40 years. (ii) Sex : Attack rate was greater in males than in During 2006, there was a large outbreak of chikungunya
females. (iii) Occupation : The attacked people were mostly in India, with 1.39 million officially reported cases spread
cultivators who visited forests accompanying their cattle or over 1 6 states; attack rates were estimated at 45 per cent in
cutting woods and (iu) Human actiuity : The epidemic period some areas (21). The outbreak was first noticed in Andhra ·
correlates well with the period of greatest human activity in Pradesh and it subsequently spread to Tamil Nadu.
the forest, i . e . , from January until the onset of rains in J u n e . Thereafter, Kerala and Karnataka were affected and then
northwards as far as Delhi. The other states involved were
(e) MODE OF TRANSMISSION
Maharashtra, Madhya Pradesh, Gujarat, Rajasthan,
The transmission cycle involves mainly monkeys and Pondicherry, Goa, Orissa, West Bengal, Uttar Pradesh,
ticks. The disease is transmitted by the bite of infective ticks, Andaman and Nicobar Islands. During 2 0 1 3 , 1 8 , 6 3 9 cases
especially nymphal stages. There is no evidence of man to were reported by the Government of India (4).
The incubation period of chikungunya fever is 4-7 days,
following which the disease has a sudden onset with fever,
(f) INCUBATION PERIOD
chills, cephalalgia, anorexia, lumbago and conjunctivitis.
Estimated to be between 3 and 8 days.
Adenopathy is also common. 60 to 80 per cent patients have
a morbilliform rash, occasionally with purpura, on the trunk
and limbs. The cutaneous eruption may recur every 3 to 7
The disease appears with a sudden onset of fever,
days. Other symptoms are coffee-coloured vomiting,
headache and severe myalgia, with prostration in some
epistaxis and petechiae. A prominent symptom, seen
patients. The acute phase lasts for about 2 weeks.
especially in adult patients is arthropathy, from which the
Gastrointestinal disturbances and haemorrhages from nose,
disease gets its name. The arthropathy is manifested by
gums, stomach and intestine may occur in severe cases.
pain, swelling and stiffness, especially of the
In a number of cases, there is a second phase metacarpophalangeal, wrist, elbow, shoulder, knee, ankle
characterized by mild meningoencephalitis after an afebrile and metatarsal joints. It appears between 3rd and 5th day
period of 7 to 2 1 days. It is manifested by a return of fever, after the onset of clinical symptoms, and it can persist for
severe headache followed by neck stiffness, coarse tremors, many months and even years. No deaths have been
abnormal reflexes and mental disturbances. The case fatality attributed to chikungunya fever ( 1 1 ) .
rate has been estimated to be 5 to 10 per cent (13).
There is no specific treatment of chikungunya infection
Diagnosis is established only after detecting the presence and it is usually self limiting. Analgesics, antipyretics like
of the virus in the blood and/or serological evidence. paracetamol, diclofenac sodium, chloroquine along with
fluid supplementation are recommended to manage
CONTROL infection and relieve fever, joint pains and swelling. Drugs
like aspirin and steroids should be avoided.
(a) CONTROL OF TICKS : Since KFD is a tick-borne
disease, control of ticks should be undertaken. For control of The disease occurs in the rainy season, when the
ticks in forests, application can be made by power mosquito vector population is at its peak. Research suggests
equipment or by aircraft-mounted equipment to dispense that the virus has a wild cycle, similar to that of yellow fever,
carbaryl, fenthion, naled or propoxur at 2 . 2 4 kg of active operating between jungle primates and mosquitoes,
ingredient per hectare (17). The spraying must be carried including Aedes africanus and members of the A. furcifer-
out in “hot spots”, i . e . , in areas where monkey deaths have taylori group. ·
been reported, within 50 metres around the spot of the
monkey deaths, besides the endemic foci. Since the heavy DIAGONSIS
tick population in the forest areas is attributed partly to the
The virus can be isolated from the blood of febrile
free roaming cattle, restriction of cattle movement is
patients by the intracerebral inoculation in suckling mice or
thought to bring about a reduction in vector population.
on VERO cells.
(b) VACCINATION : The population at risk should be
immunized with killed KFD vaccine. (c) PERSONAL In serologic diagnosis, which is the approach most
PROTECTION : Protection of individuals exposed to the risk commonly used, sere-conversion is demonstrated by
of infection by adequate clothing and insect repellents such comparing acute – and convalescent – phase sera in the
as dimethylphthalate (DMP, DEET) should be encouraged. haemagglutination inhibition, serum neutralization, or
They should examine their bodies at the end of each day for complement fixation test. The enzyme-linked
ticks and remove them promptly. The habit of sitting or lying immunosorbent assay (ELISA) is used to detect lgM. A
down on the ground should be discouraged through health reverse-transcription polymerase chain reaction (RT-PCR) I
education. nested PCR technique has also been shown to be useful in
rapidly diagnosing the disease ( 1 1 ) .
4. Chikungunya fever
A dengue-like disease caused by a group A virus, the
chikungunya virus and transmitted by Aedes mosquitoes. It (a) VECTOR CONTROL : The Aedes aegypti mosquito
is manifested by high fever and severe articular pains in the should be the main target of control activities. It requires
limbs and spinal column. The virus was first isolated from active community involvement to keep water storage
patients and mosquitoes during an epidemic in Tanzania in containers free of mosquitoes and to eliminate the other
1952-53. Chikungunya is a local word meaning “doubling breeding places of mosquitoes in and around houses and
up” owing to excruciating joint pains. The virus occurs dwellings (4). The organophosphorus insecticide, Abate is
widely in sub-Saharan Africa, India and in many areas in increasingly being used as a larvicide. It can prevent
Asia. breeding for upto 3 months when applied on sand granules;
EPIDEMIOLOGY OF COMMUNICABLE DISEASES
does not harm man and does not affect the taste of water.
Antilarval measures can prevent an epidemic, but do not
give immediate results when an epidemic has already
Brucellosis is one of the major bacterial zoonoses, and in
broken out. In such cases, anti-adult measures alone can
humans is also known as Undulent fever, Malta fever or
bring about a rapid interruption of transmission. Another
Mediterranean fever. It is occasionally transmitted to man by
technique consisting of aerosol spray of ultra low-volume
direct or indirect contact with infected animals. It is caused
(ULV) quantities of malathion or sumithion (250 ml/hectare)
by different species of the brucella group of organisms and
has been found to be effective in interrupting transmission
characterized by intermittent or irregular febrile attacks, with
and stopping epidemics of DHF. The tiny droplets kill the
profuse sweating, arthritis and an enlarged spleen. The
mosquitoes in the air as well as on water. By making 2 ULV
disease may last for several days, months or occasionally
treatments at about 10 days apart, the Aedes Research Unit
years. Brucellosis is both a severe human disease and a
in Bangkok was able to reduce adult mosquito densities by
disease of animals with serious economic consequences.
more than 98 per cent for several weeks (19, 20).
(b) VACCINE : No vaccine has yet been developed that is Problem statement
considered suitable for use.
Brucellosis is a recognized public health problem with
worldwide distribution. It is endemic wherever cattle, pigs,
5 . W e s t n i l e fever
goats and sheep are raised in large numbers. Important
An acute febrile illness caused by a group B arbovirus. endemic areas for brucellosis exist in Mediterranean zones,
The disease is endemic in Africa, the Middle East, South Europe, Central Asia, Mexico and South America. Eastern
West Asia and India, and transmitted by certain species of Mediterranean countries have experienced an increase in
Culex mosquitoes. Clinically, it is manifested by a sudden the number of cases. The disease is now rare in most
onset of fever, severe headache and malaise lasting several European countries, North America and Australia ( 1 ) .
days. In children, a maculopapular rash of short duration
Animal brucellosis is reported from practically every State
may appear. In the aged, a fatal meningo-encephalitis may
in India. However, no statistical information is available
be produced. ·
about extent of infection in man in various parts of the
country (2). ·
6 . Sandfly fever
The prevalence of human brucellosis is difficult to
Sandfly fever is known to occur in the arid regions of
estimate. Many cases remain undiagnosed either because
West Pakistan and Middle East. Its occurrence in India was
they are inapparent or because physicians in many countries
thought to be doubtful. However, in 1 9 6 7 , the sandfly fever
are unfamiliar with the disease.
virus was isolated in Aurangabad (Maharashtra) from febrile
cases. The virus was also isolated from sandflies (21). The E p i d e m i o l o g i c a l determinants
control of sandfly fever is based on the control of insect
(a) AGENT : The agents are small, gram-negative rod
References shaped, non-motile, non-sporing and intracellular
coccobacilli of the genus Brucella. Four species infect man :
1. W H O ( 1 9 6 7 ) . Tech. Rep. Ser., No.369.
2. WHO ( 2 0 1 0 ) , International travel and Health, 2 0 1 0 .
B.melitensis, B.abortus, B.suis, and B.canis. B.melitensis is
3. W H O ( 2 0 1 4 ) . Fact Sheet, No. 386, March 2 0 1 4 . the most virulent and invasive species; it usually infects
4. Govt. of India ( 2 0 1 4 ) . A n n u a l Report 2013-2014, Ministry of Health goats and occasionally sheep. B.abortus is less virulent and
and Family Welfare, New Delhi. is primarily a disease of cattle. B.suis is of intermediate
5. Govt. of India ( 2 0 1 2 ) , A n n u a l Report 2011-2012, DGHS, Ministry of virulence and chiefly infects pigs. B.canis is a parasite of
Health and Family Welfare, New Delhi.
dogs. (b) RESERVOIR OF INFECTION : Main reservoirs of
6. Govt. of India ( 2 0 1 4 ) , National Health Profile 2013, DGHS, Ministry of
human infection are cattle, sheep, goats, swine, buffaloes,
Health and Family Welfare, New Delhi.
horses and dogs. In animals the disease can cause abortion,
7. WHO ( 1979). Japanese Encephalitis, Technical Information and
premature expulsion of the foetus or death. Cross infections
Guidelines for Treatment, SEA/CD/79, WHO, New Delhi.
can often occur between animal species. The infected
8. National Institute of Virology, Pune ( 1980). Japanese Encephalitis in
India, ICMR, New Delhi. animals excrete Brucella in the urine, milk, placenta, uterine
9. WHO (2006), Weekly Epidemiological Record, No. 34/35, 25th Aug. and vaginal discharges particularly during a birth or
2006. abortion. The animals may remain infected for life.
10. W H O ( 2 0 0 5 ) , International travel and health 2005.
11. Pan American Health Organization (2003), Zoonoses and Host factors
Communicable Diseases Common to Man and A n i m a l 3rd Ed., Vol. II.
Human brucellosis is predominantly a disease of adult
12. Govt. of India (2009), Guidelines, Clinical Management of Acute
Encephalitis syndrome including Japanese Encephalitis, DNVBDCP, males. Farmers, shepherds, butchers, and abattoir workers,
DGHS, Ministry of Health and Family Welfare, New Delhi. veterinarians and laboratory workers are particularly at
13. WHO (1985) Tech. Rep. Ser., 7 2 1 . special risk because of occupational exposure. Immunity
14. NICO ( 1 9 8 5 ) . Manual of Zoonosis.
15. Govt. of India (2006), Health Information of India 2005, Ministry of
Health and Family Welfare, New Delhi. Environmental factors
16. Singh K . R . P. ( 1 9 7 1 ) . Indian. J. Med. Res., 5 9 : 3 1 2 .
Brucellosis is most prevalent under conditions of
17. W H O ( 1 9 8 4 ) . Chemical methods for the Control of arthropod vectors
and pests of Public Health importance. advanced domestication of animals in the absence of
18. WHO (2006), Weekly Epidemiological Record No. 43, 27th Oct. 2006. correspondingly advanced standards of · hygiene.
19. WHO ( 1 9 7 2 ) . World Health, Aug-Sept., 1 9 7 2 . Overcrowding of herds, high rainfall, lack of exposure to
20. W H O ( 1 9 7 2 ) . WHO Chronicle, 26, 463. sunlight, unhygienic practices in milk and meat production,
21. WHO ( 1 9 7 5 ) . Wkly Epid Rec., No. 23, 6 June 1975. all favour the spread of brucellosis. The infection can travel