This document summarizes information about three arthropod-borne infections: plague, malaria, and filariases. It describes the causative agents, modes of transmission, symptoms, treatment and prevention methods for each. Plague is caused by the bacterium Yersinia pestis and transmitted by rat fleas. Malaria is caused by Plasmodium parasites and transmitted through the bites of infected Anopheles mosquitoes. Filariases are caused by parasitic nematodes and transmitted by various blood-sucking arthropods such as mosquitoes. Prevention strategies include vector control, vaccination, chemotherapy and improving sanitation.

1. DEVIPRIYA P V
M PHARM
Arthropod borne
infections

2. CONTENTS
 Plague
 Malaria
 Filariases

3. PLAGUE
Causative agent:
 Yersinia Pseudotuberculous Pestis (a gram negative, non-
motile, cocco bacillus).
 Vector: The vector of plague is rat flea
 Reservoir of infection: Wild rodents
 Sources of infection are infected rodents, fleas and cases
of pneumonic plague (severe lung infection caused by the
bacterium Yersinia pestis).
Mode of transmission:
 The Y pestis is transmitted between rodents by fleas .
 After the death of rat, affected flea leave the rat & bite a
man.
 The infection spread from man to man by droplets.

4. Prevention and control:
 Control can be done by early diagnosis, notification, isolation ,
disinfection of patient’s sputum and treatment.
 In adults tetracycline 500 mg q.i.d orally is the drug of choice.
 Cotrimoxazole is given for children.
 In several cases , streptomycin is given intramuscularly in the
dose of 30 mg/kg body weight per day in two divided doses for
10 days in addition to either of the drugs,
 Control of fleas can be done by their destruction, by spraying
DDT & BHC.
 Control is done by mass destruction, improvement of housing.
 Vaccination is a valuable prevention
 Plague vaccine (formalin killed plague bacilli) is given
subcutaneously in two doses of 0.5 and 1.0 ml at 1 to 2 weeks
interval.
 Booster dose is given for every 6 months for those who are at

5. MALARIA
 A group of infection caused by infection with specific
sporozoan parasites of genus plasmodium and transmitted
to man by infected female Anopheles mosquito.
 Characterized by episodes of chills and fever with periods of
latency(delay), enlargement of spleen and secondary
anaemia.
Stages of malaria:
(A)Cold stage (B)Hot stage (C)Sweating stage.
Cold stage :
 Sudden onset of fever with rigor and chills.
 This stage lasts between 15 minutes to one hour
Hot stage:
 Headache & burning hot & the casts off clothes
 This stage lasts from 2 to 6 hours.

6. Sweating stage:
 Profuse sweating.
 This stage lasts from 2 to 4 hours.
 Febrile paroxysms occurs repeatedly after a period of 2 to 3
days depending on the type of the malarial parasite.
Causative agent:
 Caused by 4 species of malaria parasite.
1. Plasmodium vivax (responsible for 70% cases in India),
2. Plasmodium falciparum,
3. Plasmodium malarae,
4. Plasmodium ovole
 The malarial parasite undergoes two cycles of development-
asexual cycle in man and sexual cycle in mosquito

7. Mode of transmission:
(a)Vector transmission:
 Transmitted by the bite of female Anopheles mosquitoes
(b)Direct transmission:
 Transmitted by infected needles, blood transfusions etc
(c)Congenital infection:
 Occur in new born from infected mother.
Incubation period:
 The time between mosquito bite and the appearance of fever
is more than 10 days ranging from 12 to 40 days

8. Prevention and control:
 WHO expert Committee on Malaria (1979)
Measures to be taken by the individual:
 Prevention of man / vector contact by using repellents,
protective clothing , bed nets etc.
 Destruction of adult mosquitoes by domestic sprays.
 Destruction of mosquito larvae by peridomestic sanitation,
intermittent drying of water containers.
 Source reduction of mosquitoes by filling, small scale
drainage and other forms of water management.
 Measures against malaria parasite include
chemoprophylaxis and chemotherapy
Measures to be taken by the community.
 Prevention of man / vector contact- site selection and
screening of houses.
 Destruction of adult mosquitoes- spraying insecticides.
 Destruction of mosquito larvae- using larvicides

9.  Source reduction- prevention of man made malaria,
environmental sanitation, water management , drainage
schemes.
 Measures against malaria parasite- presumptive treatment,
radical treatment, mass drug administration.
Treatment of malaria:
 Presumptive treatment should be given to all fever cases
which are assumed to be malaria.
 For this, choloroquine 250 mg is given, collect the blood
simultaneously for microscopic examination.
 If the slide is positive , then the treatment consists of
 1st day: choloroquine 600 mg + Primaquine 15 mg
 Next 4 days: Primaquine is given in a dose of 15 mg per day
 Antimalarial vaccine: Clinical trials are in process to develop
malaria vaccine

10. FILARIASES
 The group of diseases caused by certain nematodes of the
family Filariodea
 Transmitted to man by certain blood sucking arthropods.
 The disease can be lymphatic filariasis or non- lymphatic
filariasis
Lymphatic filariasis:
 Caused by W. Bancrofti, B. Malayi, B. Timori.
 Transmitted by the bite of infected mosquitoes.
 Adult worm live in lymphatic vessels but their offspring
(microfilaries) circulates in the peripheral blood and are
available to infect the mosquito.

11. Causative agent:
 In India, Lymphatic filariasis is caused by W. Bancrofti,
B. Malayi.
 The infection is transmitted to man by the bite of
infected mosquitoes.
 Man is the definitive host and mosquito is the
intermediate host
Control of filariasis:
 Control is based on chemotherapy and vector control.
Chemotherapy :
 Drug used is Diethylcarbamazine(DEC) (Hetrazan
tablets)
 For W. Bancrofti infection the dose of DEC is 6 mg per
kg body weight per daily orally after meal in divided
doses for 12 days.
 For B. Malayi DEC is given in a dose ranging from 3

12. Vector control:
 Elimination of breeding places of mosquitoes by
adequate sanitation and underground waste water
disposal system
 Destruction of adult mosquitoes by using insecticides
 Putting larvicidal oil on collected waste or using
organophosphorous larvicides