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Zoonoses 4th year 25-3-2017 Dr.Osamah muwafg

West Nile Fever (WNF)

AGENT

RNA virus, genus Flavivirus (group B), family Togaviridae

RECOGNITION

Syndrome: Human:

1. Ranges in severity from subclinical to a febrile course of

short duration to encephalitis

2. more serious illness in elderly persons than in children
3. Most common signs include sudden onset of fever, headache,

enlarged lymph nodes,

4. Maculopapular rash on the trunk, though ocular, muscular,

and joint pain may also occur.

5. Duration typically is about 3-5 days, generally followed by

rapid and complete recovery.

6. Convalescence is sometimes prolonged and accompanied by

profound weakness.

7. Myocarditis, meningitis, and encephalitis are occasional

complications.

Animal:

1.  Most infections are subclinical.
2.  Horses may occasionally develop meningoencephalitis.
3.  No other domestic mammal clinically affected.
4.  Peridomestic  birds,  such  as  pigeons,  turtledoves,  and  crows

may be affected, as may some wild birds.

Incubation period: Human, 3-6 days.

Zoonoses 4th year 25-3-2017 Dr.Osamah muwafg

Case fatality rate: Negligible in humans; up to 25% in horses, and
high in experimentally infected crows.

Confirmatory tests:

Virus isolation during acute phase, or serologic testing (SN) of
paired sera.

Occurrence:

1. Occurs in summer, is both endemic and epidemic.
2. Widely distributed throughout Africa, Asia, and Europe

where the virus has been isolated from humans, other
mammals, birds, and arthropods.

3. Endemic in the Nile Delta,
4. epidemics occur in Israel, and occurs sporadically in South

Africa.

5. Human prevalence of infection in Egypt may exceed 60%.

Transmission:

1. Mosquitoborne.
2. Birds are the reservoir, developing a persistent, high-titer

viremia that allows infection of Culex mosquitoes.

3. Humans, sheep, and cattle, are accidental hosts that do not

develop viremia sufficient to infect vectors.

CONTROL AND PREVENTION

Individual/herd:

1. Prevent mosquito bites with protective clothing and use of

repellents.

2. No vaccine is available.

Local/community:

Zoonoses 4th year 25-3-2017 Dr.Osamah muwafg

1. Vector control is difficult because the species of mosquito

that transmits the infection to humans is not well established
in all areas affected.

2. Cula mosquitoes transmit infection bird-to-bird, but may not

infect humans.

3. Another vector that connects the wild cycle with human

outbreaks is likely, and control of this latter vector is
important.

Yellow Fever (YF)

AGENT

RNA virus, genus Flavivirus (group B), family Togaviridae

RECOGNITION

Syndrome: Human:

1. Subclinical to severe, life-threatening disease of short

duration.

2. Mild cases may be indeterminate.
3. Typically, begins with sudden onset of high fever, headache,

chills, backache, muscle pain, prostration, nausea, and
vomiting.

4. Fever may subside after 3-4 days, then return in the second

phase of illness,

5. during which hepatic and renal involvement and hemorrhage

may occur.

6. Nasal and oral bleeding, hematemesis ("black vomit"), and

melena occur.

Zoonoses 4th year 25-3-2017 Dr.Osamah muwafg

7. The name derives from the jaundice that often results from

liver impairment.

8. Most deaths occur between days 3 and 7, with prognosis

improving if survive at least 10 days.

Animal:

1. Nonhuman primates may be affected, with varying degrees of

severity among species.

2. Monkeys in the Americas are more severely affected and

have  a  higher  mortality  rate  than  those  in  Africa,  a  possible
factor being YF has long been  endemic in Africa whereas it
is more recent in Neotropical regions.

3. The clinical course in primates is similar to that in humans.

Incubation period: In humans, 3-6 days.

Case fatality rate:

1. In endemic regions, often less than 5%,
2. but in nonindigenous groups and in epidemics fatalities may

exceed 50%.

Confirmatory tests:

1. Virus isolation during the first few days of illness is most

reliable.

2.  Viral antigen can be detected in serum by ELISA testing.
3.  Serologic tests include HI, SN, CF, and IFA.
4.  Cross  reactions,  however,  can  occur  with  other  flaviviruses,

and

antibodies

developed

after

vaccination

are

indistinguishable from those produced as a result of infection.

Zoonoses 4th year 25-3-2017 Dr.Osamah muwafg

Occurrence:

1.  Restricted to Africa and the Americas.
2.  In Africa, both urban and sylvatic cycles of infection occur.
3.  The urban cycle occurs mainly in savannah areas, particularly

those bordering rain forests, such as in Burkina Faso and
Nigeria.

4. Sylvatic YF occurs from the Sahara east to Ethiopia and

Somalia and south as far as Angola and Zaire.

5. In the Americas, urban YF no longer exists, because of

successful urban mosquito eradication programs, but the
sylvatic cycle continues in forests of northern South America.

6. Most human cases occur in the Amazon Basin, the plains of

southeastern Colombia, and eastern Bolivia and Peru.

Transmission:

Mosquitoborne.

In Africa, other species of Aedes can transfer the virus from
monkeys to humans.

CONTROL AND PREVENTION

Individual/herd:

1. Vaccinate travelers to endemic areas.
2. Vaccinate family members and other contacts of YF patients.

Local/community:

1. For urban YF, mass vaccination campaigns, mosquito

control.

Zoonoses 4th year 25-3-2017 Dr.Osamah muwafg

2. For sylvan YF, vaccinate people living near or entering

affected forests and avoid those areas for one week post-
vaccination.

National/international:

1. If YF in a human is discovered in a nonendemic area, the

WHO and adjacent countries must be notified immediately,
as specified in the International Health Regulations.

2. YF among nonhuman vertebrates in newly discovered or

reactivated foci must also be reported.

3. Monkeys and other nonhuman primates arriving in YF-free

areas from areas where YF occurs must be quarantined for 7
days.

4. Proof of vaccination against YF is required by many

countries for travelers who have come from or through areas
where YF occurs.

Nairobi Sheep Disease (NSD)

AGENT

RNA virus, genus Nairovirus (ungrouped), family Bunyaviridae

RECOGNITION

Syndrome: Human:

1. Usually subclinical.
2. Some experience a transient influenza-like syndrome with a

diphasic fever.

Zoonoses 4th year 25-3-2017 Dr.Osamah muwafg

Animal:

1.  A hemorrhagic gastroenteritis occurs in sheep and goats.
2.  Usually subclinical among indigenous animals,
3.  whereas  newly  introduced  susceptible  animals  become

anoretic, have a mucopurulent nasal discharge and a fetid
diarrhea which eventually becomes bloody.

4. Pregnant animals frequently abort.
5. Death may occur in 24 hours.

Case fatality rate: For humans, 0%. For sheep, 30%-90%; for
goats,

Incubation period: 4-15 days.

Confirmatory tests:

Identify virus microscopically (FA) in mice or tissue culture
infected from blood, spleen, or mesenteric node of patient. Detect
antibody by IFA.

Occurrence:

1. Endemic in East Africa
2. serologic evidence of infection from Ethiopia to South

Africa.

3. Serologic evidence that human infection is common in

endemic areas.

4. Outbreaks in small ruminants occur when susceptible animals

are moved into endemic areas.

Zoonoses 4th year 25-3-2017 Dr.Osamah muwafg

Transmission:

1.  Tickborne,
2.  Viremia occurs during the febrile period.
3.  Rhipicephalus  appendiculatus  is  the  primary  vector,  but

Amblyomma spp. have also been incriminated.

4. The virus can survive in ticks for two years, and transovarial

and transstadial transmission occur. The virus is maintained
in a sheep-tick-sheep cycle.

5. Transmission by blood transfusion from currently viremic

persons can occur.

6. Infection results in complete immunity. 0%-30%.

CONTROL AND PREVENTION

1. Individual/herd:
2. Prevent tick attachment by wearing protective clothing and

using repellents in endemic areas.

3.  Remove attached ticks every few hours.
4.  Control ticks on animals by weekly dipping or spraying.
5.  An  attenuated  live  virus  vaccine  is  available  for  sheep  and

goats, but it is not very satisfactory.

6. An experimental inactivated vaccine has provided excellent

protection against laboratory challenge.

7. Because of the mild disease, vaccination of humans is not

indicated.

Local/community:

1. Perform serologic screening of blood donors.
2. Prevent spread of infected ticks from endemic areas by

restricting animal movement.

Zoonoses 4th year 25-3-2017 Dr.Osamah muwafg

Influenza

AGENT

RNA viruses, genus Influenzavirus (types A and B), family
Orthomyxoviridae; type C is in a separate, unnamed genus.

RECOGNITION

Syndrome: Human:

1. An acute respiratory disease.
2. Signs of types A and B typically include fever, chills,

headache  and  muscular  aches,  malaise,  pharyngitis,  and
cough.  Gastrointestinal  signs,  such  as  nausea,  vomiting,  and
diarrhea, occur more in children than in adults.

3. Type C is a milder illness, in which lacrimation, sneezing,

and runny nose are more pronounced than in A and B;

4. subclinical infection is frequent in type C.
5. Generally most severe among the elderly and those with

chronic, debilitating conditions, and other immunosuppressed
persons, and it is among these groups that most deaths occur.

6. May be complicated by pneumonia, both viral and bacterial.
7. Reye syndrome, which affects the CNS and liver, may occur

as a sequel in children who have taken aspirin during the
illness.

8. Recovery is usually complete in about a week.

Animal:

1. Type A occurs most notably in swine, horses, and birds.
2. In pigs, there is abrupt onset with inappetence, coughing,

coryza, dyspnea, and fever. Recovery in uncomplicated cases

Zoonoses 4th year 25-3-2017 Dr.Osamah muwafg

is rapid, and subclinical infections occur. Type C also occurs
in swine.

3. In horses, signs include high fever, abundant nasal discharge,

coughing, dyspnea, and depression lasting some 2-10 days,
followed by 1-3 weeks of convalescence.

4. Often more serious in colts than in mature horses.
5. Avian influenza ("fowl plague") is most known for its effects

on commercial poultry, and ranges from a subclinical or mild
infection to severe disease with high mortality.

6. Signs include anorexia, decreased egg production, coughing,

sneezing, facial edema, coryza, and diarrhea.

7. Other species from which influenza viruses have been

isolated or antibodies detected include whales, fur seals,
harbor seals, and dogs.

Incubation period: Human, 1-5 days; animal, 2-3 days.

Case fatality rate:

1. Low in humans, swine, and adult horses
2. although in some human pandemics mortality has increased

significantly.

3. High in colts and seals, and may approach 10-13% in severe

poultry outbreaks.

Confirmatory tests:

Virus isolation from throat or nasal washings early in the illness.
Serologic tests (HI, CF, SN) of paired sera.

Zoonoses 4th year 25-3-2017 Dr.Osamah muwafg

Occurrence:

1. Worldwide
2. Usually in epidemics or pandemics, with high morbidity and

generally low mortality, and sporadic cases.

3. Type A causes most pandemics and annual epidemics,
4. whereas type B outbreaks are less widespread and occur at

less-frequent intervals.

5. Sporadic cases and small clusters of infection are often

attributable to type C.

6. The attack rate during epidemics ranges 10%-30% in the

general population,

7. but in institutions, such as schools, nursing homes, etc., up to

70% of susceptible individuals may be affected.

8. Generally occurs during the autumn and winter in temperate

regions

9. in the tropics most cases occur during the rainy season, but

sporadic outbreaks may occur in any month.

Transmission:

1.  Mainly by inhalation of aerosols
2.  direct contact with droplets.
3.  Among birds, also by the fecal-oral route.

CONTROL AND PREVENTION

Individual/herd:

1. Inactivated type A vaccines are highly effective.
2. Because of the frequent changes in antigenic structure of type

A viruses, vaccination is generally effective for only one
season.

Zoonoses 4th year 25-3-2017 Dr.Osamah muwafg

3. Amantadine or rimantadine administered early in the illness

can help alleviate symptoms and reduce the amount of virus
in secretions.

4. Inactivated vaccines are also available for horses and swine.

Local/community:

Vaccination campaigns can help reduce the magnitude of
epidemics.

Newcastle Disease (ND)

AGENT

RNA virus, genus Paramyxovirus, family Paramyxoviridae

RECOGNITION

Syndrome: Human:

1. Manifests primarily as conjunctivitis, usually unilateral,
2. with congestion, lacrimation, pain, swelling of sub-

conjunctival tissues, and pre-auricular lymphadenitis.

3. Generally no systemic involvement,
4. but persons exposed to aerosols develop an influenza-like

illness of 3-4 days’ duration.

5. Recovery is complete in about a week.
6. Subclinical infections also occur.

Animal:

Among numerous bird species affected, chickens and turkeys are
especially susceptible.

Most common signs are respiratory, nervous, or both.

Zoonoses 4th year 25-3-2017 Dr.Osamah muwafg

Incubation period:

1. In humans usually 1-2 days
2. 2-15 days in birds with respiratory or CNS disease, 2-4 days

for viscerotropic.

Case fatality rate:

1. None in humans.
2. In poultry can range from none (with lentogenic strains) to

100% (in some outbreaks of velogenic visce ro tropic
disease).

Confirmatory tests:

1. In humans, virus isolation is the only definitive test because a

serologic response may not occur

2. In poultry, virus isolation early in an outbreak. Serologic tests

include HI, SN, and ELISA.

Occurrence:

1. Worldwide in wild birds, semidomestic, and domestic fowl
2. Human ND is rare, and usually occurs among laboratory

personnel, poultry abattoir workers, and poultry vaccinators
using live vaccines.

Transmission:

1. Chickens are the main reservoir.
2. NDV is spread from bird to bird mainly by aerosols, although

NDV is also present in feces; the density of birds in
commercial poultry farms facilitates transmission.

3. Humans become infected when NDV contacts the eyes, as

from aerosolized vaccines.

Zoonoses 4th year 25-3-2017 Dr.Osamah muwafg

CONTROL AND PREVENTION

Individual/herd:

Avian ND can be controlled by:

1.  maintaining good hygiene on poultry farms,
2.  separating poultry houses
3.  vaccination.

Human ND can be prevented by:

1. the use of goggles and masks when vaccinating poultry,
2. using care to avoid aerosols when working with NDV in the

laboratory.

National/international:

1. Imported live birds of any species should be quarantined
2. Imports from countries where ND occurs should be

prohibited.

Psittacosis (ornithosis) avian chlamydiosis (AC)

Chlamydophila psittaci (formerly known as Chlamydia psittaci)

Disease in humans

1.  May be subclinical, leading to under-diagnosis.
2.  incubation period of 1–2 weeks
3.  symptoms similar to influenza or a respiratory infection.

Disease in animals

1. C. psittaci is widespread in both wild and domestic birds.

Zoonoses 4th year 25-3-2017 Dr.Osamah muwafg

2. Parrots are the most frequently encountered hosts in a

companion animal setting,

3. Other potential hosts as zoonotic reservoirs include turkeys,

ducks, geese, pigeons, starlings, pheasants and birds kept for
competitive showing.

4. The organism is resistant to drying, and can be found in dust

in hen houses, pigeon lofts and other roosting sites.

Transmission

1. Transmission to humans follows inhalation of dried bird

faeces or nasal discharge from infected birds, direct contact
with birds or their feathers and by bird bite

2. human-to-human transmission may occur by the aerosol

route.

Treatment

1. Tetracycline is given at a dose of 250–500 mg three to four

times daily for at least 7 days

2. Doxycycline, azithromycin, erythromycin

Prevention

1. Education of individuals in high-risk groups.
2. Early detection of cases in birds is an important part of any

prevention strategy.

3. Reduction in stress and overcrowding is recommended to

control infective spread.

4. Placing birds suspected of having psittacosis in isolation until

they can be tested, and subsequently treated or slaughtered

5. Treatment of imported companion birds with prophylactic

antibiotics

Zoonoses 4th year 25-3-2017 Dr.Osamah muwafg

Q fever

Query fever, Balkan influenza, abattoir fever

It is caused by a rickettsia, Coxiella burnetii, an obligate
intracellular bacterium.

Disease in humans

1.  Most exposed individuals display no signs of clinical disease
2.  incubation period of between 2 and 4 weeks
3.  followed by an acute onset with high fever, associated chills,

profuse sweating and severe headache

4. fever may last anything from 9–14 days and can recur at

intervals, with a total duration of up to 3 months

5. A dry cough may be present, with pain in the chest cavity
6. A chronic form also exists that causes a prolonged

endocarditis leading to valvular damage

Transmission

1. follows exposure to infected material
2. direct contact with contaminated materials, especially the

afterbirth or material contaminated with amniotic fluid

3. Drinking milk or consuming contaminated milk
4. transmission via ticks, lice or fleas has been demonstrated

Diagnosis

serological testing: indirect immunofluorescence, complement
fixation, enzyme-linked immunosorbent assay (ELISA) and
microagglutination.

Treatment

1. C. burnetii can be difficult to treat

Zoonoses 4th year 25-3-2017 Dr.Osamah muwafg

2. tetracyclines at usual clinical doses

Prevention :

1. Good personal and environmental hygiene
2. Bedding contaminated by postpartum material and the

material itself should be carefully handled, with collection
and subsequent burying or incineration

3.  Disinfection of housing and other areas
4.  Protective clothing, including respirators, overalls and gloves
5.  Carrier animals have been subject to eradication by slaughter

policy

6. All milk and milk products should be pasteurised