Epidemiology of Diseases of Public Health

Significance

Sefonias G. (MPH, PhDc, Assistant prof)

SPH, AAU
August, 2022
Disease of public health significance

• Reportable Diseases are now referred to as "Diseases of Public Health Significance".

• Timely reporting of communicable diseases is essential for their control
• In Ethiopia, there are 22 reportable priority diseases or conditions, which are
included in the IDSR system

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List of priority disease under surveillance reporting in Ethiopia

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Why prioritize?
• Priority setting is necessary to ensure that both planning and resource
allocation are rational, explicit and transparent

• Surveillance systems are usually developed over time, with new diseases
being added and few removed.

• This often results in a long list of diseases for surveillance, impairing the
ability of the system to perform efficiently.

• In many surveillance systems data are collected which never result in public
health action,

whereas new threats are considered insufficiently or not at all.

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Priority cont…
Public health risks change over time therefore priorities should be reviewed
periodically. Because;
• Some diseases are no longer a national public health threat and yet they
remain on the national list of mandatory reportable diseases
• Diseases evolve as antigenic variants expand their host or geographical range or
as antibiotic resistance develops.
• Advanced technology and improved knowledge impact on surveillance
strategies and methods.
• The introduction of new vaccines and control programmes alters the
surveillance objective and leads to different surveillance methods.
• As demographic characteristics of populations change due to lower birth rates
and longer life expectancy, new risks may be expressed.
In order to capture data on the most important diseases and conditions and not to
overstress the surveillance system, priorities have to be set.
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When to prioritize?

• All countries should review their Good opportunities to revise priority diseases are:
• As an initial step to strengthen national surveillance, either
list of priority diseases for before or immediately after the assessment of the existing system
surveillance periodically to see if it • As part of the process of evaluation of surveillance functions;
reflects current needs. • When there is a change in the national health policy or in the
International Health Regulations;
• Prioritization only makes sense if • Following an outbreak, to take advantage of lessons learned
and public pressure
it happens within the right and political will to change;
context; • Whenever there is a new threat, or a new disease. Case of
 Political endorsement of the process COVID19.
and willingness to accept the results of
the exercise are prerequisites.

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Cycle illustrating surveillance systems strengthening activities

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How to prioritize?
• Prioritizing diseases for surveillance is not an easy process.
• It involves complex value judgments,
• such as the relative importance of early detection of a highly infectious disease compared
with monitoring endemic, common, but less severe diseases.
• Ideally, prioritization should be based on scientific evidence

• In situations where there is insufficient, inadequate, or contradictory scientific information or

it is non existent, consensus methods, such as the Delphi method, are valid approaches.

• The Delphi method provides a structure and process to harness the insight of appropriate
experts to enable decisions to be made.
 It avoids personal and political influence,
 allows individuals to change their opinion in the light of the group's response.
 Measuring the degree of agreement helps to move to a consensus.

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Prioritization process using the Delphi method consists of:
• Formulation of a list of diseases, and criteria to include/exclude diseases for
surveillance, by a steering committee;
• Discussion of the proposed criteria and disease list by participants in the
prioritization exercise;
• Formulation of a questionnaire in which participants are asked to score the diseases
against the criteria;
• Expression of individual opinion of participants through scoring the diseases against
the criteria;
• Collation and summary (using statistical parameters) of the scoring, and assessment
of agreement;
• Feedback of the individual and group ranking to the participants;
• Discussion of the results
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 Some Disease of Public Health Importance
Acute respiratory illness (ARI)
• About 90% of all ARI among under five children deaths were reported in the Sub
Saharan Africa and Southeast Asia.
• Globally, more than 12 million children with severe ARI were admitted to hospitals
every year.
• In Ethiopia, about 3.4 million children suffer from ARI annually and Ethiopia is
among the top 15 countries with highest burdens of ARI .
• It accounts for 18% of all deaths, and kills over 40,000 under five children every
year.

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ARI Cont…
• Acute respiratory infection (ARI), and particularly pneumonia, is one of leading causes of
morbidity and mortality

That accounts for 18% of deaths (WHO and UNICEF 2013).

• Ethiopian Demographic and Health Survey (EDHS) data 2016.

7% of children under age 5 had symptoms of ARI in the 2 weeks before the survey.
Treatment was sought for three out of 10 children and only 3% of these children
received treatment on the same or next day
ARI among under five children had spatial variations across the country (Moran’s I: 0.34,
p < 0.001).

Predictors of under five acute respiratory infection.

• History of diarrhea, age, working mothers, secondary school education, and
stunting.

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Published online 2020 Jan 30. doi: 10.2147/IJGM.S233782
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Disparity of ARI

• The incidence of ARI among under five children varies among countries
at large and regions in particular.
• These differences can be attributed to child, mother, environment related
factors, and co morbid diseases like: measles, diarrhoea, and malaria

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Human immune deficiency Virus (HIV)
• HIV continues to be a major global public health issue, having claimed 36.3 million
[27.2–47.8million] lives so far.
• There were an estimated 37.7 million [30.2–45.1 million] people living with HIV at
the end of 2020

Over two thirds of whom (25.4 million) are in the WHO African Region.
• In 2020, 680 000 [480 000–1.0 million] people died from HIV related causes and 1.5
million [1.0–2.0million] people acquired HIV
• Globally, 27.5 million [26.5–27.7 million] people living with HIV were receiving ART
in 2020.

This equates to a global ART coverage rate of 73% [56–88%].

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HIV/ADIS cont…
• In Ethiopia, Progress towards the 2020 90 90 90 targets for HIV was suboptimal for
the first 90

with only 78.5% of estimated people living with HIV (PLHIV) knowing
their HIV status.

• Achievements were better for the second and third 90’s:

90% of PLHIVs who know their status were on ART and

91% of those on ART had viral suppression (MOH, 2019/20).

• About 90% of the annual incident HIV infections in children under 15 are still due
to mother to child transmission (13.4%, according to UNAIDS 2019).

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HIV/ADIS Cont…

• In 2019, among the estimated HIV positive mothers that need ART for prevention
of mother to child transmission (PMTCT), 74% received antiretroviral therapy
(ART).

• PMTCT service is available in 84% of public health facilities, but only in 5% of

private facilities (SARA 2018).

• In 2019, 64% of HIV exposed infants born to HIV positive women received
virological testing for HIV;

but proportion of infants born to HIV positive mothers who received
antiretroviral prophylaxis is low

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Major challenges and gaps in response to HIV epidemic in Ethiopia
• Suboptimal HIV case finding, especially in pediatric and adolescent age groups
and in key and priority populations; and
• Gaps on overall quality of services for prevention, diagnosis, care, and
treatment.

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Tuberculosis (TB)
• Ethiopia is on track to achieving one of the three targets of the global End TB
Strategy:

• TB incidence has declined by 21% from the 2015 estimate (was against a target of
20%).

• However, progress in reducing TB mortality was only 15% (target was 35%) under
HSTP I.

• As there is no nationally representative estimate of the catastrophic costs for TB

affected households, the status of progress on the third milestone is not known.

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TB cont….
• TB case notification has been improving, with a detection rate of 71%.
• In 2019/20, TB treatment success =95% and cure rates also = 80%, (MOH, 2019)
• According to SARA 2018,

50% of health facilities offered TB diagnosis by sputum smear microscopy
examination and

39% by clinical symptoms.
• Multi drug resistant (MDR) TB is a public health concern as the number of cases
increase in Ethiopia.
• Since 2009, a cumulative of 4,906 drug resistant TB (DR TB) patients were detected
and enrolled on second line drug treatment.
• As of 2019, 59 DR TB treatment initiative centers, and
• More than 700 treatment follow up centers providing DR TB treatment services.

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Vaccine preventable disease(VPD)

• Various reports verified that the infant mortality rate is more common in low income
countries.
• Most children living in Sub Saharan Africa die every 12 months from communicable
diseases that can be prevented through vaccination.
• For example, evidence of WHO from 2001 to 2008 reviled that around 9 million
child deaths worldwide as a result of vaccine preventable diseases,

a higher proportion occurred in sub Saharan Africa, which was 4.4 million.

• In Ethiopia, vaccine preventable diseases contribute substantially to under five

mortality as well as morbidity.

Diarrhea (18%), pneumonia (18%), measles (1%), and meningitis are the leading
causes of child mortality in the country

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VPD cont….

• Ethiopia’s EPI was launched in 1980, and the routine immunization schedule
comprises six vaccine preventable diseases,

They are measles, diphtheria, pertussis, tetanus, polio, and tuberculosis

with the goal of increasing immunization coverage by 10% annually.

• Rotavirus, pneumococcal, and second dose of measles vaccines were introduced in

2011, 2013, and 2019 respectively

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Immunization Status

• In 2019, coverage with three doses of

pentavalent vaccine and all basic vaccines
among children under 1 year of age
reached 61% and 44%, respectively.

• However, about 19% of children had no

vaccination at all.

• There is also high vaccination dropout rate

with a national dropout of 13% from
pentavalent 1 to measles, with high regional
variation.

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Min EDHS 2019

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Sexually transmitted infections(STIs)

• More than 1 million sexually transmitted infections (STIs) are acquired every day
worldwide.
• Each year, there are an estimated 376 million new infections with 1 of 4 STIs:

chlamydia, gonorrhoea, syphilis and trichomoniasis
• In 2016, WHO estimated 376 million new infections with 1 of 4 STIs:

Chlamydia (127 million),

Gonorrhoea (87 million),

Syphilis (6.3 million)

Trichomoniasis (156 million).
• About 80–90% of the global burden of STIs which found in the developing world
where there is limited and/or no access to diagnostics of STIs

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STIs cont…

• An estimated 240 million people are living with chronic hepatitis B globally.

• Both HPV and hepatitis B infections are preventable with vaccination.

• A person can have an STI without having obvious symptoms of disease.

Common symptoms of STIs include;

Vaginal discharge, urethral discharge or burning in men, genital ulcers, and
abdominal pain.

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STIs cont….
In Ethiopia
• According to 2016 EDHS, Overall, 4% of women and men age 15 49 reported
having an STI and/or symptoms of an STI in the past
• 2011 EHDS, reported 3% of women and 2% of men reported having an STI or STI
symptom in the year before the survey.

• In Ethiopia, the highest reported rates of STIs are found among 15–24 years old

• 67% of women and 66% men did not seek any advice or treatment

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Prevalence of sexually transmitted infections among
students in the last 12 months, the University of
Gondar, northwest Ethiopia, 2016

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Percentage of self -reported STIs among women of reproductive age women in Ethiopia
https://doi.org/10.1016/j.heliyon.2021.e07524

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Thank you!

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