Monsoon diseases

» Dr. M. R. Ravi
Dengue fever
Dengue fever is an infectious
tropical disease caused by
the dengue virus.

» Dr. M. R. Ravi
Symptoms include
 fever,
 headache,
 muscle pains
 joint pains,
 a characteristic skin rash that is
similar to measles.

» Dr. M. R. Ravi
In a small proportion of cases the
disease develops into the life-
threatening dengue hemorrhagic
fever, resulting in bleeding, low levels
of blood platelets and blood plasma
leakage, or into dengue shock
syndrome, where dangerously low
blood pressure occurs.

» Dr. M. R. Ravi
 Dengue is transmitted by several species of mosquito
within the genus Aedes, principally A. aegypti and A.
albopictus.
 The virus has four different types; infection with one
type usually gives life long immunity to that type, but
only short-term immunity to the others.
 Subsequent infection with a different type increases
the risk of severe complications.

» Dr. M. R. Ravi
Control and prevention
 As there is no commercially available vaccine,
prevention is sought by reducing the habitat and the
number of mosquitoes and limiting exposure to bites.

Chikungunya is a relatively rare
form of viral fever ("debilitating non-
fatal viral illness." )
caused by an alphavirus that is
spread by mosquito bites from the
Aedes aegypti and Aedes albopictus
mosquito.

» Dr. M. R. Ravi
EPIDEMIOLOGICAL TRIAD
AGENT
HOST ENVIRONMENT
VECTOR

» Dr. M. R. Ravi
Aedes aegypti
» Dr. M. R. Ravi

» Dr. M. R. Ravi
Aedes albopictus
» Dr. M. R. Ravi

» Dr. M. R. Ravi
Mosquito proboscis
(scanning electron microscopy)
» Dr. M. R. Ravi

» Dr. M. R. Ravi
Mosquito mouth parts
(scanning electron microscopy)
» Dr. M. R. Ravi

» Dr. M. R. Ravi» Dr. M. R. Ravi

» Dr. M. R. Ravi
AEDES MOSQUITOES
 Household container breeders
 Breeds in
 clean water
 In all stored water for drinking, washing and bathing
 Rainwater collected in unused materials like coconut
shells, mud pots, plastic cups, tyres etc

BREEDING SOURCES
» Dr. M. R. Ravi

AEDES MOSQUITOES
 Aggressive day time Bite
 Major period of activity – sunrise and sunset

» Dr. M. R. Ravi
ENVIRONMENT
 Population explosion
 Deforestation
 Global warming
 Floods
 Competition for food
 fast movement of population

» Dr. M. R. Ravi
ENVIRONMENT
 Emergence of world as single village
 Unplanned urbanization
 Inadequacy of sanitation,
 Improper disposal of garbage and pollution of
aquatic systems
 Development of resistance in vectors to
insecticides

» Dr. M. R. Ravi
TRANSMISSION
 This virus is transmitted only by mosquitoes
 The mosquito picks up the virus from an infected
person during the viraemic period – within five
days from the day of starting of symptoms
 An infected mosquito will remain infected all its
life span and can transmit the virus each time it
bites
 An infected person cannot spread the infection
directly to other persons

» Dr. M. R. Ravi
SYMPTOMS
 Fever Which Can Reach 39 C, (102.2 F)
 Petechial or Maculopapular Rash Usually
Involving the Limbs and Trunk
 Arthralgia or Arthritis Affecting Multiple
Joints Which Can Be Debilitating.
 Headache, Conjunctival Injection and
Slight Photophobia.

DIAGNOSIS
The diagnostic tests include detection of
antigens or antibodies in the blood, using
 ELISA (or EIA - enzyme immunoassay)
 polymerase chain reaction (PCR).

» Dr. M. R. Ravi
DIFFERENTIAL DIAGNOSIS
 DENGUE
 WEST NILE FEVER
 ONYONG NYANG FEVER

» Dr. M. R. Ravi
COMPLICATIONS
 Symptoms are generally self-limiting and last
for 1–10 days.
 Arthralgia (joint pain) may persist for months or
years.
 In some patients, minor hemorrhagic signs such as
epistaxis or gingivorrhagia have also been
described

» Dr. M. R. Ravi
IS THERE ANY EFFECTIVE
TREATMENT ?
 There is no active treatment against chikv
 Presently treatment is purely symptomatic -
supportive care and rest and nutrition
 Analgesics, antipyretics and fluid supplementation
are important aspects in managing this infection.

» Dr. M. R. Ravi
TREATMENT
Self-limiting and Will
Resolve With Time.
No Specific Treatment for
Chikungunya.
 Supportive or Palliative
Medical Care With Anti-
inflammatories

» Dr. M. R. Ravi
TREATMENT
Vaccine Trials Were
Carried Out in 2000, the
Project Was Discontinued
and There Is No Vaccine
Currently Available.
Supportive care with rest
is indicated during the
acute joint symptoms.

» Dr. M. R. Ravi
TREATMENT
Movement and mild exercise
tend to improve stiffness and
morning arthralgia, but heavy
exercise may exacerbate
rheumatic symptoms.
 aspirin and nonsteroidal
antiinflammatory drugs,
chloroquine phosphate (250
mg/day) has given promising
results.

» Dr. M. R. Ravi
Signs and symptoms
 Typically, people infected with dengue virus are
asymptomatic (80%) or only have mild symptoms such
as an uncomplicated fever.
 Others have more severe illness (5%), and in a small
proportion it is life-threatening.

» Dr. M. R. Ravi
Signs and symptoms
 The incubation period (time between exposure and
onset of symptoms) ranges from 3–14 days, but most
often it is 4–7 days.
 Children often experience symptoms similar to those
of the common cold and gastroenteritis (vomiting and
diarrhea) and have a greater risk of severe
complications, though initial symptoms are generally
mild but include high fever.

» Dr. M. R. Ravi
Course of Dengue illness
» Dr. M. R. Ravi

» Dr. M. R. Ravi
Prevention
 There are no approved vaccines for the dengue virus.
Prevention thus depends on control of and protection
from the bites of the mosquito that transmits it.

» Dr. M. R. Ravi
Prevention
 The World Health Organization recommends an
Integrated Vector Control program consisting of five
elements:
 (1) Advocacy, social mobilization and legislation to
ensure that public health bodies and communities are
strengthened,
 (2) collaboration between the health and other sectors
(public and private),

» Dr. M. R. Ravi
Prevention
 (3) an integrated approach to disease control to
maximize use of resources,
 (4) evidence-based decision making to ensure any
interventions are targeted appropriately and
 (5) capacity-building to ensure an adequate response
to the local situation.

» Dr. M. R. Ravi
Control
 The primary method of controlling A. aegypti is by
eliminating its habitats.
 This is done by emptying containers of water or by
adding insecticides or biological control agents to
these areas, although spraying with organophosphate
or pyrethroid insecticides is not thought to be
effective.

» Dr. M. R. Ravi
Control
 Reducing open collections of water through
environmental modification is the preferred method
of control, given the concerns of negative health effect
from insecticides and greater logistical difficulties with
control agents.
 People can prevent mosquito bites by wearing
permethroid impregnated clothing that fully covers
the skin, using treated mosquito netting while resting,
and/or the application of insect repellent.

» Dr. M. R. Ravi
Diarrhea
 Diarrhea (AmE) (or diarrhoea) (BrE) is the condition
of having three or more loose or liquid bowel
movements per day. The most common cause is
gastroenteritis.

» Dr. M. R. Ravi
Diarrhoeal disease
Key facts
Diarrhoeal disease is the second
leading cause of death in children
under five years old. It is both
preventable and treatable.
Each year diarrhoea kills around 760
000 children under five.

» Dr. M. R. Ravi
Diarrhoeal disease
 Key facts
A significant proportion of
diarrhoeal disease can be
prevented through safe drinking-
water and adequate sanitation and
hygiene.

» Dr. M. R. Ravi
Diarrhoeal disease
 Key facts
Globally, there are nearly 1.7 billion
cases of diarrhoeal disease every year.
Diarrhoea is a leading cause of
malnutrition in children under five
years old.

» Dr. M. R. Ravi
 Dehydration
 The most severe threat posed by diarrhoea is
dehydration. During a diarrhoeal episode, water and
electrolytes (sodium, chloride, potassium and
bicarbonate) are lost through liquid stools, vomit,
sweat, urine and breathing. Dehydration occurs when
these losses are not replaced.

» Dr. M. R. Ravi
 The degree of dehydration is rated on a scale of three.
 Early dehydration – no signs or symptoms.
 Moderate dehydration:
 thirst
 restless or irritable behaviour
 decreased skin elasticity
 sunken eyes

» Dr. M. R. Ravi
 Dehydration
 Severe dehydration:
 symptoms become more severe
 shock, with diminished consciousness, lack of urine
output, cool, moist extremities, a rapid and feeble pulse,
low or undetectable blood pressure, and pale skin.
 Death can follow severe dehydration if body fluids and
electrolytes are not replenished, either through the use
of oral rehydration salts (ORS) solution, or through an
intravenous drip.

» Dr. M. R. Ravi
Diarrhoea
 Causes
 Infection: Diarrhoea is a symptom of infections
caused by a host of bacterial, viral and parasitic
organisms, most of which are spread by faeces-
contaminated water. Infection is more common when
there is a shortage of adequate sanitation and hygiene
and safe water for drinking, cooking and cleaning.
Rotavirus andEscherichia coli are the two most
common etiological agents of diarrhoea in developing
countries.

» Dr. M. R. Ravi
Diarrhea
 Oral rehydration solutions (ORS) with modest
amounts of salts and zinc tablets are the treatment of
choice and have been estimated to have saved 50
million children in the past 25 years. In cases where
ORS is not available, homemade solutions are often
used.

» Dr. M. R. Ravi
Diarrhea
 It is a common cause of death in developing countries
and the second most common cause of infant deaths
worldwide.
 The loss of fluids through diarrhea can cause
dehydration and electrolyte disturbances such as
potassium deficiency or other salt imbalances.
 In 2009 diarrhea was estimated to have caused 1.1
million deaths in people aged 5 and over and 1.5
million deaths in children under the age of 5.

» Dr. M. R. Ravi
 There are many causes of infectious diarrhea, which
include viruses, bacteria and parasites. Norovirus is
the most common cause of viral diarrhea in adults, but
rotavirus is the most common cause in children under
five years old. Adenovirus types 40 and 41, and
astroviruses cause a significant number of infections.

» Dr. M. R. Ravi
 The bacterium Campylobacter is a common cause of
bacterial diarrhea, but infections by Salmonellae,
Shigellae and some strains of Escherichia coli (E.coli)
are frequent.

» Dr. M. R. Ravi
Weil’s Disease
 The disease was first described by Adolf Weil in 1886
when he reported an "acute infectious disease
with enlargement of spleen, jaundice, and nephritis."
 Leptospira was first observed in 1907 from a post
mortem renal tissue slice.
 In 1908, Inada and Ito first identified it as the causative
organism and in 1916 noted its presence in rats.

» Dr. M. R. Ravi
Leptospirosis
 Leptospirosis also known as
 Weil's syndrome,
 canicola fever,
 canefield fever,
 nanukayami fever,
 7-day fever,
 Rat Catcher's Yellows,
 Fort Bragg fever,
 black jaundice, and
 Pretibial fever)
It is caused by infection with bacteria of the genus
Leptospira and affects humans as well as other animals.

» Dr. M. R. Ravi
Leptospirosis
 Leptospirosis is among the world's most
common diseases transmitted to people from animals.
The infection is commonly transmitted to humans by
allowing water that has been contaminated by animal
urine to come in contact with unhealed breaks in
the skin, the eyes, or with the mucous membranes.
Outside of tropical areas, leptospirosis cases have a
relatively distinct seasonality with most cases
occurring in spring and autumn.

» Dr. M. R. RaviLeptospira scanning micrograph

» Dr. M. R. Ravi
 Leptospirosis is transmitted by the urine of an infected
animal and is contagious as long as it is still moist.
Although rats, mice, and moles are important primary
hosts, a wide range of other mammals including dogs,
deer, rabbits, hedgehogs, cows, sheep, raccoons,
opossums, skunks, and certain marine mammals are
able to carry and transmit the disease as secondary
hosts.

» Dr. M. R. Ravi
 In Africa, the banded mongoose has been identified as
a carrier of the pathogen, likely in addition to a
number of other wildlife hosts in African systems.
Dogs may lick the urine of an infected animal off the
grass or soil or drink from an infected puddle.

» Dr. M. R. Ravi
Occupations at risk
 Occupations at risk include
 veterinarians,
 slaughterhouse workers,
 farmers,
 sewer maintenance workers,
 waste disposal facility workers,
 land surveyors
 Slaughterhouse workers may contract the disease
through contact with infected blood or body fluids.
 Rowers are also sometimes known to contract the
disease.

» Dr. M. R. Ravi
Symptoms
 Leptospiral infection in humans causes a range of
symptoms, and some infected persons may have no
symptoms at all.
 Leptospirosis is a biphasic disease that begins with flu-
like symptoms (fever, chills, myalgias, intense
headache).

» Dr. M. R. Ravi
Symptoms
 The first phase resolves, and the patient is briefly
asymptomatic until the second phase begins.
 This is characterized by meningitis, liver damage
(causing jaundice), and renal failure.
 The infection is often wrongly diagnosed due to the
wide range of symptoms.
 This leads to a lower registered number of cases than
exists.

» Dr. M. R. Ravi
Symptoms
 Symptoms of leptospirosis include
 high fever,
 severe headache,
 chills,
 muscle aches,
 vomiting,
 jaundice,
 red eyes,
 abdominal pain,
 Diarrhea
 rash.

» Dr. M. R. Ravi
Symptoms
Initial presentation may resemble pneumonia. The
symptoms in humans appear after a 4–14 day incubation
period.
More severe manifestations include
meningitis,
extreme fatigue,
hearing loss,
respiratory distress, a

» Dr. M. R. Ravi
Symptoms
azotemia,
(Azotemia is a medical condition characterized by abnormally
high levels of nitrogen-containing compounds, such as urea,
creatinine, various body waste compounds, and other
nitrogen-rich compounds in the blood)
renal interstitial tubular necrosis,
renal failure
liver failure
(the severe form of this disease is known as Weil's disease,
though it is sometimes named Weil Syndrome).
Cardiovascular problems are also possible.

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