This document summarizes information about two arthropod-borne infections: dengue and malaria. For dengue, it describes the viral cause, transmission via Aedes mosquitoes, clinical presentations including classical fever and dengue hemorrhagic fever, and prevention through mosquito control and vaccines. For malaria, it discusses the protozoan cause, transmission via Anopheles mosquitoes, clinical stages of fever, and prevention through presumptive treatment, radical treatment, chemoprophylaxis, and vector control measures. It also briefly mentions filariasis caused by nematodes transmitted by mosquitoes.

1. Arthropod-Borne
Infections
Dengue
Presented by Miss Sudipta Roy
East Point College of Pharmacy Bangalore

2. Dengue.
• Dengue is a viral disease belonging to the group of
arboviruses, capable of infecting humans and causing the
disease.
• Causative Agent.
• The arbovirus is transmitted through vector mosquitoes
Aedes aegypti and Aedes albopictus. The dengue virus
occurs in four serotypes:1,2,3, and 4. Fever can occur
epidemically or endemically. Epidemics may be explosive
and often start during the rainy season. The reservoir of
infection is both man and mosquito. Transmission cycle is
"Man-mosquito-Man''. Aedes-mosquito becomes infective
by feeding on a patient from the day before onset to the 5th
day of illness. This is termed as viraemia stage. After an
extrinsic incubation period of 8-10 days, the mosquito
becomes infective, and is able to transmit the infection.

3. • Once the mosquito becomes infective , it remains so
for the entire life. The illness is characterized by an
incubation period of 3-10 days, most commonly 5-6
days.
• Clinical Presentation.
• Infection may be assymptomatic or may lead to one
of the following manifestations.
• Classical dengue fever.
• Dengue heamorrhagic fever without shock.
• Dengue haemorrhagic fever with shock

4. • Classical fever.
• The onset of symptoms is sudden with chills and high
fever, intense headache, muscle and joint pains which
prevent all movement. Within 24 hours retro-orbital pain,
particularly on eye movements or eye pressure and
photophobia develops.
• Other common symptoms include extreme weakness,
anorexia, constipation, altered taste sensatoin, coliky
pain, abdominal tenderness, dragging pain in inguinal
region, sore throat, and general depression. Fever is
usually between 39-40 degree centrigrade. The skin
eruption appears in 80% of cases during remission or
second febrile phase. The rash lasts for 2 hours to several
days and may be followed by desquamation. Fever lasts
for about 5 days.

5. Dengue Heamorrhhagic Fevere
(DHF).
• It is a severe form of dengue fever, caused by infection with
more than one dengue virus . The first infection probably
sensitizes the patient, while the second appears to produce
an immunological consequences. DHF is transmitted by A.
aegypti following an incubation period of 4-6 days, the
illness commonly begins abruptly with fever accompanied
by facial flushing and headache. Anorexia, vomiting and
epigastric discomfort, tenderness at the right costal margin
and generalized abdominal pain are common. The major
pathophysiological changes in DHF are plasma leakage and
abdominal heamostasis as manifested by a rising
heamatocrit value and moderate to marked
thrombocytopenia. Thromboctyopenia (100,000/mm3 or
less) and heamatocrit are increased by 20% or more to the
base line value are indicative of DHF.

6. • Dengue Shock Syndrome (DSS).
• It has all clinical manifestations of DHF along with shock
represented by rapid and weak pulse with narrowing of pulse
pressure (20 mmHg or less) or hypotension, with presence of
cold, clammy skin and restlessness.
• Role of Pharmacist in Education and Prevention.
• Following control measures are suggested.
• Mosquito control: The vector of dengue fever , A aegypti breed in
and around houses and can be controlled by individual and
community action. The most common action is to keep water
flowing and avoid accumulation of unhygienic stagnant water.
• Vaccines: No satisfactory vaccine is available.
• Other measures: Isolation under bed nets during first few days
can provide individual protection against mosquitoes.

7. Malaria.
• It is a protozoal disease caused by the infection
with a parasite.
• Causative Agent.
• The causative agent is Plasmodium vivax,
Plasmodium falciparum, Plasmodium malariae and
Plasmodium ovale.
• The malarial parasite undergoes two cycles of
development, the human cycle (asexual cycle) and
the mosquito cycle (sexual cylce). Man is the
intermediate host and mosquito, the definitive
host. The interrelation between the two cycles is
shown in the figure.

8. • Malaria is transmitted by the bite of certain species
of infected, female anopheles mosquitoes. A single
infected vector during her life time, may infect
several persons. The mosquito is not infective
unless the sporozytes are present in its salivary
glands. Accidentally blood transfusion can pose a
problem of malaria because the parasites keep
their infective activity during atleast 14 days in
blood bottles stored at -4 degree centrigrade.
• Incubation period varies with the species of
parasite. It is 12 (9-14) days for P. Falciparum.

9. Clinical Presentation.
• A typical malarial attack comprises three distinct
stages.
• 1. Cold Stage.
• The onset is with headache, nausea and chilly
sensation followed in an hour or so by rigors.
Headache is often severe and commonly there is
vomiting. In early part of the stage, skin feels cold ,
later it becomes hot . Parasites are usually
demonstrated in blood. The pulse is rapid and may be
weak. This stage lasts for 1/4 tp 1 hour.

10. • Hot stage.
• The temperature rises rapidly to 39 degree to 41
degree centrigrade.
• The patient feels burning hot and casts off his clothes.
The skin is hot and dry to touch. Headache is intense
but nausea commonly diminishes. The pulse is full and
respiration is rapid . This stage lasts for 2-6 hours.
• Sweating stage.
• Fever comes down with profuse sweating. The
temperature drops rapidly to normal and skin is cool
and moist. The pulse rate becomes slower, parient feels
releived and often falls asleep. This stage lasts for 2-4
hours.

11. • The clinical features of malaria vary from mild to
severe and complicated based on species of the
parasites, the patient's state of immunity, the
intensity of infection and also the presence of
concomitant conditions like malnutrition or other
diseases. Alternate fever and chilling cold occur on
every third or fourth day depending on the species
of the parasite involved. The peaks of the fever
coincide with the release into the blood stream of
successive batches of merozites. A typical cycle of
cold, hot and sweating stage is followed by an
afebrile period in which the patient feels greatly
releived.

12. • Out of the four species , P. falciparum may lead to
cerebral malaria, acute renal failure, liver damage,
gastro-intestinal symptoms, dehydration, collapse,
aneamia etc. The complications of P. vivax, P. ovale
and P. malariae are aneamia, splenomegaly ,
enlargement of liver, renal complications etc.

13. Role of Pharmacist in Education
and Prevention.
• There are two different approaches to malaria control:
• The management of malaria cases in the community.
• There are three strategies for the control of disease.
• Presumptive Treatment:
• It means that all fever cases are assumed to be due to
malaria. All surveillance workers are administered a
single dose of chloroquine phosphate in 600 mg doses
(4 tablets). In the areas with P.falciparum resistant
strain, Amodiaquine 600 mg or Sulphalene 100 mg +
Pyrimethamine 50 mg should be given.

14. • Radical Treatment.
• It changes with the type of infection P.falciparum,
P.ovale, P.vivax,P. malariae and mixed infections:
single dose of 600 mg chloroquine +15 mg
primaquine on first day followed by 15 mg
primaquine daily for next four days + Artemther
• Short-term chemoprophylaxis is done with
doxycycline 100 mg daily, and
• Long-term chemoprophylaxis is done with
mefloquine 5 mg/kg weekly.

15. • Active intervention to cntrol or interrupt malaria
transmission with community participation.
• Vector control measures are the primary weapons
to control malaria in endemic areas.
• These efforts are sub-divided into two sub-types.
• Anti-adult measures.
• It involves spraying insecticides like DDT, Malathion,
fenitrothion. It is observed that discontinuation of
spraying very often leads to resurgence of malaria.
DDT is very common, however due to resistance to
DDT, malathion/fenitrothion as organo-

16. • Individual protection with the use of mosquito
repellants, protective clothing, bed nets impregnated
with insecticides, mosquito coils are suggested.
• Anti-larval measures.
• Few larvicides like temephos are suggested. Repeated
use of larvicides make it more costly. Reduction of
source including drainage, management of water
level, changing the salt content of water and
intermittent irrigation are some of the methods of
controlling malaria.

17. • National Malaria Eradication Programme is being
implented by Government of India.
• Vaccine against malaria is under clinical
development.
• Filiariasis.
• The commonly used term is Lymphatic Filariasis. It
covers infection caused by three closely related
nematode worms. All infetions are transmitted by
the bites of infected mosquitoes. The disease is not
fatal , but causes considerable suffering, deformity
and disability.

18. • Causative Agent :
• The commonly infectives nematodes are
Wuchereria bancrofti, Brugia malayi and Brugia
timori. All the the parasites have similar lifecycles in
man. Adult worms live in lymphatic vessels of
infected individuals, while their offspring,
microfilaria circultes in peripheral blood and are
available to infect mosquito vectors when they
come to feed. Whenever an infected mosquito
bites a person , the parasite os deposited near the
site of puncture. It passes through the punctured
skin or may penetrate the skin on its own and

19. • Incidence of the disease dependens on man-
mosquito contact.The incubation period is 8 to 16
months from the invasion of the infected larvae.
• The clinical presentation can be divided into two
distinct phases.
• 1. Lymphatic Filaroasis.
• In this phase, four stages have been described .
• Asymptomatic amicrofilaria.
• In all endemic areas a proportion of population
neither have microilaria in their body , nor do they
show clinical manifestation of the diseases,

20. • Asymptomatic microfilaria.
• Some individuals in the endemic areas do show
microfilaria in their body, but they continue to be
without any symptoms , may be for months or even
years. These carriers are source of infection in the
community. Collection of blood samples during
night can show presence of the infective organisms.

21. • Stage of acute of manifestation.
• In the infected patients, during first few months or
even years, there are recurrent episodes of acute
inflammation in lymph glands and vessels. The
clinical manifestations include filarial fever,
lypmhangitis, lymphoedema, of various parts of the
body and of epididymoorchitis in the male.
• Stage of Chronic Obstructive Lesions:
• The chronic stage usually develops 10-15 years
after the first acute attack. This phase is due
fibrosis and obstruction of lymphatic vessels
causing permanent structural changes.

22. • Elephantiasis is the primary symptom in chronic cases
affecting legs, scrotum, arms, penis, vulva and
breasts.
• Occult filariasis.
• The occult filariasis refers to filarial infections in
which the classical manifestions of the disease are
not present and the microfilaria is not found in the
blood. It is beleived to result from a hypersensitivity
reaction to filarial antigens derived from microfilaria.
The best known example is topical pulmonary
eosinophilia.

23. • Rol of Pharmacist in Eradication and Prevention.
• Two kinds of preventive measures are suggested:
• Chemotherapy.
• Two drugs have been recommended :
Diethylcarbamazine citrate: the recommended
dose for W.bancrofti infection is 6 mg/kg, and 3-6
mg/kg for B.Malaye infection orally for 10 days.

24. • Ivermecitin: The recommended dose is 200-400
mg/kg as a single oral dose.
• Vector control.
• The most important element in vector control is the
reduction of target mosquito population in order to
stop or reduce transmission quickly.
• Control of vectors is done by three following
measures.

25. • Antilarval measures.
• The ideal method is elimination of breeding places of
mosquitoes by providing adequate sanitation and
underground waste water disposal system. In addition,
chemical control by uing mosquito larvicidal oil, pyrosone
oil or organo-phosphorous larvicides like temephons or
phenthion is suggested. Growth of pistia plant in aquatic
vegetation is said to be reason to promotw growth of
mosquitoes, hence removal of the plant is suggested. Use
of herbicides like phenoxylene 30 or Shell Weed Killer D is
recommended for destroying aquatic vegetation. In
addition, environmental measures like filling up of ditches
, and cesspools , drainage of stagnant water, adequate
maintenance of septic tanks and soakage pits are
suggested.

26. • Anti-adult measures.
• Since mosquitoes have shown resistance to few
synthetic pesticides, pyrethrum as a space spray is
suggested.
• Personal prophylaxis.
• The most effective preventive measure is avoiding
mosquito bites by using mosquito nets.

27. • Chikunhunya.
• Chikungunya is a viral disease that is transmitted to
people by mosquitoes.
• In late 2013, chikungunya was found for the first
time in the Americas on islands in the Caribbean.
• The virus is passed to humans by two species of
mosquito of the genus Aedes: A. albopictus and A.
aegypti. Animal reservoirs of the virus include
monkeys, birds, cattke and rodents. This is in
contrast to dengue, for which only primates are
hosts, Same types of mosquitoes transmit dengue
visurs. These mosquitoes bite mostly during the

28. • Causative Agent.
• It is caused by chikungunia virus. It is an alphavirus
with a positive-sense single-stranded RNA genome
of about 11.6 kb.
• Clinical presentation.
• Chikungunia usually starts suddenly with fever,
chills, headache, nausea, vomiting, joint pain and
rash. This refers to the contorted (or stopped)
posture of patients who are afflicted with the
severe joint pain (arthrits) which is the most
common feature of the disease. Frequently, the
infection causes no symptoms, especially in

29. Role of Pharmacist in Education
and Prevention.
• There is neither chikungunya virus vaccine nor drugs
are available to cure the infection.
• Prevention, therefore, centers on avoiding mosquito
bites. Eliminating mosquito breeding sites is another
key prevention measures. To prevent mosquito bites,
following things are recommeded.
• Use mosquito repellants on skin and clothing.
• When indoors, stay in well-screened areas. Use bed
nets if sleeping in areas that are not screened or air-
conditioned.
• When working outdoors, during day times, wear long-
sleeved shirts and long pants to avoid mosquito bites.

30. • Following things are specifically recommended for
mosquito control.
• Source Reduction Method.
• By eliminating of all potential vector breeding
places near the domestic or peridomestic areas.
• Not allowing storage of water for more than a
week. This could be achieved by emptying and
drying the water containers once in a week.
• Straining of stored water by using a clean cloth
once a week to remove the mosquito larvare from
water and water can be reused. The sieved cloth

31. Use of larvicides.
• Where the water cannot be removed but used for
cattle or other purposes, Temephos can be used
once a week at a dose of 1 ppm (parts per million)
• Pyrethrum extract (0.1% ready to use emulsion)
can be sprayed in rooms (not outside) to kill the
adult mosquitoes hiding in the house.

32. • Define the term epidemiology and elaborate on
epidemic, endemic and pandemic.
• Describe epidemiology of communicable diseases.
• Discuss importance of medical microbiology with
reference to three important microbial diseases.
• Describe dynamics of disease transmission.
• Enlist clinically important respiratory infection and
describe any one with clinical presentation.

33. • Desribe any two respiratory infections.
• Describe any two intestinal infections.
• Enlist intestinal infections and describe any one of
them.
• Describe any two arthropod -borne infections.
• Describe any two surface infections.

34. • Desribe causative agent, clinical presentation and
role of pharmacists in following infections:
• Chikungunya
• Dengue
• Malaria
• Filiariasis