Content :

Malaria in Elderly Subjects

April 1st, 2008

Even today, malaria remains a major public health problem in countries within the intertropical zone,

especially in African countries south of the Sahara. WHO statistics for this disease are henceforth “conventional”: over 300 million cases of malaria worldwide and over one million deaths, 90% of which were recorded in sub-Saharan Africa, mainly in children under 5 years of age [WHO/UNICEF The Africa Report-2003].

In stable malaria-endemic geographical areas, this infant-juvenile section of the population is certainly the most vulnerable and is the most closely monitored, together with pregnant women. The 2000 Abuja targets, involving all the National Malaria Control Programs, focus in particular on these high-risk groups in RBM strategies to reduce morbidity and mortality levels associated with malaria [WHO the African Summit on RBM-2000]. For all that, adults and elderly subjects are also victims of the disease, particularly in areas of endemic instability where the populations are not sufficiently exposed to recurrent malarial infestations which could enable them to acquire prophylactic immunity. The same applies in countries unaffected by malaria, the inhabitants of which are at major risk when visiting a malaria-endemic area.

Very little documentation exists on malaria in elderly subjects (≥ 60 years of age)

and information often has to be sifted out from published scientific data relating to adult malaria in general. There are undoubtedly several reasons for this. From a demographic standpoint, elderly subjects represent only a small proportion of the population in developing countries. Furthermore, from an epidemiological perspective, the proportion of elderly subjects among patients suffering from mild or severe forms of malaria is also small, i.e. of the order of 5 to 6%, whether these are imported cases recorded in the non-immune populations of Northern countries [N. Mühlberger et al., 2003] or native populations in countries with endemic malaria [Soumare et al., 1999]. The scarce data available nevertheless shows that, in many respects, elderly subjects are at greater risk than young subjects when confronted with Plasmodium falciparum malaria - a greater parasite density, a longer hospital stay [Gjorup & Ronn, 2002], more (essentially neurological) complications and a significantly higher rate of mortality [N. Mühlberger et al., 2003]. These European data are indicative of the characteristics of imported malaria affecting non-immune populations. Even in highly endemic areas, however, the advanced age of malarial patients (≥ 65 years of age) is recognized as a factor of poor prognosis [Eholié et al., 2004]. Aging of the immune system, nutritional disorders and underlying diseases (cardiovascular, respiratory and renal), which are more prevalent in this age group, are all factors which can, in fact, exacerbate malaria-related mortality in elderly subjects, even in areas with a high rate of malarial infestation.

Clinically, bouts of malaria in elderly patients can be worrying,

particularly in non-immune subjects. Asthenia, diarrhea and respiratory and genito-urinary symptoms tend to be more frequently associated with the disease whereas fever and headaches are less common [N Mühlberger et al., 2002]. Self-medication, frequent and often inappropriate in endemic areas, can also alter the clinical picture. Diagnostic and therapeutic management may therefore be delayed, which increases the risk of onset of complications and death in elderly patients.

Malaria in elderly subjects must be considered as a medical emergency,

even in semi-immune populations. The treatment of this disease does not, however, have any specific features other than those associated with the concomitant management of possible age-related problems (undernutrition, water/electrolyte imbalance, decompensation of latent diseases and bedsore complications).

As for its prevention, the National Malaria Control Programs offer no specific measures targeting this age bracket of the population in malaria-infected countries.

Conversely, in non-endemic countries, chemoprophylaxis is recommended for visitors to endemic regions and elderly subjects are included in this particular category. This preventive measure does not, however, afford total protection. Even in cases of good treatment compliance, malaria can nevertheless always develop, albeit to a lesser extent. Moreover, adverse drug reactions have been reported in 9.7% of cases [Mittelholzer et al, 1996]. Regardless of outcome, chemoprophylaxis is a valid recommendation for travelers that should take into account varying resistance of the malarial parasite in different geographical regions together with tolerance to recommended anti-malarial medication. In all cases, the use of an insecticide-saturated mosquito net should be part and parcel of the recommended prophylactic “package” for elderly subjects, with the other vector control measures also playing an important role in malaria-infected countries.

Finally, malaria in elderly subjects appears to only generate interest in non-immune populations,

particularly travelers. Given the often precarious physiological condition of patients in this age group, specific measures should be stipulated and implemented in order to prevent them from contracting the disease in the first place or from developing complications. Indeed, this dreadful parasitosis can only lead them to embark upon a trip to the “land of no return”.

References

1. WHO/UNICEF. The Africa report-2003. WHO/CDS/MAL/2003.1093

2. WHO. The African Summit on Roll Back Malaria. Abuja, Nigeria, 25 April 2000. WHO/CDS/RBM/2000.17

3. N. Mühlberger, T. Jelinek, R.H. Behrens et al. Age as a risk factor for severe manifestations and fatal outcome of falciparum malaria in European patients: observations from TropNetEurop and SIMPID Surveillance Data. CID 2003; 36:990-995.

4. Soumaré M., Diop BM., Ndour CT et al. Aspects épidémiologiques, cliniques et thérapeutiques du paludisme grave de l’adulte dans le service des maladies infectieuses du CHU de Dakar. Dakar Médical, 1999, 44, 1, 8-11.

5. Gjorup IE, Ronn A. Malaria in elderly nonimmune travellers. J Travel Med 2002; 9:91-93.

6. SP Eholié, E. Ehui, K. Adou-Bryn et al. Paludisme grave de l’adulte autochtone à Abidjan (Côte d’Ivoire). Bull Soc Pathol Exot, 2004, 97, 5, 340-344.

7. N. Mülhberger, T. Jelinek, R.Behrens et al. Falciparum malaria in elderly patients. Observations from TropNetEurop and SIMPID Surveillance Data. (Abstract) 51st Annual meeting of the ASTMH, Denver, EEUU, November 2002.

8. M-L Mittelholzer, M. Wall, R. Steffen, D. Stürchler. Malaria prophylaxis in different age groups. J Travel Med 1996; 3 (4): 219-223.