Community Medicine lecture on Arthropod borne diseases in keeping with CBME curriculum. From Dr. Mandar Baviskar, Asso Prof Community Medicine, Dr. BVP RMC, Loni, Maharashtra

1. Dr. Mandar Baviskar MD
CM 8.1 (04): Epidemiology, control measures including essential lab tests at primary
level for Arthropod Borne Diseases (Malaria, Dengue, Chikungunya, JE, Zika, Filaria)
K. Park, 25th ed., Page: 269-315

2.  Enumerate & Comprehend the Agent, Host & Environment factors associated with
common arthropod borne diseases (Malaria, Dengue, Zika, Chikungunya, JE, Filaria
etc.)
 Enumerate & Comprehend indications for common lab tests & vector control
measures including Integrated Vector Control.
 Comprehend role of National Health Programs & Global Disease Control Strategies
for vector borne disease control.

3.  India is Cat. A (Hyper-endemic) for Dengue
 Agent Factors: Flavivirus with 4 serotype (DEN-1,2,3,4)
 Vector: Aedes mosquito
 Bites infected individual (From 1 day before to 5th day after symptom onset)
 Domesticated & nervous feeders
 Mosquito is infective for life. Trans-ovarian transmission in mosquitos
 Multiple strains cause severe disease
 Host Factors: Infants, Obese, Pregnant, Peptic ulcer disease, dysmenorrhea, G6PD
deficiency, haemoglobinopathies, congenital & chronic diseases, frequent NASID
intake are conditions that increase risk of adverse outcomes.
 Environmental Factors: Rainfall, humidity, water storage (Best 16-30 Celsius, 60%-
80% humidity). Rise in temperature reduces incubation period and increases
dehydration thus increased likelihood of being bitten.
 Incubation Period: 3-10 days (commonly 5-6 days)

4.  Asymptomatic
 Acute Febrile Illness
 Classical Dengue Fever: Sudden onset, high grade, biphasic fever, with chills,
headache, muscle and joint pain, retro-orbital pain. Weakness, Abdominal pain,
altered taste, anorexia.
 Rash: 80% cases. 1-2 days during remission or second fever phase, 3-4 days scarletiform
with mottling itching, hyperaethesia, and desquamation.
 Dengue Haemorrhagic Fever: Severe form of Dengue
1. Febrile Phase: First 3 days
2. Critical Phase: 3-7 days
3. Recovery Phase: 3 days after critical Phase
 Dengue Shock Syndrome: Around 5 days after onset. Hypotensive shock with multi-
organ failure

7.  Mosquito Control
 Vaccine: CYD-TDV (0,6,12 months 0.5ml for 9-45 years) NaCl diluent.
Contraindicated in HIV, Pregnancy, Lactation, H/o Allergy
 Personal Protective Measures
 Health Awareness: May 16th is National Dengue Day
 Global Strategy for Dengue Prevention & Control (2012-2020)
1. Estimate true burden of disease by 2015
2. Reduce mortality by 50%
3. Reduce morbidity by 25%
 National Vector Borne Disease Control Program (NVBPCP)
 Notification: IDSP

8.  216 million cases & 4.5 lakh deaths worldwide
 0.84 million cases in India & 104 deaths
 Agent Factors: Plasmodium parasite transmitted by Anopheles mosquitos
 Falciparum, Vivax, Ovale, Malariae types
 Rural, Urban, Tribal, Border, Forest, Floods
 Man is intermediate host & mosquito is definitive host.
 Human reservoir (who harbors gametocytes) is infective
 Ovale & vivax may relapse
 Host Factors: Race, Pregnancy, SES, Housing, Migration, Habits, Immunity
 Environmental Factors:
 Season, Temperature, Humidity, Rainfall, Man made breeding sites, Altitude
 Vector Density, Life span, Choice host, Resting habits, Breeding habits, Time of bite
 Resistance to insecticides

9.  Transmission: Mosquito bite (MC), Blood transfusion & Congenital(rare)
 Incubation period: Falciparum: 12 days(8-17), vivax: 28 days
 Clinical Features:
 Cold Stage: Chills, lassitude, tachycardia (1 hour)
 Hot Stage: Fever, Headache, Tachypnea, (2-6 hours)
 Sweating Stage: Fever drops, sweating, patient seeps (2-4 hours)
 Falciparum & vivax 48 hour cycles, Malariae 72 hour cycle
 May not be seen now a days
 Diagnosis:
 Microscopy: JSB stain
 RDT
 Serology

10.  Older: Spleen rate, Parasite Rate
 Current:
1. Annual Parasite Incidence (API) [>2 High risk]
2. Annual Blood Examination Rate (ABER) [operational efficiency]
 Slide Positivity Rate & Falciparum Rate
 Vector Indices
 Human blood Index
 Sporozoite Rate
 Mosquito Density
 Bite rate
 Inoculation rate

11.  Surveillance
 Case Detection (Active & Passive)
 Sentinal Surveillance
 Early Diagnosis & Treatment
 Integrated Vector Control
 Indoor Residual Spraying
 Bed nets
 Antilarval measures
 Epidemic preparedness
 Supportive
 Capacity Building
 BCC
 Collaboration
 Monitoring & Evaluation
 Research

16. Vaccine in Phase III trials
NVBDCP

17.  Globally ~120 million
 Agent Factors: 8 species (MC-W.bancrofti, B.malayi, B. timori). Transmitted by bite of
mosquitos (MC -Culex). Microfilariae(Mf) infective & nocturnal
 Host Factors: Man is definitive host, mosquito is intermediate. Female viviparous can
birth upto 50000 Mf/ day. Enter blood via lymph & clog the system.
 Disease travels with Young migrants and thrives in unsanitary slums.
 Pre-patent period: Inoculation Appearance of Mf
 Clinical Incubation Period: 8-16 months
 Extrinsic incubation period : 10-14 days
 Reservoirs: Monkeys, dogs and cats
 Clinical Manifestation:
 Lymphatic: Asymptomatic Acute lymphangitis Chronic obstructive(Elephantitis)
 Occult: Immune Hypersensitivity (Tropical Pulmonary Eosinophilia)

18. Survey
 Mass Blood Survey: Thick film, Membrane filter, DEC provocation Test
 Clinical Survey
 Serological Tests: complement fixing
 Xenodiagnosis: Mosquitos allowed to feed on the patient & dissected 2
weeks later
 Entomological Survey
Treatment
 Amoxicillin, Analgesic, Antipyretics, Surgical Rx
 Diethylcarbamazine citrate (DEC) 6mg/kg 12 doses
 Ivermectine 150-200 microgram/kg
 Integrated Vector Control

19.  Chikungunya means ‘to double over’ in
Tanzanian
 Agent: Chikungunya virus (Arbovirus)
 Vector: Aedes mosquito
 Incubation Period: 4-7 days
 Diagnosis:
 ELISA
 RT-PCR
 VERO cell culture
 Clinical Features
 Fever
 Joint pains
 Lymphadenopathy
 Conjunctivitis
 Lumbago
 Anorexia
 Treatment
 Self limiting
 Symptomatic
 Prevention
 Integrated Vector Control

20.  Agent: JE VIRUS –FLAVIVIRUS
 Vector: Culex Mosquitos
 Reservoir: Pigs, Cattle, Birds
 Host: Age(extremes),Migration,
agriculture, males
 Environment: Seasonal(rain), Cyclical
trends
 No man to man transmission as man is
incidental “dead end” host.
 Incubation period: 5-15 days

21.  PRODROMAL PHASE(6 days): High
grade fever, headache, malaise
 ENCEPHALITIC STAGE: High fever,
severe head ache, nuchal rigidity,
focal, CNS signs, seizures, altered
sensorium, doll’s eye moments,
absent corneal reflex, pupillary reflex,
deviation of angle of mouth, loss of
consciousness etc.
 Symptoms and signs of raised ICT-
headache, vomiting, hemiplegia,
bradycardia, irregular breathing.
 Signs and symptoms of meningeal
irration-kernigs sign
 LATE STAGE: Begins when active
inflammation is at end i.e. temp. and ESR
touch normal. Mental impairment, Increased
deep tendon reflexes, Paresis of UMN lesion
 LMN lesion type, Speech impairment
 Diagnosis: CSF Serology
 Complications: Death 35 - 50% - short
prodromal stage, deep coma, hypertonia,
tachypnea In children early mortality.

22.  No specific treatment per se.
 Vector control is the main mode of
prevention of an individual and
community as a whole.
 Control of amplifier hosts.
 Vaccination

23.  Agent: Arbovirus group. Falvivirus. First reported Uganda 1947.
 Transmitted by Aedes mosquito
 Environmental factors: Same as Dengue fever
 Incubation period: 2-7 days
 Clinical Presentation: Symptoms include fever, rash, muscle & joint pain, malaise
 Brazil outbreak, Associated with Microcephaly & Guillian Barre Syndrome
 Trans-placental infection reported
 H/o of travel
 Diagnosis: PCR (NIV, Pune)
 Prevention: Integrated Vector Control measures
 Treatment: Symptomatic Rx, Antenatal Diagnostic testing & counseling

24.  Anti Larval Measures:
 Environmental
 Chemical
 Biological
 Anti-Adult Measures:
 Residual Sprays
 Space Sprays
 Genetic Control
 Personal Protective Measures:
 Nets
 Screens
 Repellents

25. Homework:
Epidemiological
Factors
Malaria Dengue Zika Filaria
Agent Factors
Host Factors
Environment Factors
Incubation Period
Transmission
Diagnosis
Treatment
Prevention & Control
Measures