Malaria Surveillance

MALARIA SURVEILLANCE
Objectives of malaria surveillance
Malaria surveillance connotes the maintenance of an on-going watch/
vigil over the status of malaria in a group or community. The main purpose of
surveillance is to detect changes in trends or distribution in malaria and other
vector borne diseases in order to initiate investigative or control measures. It
provides a basis for measuring the effectiveness of anti-malaria programme.
Malaria surveillance includes laboratory confirmation of presumptive diagnosis,
finding out the source of infection and identification of all cases and susceptible
contacts and still others who are at risk in order to prevent further spread of the
disease. The ultimate objective of malaria surveillance is prevention and
control of malaria in the community.
Malaria surveillance is an essential pre-reuisite to the rational design and
evaluation of a malarial control programme.
!. Malaria surveillance is an integral part of rimar! "ealt# Care
s!stem
"The disease load# or "disease potential# of malaria in the community is
governed by different parameters such as $infected persons%, "susceptible
persons#, and $vector and environmental conditions%. &lthough the case
detection and its treatment is not the end of all endeavours, early detection of a
case and its radical treatment would reduce the risk of infecting vector
mosuitoes and thus reducing transmission of malaria in the community. The
timely collection and e'amination of blood smear is the key element in the
(ational Malarial )ontrol *trategy. If all the detected cases are given radical
treatment early, it will certainly lead to depletion of the human reservoir of
malaria parasite in the community.
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$%& 'ortnig#tl! (omiciliar! visits
+nder the (ational ,ector -orne .iseases )ontrol /rogramme, the active
case detection is carried out by multipurpose health workers 0male1 under
primary health care system. The fortnightly periodicity of domiciliary visits suits
the technical reuirement of malaria disease management. -y fortnightly visits
a large number of secondary cases can be avoided in the community where
malaria transmission is seasonal but well established. )omponents of the
activities under the active case detection during fortnightly visits are2
0i1 search for a fever case or who had fever in between the visits of
M/3
0ii1 collection of blood smear from such cases
0iii1 administration of appropriate anti-malarial0s1
Technical justification for a fortnightly blood smear collection is based on
transmission dynamics of malaria. The incubation interval in case of P.vivax is
appro'imately !! days while for P.falciparum it is 45 days. Thus, surveillance
cycle of less than one incubation interval will catch most of the secondary
cases before the commencement of ne't cycle. Through this activity, the
malaria surveillance can be measured.
6owever, over the years, the strength of the M/3s0M1 has been depleting.
There is shortage of M/3s in all the states. In some states the shortage may
be as high as 789 or more of the sanctioned strength. :or the timely and
regular surveillance these field level functionaries are crucial. The /rimary
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Incubation interval) It denotes the duration of the full cycle of malaria
parasite. It is the sum of the time taken for the development of the parasite in
the mosuito and that in the human being.
6ealth )are system in our country provides one M/30male1, for 4888
population in hilly and tribal areas and 5888 population in other areas. The
manpower envisaged under the plan is adeuate to cater to the needs of the
active case detection for malaria control if all the positions of M/3s are filled.
$%$% 'ever *reatment (epots +'*(s,
To avoid delay in detection of cases which occur in between visits of M/3, it
can be supplemented with establishment of :ever Treatment .epots in villages
especially in areas which are remote/ inaccessible and have low population
density, for e'ample in hilly terrain of ;harkhand, )hattisgarh and M/ and arid
areas of <ajasthan. The :T. holder should be given training for one or two
days at the /6) 6eaduarters in the collection of blood smears, administration
of presumptive treatment, impregnation of bed nets, promotion of larvivorous
fish etc. 6e should be paid T&/.&/honorarium as per guidelines of (,-.)/
for attending training.
$%$ -loo. smear collection is important
-lood smear collection is necessary to have parasite confirmation, especially in
view of the fact that large areas in the country have predominant infection with
P.falciparum. There are some areas with poor therapeutic efficacy of the
chlorouine or sulfado'ine-/yremethamine against P.falciparum. In these
areas, treatment is done with alternative drug regimen for P.falciparum cases
on microscopic confirmation of the diagnosis. Indiscriminate use of second line
drugs like 0&rtesunate-*ulfado'ine combination therapy 0&)T1 under the
presumptive treatment is always disastrous and precipitates the multi drug
resistant strains of P.falciparum. Therefore active case detection is essential
for all areas of the country and the same should be further supported by
establishment of :ever Treatment .epots 0:T.s1.
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4. assive Case (etection +C(,
&ll &llopathic, &yurvedic, 6omeopathic, *iddha medicine dispensaries in the
health sector should be identified and involved in passive case detection. &ll
the fever cases attending the hospital should be screened for malaria and given
presumptive treatment. In addition this is to be carried out at the village level
by voluntary workers drawn from local residents or voluntary agencies
operating locally or &nganwadi workers, private practitioners etc. In view of the
shortage of M/3s for conducting active surveillance, it is of utmost importance
that passive collection of blood smears from fever case should be increased.
The .istrict Malaria officers with the help of /6) staff should carry out the
mapping for private clinics and other functionaries who can act as /). center.
They should be imparted induction/ orientation training, in malaria before they
start operating as /). center.
Malaria clinics are to be established in all the health institutions in high risk
areas wherein the blood smears are e'amined on the same day and <T given.
M/30M1 should contact all :T.s/ ..)s/ ,oluntary workers etc. of his area at
least once a fortnight in his area and collect blood smears for transmission to
laboratory, besides replenishing of micro slides and/ or drugs, wherever
necessary.
/% Rapi. 'ever Surve!) In case of an epidemic outbreak, every village in
the suspected epidemic =one is covered in a short duration by deploying
additional man power. 6ouse to house visits are undertaken and all fever
cases are screened by taking blood smears. These blood smears are to be
e'amined at the earliest preferably at a temporary field laboratory at the village
level.
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/%&% Mass surve!) &s an alternative to <apid :ever *urvey, mass survey of
the entire population may be carried out in the suspected epidemic =one. 6ere
all the population irrespective of age, se' or fever status is screened by taking
blood smear. *pecially children must be included in survey.
To carry out these special surveys, it is always advantageous to establish field
laboratories by pooling laboratory technicians from adjoining /6), .istricts,
>onal offices or *tate 6?s. The peripheral staff should also be pooled from the
neighbouring /6) areas to collect blood smears so as to cover the entire
population as uickly as possible. The operation should be over in @ to A8
days. &ll persons whose blood smears are collected should be given
presumptive treatment or mass radical treatment. -lood smears collected
should be e'amined within !B hours.
0% (rug (istribution Centre +((C,
If it is not possible to have :T., the medical officer should establish ..). The
function of ..)s are the same as those of :T.s, e'cept that the ..cs do not
take blood slides but administer drugs to fever cases. ,olunteers identified for
running ..)s should be imported one-two day induction/ orientation training in
identification of fever cases, administration of presumptive treatment, promotion
of preventive measures like distribution C impregnation of bed nets, larvivorous
fish, source reduction etc. for vector control.
1% E2amination of bloo. smears
The blood smears collected by &). C /). are to be e'amined e'peditiously.
+nder the current situation, in most of the places, there is considerable time lag
between collection and e'amination of blood smears due to inadeuate
facilities. The laboratory for malaria microscopy should be decentrali=ed and
brought as near to the community as possible. &ll efforts should be made to
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reduce the time lag between blood smear collection and e'amination by
utili=ing e'isting facilities available both in public C private sectors.
Annual bloo. smears e2amination rate an. its vali.it!
Malaria surveillance presumes that every malaria case will present itself with
symptoms of fever at some point of time during the course of infection.
Therefore, if all fever cases occurring in the community are kept under
surveillance over a period of time and their blood smears are e'amined for
malaria parasite, the total malaria parasite load can be e'amined. 6owever,
there are some e'ceptions. *ome of the malaria patients who give history of
fever during the past fortnight but do not have the fever at the time of blood
smear collection may not show microscopically detected parasitaemia in the
peripheral blood. Dn the other hand some afebrile persons can be positive for
malaria parasite. Dn account of operational as well as technical reasons
fortnightly surveillance is recommended. Establishment of :T.s has improved
surveillance status of malaria case detection as community coverage is more
e'tensive.
The level of &-E< depends on the number of fever case in the community.
The fever rate in the community fluctuates widely from month to month and
year to year. These fluctuations are due to other viral and bacterial infections
prevalent in the area. :or accurate estimates of malaria endemicity, the blood
smear e'amination rate specially the Monthly -lood E'amination <ate 0M-E<1
rate should be eual to fever rate of the month in the community. Therefore it is
necessary to ensure that all persons having fever during malaria transmission
months are included in the total blood slides e'amined during the year.
The M-E< norms of 8.F percent during non-transmission season and A.! to A.F
percent during transmission season were laid down in the Indian Malaria
Eradication /rogramme. M-E< should be monitored M/3 wise by the
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medical officer in charge during monthly meeting at the /6) in order to assess
the surveillance operation in the /6) area.
In both the cases i.e. &-E< and M-E< the denominator is common because
the entire population is covered during each fortnightly domiciliary visit by
M/30male1. &-E< is the cumulative sum of monthly rates during the year.
3hile collecting &-E< or M-E<, blood slides collected by all agencies are
taken into account, i.e blood smears collected through &)., /)., :T. or any
other voluntary agency during the same period. 6owever, number of blood
smears collected and e'amined during a mass survey and their results should
not be included while calculating &-E< or M-E<.
&-E< G (o. of blood smears collected during the year ' A88
/opulation covered under surveillance
M-E< G (o. of blood smears collected during the month ' A88
/opulation covered under surveillance
:or accurate estimates of malaria endemicity, the blood smears e'amination
rate especially the M-E< should be eual to fever rate of the month in the
community.
&-E</ M-E< is an inde' of operational efficacy of the programme. The
&nnual /arasite Incidence 0&/I1 depends upon the &-E<. & sufficient number
of blood slides should be systematically obtained and e'amined for malaria
parasite to work out accurate &/I.
Sli.e ositivit! Rate +SR,)
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The *lide /ositivity <ate among the blood smears collected through both active
and passive surveillance gives a more accurate information on distribution of
malaria infection in the community over a period of time. Monthly */< can be
calculated to find out the seasonal rise and fall in malaria prevalence in the
community. */< among children !-H years of age can be utili=ed for
comparison with pre-control )hild /arasite <ates to assess the impact of
control measures on local malaria endemicity and transmission. */< in the
age group of less than one year 0Infant /arasite <ate1 can be utili=ed for
assessment of the impact of control operations. The */< of blood slides
collected from cases currently having fever will be higher than the */< of the
slides collected from cases with history of fever. Therefore, higher positivity
rates are obtained in blood smears collected at the /).. Trends in */< can
be utili=ed for predicting epidemic situations in the area. If monthly */<
e'ceeds by ! I times of the standard deviation observed in */< of the
preceding 4 years or preceding 4 months of the same year, an epidemic build
up in the area can be suspected. Monthly or yearly trends of */< are utili=ed
to study the impact of control operations.
*/< is measured as follows2
(o. of blood smears found positive for malaria parasite J A88
(o. of blood smears e'amined
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