Bollettino epidemiologico nazionale

Malaria in Italy, 2000-2001

 Roberto Romi (1), Daniela Boccolini (1), Stefania D’Amato (2), Dina Caraffa De Stefano (2), and Giancarlo Majori (1)

(1) Laboratory of Parasitology, ISS - (2) General Office of Prevention, Ministry of Health

Malaria, which has not been endemic in Italy for the past 40 years, remains the most common imported infectious disease in the country.
Plasmodium falciparum malaria was eradicated soon after the launching of the 1947-1952 five year plan of the fight against malaria, while sporadic cases of Plasmodium vivax malaria continued to occur until 1962. In 1970, the World Health Organization declared Italy officially malaria-free.

A surveillance system for malaria, integrated within the National Health Service, has the objective of monitoring possible reintroduction of transmission. The system is designed to monitor and define the epidemiologic profile of imported cases, and to identify any local transmission such that immediate action can be undertaken. As for a number of other infectious diseases, malaria notification is mandatory; local health agencies notify cases to Office III of the Department of Prevention of the Ministry of Health. Thick smears are sent along with the notifications, which are then forwarded to the Laboratory of Parasitology for laboratory confirmation.

Prior to 1985, the number of imported cases was consistently below 100 per year (1). Since that time, however, the annual number of imported cases has increased consistently, reaching a peak of more than 1000 cases in 1999 (2,3). Until 1994, increases occurred both in immigrants and Italian citizens. Since 1995, however, further increases have been limited only to immigrants, while the number of cases in Italian citizens has progressively decreased. Of the more than 8000 caes of malaria notified to the Minister of Health during the decade 1989-1999, 7953 were confirmed by the ISS; 4026 (51%) were among Italians and 3, 927 (49%) were among immigrants. Imported cases accounted for 7935 (99.7%), while in 20 (0.3%), the disease was contracted in Italy. Among these, 8 were transfusion-associated, 2 were the result of contaminated syringes shared by injection drug users or needlesticks among health workers, and 9 were of unknown origin, although they could have been reasonably attributed to accidental importation of vectors since 2 cases had airport contact and an additional 7 had contact with baggage. One case was transitted by endogenous Anopheles mosquitoes, representing the first and only case after the eradication of malaria in Italy (4). During the same decade 65 P. falciparum malaria deaths occurred, resulting in a fatality rate of 1.2%.

In 2000, an inversion of prior trends began and the number of imported malaria cases decreased 10% with respect to 1999. This trend continued in 2001, with an additional 9% decline in cases. The Table shows information on various characteristics of the confirmed cases diagnosed in 2000 and 2001.

In the two-year period 2000-2001, Italian citizens accounted for 29% of the total cases, confirming the continued decline in cases in this group and the continued increases in immigrants, who accounted for the remaining 61%. The most common species identified was P. falciparum, which during the two year period represented more than 80% of the cases, followed by P. vivax, P. ovale, and P. malariae, which accounted respectively for 9%, 8% and 1.5% of the cases. Over the two-year period, the cases were contracted in 60 different countries, 44 of which were in Africa (73%), 8 in Central and South America, 7 in Asia, and 1 in Oceania (Papua New Guinea). The immigrants with malaria were predominantly from West Africa (94%), in particular from 4 countries (Ghana, Nigeria, Senegal, and Ivory Coast). As a result of the changing patterns, P. ovale is now second only to P. falciparum as the most common species, and in 2001, exceeded for the first time P. vivax.

Of a total of 1924 thick smears sent to the ISS for confirmation of diagnosis during 2000-2001, the diagnosis was confirmed by the ISS in 82.5% of the cases. Among the non-confirmed cases (17.5%), 40% represented erroneous diagnoses, 42% were inadequate specimens, and 18% were negative.

Recommendations

All travelers and workers who find themselves in endemic areas should consult their physician or the appropriate service in their local health agencies to determine which type of prophylaxis is warranted for their destinations. Physicians can in turn consult the following sites for updates on malarious areas and recommended prophylaxis:

• www.iss.it/sanita/index.htm (Istituto Superiore di Sanità)

• www.sanita.it/malinf (Ministry of Health)

• www.who.int/ith/index/html (World Health Organization)

No drug is free of side effects and therefore prophylaxis should be prescribed only as necessary. If prophylaxis is necessary, the drug should be appropriate for the area to which the individual is travelling.  Antimalarial drugs which are taken as a single weekly dose should be started one week before the trip and should be taken weekly during the travel and for 4 weeks after the traveller’s return. Mefloquine prophylaxis should ideally be started 2-3 weeks prior to departure to ascertain the presence of possible side effects and prescribe alternative drugs if necessary. Drugs that are administered on a daily basis should be initiated a day prior to departure. Groups at risk include pregnant women and children, who should receive only certain drugs at specific doses.

No antimalarial drug can provide complete protection, and therefore in case of fever, with or without other symptoms, one week to 8 months after exposure P. falciparum malaria should always be considered. Relapses of P. vivax and P. ovale are not prevented by the common forms of prophylaxis. In case of suspected malaria, medical attention should be sought and thick smear examinations should be done of blood obtained at appropriate times.

With respect to behavioral prophylaxis, it should be recaled that the vectgors of malaria, mosquitoes belonging to the genus Anopheles, bit usually in the interval between dawn and dusk. To avoid bites, simple measures should be taken even when the traveller is taking prophylaxis. These measures include wearing long-sleaved shirts, long pants, and socks, preferably light-colored, and treating exposed skin with insect repellants. At night, if a room is not well-screened or air conditioned, the room should be carefully inspected for mosquitoes and treated with insecticides as needed; were necessary, bed nets can be used.

References

1.    Sabatinelli G,  Majori G. Eurosurveillance 1998; 3 (4): 38-40.
2.    Romi R, Boccolini D, Majori G. Eurosurveillance 1999;  4 (7/8): 85‑87.
3.    Romi R, Boccolini D, Majori G. Eurosurveillance 2001;  6 (10): 143‑147.
4.    Baldari M, Tamburro A, Sabatinelli G, Romi R, et al. Lancet 1998; 351:1246‑1248.