Keywords

1 Introduction

Malawi, with a population of 15 million people, shares borders with three southern Africa countries: Tanzania to the north, Mozambique to the south, and Zambia to the west. It is divided into eight agro-ecological zones referred to as agricultural development divisions (ADDs). There are 28 agricultural administrative offices (District Agriculture Offices) distributed throughout Malawi with a number of sub-district offices known as extension planning areas (EPAs) located in each of the districts (Fig. 16.1).

Fig. 16.1
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Map of Malawi showing ADDs, District Agriculture Offices, and Extension Planning Areas

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Malawi has an agriculture-based economy that provides employment to about 80% of the national workforce and generates over 80% of the country’s foreign exchange earnings. The livestock sector generates about 11% of the Gross Domestic Product (GDP) and about 36% of the value of all agricultural products. The dairy sector consists of a small, commercial, market-oriented segment owning 3.4% of the cattle in the country, and a smallholder, subsistence-farming segment that mainly provides produce for home consumption, and a small surplus of products that are sold on the open market. Currently, there are too few commercial milk processors in Malawi, and those present operate below their capacity due to different factors, including poor road networks, and the lack of cooling and storage facilities.

Because of their low milk yield (2–3 l per day), most Malawian cattle (zebus) are not kept solely for dairying (Tebug et al. 2012) but they also provide an additional income through: provision of manure, provision of animal traction, and by serving as social security. In addition to the estimated 1.4 million cattle, there are also 6.3 million goats, 3.5 million pigs, 270,000 sheep, and 7.4 million chickens in Malawi.

2 Animal Husbandry

Different dairy farming systems exist in Malawi. Traditionally, and particularly in the Northern Region, where milk constitutes an integral part of the daily human diet, cattle rearing also involves milk production using indigenous zebu breeds. These herds graze on natural pastures shared by communities belonging to a particular dipping group. There are about 300 cattle-dipping stations evenly distributed throughout the country to which farmers used to bring their herds of cattle fortnightly for ectoparasite control during the rainy season from November to April. This practice caused intermingling of herds, and it was conducive to the spread of diseases between herds.

The colonial settlers who started importing and rearing dairy cattle well before the country’s independence in 1964, initially, identified the need for the development of smallholder dairy farming around the country’s major cities to satisfy the increasing needs for dairy products because of the population increase and urbanization. These farms are predominantly located close to Blantyre in the Southern Region, Lilongwe in the Central Region, and Mzuzu in the Northern Region. Because of the increasing demand for milk in the country’s major cities and the heightened awareness of the importance of dairy production, the smallholder dairy industry became a focus for improvement by the Malawian Government in 1969. This culminated in the initiation of a government-supported crossbreeding program in 1973, involving zebu and Holstein-Friesians (Munthali et al. 1992). Currently, several international agencies, corporations, and NGOs are partnering with the Government of Malawi and other stakeholders such as the Malawi Milk Marketing Project, the Malawi Dairy Business Development Program, and the Small Scale Livestock and Livelihood Promotion (SSLLP) to create programs to further expand the dairy industry. As a result of these efforts, there was an increase of 65% in the dairy cattle population between 2004 and 2010 (Banda et al. 2012) although the number of cattle in the sector still comprises less than 5% of the total Malawian cattle population (Kaneene et al. 2016).

There are over 8000 smallholder farmers in Malawi, organized into about 50 Milk Bulking Groups (MBGs). These MBGs are managed by farmers and are tasked with collecting milk from members within an 8–10 km radius and for testing milk (for specific gravity and acidity) before it is pooled in a cooling tank from where it is collected by the commercial milk processors (Banda et al. 2011). Majority of the smallholder farmers (78%) own one to two animals and only 7% own more than five animals. The average animal holding per farmer is only 2.2 heads of cattle (Banda et al. 2011). 

Commercial dairy farms are few and far between. Pure Holstein-Friesians and Jerseys and their crosses represent, respectively, 0.6 and 2.7% of dairy cattle Chagunda et al. (1998), but they produce, respectively, 10 and 27% of the annual milk produced (Kaneene et al. 2016).

The abundance of animal diseases is one of the major impediments for livestock production in Malawi. A number of these diseases have a multi-dimensional impact, because they affect both humans and animals. In the following sections, bovine tuberculosis (BTB) in Malawi is discussed.

3 Bovine Tuberculosis in Malawi

Information about BTB in Malawi is poorly documented. Its prevalence, however, was such that during the mid-1950s and 1960s the authorities instituted an experimental BCG vaccination program in an attempt to control the disease (see Sect. 16.6.1). The current available information about the prevalence and distribution of BTB is scanty and insufficient to serve as a basis for planning a comprehensive control program in the country (Tables 16.1 and 16.2). There appears to be a marked variation in the prevalence and extent of the distribution of the disease throughout the country (Berggren 1977, 1981; Bedard et al. 1993; Moodie 1977; Tebug 2012). More recent reports covering an 11-year period between 2005 and 2015 indicate that BTB is present in all the ADDs throughout the country, but that certain districts recorded no evidence of the infection over the years (Table 16.2). That no cases were recorded is not necessarily an indication that the disease does not occur in those districts, but it is rather a reflection of the lack of adequate routine abattoir inspection and the shortage of adequately trained human resources to cover all the districts to detect the disease by tuberculin skin testing or at abattoirs doing routine meat inspection (Table 16.3). To deal with these issues, the Department of Animal Health and Livestock Development (DAHLD) is sending officials for training programs in countries with adequate competencies, such as Botswana, in addition to offering in-house refresher courses.

Table 16.1 Summary of BTB surveys conducted in Malawi
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Table 16.2 BTB in Malawi, by district, during 2005–2015
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Table 16.3 The number of veterinarians in different sectors in Malawi
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4 The Epidemiology of BTB in Malawi

Limited data are available for the distribution, spread, and impact of BTB in Malawi. The number of animals and individual herds infected, sources of infection, the modes of spread, and other drivers of the epidemiology of the disease are poorly investigated. Some information is available for the following parameters:

Age

There are contradictory data indicating that in Malawi the prevalence of BTB and age are not linked (Bedard et al. 1993). Generally, however, very few calves react to the CCT (Berggren 1981). These contradictory findings may be related to a number of factors that were not further investigated.

Breed

Although there are differences of opinion as to whether breed does, in fact, determine susceptibility, a number of studies seem to support this notion, and many of the differences in the prevalence of BTB in Malawi can be attributed to the location of a specific breed of cattle (Bedard et al. 1993). In southern Malawi 54.5% of zebu cattle carcasses were totally condemned compared to the 66.7% of the Sussex breed (Ellwood and Waddington 1972). Of cattle tested at dip tank sites (representing village zebu cattle), 4.8% reacted to the CCT, while in the bulking-group animals (dairy farms with introduced European breeds), 2.6% reacted. Taking breed into consideration, only 2.7% of the pure- and crossbred dairy cows were positive, compared to 4.7% of the zebu cattle. The data are contradictory and the reactors are often found in clusters within dip tank or bulking groups. The type of farming practice appears more likely to be the cause of the perceived breed predisposition to the disease.

Sex

Only one study in Malawi assessed the relationship between the prevalence of BTB and the sex of the animal. The number of reactors was significantly higher in oxen (9.6%) and bulls (8.4%) than in females (3.3%) (Bedard et al. 1993). This has been attributed to the strenuous work to which the males are subjected and their longer life expectancy, compared to cows, that facilitate them to more easily contract BTB. This pattern is difficult to explain since dairy cows are kept in a semi-intensive type of management system, and a higher prevalence rate would thus have been expected. The high prevalence in bulls could be the consequence of the local bull-hiring practice, in which bulls are used for natural mating as an alternative for the often-inadequate artificial insemination (AI) service (Chagunda et al. 1998). Since very few Malawian farmers (9.2%) own bulls (Banda et al. 2011), they are shared by several farms, which increase their risk of acquiring BTB.

Geographic Location

There was a general belief that BTB was unevenly spread in Malawi and that higher prevalence rates were recorded in the northern region (Bedard et al. 1993). Other studies (Bedard et al. 1993; Ellwood and Waddington 1972) similarly indicated a clustering of BTB in certain geographic areas and herds, but methodological differences might account for these discrepancies. The reports of the Central Veterinary Laboratory for the period 2011–2015 (Table 16.2) provided more comprehensive data. The largest number of BTB outbreaks occurred in Lilongwe and Kasungu (central) and Mzuzu (north) ADDs that is likely to be due to the concentration of smallholder dairy farms that are subject to compulsory screening for BTB because of public health requirements. The ADDs with the highest number of BTB outbreaks (Shire Valley and Blantyre) are in the South with its concentration of commercial feedlots that are able to pay for BTB screening services. The existing information remains fragmented and is mostly gathered by passive surveillance and opportunistic tuberculin skin testing operations.

Spatial clustering of BTB may be associated with other unknown locality-specific determinants. While the role of wildlife in the epidemiology of BTB in Malawi is unknown, disease hotspots, as is seen in Zambia, may be associated with the presence of wildlife reservoirs (Munyeme et al. 2010). These matters need to be resolved to better understand the epidemiology of the BTB in Malawi and to plan future control strategies.

Herd Management

Livestock management practices in Malawi are linked to their geographic location, and the type of system seems to play a pivotal role in determining the prevalence of the disease. Dip tank cattle have a higher BTB prevalence than cattle from bulking groups probably because of their large herd sizes and the intermingling of animals around the dipping tanks (Bedard et al. 1993). In terms of determining priorities for future BTB control programs, it would probably be more appropriate to focus on either bulking or dipping tank groups, rather than to use the data based on geographic location, breed, or sex to determine priority areas in which to initiate control programs.

Several factors are likely to contribute to the increased risk of BTB in smallholder dairy farms in Malawi. The importation of pure-bred dairy cattle, mostly from Zambia and South Africa, may further contribute to the problem because of the occurrence of BTB in cattle and wildlife populations in those countries (Michel et al. 2006; Munyeme et al. 2010).

5 Human TB Due to M. bovis

It is unknown what the contribution of zoonotic TB is to the total number of human TB cases in Malawi since laboratory facilities that allows differentiation between M. bovis and M. tuberculosis are not readily available. It is alarming though that a prevalence of as high as 42.8% M. bovis-positive specimens have been reported in TB patients in some sections in Malawi (Bedard et al. 1993). These hotspots appear to occur in areas where European cattle breeds had initially been introduced to establish a dairy industry.

A more recent epidemiologic study of human TB in Malawi (Nyirenda 2006) revealed a 45% increase in notified cases between 1994 and 2003; about half of these were reported from the urban districts of Blantyre, Zomba, Lilongwe, and Mzuzu. Overcrowding and the HIV epidemic appear to be the main driving forces of this increase. Of the new TB cases reported, 23% (range = 20–27%) during the period were extra-pulmonary, and many of them are likely to be zoonotic M. bovis infections (Kazwala et al. 2001). Owing to the ongoing population growth and urbanization, smallholder dairy farming in Malawi is expected to expand to meet the increasing demand for milk and milk products (Tebug et al. 2012), and unless BTB is adequately controlled, it should be expected that zoonotic TB would remain a major risk factor for the general population.

It is concerning that there is a varying and sometimes very limited awareness by the general population about zoonotic tuberculosis and the persistence of unhygienic practices that increase the risk of contracting zoonotic TB. Although in one survey 74.3% (n = 140) of respondents knew that M. bovis can be transmitted to humans and 67.0% knew that it is transmitted by infected milk, 96.4% of the respondents reported that they still engage in risky farm practices, including the sale (67.0%) and consumption (34.0%) of unpasteurized milk (Tebug et al. 2014). The practice of souring milk into “Chambiko” (instead of boiling or pasteurization) too does not fully eliminate the risk of exposure to milk-borne M. bovis (Hailemariam 2014). It is difficult to explain the mismatch between farmers’ awareness levels about zoonotic TB and their lack of application of preventive measures (Tebug 2013). There thus remains an urgent need to raise the awareness of all stakeholders about the risk and the control measures of zoonotic TB given the extent of their exposure to M. bovis-infected milk.

6 Control of Bovine Tuberculosis in Malawi

6.1 Vaccination

BCG vaccination was used from the early 1960s to the 1970s in an attempt to control BTB in Malawi following a decision by the Department of Veterinary Services that the test-and-slaughter policy was impracticable, and that it would not allow eradication of BTB from the northern part of Malawi. Early results suggested that vaccination with BCG reduced the spread of BTB in the herds and the number of the condemned carcasses at the abattoirs (Ellwood and Waddington 1972; Moodie 1977), but it later transpired that BCG vaccination had no protective effect against infection with M. bovis (Berggren 1981). The situation remains the same today as no effective vaccine has yet been developed for the control of the disease in livestock or in wildlife.

6.2 Test-and-Slaughter Policy

Currently, due to cost and the lack of awareness, surveillance of BTB is not regularly conducted in Malawi. In one report only 19.0% of the farms reported ever testing their animals for BTB; the remaining 81% have never been tested (Tebug et al. 2014). It is clear too that the test-and-slaughter approach to control BTB is not easy to implement unless it makes provision for compensation for financial losses following slaughtering of the positive reactors. Because of financial and other constraints, and other priorities, the Malawian government is currently not in a position to fund such a campaign.

An approach that is practical and that will be embraced by all stakeholders, including the government allowing the control of the disease is outlined below:

  1. 1.

    Screening for BTB in Malawi should be based on immunological reactions, specifically the tuberculin skin test, because the few and non-specific clinical signs of BTB do not allow a clinical diagnosis of the disease ante-mortally (Berggren 1981).

  2. 2.

    As is the case in many of the neighboring countries (Kankya et al. 2011), the abundance of atypical mycobacteria (Chilima et al. 2006) and logistical constraints do not allow the use of the SIT for screening, and the CCT should be used in future BTB control programs.

  3. 3.

    There are two broad categories of cattle husbandry in Malawi: the smallholder dairy sector (MBGs) and the dipping tank group. The two management groups carry different burdens of the infection, and it is essential that priority be given to control programs directed at one or the other based on an objective assessment of the public health risks that they pose in Malawi. Control programs can then be expanded to other sectors when capacity allows.

In the interim, there are several measures that could be applied immediately in each sector to halt the spread of BTB in Malawi:

Control Activities in MBGs

Small-scale dairy farming is still nascent in Malawi. Farmers, mainly women and those from underprivileged communities, usually acquire dairy cows through loans or as gifts from aid organizations in an attempt to bolster food security. Several of these donors, particularly the NGOs, also provide basic training in dairy management and health as part of the loan process, coined as the pass-on program, that can easily be extended into BTB awareness programs. Furthermore, the Department of Animal Health and Livestock Development should partner with aid organizations to make sure that heifers/cows originate only from BTB-free farms, and that they are tuberculin-tested before relocation to ensure that the newly established farms are BTB-free. It is also important to ensure that these cattle are housed in well-ventilated, clean premises and that they are isolated from other animals that are potentially infected with M. bovis.

The existing MBGs, composed on average of 42 members, are registered locally and have fairly adequate access to services and markets (Tebug et al. 2012; Kaneene et al. 2016). For the purpose of BTB control, each MBG should be treated as an epidemiological unit. As few animals are kept on each participating farm, tuberculin testing can be conducted in this sector with relative ease. If all the stakeholders, including the government, aid organizations, and farmers could be convinced to contribute towards the costs, BTB can be eradicated from this sector with a minimum of sacrifice and without adversely affecting other governmental financial commitments. It is also important to raise farmers’ awareness about the value of personal and general farm hygiene, the association of BTB with dairy operations, and the value of pasteurizing milk, particularly for children.

Control Activities Involving Dipping Tank Groups

These herds are rounded-up periodically, and it is important to consider each dipping tank (area) as an epidemiological unit when devising BTB control strategies (Bedard et al. 1993). The lack of farmer cooperation when undertaking BTB surveys at village level, which requires farmers to present their animals at a dipping station (often located 10–15 km from a village) on two successive occasions at a specific time interval, previously resulted in the number of cattle presented for tuberculin testing being too small (Berggren 1981). Designing a BTB control program for village cattle in Malawi therefore needs a lot of thinking, and a solution to the problem should be devised.

In the interim, two activities can be implemented:

  • Although it is true that only intensive strategies such as national testing programs are effective to control BTB (Brooks-Pollock et al. 2014), this approach is too costly and impractical to apply to village cattle in Malawi. As an alternative, the use of abattoir inspection, if systematically applied, can provide information about the area-based prevalence of BTB,

  • Irrespective of what is done, public education is pivotal in these operations and any campaign to reduce the prevalence of BTB and zoonotic TB should be supported by comprehensive educational programs, including encouraging boiling milk before consumption.

7 Conclusion

In summary, implementing and sustaining a BTB control program is a difficult and costly task. However, it is always important to begin with the end in mind:

  • Therefore, the objective of the program has to be stated clearly from the outset.

  • The national coordinating office, led by the Department of Animal Health and Livestock Development, should be given a clear mandate for developing an activity roadmap.

  • It is necessary to develop policy documents (legal, administrative) and technical guidelines, including standard operating procedures.

  • It is equally essential to establish standards for training, surveillance, and diagnosis at the national level.

  • Epidemiologic research is an integral part of any BTB control program. Therefore, apart from enhancing the diagnostic capability, it is also important to enhance the computing ability of researchers at various levels.

  • Because of the volume and cost of the work, Malawi needs financial and technical assistance from international donors to strengthen its personnel, diagnostic, and institutional capacity.