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In 1999-2000, a total of 2060 malaria cases were reported by the ISS.
Most of the patients took inappropriate treatments or did not have any
prophylaxis. Ninety-three per cent became infected in African malarious
countries, 4% in Asian countries, and 3% in Latin America. P. falciparum
accounted for 84% of the cases, followed by P. vivax (8%),
P. ovale (5%), and P. malariae (2%). Deaths corresponded
to an annual case fatality rate of 0.3% in 1999 and 0.5% in 2000. In general,
imported malaria cases reflect the number of Italian travellers who underestimate
the infection risk in Asian and Latin American malarious countries and
permanent residents of African origin who visit their relatives in their
native countries.
Malaria is no longer endemic in Italy, but it is the
disease most commonly imported into the country. Plasmodium falciparum
malaria was eliminated from Italy in the 1950s, where as sporadic P. vivax
cases occurred until 1962 in Sicily (1,2). In 1970, the World Health Organization
(WHO) officially declared Italy malaria free. A surveillance system was
established to prevent a possible return of malaria transmission and to
monitor the epidemiology of imported cases. Until 1985, less than 100
cases of imported malaria were reported each year (3). Since then this
figure has increased constantly, reaching a peak of 973 cases in 1998
(4). In the decade 1989-98, a total of 6871 malaria cases were officially
confirmed; 6852 (99.7%) patients were infected while visiting malarious
countries, and 19 (0.3%) were infected locally (4,5). Eighteen of the
cases infected in Italy were classified as induced malaria (nine cases),
airport malaria (two cases), and baggage malaria (seven cases) (3), and
one case as introduced malaria; this was the first case transmitted by
indigenous mosquitoes after malaria elimination in Italy (6). We report
the epidemiological data on imported malaria in 1999 and 2000 and compare
them with data from the previous decade. An evaluation of the incidence
of malaria in Italian travellers to malarious countries is also reported.
Methods
In Italy, the reporting of malaria cases and 43 other
infectious diseases is mandatory. Local public health laboratories diagnose
clinical cases by microscopic examination of blood smears. Po-sitive cases
are notified to the department for prevention of the health ministry on
a standard notification form that includes epidemiological data. Blood
smears are sent to the malaria unit of the laboratory of parasitology
at the Istituto Superiore di Sanità (ISS) for confirmation of the
diagnosis. Malaria cases are classified by origin, following WHO terminology
(7): a malaria case is classified as "imported" if the infection
was acquired outside the area where the case is diagnosed; malaria is
"autochthonous " when contracted locally. Autochthonous cases
are said to be "induced" if they result from blood transfusion
or another form of parenteral inoculation. Secondary cases contracted
locally (through mosquito bites) but derived from imported cases are referred
to as "introduced" malaria. At the ISS, data are entered into
a database and analysed.
Statistics on intercontinental travellers from Italy
to countries where malaria is endemic were provided by the transport and
aviation ministry. These data took into account only passengers leaving
Italian airports by national or international airlines.
Results
In the past two years, a total of 2060 cases of malaria
were confirmed by the ISS: 1083 in 1999, and 977 in 2000 (figure 1). In
both 1999 and 2000, only one case each of P. falciparum malaria
was caused by blood transfusion.
In 1999, out of the total imported cases, 337 (31%) were
in Italian nationals travelling for leisure or business, 746 (69%) in
foreign nationals; in 2000, 262 (27%) were in Italians and 714 (73%) in
foreign nationals. Analysis of all cases in 1999-2000 showed that 93%
(1912) of patients became infected in Africa, 4% (88) in Asia, 3% (54)
in Latin America, and less than 1% (4) in Papua New Guinea. P. falciparum
accounted for the highest number of cases (84%, 1734), followed by P.
vivax (8%, 171), P. ovale (5%, 109), and P. malariae
(2%, 37). Mixed infections accounted for less than 1% (9).
Seven deaths caused by falciparum malaria were reported
in this two year period (three in 1999, and four in 2000) (figure 2).
Of the six Italians who died, three contracted malaria in Kenya and the
others in Madagascar, Senegal, and Burkina Faso. One of the patients who
died in 2000 was a Chinese citizen who had visited many African countries.
Deaths corresponded to an annual case fatality rate of 0.3% in 1999 and
0.5% in 2000.
Five hundred and ninety eight Italian nationals contracted
malaria in more than 50 countries, but about half became infected in only
five African countries: Kenya (18%; n= 108), Côte d’Ivoire (14%;
n= 84), Tanzania (in particular Zanzibar) (10%; n= 60), Madagascar (6%;
n= 36), and Senegal (6%; n= 35). P. falciparum was responsible for 81%
(486) of cases in Italian nationals who became infected in Africa, and
P. vivax for 79% (74) of cases infected in other continents.
Of the foreign nationals, 96% (1402) were African immigrants.
Seventy-nine per cent (1114) of these became infected in only four countries:
Senegal (37%; n= 519), Ghana (21%; n= 294), Nigeria (14%; n= 196), and
Côte d’Ivoire (7.5%; n= 105). P. falciparum accounted
for 83% (1215) of infections acquired in Africa by foreign nationals,
and P. vivax for 74% (40) of those contracted in other conti-nents. Among
African immigrants, 76% (1110) of the malaria cases occurred in permanent
residents in Italy who contracted malaria while visiting their relatives
in malarious native lands; 24% (350) were immigrants newly arrived in
Italy.
The table shows the incidence of malaria in Italian travellers
who visited malarious countries in 1998-2000. The incidence in Africa
was 0.7-1.0 per thousand, 0.05-0.1/1000 in Asia, and 0.009-0.02/1000 in
Latin America.
Report forms from 1999-2000 showed that among the Italians
who contracted malaria 4% (24) had taken adequate che-moprophylaxis regularly
while travelling abroad, 22% (32) had taken incomplete or inadequate prophylaxis,
and 74% (442) had not taken any.
No cases of resistance to the current antimalarial drugs
used to treat P. falciparum (quinine, mefloquine, halofanthrine, and sulfadoxine/sulfalene-pyrimethamine)
were reported in either 1999 or 2000.
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Table
Incidence of malaria in Italian travellers visiting malarious
countries, 1998-2000
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Countries
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1998
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1999
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2000
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Africa
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No. of Italian travellers
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353 149
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346 265
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354 924
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No. of malaria cases
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362
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313
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242
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Incidence/1000
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1
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0.9
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0.7
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Asia
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No. of Italian travellers
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194 948
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202 314
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243 141
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No. of malaria cases
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19
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14
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13
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Incidence/1000
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0.1
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0.07
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0.05
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Latin America
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No. of Italian travellers
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430 648
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428 775
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457 190
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No. of malaria cases
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4
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10
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8
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Incidence/1000
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0.009
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0.02
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0.02
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Discussion
In 1999, the overall pattern of imported malaria in Italy
followed the same trend of the previous decade (9): compared with 1998,
the total number of cases increased by about 10% (973 versus 1083), and
the number of cases in foreign nationals by 21%
(588 vs 746), whereas cases in Italian nationals decreased
by 12% (385 vs 337). In 2000, for the first time in years, a reduction
of 9.8% (977 vs 1083) compared with 1999 was reported, which was more
marked among Italian nationals (22%; 263 vs 337) than among foreign nationals
(4%; 714 vs 746).
The number of malaria cases in Italian nationals gradually
increased until the mid 1990s (figure 1), which reflects the growing number
of intercontinental travel- lers to malarious areas (8,9). From 1990 to
1998, the flow of travellers from Italy to countries in Africa, Asia,
and Latin America, where malaria is endemic has doubled (8). In 1999-2000,
although the number of travellers to countries where malaria is endemic
has continued to grow (table), the mean incidence of malaria in travellers
who had visited African countries was half that of the past decade, whereas
the incidence in people visiting Asia and Latin America did not show any
significant decrease (9). Italians now seem to be more informed and aware
of the risks they take when visiting African countries where malaria is
endemic, but they underestimate those involved in visiting Asian and Latin
American countries. The extent of this risk is 10-20 and 30-40 times greater
for Italians visiting African countries where malaria is endemic than
for those visiting Asia and Latin America, respectively.
The constant decrease of malaria cases in Italian nationals
could, however, be the result of the recent attention given to the problem
by the health information systems and the national mass media, that malaria
cases contracted in Africa represented 92.5% of the total cases reported
in 1999-2000. Nevertheless, many Italian travellers to countries where
malaria is endemic still do not take appropriate prophylaxis.
The seven deaths in 1999-2000 resulted from a delay in
diagnosis or hospital admission or both. The fatality ratio recorded in
the past two years seems to have stabilised at the same level reached
in 1998 (<0.5%), after the higher mean value reported in the previous
decade (figure 2). Making accurate information
on prophylaxis available to Italian travellers and improving
the management of malaria cases from diagnosis to treatment may further
reduce mortality.
Conclusions
The number of malaria cases among foreign nationals increased
continuously until 1999, with a slight decrease in 2000 (figure 1). Nevertheless,
also in 2000, the difference between cases occurring in Italians and non-Italians
increased, the foreign nationals representing almost 73% (714) of the
total cases. Most (93%; n= 664) were Africans, an increase of 6% compared
with the mean rate of the past decade (87% in 1989-1998 (5133/5907)) (9).
As a consequence, a marked rise in the rate of P. falciparum infections
among foreign nationals was also observed (an average of 83% in 1999-2000
versus 75% in 1989-98).
Imported malaria in Italy seems to be gradually developing
into a problem among immigrants from areas where malaria is endemic, in
particular from West Africa. According to the statistics currently available,
this is related to the rising flow of immigration from Africa. Moreover,
access to the national health service, recently offered to those immigrants
who are permanent residents, has contributed to the rise in the number
of patients asking for health care. Most of the African immigrants who
contracted malaria live permanently in Italy, and they usually underestimate
the risks they take visiting their native lands after a long period of
stay in a non-malarious country. The health service should provide better
information about the risk of malaria to African immigrants to reduce
morbidity and prevent deaths from malaria in this group.
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