» Dr. M. R. Ravi
» 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
» 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 albopictusmosquito.
» Dr. M. R. Ravi
» Dr. M. R. Ravi
EPIDEMIOLOGICAL TRIADAGENT
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
» Dr. M. R. Ravi
» Dr. M. R. Ravi
» 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 nonsteroidalantiinflammatory 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» Dr. M. R. Ravi
» 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 diseaseKey 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
SymptomsInitial 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
Symptomsazotemia,
(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.
» Dr. M. R. Ravi» Dr. M. R. Ravi