Prevalence of HBsAg in blood donors in four
selected provinces(Kemri/Jica 1994 report)
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Hepatitis B liver disease

• Acute sporadic hepatitis in Kenya
• 1982-1983 Greenfield studied 94 cases of acute
  sporadic hepatitis -----He found 70 to be due to
  HBV infection
• .
• 2001Atina Ogutu studied 84 cases of acute
  icteric hepatitis at KNH---HBV accounted for 26
  of all age groups but 30 of those gt15yrs.

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Prevalence of HBsAg in patients with chronic
hepatitis in Kenya

• prevalence of The HBsAg in Kenyan patients wih
  chronic hepatitis
• is 20-43

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Prevalence of HBsAg in patients with liver
cirrhosis in Kenya

• The reported prevalence of HbsAg in Kenyan
  patients with cirrhosis is 22-60

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Prevalence of HbsAg in patients with hepatoma
Range is 40-70
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TRASMISION OF HBV IN KENYA

• HORIZONTAL
• Most important than vertical (Greenfield et al
  1986 Wankya et al, 1979).
• Intrafamilial spread important
• Between siblings
• Between spouses
• (Bowry 1983, Greenfield 1986, Okoth 1983.)

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Transmission of HBV cont.

• Intrafamilial gtSchool spread.
• (Okoth et al 1990 )
• Most infections in offsprings of both HbsAg ve
  -ve cohort mothers start after 3 months of age.
• (Greenfield et al 1986)
• There is high infection rates in infants
  children with highest prevalence reached by age
  10yrs.
• (Wankya 1979, Bowry 1983.)

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Horizontal transmission cont.

• The higher infection rates in children infants
  in Kenya could be because of the pattern of HbeAg
  prevalence. (see table)

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Table Age prevalence of HbeAg/Anti-Hbe in Kenya
Okoth et al EAMJ vol.67 ,1990.
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Perinatal transmission in Kenya

• Two important studies in Kenya
• Greenfield Study
• Okoth Study
• An ongoing 3rd. Study

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Perinatal Greenfield Study(J.Med.Vir.191986)

• Screened gt 3000 pregnant mothers
• 51 mothers (8) were found to be HBsAg ve
• The 51 offsprings from the above HBsAg ve
  mothers were followed up for 6-11 months.

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Greenfield Study on perinatal transmission Cont.

• Outcome of the 51 offsprings (HBsAg ve) during
  the follow up period
• 3 children had active HBV infection
• ie. HBsAg ve high titres HBcAb
• 40 children were ve for HbsAg.

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Greenfield Perinatal transmission cont.

• 3 children had no active infection
• I.e.had transient HbsAg ve
• With falling anti-Hbc
• 5 children had probable infection I.e.
• HbsAg ve,
• HbcAb ve.

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Greenfield Perinatal transmission cont.

• Only 3 children in the HbsAg ve. Cohort mothers
  became HbsAg ve.
• Most mothers were anti-Hbe ve
• The onset of infection in offspring in both HbsAg
  ve -ve cohort mothers started after 3 months
  of age.
• The delay in the ve cohort could have been due
  to low infecting dose of HBV.

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Greenfield Study on perinatal transmission.Conclu
sions

• Only a minority of Kenyan children are infected
  in the perinatal period.
• These will be infants born to HbeAg ve. Carrier
  mothers who exhibit high levels of HBV
  replication.
• In the majority of childre lt1 year of age
  infection appears to be due to horizontal modes
  of transmission
• Older siblings may be the source of the infection.

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Perinatal transmission Okoth et al. study

• Study 1EAMJ 671990.
• He studied 55 HbsAg pregnant women in a rural
  community
• 24 new born babies to HbsAg mothers were followed
  every 3-4 months.
• 2 out of 5 (40) of those born to HbsAg, HbeAg
  ve mothers became HbsAg ve within 12 months.
• The 2 babies became ve around 11-12th. Month of
  age.

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Okoth study 1 cont.

• Babies born to all other HbeAg category of
  mothers did not become HbsAg ve by 12 m0nths.
• I.e.HBeAg-ve, HbeAb-ve
• OR
• HbeAbve,HbeAg-ve

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Okoth et al Study 2EAMJ 681991

• In this study 41 infants whose mothers were HBV
  carriers were f0llowed up every 6 months.
• 6 infants became HBV chronic carriers
• 5 born to HBeAg ve 1 born to HbeAg-
• HbsAg mothers HbsAg mothers
• Status of sibs not All 3 siblings(2sisters
• Mentioned 1 brother) were HbeAg
• HbsAg
• The 5 babies were 1st.
• Found HbsAg at around
• The following ages1,3,8, Horizontal
  transmission
• 1020 months ?vertical
• ?Horizontal modes (Baby ve at
  around 22months of age.

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Conclusions on possible modes of HBV transmission
in Kenya

• Horizontal transmission plays a significant role.
• Perinatal transmission is also present but
  appears to be less common than horizontal
• Sexual transmission do exist but no study has
  been directed to this
• However in Okoths study( 1990), there was a
  significant rise of HbcAb ve at age 16-20 yrs.
• attributed this to increased sexual
  transmission.

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Conclusions on possible modes of HBV
transmission.(2)

• Parenteral transmission
• This must be much less as blood is being
  screened for HBsAg most health institutions now
  use sterile needles.
• Taditional habits like circumcision is more
  practiced in hospitals.
• Intravenous drug abuse is not a common problem in
  Kenya.

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