Dengue ,malaria overdiagnosis, Africa Email:bobgatanyi@yahoo.com

1. “The Burden of Dengue in Africa
is Being Mask By Malaria Over-
diagnosis”
FACULTY OF HEALTH SCIENCES
UNIVERSITY OF BUEA
TANYI PRIDE BOBGA
Dr. Kenji Obadiah
Supervision

2. Background
• Diagnosis of febrile illnesses in Africa mostly focuses on
confirming or ruling out malaria.
• Because of the high rate of malaria over-diagnosis in Africa, other
febrile illnesses such as dengue, leptospirosis, sepsis maybe
often misdiagnosed as malaria.
• Dengue is an important but unrecognized cause of febrile illness
in Africa.
• The epidemiology of dengue in Africa is poorly understood due to
lack of active surveillance system for the disease.

3. Rationale
To establish strong consensus that not
all febrile illnesses in Africa or Cameroon
are as a result of malaria. Therefore to
bring to awareness that the answer to
the true prevalence of dengue in Africa
will be deconstructing malaria as cause
of most febrile illnesses.

4. Objective
General
• To review adequate literature to show Africa as a next front for
dengue epidermics
Specific
• Deconstruct the idea of all fevers attributed to malaria (malaria
over-diagnosis)
• Reviewed the Dengue and malaria situation in Africa
• Discuss the confusion between Malaria and Dengue diagnosis in
Africa
• Recommend Dengue follow up based on successful control
strategies in south east Asia

5. Malaria
• Malaria is caused by a parasite called Plasmodium, which is
transmitted via the bite of a infected female anopheles
mosquitoe.
• Half of the world's population is at risk for malaria
• Every minute, a child dies from malaria
• Pregnant women are particularly at risk of malaria
• Early diagnosis and prompt treatment of malaria prevents
deaths
• Sleeping under long-lasting insecticidal nets protects against
malaria

6. Malaria Epidemiology

7. Malaria Over diagnosis in Cameroon
• Less than 50% of suspected malaria cases in Cameroon are
being sent to the lab for MP testing (Mangham et al., 2011).
• Patient pressure not seen as influencing presumptive
antimalarial treatment (Chandler et al., 2012).
• Clinical diagnosis of malaria seems to be traditional among
health professionals in Cameroon.
• Patients incur 10-25% more cost than would have been if
clinicians adhere to MP negative test results (Lubell et al.,
2008).

8. Malaria Over diagnosis
PLoS ONE 6(1): e14627. doi:10.1371/journal.pone.0014627
ACT prescription practices of health workers after RDT introduction

9. Malaria Treatment Practices
Estimated proportion of people who tested positive for malaria before
treatment in Africa
Courtesy of Justin Cohen

10. Malaria treatment challenges in Cameroon
• Antimalarials are over prescribed in Cameroon (Mangham et al.,
2011; Chandler et al., 2012).
• Most clinical decisions on the treatment of malaria not based on
parasite guidelines proposed by WHO.
• Self-treatment of malaria is common in Cameroon (Nsagha et al.,
2011)
• Over 70% of patients who received antimalarials from medicine
dealers were found to be negative for MP (Mangham et al., 2011)

11. Malaria treatment challenges
The Pan African Medical Journal. 2011;9:8
Source of getting antimalarials in Cameroon

12. Consequences of Malaria over diagnosis
• Indiscriminate use of anti-malarials that have been recorded in
Africa, can potentially lead to development of drug resistance.
• The fear is that should artemisinins fail, there is paucity of
alternative antimalarials.
• Other causes of fever go untreated
• Patients incure more cost

13. Dengue
• Dengue is transmitted by the bite of an Aedes
mosquito infected with any one of the four
dengue serotypes (De 1, 2, 3, and 4).
• It occurs in tropical and sub-tropical areas of the
world.
• There are no specific antiviral medicines for
dengue.
• It is important to maintain hydration.

14. Dengue: Clinical manifestation

15. Dengue: Diagnosis

16. Global Burden of Dengue

17. Dengue situation in Africa
• Dengue is under recognized and under reported in Africa (DE
Laval et al., 2012; Amarasinghe et al., 2011).
• Dengue is not always included in the differential diagnosis of
febrile illnesses.
• Dengue infections could be a major public health problem in
Cameroon that is being under recognized.

18. Dengue and Aedes aegypti in Africa
Paediatric Int Child Health. 2012 May; 32(s1): 18–21.
Dengue virus and Ae.
Aegypti reported in 32
African countries.
Ae. Aegypti without dengue
reported in 13 African countries

19. Distribution of Aedes in three major
Cameroonian towns
The Royal Entomological Society, Medical and Veterinary Entomology, 24, 132–141

20. Breeding sites of dengue vectors

21. Evidence of Dengue in Cameroon
Seroprevalence and distribution of Flaviviridae, Togaviridae and Bunyaviridae
Arboviral infections in rural Cameroonian Adults
• N=256
• 32 (12.5%)
DEN-2
• 17 (6.6%) WN
• 69 (26.9%) YF
Flaviviridae Togaviridae Bunyavi
ridae
Site
no.
DEN-2 WN YF CHIK* ONN* SIN TAH
I 10 0 13 87 87 0 30
II 7 3 38 90 90 0 34
III 58 17 33 67 75 13 42
IV 23 15 19 27 27 8 25
V 7 3 30 17 17 3 27
VI 0 17 7 10 10 33 33
VII 0 4 21 7 7 0 39
VIII 17 3 63 77 80 10 37
IX 0 0 17 38 38 3 52
* Cross-reactivity may occur.
Am J Trop Med Hyg June 2006 vol. 74 no. 6 1078-1083

22. Arboviruses in Nigeria
Distribution of DENV, CHIKV, WNV, YFV, in febrile patient sera by sex in Nigeria
• N=310
• 193 (67.71%) had
neutralizing antibodies
against DENV
• 143 (50.17%) against CHIKV
• 71 (24.91%) against WNV
• 25 (8.77%) against YFV
J Infect Dev Ctries 2013; 7(1):051-059.

23. Arboviruses in Tanzania
Prevalence of CHIKV and DENV infections among febrile patients, Northern
Tanzania 2007-2008
Am. J. Trop. Med. Hyg., 86(1), 2012, pp. 171–177

24. Similarities and differences between malaria and
dengue infection
Characteristics Malaria
infection
Dengue
Infection
Mode of transmission Anopheles mosquito Aedes mosquito
Fever Acute and chronic Acute
Myalgia Detectable Common
Shock Possible Possible
Blood parasite Positive Negative
Hemoconcentration Usually negative Usually positive
Thrombocytopenia Usually negative Usually positive
Bleeding Rare Possible
Hemolysis Possible Rare
Treatment Antimalarial drugs Fluid therapy

26. Dengue Control
• Travel
• Vector control
• Urban control
• etc

27. Is malaria and dengue co-infection
possible????
malaria
dengue
?

28. Overlap between dengue and malaria
Do mosquitoes love your home and yard?
Anopheles
Aedes
Aedes
Aedes
Anopheles

29. Overlap between dengue and malaria in
Cameroon

30. Clinical presentation of dengue and malaria co-
infection
Characteristics Co-infection
Fever Acute febrile illness
Myalgia Common
Shock Possible
Blood parasite Positive
Hemoconcentration Usually positive
Thrombocytopenia Usually positive
Bleeding Possible
Hemolysis Possible
Treatment Antimalarial drugs with fluid therapy

31. Evidence of arbovirus and malaria co-
infections
J Infect Dev Ctries 2013; 7(1):051-059.
• 219 sera samples (76.8%)
tested positive for more than
one arbovirus in the absence
of malaria or typhoid,
• 85 (29.8%) in the presence of
malaria (n = 14) or typhoid (n
= 23) virus coinfection coinfection with malaria

32. Supplementary figure
Epelboin et al. Malaria Journal 2012 11:142
Monthly cases of malaria, dengue fever (curves) and dengue and malaria
co-infection (columns) in the Emergency department of Cayenne Hospital,
French Guiana, between June 2004 and February 2010

33. Patient of dengue and
falciparum malaria with sub-
conjuctival haemorrhage.
J Vector Borne Dis 49, December 2012

34. Conclusion
 The prevalence of malaria is
overdiagnosed
 There is need for locally
available diagnostic methods in
Africa.
 Overdiagnosis of malaria maybe
overshadowing the true burden
of Certain diseases in Africa